diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 5f2f884..73856ba 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -186,6 +186,11 @@
         ## Unzip and remove the artifact
         unzip artifacts.zip
         rm artifacts.zip
+    - name: initialize vcpkg
+      uses: actions/checkout@v2
+      with:
+        repository: 'microsoft/vcpkg'
+        path: 'compat/vcbuild/vcpkg'
     - name: download vcpkg artifacts
       shell: powershell
       run: |
diff --git a/.mailmap b/.mailmap
index bde7aba..9c6a446 100644
--- a/.mailmap
+++ b/.mailmap
@@ -220,6 +220,7 @@
 Philippe Bruhat <book@cpan.org>
 Ralf Thielow <ralf.thielow@gmail.com> <ralf.thielow@googlemail.com>
 Ramsay Jones <ramsay@ramsayjones.plus.com> <ramsay@ramsay1.demon.co.uk>
+Ramkumar Ramachandra <r@artagnon.com> <artagnon@gmail.com>
 Randall S. Becker <randall.becker@nexbridge.ca> <rsbecker@nexbridge.com>
 René Scharfe <l.s.r@web.de> <rene.scharfe@lsrfire.ath.cx>
 René Scharfe <l.s.r@web.de> Rene Scharfe
diff --git a/Documentation/Makefile b/Documentation/Makefile
index 81d1bf7..874a01d 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -76,6 +76,7 @@
 SP_ARTICLES += howto/rebase-from-internal-branch
 SP_ARTICLES += howto/keep-canonical-history-correct
 SP_ARTICLES += howto/maintain-git
+SP_ARTICLES += howto/coordinate-embargoed-releases
 API_DOCS = $(patsubst %.txt,%,$(filter-out technical/api-index-skel.txt technical/api-index.txt, $(wildcard technical/api-*.txt)))
 SP_ARTICLES += $(API_DOCS)
 
diff --git a/Documentation/RelNotes/2.31.1.txt b/Documentation/RelNotes/2.31.1.txt
new file mode 100644
index 0000000..f9b06b8
--- /dev/null
+++ b/Documentation/RelNotes/2.31.1.txt
@@ -0,0 +1,27 @@
+Git 2.31.1 Release Notes
+========================
+
+Fixes since v2.31
+-----------------
+
+ * The fsmonitor interface read from its input without making sure
+   there is something to read from.  This bug is new in 2.31
+   timeframe.
+
+ * The data structure used by fsmonitor interface was not properly
+   duplicated during an in-core merge, leading to use-after-free etc.
+
+ * "git bisect" reimplemented more in C during 2.30 timeframe did not
+   take an annotated tag as a good/bad endpoint well.  This regression
+   has been corrected.
+
+ * Fix macros that can silently inject unintended null-statements.
+
+ * CALLOC_ARRAY() macro replaces many uses of xcalloc().
+
+ * Update insn in Makefile comments to run fuzz-all target.
+
+ * Fix a corner case bug in "git mv" on case insensitive systems,
+   which was introduced in 2.29 timeframe.
+
+Also contains various documentation updates and code clean-ups.
diff --git a/Documentation/RelNotes/2.32.0.txt b/Documentation/RelNotes/2.32.0.txt
new file mode 100644
index 0000000..d69e69f
--- /dev/null
+++ b/Documentation/RelNotes/2.32.0.txt
@@ -0,0 +1,141 @@
+Git 2.32 Release Notes
+======================
+
+Backward compatibility notes
+----------------------------
+
+ * ".gitattributes", ".gitignore", and ".mailmap" files that are
+   symbolic links are ignored.
+
+
+Updates since v2.31
+-------------------
+
+UI, Workflows & Features
+
+ * It does not make sense to make ".gitattributes", ".gitignore" and
+   ".mailmap" symlinks, as they are supposed to be usable from the
+   object store (think: bare repositories where HEAD:.mailmap etc. are
+   used).  When these files are symbolic links, we used to read the
+   contents of the files pointed by them by mistake, which has been
+   corrected.
+
+ * "git stash show" learned to optionally show untracked part of the
+   stash.
+
+ * "git log --format='...'" learned "%(describe)" placeholder.
+
+ * "git repack" so far has been only capable of repacking everything
+   under the sun into a single pack (or split by size).  A cleverer
+   strategy to reduce the cost of repacking a repository has been
+   introduced.
+
+ * The http codepath learned to let the credential layer to cache the
+   password used to unlock a certificate that has successfully been
+   used.
+
+ * "git commit --fixup=<commit>", which was to tweak the changes made
+   to the contents while keeping the original log message intact,
+   learned "--fixup=(amend|reword):<commit>", that can be used to
+   tweak both the message and the contents, and only the message,
+   respectively.
+
+ * When accessing a server with a URL like https://user:pass@site/, we
+   did not to fall back to the basic authentication with the
+   credential material embedded in the URL after the "Negotiate"
+   authentication failed.  Now we do.
+
+ * "git send-email" learned to honor the core.hooksPath configuration.
+
+ * "git format-patch -v<n>" learned to allow a reroll count that is
+   not an integer.
+
+
+Performance, Internal Implementation, Development Support etc.
+
+ * Rename detection rework continues.
+
+ * GIT_TEST_FAIL_PREREQS is a mechanism to skip test pieces with
+   prerequisites to catch broken tests that depend on the side effects
+   of optional pieces, but did not work at all when negative
+   prerequisites were involved.
+   (merge 27d578d904 jk/fail-prereq-testfix later to maint).
+
+ * "git diff-index" codepath has been taught to trust fsmonitor status
+   to reduce number of lstat() calls.
+   (merge 7e5aa13d2c nk/diff-index-fsmonitor later to maint).
+
+ * Reorganize Makefile to allow building git.o and other essential
+   objects without extra stuff needed only for testing.
+
+ * Preparatory API changes for parallel checkout.
+
+ * A simple IPC interface gets introduced to build services like
+   fsmonitor on top.
+
+
+Fixes since v2.31
+-----------------
+
+ * The fsmonitor interface read from its input without making sure
+   there is something to read from.  This bug is new in 2.31
+   timeframe.
+
+ * The data structure used by fsmonitor interface was not properly
+   duplicated during an in-core merge, leading to use-after-free etc.
+
+ * "git bisect" reimplemented more in C during 2.30 timeframe did not
+   take an annotated tag as a good/bad endpoint well.  This regression
+   has been corrected.
+
+ * Fix macros that can silently inject unintended null-statements.
+
+ * CALLOC_ARRAY() macro replaces many uses of xcalloc().
+
+ * Update insn in Makefile comments to run fuzz-all target.
+
+ * Fix a corner case bug in "git mv" on case insensitive systems,
+   which was introduced in 2.29 timeframe.
+
+ * We had a code to diagnose and die cleanly when a required
+   clean/smudge filter is missing, but an assert before that
+   unnecessarily fired, hiding the end-user facing die() message.
+   (merge 6fab35f748 mt/cleanly-die-upon-missing-required-filter later to maint).
+
+ * Update C code that sets a few configuration variables when a remote
+   is configured so that it spells configuration variable names in the
+   canonical camelCase.
+   (merge 0f1da600e6 ab/remote-write-config-in-camel-case later to maint).
+
+ * A new configuration variable has been introduced to allow choosing
+   which version of the generation number gets used in the
+   commit-graph file.
+   (merge 702110aac6 ds/commit-graph-generation-config later to maint).
+
+ * Perf test update to work better in secondary worktrees.
+   (merge 36e834abc1 jk/perf-in-worktrees later to maint).
+
+ * Updates to memory allocation code around the use of pcre2 library.
+   (merge c1760352e0 ab/grep-pcre2-allocfix later to maint).
+
+ * "git -c core.bare=false clone --bare ..." would have segfaulted,
+   which has been corrected.
+   (merge 75555676ad bc/clone-bare-with-conflicting-config later to maint).
+
+ * When "git checkout" removes a path that does not exist in the
+   commit it is checking out, it wasn't careful enough not to follow
+   symbolic links, which has been corrected.
+   (merge fab78a0c3d mt/checkout-remove-nofollow later to maint).
+
+ * Other code cleanup, docfix, build fix, etc.
+   (merge f451960708 dl/cat-file-doc-cleanup later to maint).
+   (merge 12604a8d0c sv/t9801-test-path-is-file-cleanup later to maint).
+   (merge ea7e63921c jr/doc-ignore-typofix later to maint).
+   (merge 23c781f173 ps/update-ref-trans-hook-doc later to maint).
+   (merge 42efa1231a jk/filter-branch-sha256 later to maint).
+   (merge 4c8e3dca6e tb/push-simple-uses-branch-merge-config later to maint).
+   (merge 6534d436a2 bs/asciidoctor-installation-hints later to maint).
+   (merge 47957485b3 ab/read-tree later to maint).
+   (merge 2be927f3d1 ab/diff-no-index-tests later to maint).
+   (merge 76593c09bb ab/detox-gettext-tests later to maint).
+   (merge 28e29ee38b jc/doc-format-patch-clarify later to maint).
diff --git a/Documentation/config.txt b/Documentation/config.txt
index d08e83a..bf82766 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -46,7 +46,7 @@
 newline and the null byte. Doublequote `"` and backslash can be included
 by escaping them as `\"` and `\\`, respectively. Backslashes preceding
 other characters are dropped when reading; for example, `\t` is read as
-`t` and `\0` is read as `0` Section headers cannot span multiple lines.
+`t` and `\0` is read as `0`. Section headers cannot span multiple lines.
 Variables may belong directly to a section or to a given subsection. You
 can have `[section]` if you have `[section "subsection"]`, but you don't
 need to.
diff --git a/Documentation/config/commitgraph.txt b/Documentation/config/commitgraph.txt
index 4582c39..30604e4 100644
--- a/Documentation/config/commitgraph.txt
+++ b/Documentation/config/commitgraph.txt
@@ -1,3 +1,9 @@
+commitGraph.generationVersion::
+	Specifies the type of generation number version to use when writing
+	or reading the commit-graph file. If version 1 is specified, then
+	the corrected commit dates will not be written or read. Defaults to
+	2.
+
 commitGraph.maxNewFilters::
 	Specifies the default value for the `--max-new-filters` option of `git
 	commit-graph write` (c.f., linkgit:git-commit-graph[1]).
diff --git a/Documentation/config/rebase.txt b/Documentation/config/rebase.txt
index 214f31b..8c979cb 100644
--- a/Documentation/config/rebase.txt
+++ b/Documentation/config/rebase.txt
@@ -1,10 +1,3 @@
-rebase.useBuiltin::
-	Unused configuration variable. Used in Git versions 2.20 and
-	2.21 as an escape hatch to enable the legacy shellscript
-	implementation of rebase. Now the built-in rewrite of it in C
-	is always used. Setting this will emit a warning, to alert any
-	remaining users that setting this now does nothing.
-
 rebase.backend::
 	Default backend to use for rebasing.  Possible choices are
 	'apply' or 'merge'.  In the future, if the merge backend gains
diff --git a/Documentation/config/stash.txt b/Documentation/config/stash.txt
index 00eb354..413f907 100644
--- a/Documentation/config/stash.txt
+++ b/Documentation/config/stash.txt
@@ -5,6 +5,11 @@
 	is always used. Setting this will emit a warning, to alert any
 	remaining users that setting this now does nothing.
 
+stash.showIncludeUntracked::
+	If this is set to true, the `git stash show` command without an
+	option will show the untracked files of a stash entry.  Defaults to
+	false. See description of 'show' command in linkgit:git-stash[1].
+
 stash.showPatch::
 	If this is set to true, the `git stash show` command without an
 	option will show the stash entry in patch form.  Defaults to false.
diff --git a/Documentation/git-cat-file.txt b/Documentation/git-cat-file.txt
index 8e192d8..4eb0421 100644
--- a/Documentation/git-cat-file.txt
+++ b/Documentation/git-cat-file.txt
@@ -35,42 +35,42 @@
 
 -t::
 	Instead of the content, show the object type identified by
-	<object>.
+	`<object>`.
 
 -s::
 	Instead of the content, show the object size identified by
-	<object>.
+	`<object>`.
 
 -e::
-	Exit with zero status if <object> exists and is a valid
-	object. If <object> is of an invalid format exit with non-zero and
+	Exit with zero status if `<object>` exists and is a valid
+	object. If `<object>` is of an invalid format exit with non-zero and
 	emits an error on stderr.
 
 -p::
-	Pretty-print the contents of <object> based on its type.
+	Pretty-print the contents of `<object>` based on its type.
 
 <type>::
-	Typically this matches the real type of <object> but asking
+	Typically this matches the real type of `<object>` but asking
 	for a type that can trivially be dereferenced from the given
-	<object> is also permitted.  An example is to ask for a
-	"tree" with <object> being a commit object that contains it,
-	or to ask for a "blob" with <object> being a tag object that
+	`<object>` is also permitted.  An example is to ask for a
+	"tree" with `<object>` being a commit object that contains it,
+	or to ask for a "blob" with `<object>` being a tag object that
 	points at it.
 
 --textconv::
 	Show the content as transformed by a textconv filter. In this case,
-	<object> has to be of the form <tree-ish>:<path>, or :<path> in
+	`<object>` has to be of the form `<tree-ish>:<path>`, or `:<path>` in
 	order to apply the filter to the content recorded in the index at
-	<path>.
+	`<path>`.
 
 --filters::
 	Show the content as converted by the filters configured in
-	the current working tree for the given <path> (i.e. smudge filters,
-	end-of-line conversion, etc). In this case, <object> has to be of
-	the form <tree-ish>:<path>, or :<path>.
+	the current working tree for the given `<path>` (i.e. smudge filters,
+	end-of-line conversion, etc). In this case, `<object>` has to be of
+	the form `<tree-ish>:<path>`, or `:<path>`.
 
 --path=<path>::
-	For use with --textconv or --filters, to allow specifying an object
+	For use with `--textconv` or `--filters`, to allow specifying an object
 	name and a path separately, e.g. when it is difficult to figure out
 	the revision from which the blob came.
 
@@ -115,15 +115,15 @@
 	repository.
 
 --allow-unknown-type::
-	Allow -s or -t to query broken/corrupt objects of unknown type.
+	Allow `-s` or `-t` to query broken/corrupt objects of unknown type.
 
 --follow-symlinks::
-	With --batch or --batch-check, follow symlinks inside the
+	With `--batch` or `--batch-check`, follow symlinks inside the
 	repository when requesting objects with extended SHA-1
 	expressions of the form tree-ish:path-in-tree.  Instead of
 	providing output about the link itself, provide output about
 	the linked-to object.  If a symlink points outside the
-	tree-ish (e.g. a link to /foo or a root-level link to ../foo),
+	tree-ish (e.g. a link to `/foo` or a root-level link to `../foo`),
 	the portion of the link which is outside the tree will be
 	printed.
 +
@@ -175,15 +175,15 @@
 
 OUTPUT
 ------
-If `-t` is specified, one of the <type>.
+If `-t` is specified, one of the `<type>`.
 
-If `-s` is specified, the size of the <object> in bytes.
+If `-s` is specified, the size of the `<object>` in bytes.
 
-If `-e` is specified, no output, unless the <object> is malformed.
+If `-e` is specified, no output, unless the `<object>` is malformed.
 
-If `-p` is specified, the contents of <object> are pretty-printed.
+If `-p` is specified, the contents of `<object>` are pretty-printed.
 
-If <type> is specified, the raw (though uncompressed) contents of the <object>
+If `<type>` is specified, the raw (though uncompressed) contents of the `<object>`
 will be returned.
 
 BATCH OUTPUT
@@ -200,7 +200,7 @@
 newline. The available atoms are:
 
 `objectname`::
-	The 40-hex object name of the object.
+	The full hex representation of the object name.
 
 `objecttype`::
 	The type of the object (the same as `cat-file -t` reports).
@@ -215,8 +215,9 @@
 
 `deltabase`::
 	If the object is stored as a delta on-disk, this expands to the
-	40-hex sha1 of the delta base object. Otherwise, expands to the
-	null sha1 (40 zeroes). See `CAVEATS` below.
+	full hex representation of the delta base object name.
+	Otherwise, expands to the null OID (all zeroes). See `CAVEATS`
+	below.
 
 `rest`::
 	If this atom is used in the output string, input lines are split
@@ -235,14 +236,14 @@
 For example, `--batch` without a custom format would produce:
 
 ------------
-<sha1> SP <type> SP <size> LF
+<oid> SP <type> SP <size> LF
 <contents> LF
 ------------
 
 Whereas `--batch-check='%(objectname) %(objecttype)'` would produce:
 
 ------------
-<sha1> SP <type> LF
+<oid> SP <type> LF
 ------------
 
 If a name is specified on stdin that cannot be resolved to an object in
@@ -258,7 +259,7 @@
 <object> SP ambiguous LF
 ------------
 
-If --follow-symlinks is used, and a symlink in the repository points
+If `--follow-symlinks` is used, and a symlink in the repository points
 outside the repository, then `cat-file` will ignore any custom format
 and print:
 
@@ -267,11 +268,11 @@
 <symlink> LF
 ------------
 
-The symlink will either be absolute (beginning with a /), or relative
-to the tree root.  For instance, if dir/link points to ../../foo, then
-<symlink> will be ../foo.  <size> is the size of the symlink in bytes.
+The symlink will either be absolute (beginning with a `/`), or relative
+to the tree root.  For instance, if dir/link points to `../../foo`, then
+`<symlink>` will be `../foo`.  `<size>` is the size of the symlink in bytes.
 
-If --follow-symlinks is used, the following error messages will be
+If `--follow-symlinks` is used, the following error messages will be
 displayed:
 
 ------------
diff --git a/Documentation/git-commit.txt b/Documentation/git-commit.txt
index 17150fa..340c5fb 100644
--- a/Documentation/git-commit.txt
+++ b/Documentation/git-commit.txt
@@ -9,12 +9,13 @@
 --------
 [verse]
 'git commit' [-a | --interactive | --patch] [-s] [-v] [-u<mode>] [--amend]
-	   [--dry-run] [(-c | -C | --fixup | --squash) <commit>]
+	   [--dry-run] [(-c | -C | --squash) <commit> | --fixup [(amend|reword):]<commit>)]
 	   [-F <file> | -m <msg>] [--reset-author] [--allow-empty]
 	   [--allow-empty-message] [--no-verify] [-e] [--author=<author>]
 	   [--date=<date>] [--cleanup=<mode>] [--[no-]status]
 	   [-i | -o] [--pathspec-from-file=<file> [--pathspec-file-nul]]
-	   [-S[<keyid>]] [--] [<pathspec>...]
+	   [(--trailer <token>[(=|:)<value>])...] [-S[<keyid>]]
+	   [--] [<pathspec>...]
 
 DESCRIPTION
 -----------
@@ -86,11 +87,44 @@
 	Like '-C', but with `-c` the editor is invoked, so that
 	the user can further edit the commit message.
 
---fixup=<commit>::
-	Construct a commit message for use with `rebase --autosquash`.
-	The commit message will be the subject line from the specified
-	commit with a prefix of "fixup! ".  See linkgit:git-rebase[1]
-	for details.
+--fixup=[(amend|reword):]<commit>::
+	Create a new commit which "fixes up" `<commit>` when applied with
+	`git rebase --autosquash`. Plain `--fixup=<commit>` creates a
+	"fixup!" commit which changes the content of `<commit>` but leaves
+	its log message untouched. `--fixup=amend:<commit>` is similar but
+	creates an "amend!" commit which also replaces the log message of
+	`<commit>` with the log message of the "amend!" commit.
+	`--fixup=reword:<commit>` creates an "amend!" commit which
+	replaces the log message of `<commit>` with its own log message
+	but makes no changes to the content of `<commit>`.
++
+The commit created by plain `--fixup=<commit>` has a subject
+composed of "fixup!" followed by the subject line from <commit>,
+and is recognized specially by `git rebase --autosquash`. The `-m`
+option may be used to supplement the log message of the created
+commit, but the additional commentary will be thrown away once the
+"fixup!" commit is squashed into `<commit>` by
+`git rebase --autosquash`.
++
+The commit created by `--fixup=amend:<commit>` is similar but its
+subject is instead prefixed with "amend!". The log message of
+<commit> is copied into the log message of the "amend!" commit and
+opened in an editor so it can be refined. When `git rebase
+--autosquash` squashes the "amend!" commit into `<commit>`, the
+log message of `<commit>` is replaced by the refined log message
+from the "amend!" commit. It is an error for the "amend!" commit's
+log message to be empty unless `--allow-empty-message` is
+specified.
++
+`--fixup=reword:<commit>` is shorthand for `--fixup=amend:<commit>
+--only`. It creates an "amend!" commit with only a log message
+(ignoring any changes staged in the index). When squashed by `git
+rebase --autosquash`, it replaces the log message of `<commit>`
+without making any other changes.
++
+Neither "fixup!" nor "amend!" commits change authorship of
+`<commit>` when applied by `git rebase --autosquash`.
+See linkgit:git-rebase[1] for details.
 
 --squash=<commit>::
 	Construct a commit message for use with `rebase --autosquash`.
@@ -166,6 +200,17 @@
 
 include::signoff-option.txt[]
 
+--trailer <token>[(=|:)<value>]::
+	Specify a (<token>, <value>) pair that should be applied as a
+	trailer. (e.g. `git commit --trailer "Signed-off-by:C O Mitter \
+	<committer@example.com>" --trailer "Helped-by:C O Mitter \
+	<committer@example.com>"` will add the "Signed-off-by" trailer
+	and the "Helped-by" trailer to the commit message.)
+	The `trailer.*` configuration variables
+	(linkgit:git-interpret-trailers[1]) can be used to define if
+	a duplicated trailer is omitted, where in the run of trailers
+	each trailer would appear, and other details.
+
 -n::
 --no-verify::
 	This option bypasses the pre-commit and commit-msg hooks.
diff --git a/Documentation/git-format-patch.txt b/Documentation/git-format-patch.txt
index 3e49bf2..911da18 100644
--- a/Documentation/git-format-patch.txt
+++ b/Documentation/git-format-patch.txt
@@ -36,11 +36,28 @@
 DESCRIPTION
 -----------
 
-Prepare each commit with its patch in
-one file per commit, formatted to resemble UNIX mailbox format.
+Prepare each commit with its "patch" in
+one "message" per commit, formatted to resemble a UNIX mailbox.
 The output of this command is convenient for e-mail submission or
 for use with 'git am'.
 
+A "message" generated by the command consists of three parts:
+
+* A brief metadata header that begins with `From <commit>`
+  with a fixed `Mon Sep 17 00:00:00 2001` datestamp to help programs
+  like "file(1)" to recognize that the file is an output from this
+  command, fields that record the author identity, the author date,
+  and the title of the change (taken from the first paragraph of the
+  commit log message).
+
+* The second and subsequent paragraphs of the commit log message.
+
+* The "patch", which is the "diff -p --stat" output (see
+  linkgit:git-diff[1]) between the commit and its parent.
+
+The log message and the patch is separated by a line with a
+three-dash line.
+
 There are two ways to specify which commits to operate on.
 
 1. A single commit, <since>, specifies that the commits leading
@@ -221,6 +238,11 @@
 	`--subject-prefix` option) has ` v<n>` appended to it.  E.g.
 	`--reroll-count=4` may produce `v4-0001-add-makefile.patch`
 	file that has "Subject: [PATCH v4 1/20] Add makefile" in it.
+	`<n>` does not have to be an integer (e.g. "--reroll-count=4.4",
+	or "--reroll-count=4rev2" are allowed), but the downside of
+	using such a reroll-count is that the range-diff/interdiff
+	with the previous version does not state exactly which
+	version the new interation is compared against.
 
 --to=<email>::
 	Add a `To:` header to the email headers. This is in addition
diff --git a/Documentation/git-pack-objects.txt b/Documentation/git-pack-objects.txt
index f85cb7e..25d9fbe 100644
--- a/Documentation/git-pack-objects.txt
+++ b/Documentation/git-pack-objects.txt
@@ -85,6 +85,16 @@
 	reference was included in the resulting packfile.  This
 	can be useful to send new tags to native Git clients.
 
+--stdin-packs::
+	Read the basenames of packfiles (e.g., `pack-1234abcd.pack`)
+	from the standard input, instead of object names or revision
+	arguments. The resulting pack contains all objects listed in the
+	included packs (those not beginning with `^`), excluding any
+	objects listed in the excluded packs (beginning with `^`).
++
+Incompatible with `--revs`, or options that imply `--revs` (such as
+`--all`), with the exception of `--unpacked`, which is compatible.
+
 --window=<n>::
 --depth=<n>::
 	These two options affect how the objects contained in
diff --git a/Documentation/git-push.txt b/Documentation/git-push.txt
index ab103c8..a953c7c 100644
--- a/Documentation/git-push.txt
+++ b/Documentation/git-push.txt
@@ -600,7 +600,7 @@
 
 `git push origin`::
 	Without additional configuration, pushes the current branch to
-	the configured upstream (`remote.origin.merge` configuration
+	the configured upstream (`branch.<name>.merge` configuration
 	variable) if it has the same name as the current branch, and
 	errors out without pushing otherwise.
 +
diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index a0487b5..f08ae27 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -593,16 +593,17 @@
 
 --autosquash::
 --no-autosquash::
-	When the commit log message begins with "squash! ..." (or
-	"fixup! ..."), and there is already a commit in the todo list that
-	matches the same `...`, automatically modify the todo list of rebase
-	-i so that the commit marked for squashing comes right after the
-	commit to be modified, and change the action of the moved commit
-	from `pick` to `squash` (or `fixup`).  A commit matches the `...` if
-	the commit subject matches, or if the `...` refers to the commit's
-	hash. As a fall-back, partial matches of the commit subject work,
-	too.  The recommended way to create fixup/squash commits is by using
-	the `--fixup`/`--squash` options of linkgit:git-commit[1].
+	When the commit log message begins with "squash! ..." or "fixup! ..."
+	or "amend! ...", and there is already a commit in the todo list that
+	matches the same `...`, automatically modify the todo list of
+	`rebase -i`, so that the commit marked for squashing comes right after
+	the commit to be modified, and change the action of the moved commit
+	from `pick` to `squash` or `fixup` or `fixup -C` respectively. A commit
+	matches the `...` if the commit subject matches, or if the `...` refers
+	to the commit's hash. As a fall-back, partial matches of the commit
+	subject work, too. The recommended way to create fixup/amend/squash
+	commits is by using the `--fixup`, `--fixup=amend:` or `--fixup=reword:`
+	and `--squash` options respectively of linkgit:git-commit[1].
 +
 If the `--autosquash` option is enabled by default using the
 configuration variable `rebase.autoSquash`, this option can be
@@ -887,9 +888,17 @@
 "pick" for the second and subsequent commits with "squash" or "fixup".
 If the commits had different authors, the folded commit will be
 attributed to the author of the first commit.  The suggested commit
-message for the folded commit is the concatenation of the commit
-messages of the first commit and of those with the "squash" command,
-but omits the commit messages of commits with the "fixup" command.
+message for the folded commit is the concatenation of the first
+commit's message with those identified by "squash" commands, omitting the
+messages of commits identified by "fixup" commands, unless "fixup -c"
+is used.  In that case the suggested commit message is only the message
+of the "fixup -c" commit, and an editor is opened allowing you to edit
+the message.  The contents (patch) of the "fixup -c" commit are still
+incorporated into the folded commit. If there is more than one "fixup -c"
+commit, the message from the final one is used.  You can also use
+"fixup -C" to get the same behavior as "fixup -c" except without opening
+an editor.
+
 
 'git rebase' will stop when "pick" has been replaced with "edit" or
 when a command fails due to merge errors. When you are done editing
diff --git a/Documentation/git-repack.txt b/Documentation/git-repack.txt
index fbd4b4a..317d63c 100644
--- a/Documentation/git-repack.txt
+++ b/Documentation/git-repack.txt
@@ -165,6 +165,29 @@
 	Pass the `--delta-islands` option to `git-pack-objects`, see
 	linkgit:git-pack-objects[1].
 
+-g=<factor>::
+--geometric=<factor>::
+	Arrange resulting pack structure so that each successive pack
+	contains at least `<factor>` times the number of objects as the
+	next-largest pack.
++
+`git repack` ensures this by determining a "cut" of packfiles that need
+to be repacked into one in order to ensure a geometric progression. It
+picks the smallest set of packfiles such that as many of the larger
+packfiles (by count of objects contained in that pack) may be left
+intact.
++
+Unlike other repack modes, the set of objects to pack is determined
+uniquely by the set of packs being "rolled-up"; in other words, the
+packs determined to need to be combined in order to restore a geometric
+progression.
++
+When `--unpacked` is specified, loose objects are implicitly included in
+this "roll-up", without respect to their reachability. This is subject
+to change in the future. This option (implying a drastically different
+repack mode) is not guaranteed to work with all other combinations of
+option to `git repack`).
+
 CONFIGURATION
 -------------
 
diff --git a/Documentation/git-stash.txt b/Documentation/git-stash.txt
index f1197d6..a8c8c32 100644
--- a/Documentation/git-stash.txt
+++ b/Documentation/git-stash.txt
@@ -9,7 +9,7 @@
 --------
 [verse]
 'git stash' list [<log-options>]
-'git stash' show [<diff-options>] [<stash>]
+'git stash' show [-u|--include-untracked|--only-untracked] [<diff-options>] [<stash>]
 'git stash' drop [-q|--quiet] [<stash>]
 'git stash' ( pop | apply ) [--index] [-q|--quiet] [<stash>]
 'git stash' branch <branchname> [<stash>]
@@ -83,7 +83,7 @@
 The command takes options applicable to the 'git log'
 command to control what is shown and how. See linkgit:git-log[1].
 
-show [<diff-options>] [<stash>]::
+show [-u|--include-untracked|--only-untracked] [<diff-options>] [<stash>]::
 
 	Show the changes recorded in the stash entry as a diff between the
 	stashed contents and the commit back when the stash entry was first
@@ -91,8 +91,8 @@
 	By default, the command shows the diffstat, but it will accept any
 	format known to 'git diff' (e.g., `git stash show -p stash@{1}`
 	to view the second most recent entry in patch form).
-	You can use stash.showStat and/or stash.showPatch config variables
-	to change the default behavior.
+	You can use stash.showIncludeUntracked, stash.showStat, and
+	stash.showPatch config variables to change the default behavior.
 
 pop [--index] [-q|--quiet] [<stash>]::
 
@@ -160,10 +160,18 @@
 
 -u::
 --include-untracked::
-	This option is only valid for `push` and `save` commands.
+--no-include-untracked::
+	When used with the `push` and `save` commands,
+	all untracked files are also stashed and then cleaned up with
+	`git clean`.
 +
-All untracked files are also stashed and then cleaned up with
-`git clean`.
+When used with the `show` command, show the untracked files in the stash
+entry as part of the diff.
+
+--only-untracked::
+	This option is only valid for the `show` command.
++
+Show only the untracked files in the stash entry as part of the diff.
 
 --index::
 	This option is only valid for `pop` and `apply` commands.
diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index e84e104..0a60472 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -1174,7 +1174,8 @@
 as those for the option `--pretty=format:` of linkgit:git-log[1],
 except that they need to be wrapped like this: `$Format:PLACEHOLDERS$`
 in the file.  E.g. the string `$Format:%H$` will be replaced by the
-commit hash.
+commit hash.  However, only one `%(describe)` placeholder is expanded
+per archive to avoid denial-of-service attacks.
 
 
 Packing objects
diff --git a/Documentation/gitdiffcore.txt b/Documentation/gitdiffcore.txt
index 1c72696..0d57f86 100644
--- a/Documentation/gitdiffcore.txt
+++ b/Documentation/gitdiffcore.txt
@@ -187,7 +187,7 @@
 better matches.  At most, one comparison is done per file in this
 preliminary pass; so if there are several remaining ext.txt files
 throughout the directory hierarchy after exact rename detection, this
-preliminary step will be skipped for those files.
+preliminary step may be skipped for those files.
 
 Note.  When the "-C" option is used with `--find-copies-harder`
 option, 'git diff-{asterisk}' commands feed unmodified filepairs to
diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt
index 1f3b57d..b51959f 100644
--- a/Documentation/githooks.txt
+++ b/Documentation/githooks.txt
@@ -138,7 +138,7 @@
 configuration option `commit.template` is set); `merge` (if the
 commit is a merge or a `.git/MERGE_MSG` file exists); `squash`
 (if a `.git/SQUASH_MSG` file exists); or `commit`, followed by
-a commit SHA-1 (if a `-c`, `-C` or `--amend` option was given).
+a commit object name (if a `-c`, `-C` or `--amend` option was given).
 
 If the exit status is non-zero, `git commit` will abort.
 
@@ -231,19 +231,19 @@
 Information about what is to be pushed is provided on the hook's standard
 input with lines of the form:
 
-  <local ref> SP <local sha1> SP <remote ref> SP <remote sha1> LF
+  <local ref> SP <local object name> SP <remote ref> SP <remote object name> LF
 
 For instance, if the command +git push origin master:foreign+ were run the
 hook would receive a line like the following:
 
   refs/heads/master 67890 refs/heads/foreign 12345
 
-although the full, 40-character SHA-1s would be supplied.  If the foreign ref
-does not yet exist the `<remote SHA-1>` will be 40 `0`.  If a ref is to be
-deleted, the `<local ref>` will be supplied as `(delete)` and the `<local
-SHA-1>` will be 40 `0`.  If the local commit was specified by something other
-than a name which could be expanded (such as `HEAD~`, or a SHA-1) it will be
-supplied as it was originally given.
+although the full object name would be supplied.  If the foreign ref does not
+yet exist the `<remote object name>` will be the all-zeroes object name.  If a
+ref is to be deleted, the `<local ref>` will be supplied as `(delete)` and the
+`<local object name>` will be the all-zeroes object name.  If the local commit
+was specified by something other than a name which could be expanded (such as
+`HEAD~`, or an object name) it will be supplied as it was originally given.
 
 If this hook exits with a non-zero status, `git push` will abort without
 pushing anything.  Information about why the push is rejected may be sent
@@ -268,7 +268,7 @@
 where `<old-value>` is the old object name stored in the ref,
 `<new-value>` is the new object name to be stored in the ref and
 `<ref-name>` is the full name of the ref.
-When creating a new ref, `<old-value>` is 40 `0`.
+When creating a new ref, `<old-value>` is the all-zeroes object name.
 
 If the hook exits with non-zero status, none of the refs will be
 updated. If the hook exits with zero, updating of individual refs can
@@ -473,7 +473,8 @@
 
 This hook is invoked by any Git command that performs reference
 updates. It executes whenever a reference transaction is prepared,
-committed or aborted and may thus get called multiple times.
+committed or aborted and may thus get called multiple times. The hook
+does not cover symbolic references (but that may change in the future).
 
 The hook takes exactly one argument, which is the current state the
 given reference transaction is in:
@@ -492,6 +493,14 @@
 
   <old-value> SP <new-value> SP <ref-name> LF
 
+where `<old-value>` is the old object name passed into the reference
+transaction, `<new-value>` is the new object name to be stored in the
+ref and `<ref-name>` is the full name of the ref. When force updating
+the reference regardless of its current value or when the reference is
+to be created anew, `<old-value>` is the all-zeroes object name. To
+distinguish these cases, you can inspect the current value of
+`<ref-name>` via `git rev-parse`.
+
 The exit status of the hook is ignored for any state except for the
 "prepared" state. In the "prepared" state, a non-zero exit status will
 cause the transaction to be aborted. The hook will not be called with
@@ -550,7 +559,7 @@
 The hook receives a list of the rewritten commits on stdin, in the
 format
 
-  <old-sha1> SP <new-sha1> [ SP <extra-info> ] LF
+  <old-object-name> SP <new-object-name> [ SP <extra-info> ] LF
 
 The 'extra-info' is again command-dependent.  If it is empty, the
 preceding SP is also omitted.  Currently, no commands pass any
@@ -566,7 +575,7 @@
 	For the 'squash' and 'fixup' operation, all commits that were
 	squashed are listed as being rewritten to the squashed commit.
 	This means that there will be several lines sharing the same
-	'new-sha1'.
+	'new-object-name'.
 +
 The commits are guaranteed to be listed in the order that they were
 processed by rebase.
diff --git a/Documentation/gitignore.txt b/Documentation/gitignore.txt
index d47b1ae..5751603 100644
--- a/Documentation/gitignore.txt
+++ b/Documentation/gitignore.txt
@@ -153,7 +153,7 @@
 --------
 
  - The pattern `hello.*` matches any file or folder
-   whose name begins with `hello`. If one wants to restrict
+   whose name begins with `hello.`. If one wants to restrict
    this only to the directory and not in its subdirectories,
    one can prepend the pattern with a slash, i.e. `/hello.*`;
    the pattern now matches `hello.txt`, `hello.c` but not
diff --git a/Documentation/howto/coordinate-embargoed-releases.txt b/Documentation/howto/coordinate-embargoed-releases.txt
new file mode 100644
index 0000000..601aae8
--- /dev/null
+++ b/Documentation/howto/coordinate-embargoed-releases.txt
@@ -0,0 +1,131 @@
+Content-type: text/asciidoc
+Abstract: When a critical vulnerability is discovered and fixed, we follow this
+ script to coordinate a public release.
+
+How we coordinate embargoed releases
+====================================
+
+To protect Git users from critical vulnerabilities, we do not just release
+fixed versions like regular maintenance releases. Instead, we coordinate
+releases with packagers, keeping the fixes under an embargo until the release
+date. That way, users will have a chance to upgrade on that date, no matter
+what Operating System or distribution they run.
+
+Open a Security Advisory draft
+------------------------------
+
+The first step is to https://github.com/git/git/security/advisories/new[open an
+advisory]. Technically, it is not necessary, but it is convenient and saves a
+bit of hassle. This advisory can also be used to obtain the CVE number and it
+will give us a private fork associated with it that can be used to collaborate
+on a fix.
+
+Release date of the embargoed version
+-------------------------------------
+
+If the vulnerability affects Windows users, we want to have our friends over at
+Visual Studio on board. This means we need to target a "Patch Tuesday" (i.e. a
+second Tuesday of the month), at the minimum three weeks from heads-up to
+coordinated release.
+
+If the vulnerability affects the server side, or can benefit from scans on the
+server side (i.e. if `git fsck` can detect an attack), it is important to give
+all involved Git repository hosting sites enough time to scan all of those
+repositories.
+
+Notifying the Linux distributions
+---------------------------------
+
+At most two weeks before release date, we need to send a notification to
+distros@vs.openwall.org, preferably less than 7 days before the release date.
+This will reach most (all?) Linux distributions. See an example below, and the
+guidelines for this mailing list at
+https://oss-security.openwall.org/wiki/mailing-lists/distros#how-to-use-the-lists[here].
+
+Once the version has been published, we send a note about that to oss-security.
+As an example, see https://www.openwall.com/lists/oss-security/2019/12/13/1[the
+v2.24.1 mail];
+https://oss-security.openwall.org/wiki/mailing-lists/oss-security[Here] are
+their guidelines.
+
+The mail to oss-security should also describe the exploit, and give credit to
+the reporter(s): security researchers still receive too little respect for the
+invaluable service they provide, and public credit goes a long way to keep them
+paid by their respective organizations.
+
+Technically, describing any exploit can be delayed up to 7 days, but we usually
+refrain from doing that, including it right away.
+
+As a courtesy we typically attach a Git bundle (as `.tar.xz` because the list
+will drop `.bundle` attachments) in the mail to distros@ so that the involved
+parties can take care of integrating/backporting them. This bundle is typically
+created using a command like this:
+
+	git bundle create cve-xxx.bundle ^origin/master vA.B.C vD.E.F
+	tar cJvf cve-xxx.bundle.tar.xz cve-xxx.bundle
+
+Example mail to distros@vs.openwall.org
+---------------------------------------
+
+....
+To: distros@vs.openwall.org
+Cc: git-security@googlegroups.com, <other people involved in the report/fix>
+Subject: [vs] Upcoming Git security fix release
+
+Team,
+
+The Git project will release new versions on <date> at 10am Pacific Time or
+soon thereafter. I have attached a Git bundle (embedded in a `.tar.xz` to avoid
+it being dropped) which you can fetch into a clone of
+https://github.com/git/git via `git fetch --tags /path/to/cve-xxx.bundle`,
+containing the tags for versions <versions>.
+
+You can verify with `git tag -v <tag>` that the versions were signed by
+the Git maintainer, using the same GPG key as e.g. v2.24.0.
+
+Please use these tags to prepare `git` packages for your various
+distributions, using the appropriate tagged versions. The added test cases
+help verify the correctness.
+
+The addressed issues are:
+
+<list of CVEs with a short description, typically copy/pasted from Git's
+release notes, usually demo exploit(s), too>
+
+Credit for finding the vulnerability goes to <reporter>, credit for fixing
+it goes to <developer>.
+
+Thanks,
+<name>
+
+....
+
+Example mail to oss-security@lists.openwall.com
+-----------------------------------------------
+
+....
+To: oss-security@lists.openwall.com
+Cc: git-security@googlegroups.com, <other people involved in the report/fix>
+Subject: git: <copy from security advisory>
+
+Team,
+
+The Git project released new versions on <date>, addressing <CVE>.
+
+All supported platforms are affected in one way or another, and all Git
+versions all the way back to <version> are affected. The fixed versions are:
+<versions>.
+
+Link to the announcement: <link to lore.kernel.org/git>
+
+We highly recommend to upgrade.
+
+The addressed issues are:
+* <list of CVEs and their explanations, along with demo exploits>
+
+Credit for finding the vulnerability goes to <reporter>, credit for fixing
+it goes to <developer>.
+
+Thanks,
+<name>
+....
diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index 6b59e28..4513306 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -208,6 +208,19 @@
 '%cs':: committer date, short format (`YYYY-MM-DD`)
 '%d':: ref names, like the --decorate option of linkgit:git-log[1]
 '%D':: ref names without the " (", ")" wrapping.
+'%(describe[:options])':: human-readable name, like
+			  linkgit:git-describe[1]; empty string for
+			  undescribable commits.  The `describe` string
+			  may be followed by a colon and zero or more
+			  comma-separated options.  Descriptions can be
+			  inconsistent when tags are added or removed at
+			  the same time.
++
+** 'match=<pattern>': Only consider tags matching the given
+   `glob(7)` pattern, excluding the "refs/tags/" prefix.
+** 'exclude=<pattern>': Do not consider tags matching the given
+   `glob(7)` pattern, excluding the "refs/tags/" prefix.
+
 '%S':: ref name given on the command line by which the commit was reached
        (like `git log --source`), only works with `git log`
 '%e':: encoding
diff --git a/Documentation/technical/api-simple-ipc.txt b/Documentation/technical/api-simple-ipc.txt
new file mode 100644
index 0000000..d79ad32
--- /dev/null
+++ b/Documentation/technical/api-simple-ipc.txt
@@ -0,0 +1,105 @@
+Simple-IPC API
+==============
+
+The Simple-IPC API is a collection of `ipc_` prefixed library routines
+and a basic communication protocol that allow an IPC-client process to
+send an application-specific IPC-request message to an IPC-server
+process and receive an application-specific IPC-response message.
+
+Communication occurs over a named pipe on Windows and a Unix domain
+socket on other platforms.  IPC-clients and IPC-servers rendezvous at
+a previously agreed-to application-specific pathname (which is outside
+the scope of this design) that is local to the computer system.
+
+The IPC-server routines within the server application process create a
+thread pool to listen for connections and receive request messages
+from multiple concurrent IPC-clients.  When received, these messages
+are dispatched up to the server application callbacks for handling.
+IPC-server routines then incrementally relay responses back to the
+IPC-client.
+
+The IPC-client routines within a client application process connect
+to the IPC-server and send a request message and wait for a response.
+When received, the response is returned back the caller.
+
+For example, the `fsmonitor--daemon` feature will be built as a server
+application on top of the IPC-server library routines.  It will have
+threads watching for file system events and a thread pool waiting for
+client connections.  Clients, such as `git status` will request a list
+of file system events since a point in time and the server will
+respond with a list of changed files and directories.  The formats of
+the request and response are application-specific; the IPC-client and
+IPC-server routines treat them as opaque byte streams.
+
+
+Comparison with sub-process model
+---------------------------------
+
+The Simple-IPC mechanism differs from the existing `sub-process.c`
+model (Documentation/technical/long-running-process-protocol.txt) and
+used by applications like Git-LFS.  In the LFS-style sub-process model
+the helper is started by the foreground process, communication happens
+via a pair of file descriptors bound to the stdin/stdout of the
+sub-process, the sub-process only serves the current foreground
+process, and the sub-process exits when the foreground process
+terminates.
+
+In the Simple-IPC model the server is a very long-running service.  It
+can service many clients at the same time and has a private socket or
+named pipe connection to each active client.  It might be started
+(on-demand) by the current client process or it might have been
+started by a previous client or by the OS at boot time.  The server
+process is not associated with a terminal and it persists after
+clients terminate.  Clients do not have access to the stdin/stdout of
+the server process and therefore must communicate over sockets or
+named pipes.
+
+
+Server startup and shutdown
+---------------------------
+
+How an application server based upon IPC-server is started is also
+outside the scope of the Simple-IPC design and is a property of the
+application using it.  For example, the server might be started or
+restarted during routine maintenance operations, or it might be
+started as a system service during the system boot-up sequence, or it
+might be started on-demand by a foreground Git command when needed.
+
+Similarly, server shutdown is a property of the application using
+the simple-ipc routines.  For example, the server might decide to
+shutdown when idle or only upon explicit request.
+
+
+Simple-IPC protocol
+-------------------
+
+The Simple-IPC protocol consists of a single request message from the
+client and an optional response message from the server.  Both the
+client and server messages are unlimited in length and are terminated
+with a flush packet.
+
+The pkt-line routines (Documentation/technical/protocol-common.txt)
+are used to simplify buffer management during message generation,
+transmission, and reception.  A flush packet is used to mark the end
+of the message.  This allows the sender to incrementally generate and
+transmit the message.  It allows the receiver to incrementally receive
+the message in chunks and to know when they have received the entire
+message.
+
+The actual byte format of the client request and server response
+messages are application specific.  The IPC layer transmits and
+receives them as opaque byte buffers without any concern for the
+content within.  It is the job of the calling application layer to
+understand the contents of the request and response messages.
+
+
+Summary
+-------
+
+Conceptually, the Simple-IPC protocol is similar to an HTTP REST
+request.  Clients connect, make an application-specific and
+stateless request, receive an application-specific
+response, and disconnect.  It is a one round trip facility for
+querying the server.  The Simple-IPC routines hide the socket,
+named pipe, and thread pool details and allow the application
+layer to focus on the application at hand.
diff --git a/GIT-VERSION-GEN b/GIT-VERSION-GEN
index 8f6334d..d2ff917 100755
--- a/GIT-VERSION-GEN
+++ b/GIT-VERSION-GEN
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 GVF=GIT-VERSION-FILE
-DEF_VER=v2.31.0
+DEF_VER=v2.31.GIT
 
 LF='
 '
diff --git a/INSTALL b/INSTALL
index 8474ad0..66389ce 100644
--- a/INSTALL
+++ b/INSTALL
@@ -197,7 +197,9 @@
    Building and installing the pdf file additionally requires
    dblatex.  Version >= 0.2.7 is known to work.
 
-   All formats require at least asciidoc 8.4.1.
+   All formats require at least asciidoc 8.4.1. Alternatively, you can
+   use Asciidoctor (requires Ruby) by passing USE_ASCIIDOCTOR=YesPlease
+   to make. You need at least Asciidoctor version 1.5.
 
    There are also "make quick-install-doc", "make quick-install-man"
    and "make quick-install-html" which install preformatted man pages
diff --git a/Makefile b/Makefile
index dfb0f10..a6a73c5 100644
--- a/Makefile
+++ b/Makefile
@@ -578,7 +578,9 @@
 EXTRA_CPPFLAGS =
 FUZZ_OBJS =
 FUZZ_PROGRAMS =
+GIT_OBJS =
 LIB_OBJS =
+OBJECTS =
 PROGRAM_OBJS =
 PROGRAMS =
 EXCLUDED_PROGRAMS =
@@ -587,6 +589,7 @@
 SCRIPT_SH =
 SCRIPT_LIB =
 TEST_BUILTINS_OBJS =
+TEST_OBJS =
 TEST_PROGRAMS_NEED_X =
 THIRD_PARTY_SOURCES =
 
@@ -662,6 +665,8 @@
 FUZZ_OBJS += fuzz-commit-graph.o
 FUZZ_OBJS += fuzz-pack-headers.o
 FUZZ_OBJS += fuzz-pack-idx.o
+.PHONY: fuzz-objs
+fuzz-objs: $(FUZZ_OBJS)
 
 # Always build fuzz objects even if not testing, to prevent bit-rot.
 all:: $(FUZZ_OBJS)
@@ -679,6 +684,8 @@
 PROGRAM_OBJS += imap-send.o
 PROGRAM_OBJS += sh-i18n--envsubst.o
 PROGRAM_OBJS += shell.o
+.PHONY: program-objs
+program-objs: $(PROGRAM_OBJS)
 
 # Binary suffix, set to .exe for Windows builds
 X =
@@ -737,6 +744,7 @@
 TEST_BUILTINS_OBJS += test-sha1.o
 TEST_BUILTINS_OBJS += test-sha256.o
 TEST_BUILTINS_OBJS += test-sigchain.o
+TEST_BUILTINS_OBJS += test-simple-ipc.o
 TEST_BUILTINS_OBJS += test-strcmp-offset.o
 TEST_BUILTINS_OBJS += test-string-list.o
 TEST_BUILTINS_OBJS += test-submodule-config.o
@@ -1672,6 +1680,14 @@
 	BASIC_CFLAGS += -DNO_UNIX_SOCKETS
 else
 	LIB_OBJS += unix-socket.o
+	LIB_OBJS += unix-stream-server.o
+	LIB_OBJS += compat/simple-ipc/ipc-shared.o
+	LIB_OBJS += compat/simple-ipc/ipc-unix-socket.o
+endif
+
+ifdef USE_WIN32_IPC
+	LIB_OBJS += compat/simple-ipc/ipc-shared.o
+	LIB_OBJS += compat/simple-ipc/ipc-win32.o
 endif
 
 ifdef NO_ICONV
@@ -2378,16 +2394,30 @@
 XDIFF_OBJS += xdiff/xpatience.o
 XDIFF_OBJS += xdiff/xprepare.o
 XDIFF_OBJS += xdiff/xutils.o
+.PHONY: xdiff-objs
+xdiff-objs: $(XDIFF_OBJS)
 
 TEST_OBJS := $(patsubst %$X,%.o,$(TEST_PROGRAMS)) $(patsubst %,t/helper/%,$(TEST_BUILTINS_OBJS))
-OBJECTS := $(LIB_OBJS) $(BUILTIN_OBJS) $(PROGRAM_OBJS) $(TEST_OBJS) \
-	$(XDIFF_OBJS) \
-	$(FUZZ_OBJS) \
-	common-main.o \
-	git.o
+.PHONY: test-objs
+test-objs: $(TEST_OBJS)
+
+GIT_OBJS += $(LIB_OBJS)
+GIT_OBJS += $(BUILTIN_OBJS)
+GIT_OBJS += common-main.o
+GIT_OBJS += git.o
+.PHONY: git-objs
+git-objs: $(GIT_OBJS)
+
+OBJECTS += $(GIT_OBJS)
+OBJECTS += $(PROGRAM_OBJS)
+OBJECTS += $(TEST_OBJS)
+OBJECTS += $(XDIFF_OBJS)
+OBJECTS += $(FUZZ_OBJS)
 ifndef NO_CURL
 	OBJECTS += http.o http-walker.o remote-curl.o
 endif
+.PHONY: objects
+objects: $(OBJECTS)
 
 dep_files := $(foreach f,$(OBJECTS),$(dir $f).depend/$(notdir $f).d)
 dep_dirs := $(addsuffix .depend,$(sort $(dir $(OBJECTS))))
@@ -3299,11 +3329,11 @@
 # are not necessarily appropriate for general builds, and that vary greatly
 # depending on the compiler version used.
 #
-# An example command to build against libFuzzer from LLVM 4.0.0:
+# An example command to build against libFuzzer from LLVM 11.0.0:
 #
 # make CC=clang CXX=clang++ \
-#      CFLAGS="-fsanitize-coverage=trace-pc-guard -fsanitize=address" \
-#      LIB_FUZZING_ENGINE=/usr/lib/llvm-4.0/lib/libFuzzer.a \
+#      CFLAGS="-fsanitize=fuzzer-no-link,address" \
+#      LIB_FUZZING_ENGINE="-fsanitize=fuzzer" \
 #      fuzz-all
 #
 FUZZ_CXXFLAGS ?= $(CFLAGS)
diff --git a/RelNotes b/RelNotes
index 3324fc0..aece21e 120000
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes/2.31.0.txt
\ No newline at end of file
+Documentation/RelNotes/2.32.0.txt
\ No newline at end of file
diff --git a/SECURITY.md b/SECURITY.md
new file mode 100644
index 0000000..c720c2a
--- /dev/null
+++ b/SECURITY.md
@@ -0,0 +1,51 @@
+# Security Policy
+
+## Reporting a vulnerability
+
+Please send a detailed mail to git-security@googlegroups.com to
+report vulnerabilities in Git.
+
+Even when unsure whether the bug in question is an exploitable
+vulnerability, it is recommended to send the report to
+git-security@googlegroups.com (and obviously not to discuss the
+issue anywhere else).
+
+Vulnerabilities are expected to be discussed _only_ on that
+list, and not in public, until the official announcement on the
+Git mailing list on the release date.
+
+Examples for details to include:
+
+- Ideally a short description (or a script) to demonstrate an
+  exploit.
+- The affected platforms and scenarios (the vulnerability might
+  only affect setups with case-sensitive file systems, for
+  example).
+- The name and affiliation of the security researchers who are
+  involved in the discovery, if any.
+- Whether the vulnerability has already been disclosed.
+- How long an embargo would be required to be safe.
+
+## Supported Versions
+
+There are no official "Long Term Support" versions in Git.
+Instead, the maintenance track (i.e. the versions based on the
+most recently published feature release, also known as ".0"
+version) sees occasional updates with bug fixes.
+
+Fixes to vulnerabilities are made for the maintenance track for
+the latest feature release and merged up to the in-development
+branches. The Git project makes no formal guarantee for any
+older maintenance tracks to receive updates. In practice,
+though, critical vulnerability fixes are applied not only to the
+most recent track, but to at least a couple more maintenance
+tracks.
+
+This is typically done by making the fix on the oldest and still
+relevant maintenance track, and merging it upwards to newer and
+newer maintenance tracks.
+
+For example, v2.24.1 was released to address a couple of
+[CVEs](https://cve.mitre.org/), and at the same time v2.14.6,
+v2.15.4, v2.16.6, v2.17.3, v2.18.2, v2.19.3, v2.20.2, v2.21.1,
+v2.22.2 and v2.23.1 were released.
diff --git a/add-interactive.c b/add-interactive.c
index 9b8cdb4..36ebdbd 100644
--- a/add-interactive.c
+++ b/add-interactive.c
@@ -413,7 +413,7 @@
 
 static void add_file_item(struct string_list *files, const char *name)
 {
-	struct file_item *item = xcalloc(sizeof(*item), 1);
+	struct file_item *item = xcalloc(1, sizeof(*item));
 
 	string_list_append(files, name)->util = item;
 }
@@ -476,7 +476,7 @@
 
 			add_file_item(s->files, name);
 
-			entry = xcalloc(sizeof(*entry), 1);
+			CALLOC_ARRAY(entry, 1);
 			hashmap_entry_init(&entry->ent, hash);
 			entry->name = s->files->items[s->files->nr - 1].string;
 			entry->item = s->files->items[s->files->nr - 1].util;
@@ -1120,7 +1120,7 @@
 	int res = 0;
 
 	for (i = 0; i < ARRAY_SIZE(command_list); i++) {
-		struct command_item *util = xcalloc(sizeof(*util), 1);
+		struct command_item *util = xcalloc(1, sizeof(*util));
 		util->command = command_list[i].command;
 		string_list_append(&commands.items, command_list[i].string)
 			->util = util;
diff --git a/apply.c b/apply.c
index 668b16e..466f880 100644
--- a/apply.c
+++ b/apply.c
@@ -21,6 +21,7 @@
 #include "quote.h"
 #include "rerere.h"
 #include "apply.h"
+#include "entry.h"
 
 struct gitdiff_data {
 	struct strbuf *root;
@@ -1781,7 +1782,7 @@
 		struct fragment *fragment;
 		int len;
 
-		fragment = xcalloc(1, sizeof(*fragment));
+		CALLOC_ARRAY(fragment, 1);
 		fragment->linenr = state->linenr;
 		len = parse_fragment(state, line, size, patch, fragment);
 		if (len <= 0) {
@@ -1959,7 +1960,7 @@
 		size -= llen;
 	}
 
-	frag = xcalloc(1, sizeof(*frag));
+	CALLOC_ARRAY(frag, 1);
 	frag->patch = inflate_it(data, hunk_size, origlen);
 	frag->free_patch = 1;
 	if (!frag->patch)
@@ -4681,7 +4682,7 @@
 		struct patch *patch;
 		int nr;
 
-		patch = xcalloc(1, sizeof(*patch));
+		CALLOC_ARRAY(patch, 1);
 		patch->inaccurate_eof = !!(options & APPLY_OPT_INACCURATE_EOF);
 		patch->recount =  !!(options & APPLY_OPT_RECOUNT);
 		nr = parse_chunk(state, buf.buf + offset, buf.len - offset, patch);
diff --git a/archive-tar.c b/archive-tar.c
index a971fdc..05d2455 100644
--- a/archive-tar.c
+++ b/archive-tar.c
@@ -371,7 +371,7 @@
 
 	ar = find_tar_filter(name, namelen);
 	if (!ar) {
-		ar = xcalloc(1, sizeof(*ar));
+		CALLOC_ARRAY(ar, 1);
 		ar->name = xmemdupz(name, namelen);
 		ar->write_archive = write_tar_filter_archive;
 		ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS |
diff --git a/archive.c b/archive.c
index 5919d9e..2956155 100644
--- a/archive.c
+++ b/archive.c
@@ -37,13 +37,10 @@
 
 static void format_subst(const struct commit *commit,
 			 const char *src, size_t len,
-			 struct strbuf *buf)
+			 struct strbuf *buf, struct pretty_print_context *ctx)
 {
 	char *to_free = NULL;
 	struct strbuf fmt = STRBUF_INIT;
-	struct pretty_print_context ctx = {0};
-	ctx.date_mode.type = DATE_NORMAL;
-	ctx.abbrev = DEFAULT_ABBREV;
 
 	if (src == buf->buf)
 		to_free = strbuf_detach(buf, NULL);
@@ -61,7 +58,7 @@
 		strbuf_add(&fmt, b + 8, c - b - 8);
 
 		strbuf_add(buf, src, b - src);
-		format_commit_message(commit, fmt.buf, buf, &ctx);
+		format_commit_message(commit, fmt.buf, buf, ctx);
 		len -= c + 1 - src;
 		src  = c + 1;
 	}
@@ -94,7 +91,7 @@
 		strbuf_attach(&buf, buffer, *sizep, *sizep + 1);
 		convert_to_working_tree(args->repo->index, path, buf.buf, buf.len, &buf, &meta);
 		if (commit)
-			format_subst(commit, buf.buf, buf.len, &buf);
+			format_subst(commit, buf.buf, buf.len, &buf, args->pretty_ctx);
 		buffer = strbuf_detach(&buf, &size);
 		*sizep = size;
 	}
@@ -107,7 +104,6 @@
 	struct object_id oid;
 	int baselen, len;
 	unsigned mode;
-	int stage;
 	char path[FLEX_ARRAY];
 };
 
@@ -138,7 +134,7 @@
 }
 
 static int write_archive_entry(const struct object_id *oid, const char *base,
-		int baselen, const char *filename, unsigned mode, int stage,
+		int baselen, const char *filename, unsigned mode,
 		void *context)
 {
 	static struct strbuf path = STRBUF_INIT;
@@ -197,7 +193,7 @@
 
 static void queue_directory(const unsigned char *sha1,
 		struct strbuf *base, const char *filename,
-		unsigned mode, int stage, struct archiver_context *c)
+		unsigned mode, struct archiver_context *c)
 {
 	struct directory *d;
 	size_t len = st_add4(base->len, 1, strlen(filename), 1);
@@ -205,7 +201,6 @@
 	d->up	   = c->bottom;
 	d->baselen = base->len;
 	d->mode	   = mode;
-	d->stage   = stage;
 	c->bottom  = d;
 	d->len = xsnprintf(d->path, len, "%.*s%s/", (int)base->len, base->buf, filename);
 	hashcpy(d->oid.hash, sha1);
@@ -224,14 +219,14 @@
 		write_directory(c) ||
 		write_archive_entry(&d->oid, d->path, d->baselen,
 				    d->path + d->baselen, d->mode,
-				    d->stage, c) != READ_TREE_RECURSIVE;
+				    c) != READ_TREE_RECURSIVE;
 	free(d);
 	return ret ? -1 : 0;
 }
 
 static int queue_or_write_archive_entry(const struct object_id *oid,
 		struct strbuf *base, const char *filename,
-		unsigned mode, int stage, void *context)
+		unsigned mode, void *context)
 {
 	struct archiver_context *c = context;
 
@@ -256,14 +251,14 @@
 		if (check_attr_export_ignore(check))
 			return 0;
 		queue_directory(oid->hash, base, filename,
-				mode, stage, c);
+				mode, c);
 		return READ_TREE_RECURSIVE;
 	}
 
 	if (write_directory(c))
 		return -1;
 	return write_archive_entry(oid, base->buf, base->len, filename, mode,
-				   stage, context);
+				   context);
 }
 
 struct extra_file_info {
@@ -316,10 +311,10 @@
 		git_attr_set_direction(GIT_ATTR_INDEX);
 	}
 
-	err = read_tree_recursive(args->repo, args->tree, "",
-				  0, 0, &args->pathspec,
-				  queue_or_write_archive_entry,
-				  &context);
+	err = read_tree(args->repo, args->tree,
+			&args->pathspec,
+			queue_or_write_archive_entry,
+			&context);
 	if (err == READ_TREE_RECURSIVE)
 		err = 0;
 	while (context.bottom) {
@@ -378,7 +373,7 @@
 
 static int reject_entry(const struct object_id *oid, struct strbuf *base,
 			const char *filename, unsigned mode,
-			int stage, void *context)
+			void *context)
 {
 	int ret = -1;
 	struct path_exists_context *ctx = context;
@@ -405,9 +400,9 @@
 	ctx.args = args;
 	parse_pathspec(&ctx.pathspec, 0, 0, "", paths);
 	ctx.pathspec.recursive = 1;
-	ret = read_tree_recursive(args->repo, args->tree, "",
-				  0, 0, &ctx.pathspec,
-				  reject_entry, &ctx);
+	ret = read_tree(args->repo, args->tree,
+			&ctx.pathspec,
+			reject_entry, &ctx);
 	clear_pathspec(&ctx.pathspec);
 	return ret != 0;
 }
@@ -633,12 +628,19 @@
 		  const char *name_hint, int remote)
 {
 	const struct archiver *ar = NULL;
+	struct pretty_print_describe_status describe_status = {0};
+	struct pretty_print_context ctx = {0};
 	struct archiver_args args;
 	int rc;
 
 	git_config_get_bool("uploadarchive.allowunreachable", &remote_allow_unreachable);
 	git_config(git_default_config, NULL);
 
+	describe_status.max_invocations = 1;
+	ctx.date_mode.type = DATE_NORMAL;
+	ctx.abbrev = DEFAULT_ABBREV;
+	ctx.describe_status = &describe_status;
+	args.pretty_ctx = &ctx;
 	args.repo = repo;
 	args.prefix = prefix;
 	string_list_init(&args.extra_files, 1);
diff --git a/archive.h b/archive.h
index 33551b7..49fab71 100644
--- a/archive.h
+++ b/archive.h
@@ -5,6 +5,7 @@
 #include "pathspec.h"
 
 struct repository;
+struct pretty_print_context;
 
 struct archiver_args {
 	struct repository *repo;
@@ -22,6 +23,7 @@
 	unsigned int convert : 1;
 	int compression_level;
 	struct string_list extra_files;
+	struct pretty_print_context *pretty_ctx;
 };
 
 /* main api */
diff --git a/attr.c b/attr.c
index 4ef85d6..ac8ec7c 100644
--- a/attr.c
+++ b/attr.c
@@ -278,6 +278,10 @@
 
 static const char blank[] = " \t\r\n";
 
+/* Flags usable in read_attr() and parse_attr_line() family of functions. */
+#define READ_ATTR_MACRO_OK (1<<0)
+#define READ_ATTR_NOFOLLOW (1<<1)
+
 /*
  * Parse a whitespace-delimited attribute state (i.e., "attr",
  * "-attr", "!attr", or "attr=value") from the string starting at src.
@@ -331,7 +335,7 @@
 }
 
 static struct match_attr *parse_attr_line(const char *line, const char *src,
-					  int lineno, int macro_ok)
+					  int lineno, unsigned flags)
 {
 	int namelen;
 	int num_attr, i;
@@ -355,7 +359,7 @@
 
 	if (strlen(ATTRIBUTE_MACRO_PREFIX) < namelen &&
 	    starts_with(name, ATTRIBUTE_MACRO_PREFIX)) {
-		if (!macro_ok) {
+		if (!(flags & READ_ATTR_MACRO_OK)) {
 			fprintf_ln(stderr, _("%s not allowed: %s:%d"),
 				   name, src, lineno);
 			goto fail_return;
@@ -569,7 +573,7 @@
 	check = attr_check_alloc();
 	check->nr = cnt;
 	check->alloc = cnt;
-	check->items = xcalloc(cnt, sizeof(struct attr_check_item));
+	CALLOC_ARRAY(check->items, cnt);
 
 	check->items[0].attr = git_attr(one);
 	va_start(params, one);
@@ -653,11 +657,11 @@
 			     const char *line,
 			     const char *src,
 			     int lineno,
-			     int macro_ok)
+			     unsigned flags)
 {
 	struct match_attr *a;
 
-	a = parse_attr_line(line, src, lineno, macro_ok);
+	a = parse_attr_line(line, src, lineno, flags);
 	if (!a)
 		return;
 	ALLOC_GROW(res->attrs, res->num_matches + 1, res->alloc);
@@ -670,9 +674,10 @@
 	const char *line;
 	int lineno = 0;
 
-	res = xcalloc(1, sizeof(*res));
+	CALLOC_ARRAY(res, 1);
 	while ((line = *(list++)) != NULL)
-		handle_attr_line(res, line, "[builtin]", ++lineno, 1);
+		handle_attr_line(res, line, "[builtin]", ++lineno,
+				 READ_ATTR_MACRO_OK);
 	return res;
 }
 
@@ -698,21 +703,31 @@
 	direction = new_direction;
 }
 
-static struct attr_stack *read_attr_from_file(const char *path, int macro_ok)
+static struct attr_stack *read_attr_from_file(const char *path, unsigned flags)
 {
-	FILE *fp = fopen_or_warn(path, "r");
+	int fd;
+	FILE *fp;
 	struct attr_stack *res;
 	char buf[2048];
 	int lineno = 0;
 
-	if (!fp)
+	if (flags & READ_ATTR_NOFOLLOW)
+		fd = open_nofollow(path, O_RDONLY);
+	else
+		fd = open(path, O_RDONLY);
+
+	if (fd < 0) {
+		warn_on_fopen_errors(path);
 		return NULL;
-	res = xcalloc(1, sizeof(*res));
+	}
+	fp = xfdopen(fd, "r");
+
+	CALLOC_ARRAY(res, 1);
 	while (fgets(buf, sizeof(buf), fp)) {
 		char *bufp = buf;
 		if (!lineno)
 			skip_utf8_bom(&bufp, strlen(bufp));
-		handle_attr_line(res, bufp, path, ++lineno, macro_ok);
+		handle_attr_line(res, bufp, path, ++lineno, flags);
 	}
 	fclose(fp);
 	return res;
@@ -720,7 +735,7 @@
 
 static struct attr_stack *read_attr_from_index(const struct index_state *istate,
 					       const char *path,
-					       int macro_ok)
+					       unsigned flags)
 {
 	struct attr_stack *res;
 	char *buf, *sp;
@@ -733,7 +748,7 @@
 	if (!buf)
 		return NULL;
 
-	res = xcalloc(1, sizeof(*res));
+	CALLOC_ARRAY(res, 1);
 	for (sp = buf; *sp; ) {
 		char *ep;
 		int more;
@@ -741,7 +756,7 @@
 		ep = strchrnul(sp, '\n');
 		more = (*ep == '\n');
 		*ep = '\0';
-		handle_attr_line(res, sp, path, ++lineno, macro_ok);
+		handle_attr_line(res, sp, path, ++lineno, flags);
 		sp = ep + more;
 	}
 	free(buf);
@@ -749,19 +764,19 @@
 }
 
 static struct attr_stack *read_attr(const struct index_state *istate,
-				    const char *path, int macro_ok)
+				    const char *path, unsigned flags)
 {
 	struct attr_stack *res = NULL;
 
 	if (direction == GIT_ATTR_INDEX) {
-		res = read_attr_from_index(istate, path, macro_ok);
+		res = read_attr_from_index(istate, path, flags);
 	} else if (!is_bare_repository()) {
 		if (direction == GIT_ATTR_CHECKOUT) {
-			res = read_attr_from_index(istate, path, macro_ok);
+			res = read_attr_from_index(istate, path, flags);
 			if (!res)
-				res = read_attr_from_file(path, macro_ok);
+				res = read_attr_from_file(path, flags);
 		} else if (direction == GIT_ATTR_CHECKIN) {
-			res = read_attr_from_file(path, macro_ok);
+			res = read_attr_from_file(path, flags);
 			if (!res)
 				/*
 				 * There is no checked out .gitattributes file
@@ -769,12 +784,12 @@
 				 * We allow operation in a sparsely checked out
 				 * work tree, so read from it.
 				 */
-				res = read_attr_from_index(istate, path, macro_ok);
+				res = read_attr_from_index(istate, path, flags);
 		}
 	}
 
 	if (!res)
-		res = xcalloc(1, sizeof(*res));
+		CALLOC_ARRAY(res, 1);
 	return res;
 }
 
@@ -844,6 +859,7 @@
 				 struct attr_stack **stack)
 {
 	struct attr_stack *e;
+	unsigned flags = READ_ATTR_MACRO_OK;
 
 	if (*stack)
 		return;
@@ -854,27 +870,27 @@
 
 	/* system-wide frame */
 	if (git_attr_system()) {
-		e = read_attr_from_file(git_etc_gitattributes(), 1);
+		e = read_attr_from_file(git_etc_gitattributes(), flags);
 		push_stack(stack, e, NULL, 0);
 	}
 
 	/* home directory */
 	if (get_home_gitattributes()) {
-		e = read_attr_from_file(get_home_gitattributes(), 1);
+		e = read_attr_from_file(get_home_gitattributes(), flags);
 		push_stack(stack, e, NULL, 0);
 	}
 
 	/* root directory */
-	e = read_attr(istate, GITATTRIBUTES_FILE, 1);
+	e = read_attr(istate, GITATTRIBUTES_FILE, flags | READ_ATTR_NOFOLLOW);
 	push_stack(stack, e, xstrdup(""), 0);
 
 	/* info frame */
 	if (startup_info->have_repository)
-		e = read_attr_from_file(git_path_info_attributes(), 1);
+		e = read_attr_from_file(git_path_info_attributes(), flags);
 	else
 		e = NULL;
 	if (!e)
-		e = xcalloc(1, sizeof(struct attr_stack));
+		CALLOC_ARRAY(e, 1);
 	push_stack(stack, e, NULL, 0);
 }
 
@@ -956,7 +972,7 @@
 		strbuf_add(&pathbuf, path + pathbuf.len, (len - pathbuf.len));
 		strbuf_addf(&pathbuf, "/%s", GITATTRIBUTES_FILE);
 
-		next = read_attr(istate, pathbuf.buf, 0);
+		next = read_attr(istate, pathbuf.buf, READ_ATTR_NOFOLLOW);
 
 		/* reset the pathbuf to not include "/.gitattributes" */
 		strbuf_setlen(&pathbuf, len);
diff --git a/bisect.c b/bisect.c
index ae48d19..af2863d 100644
--- a/bisect.c
+++ b/bisect.c
@@ -423,7 +423,7 @@
 	show_list("bisection 2 sorted", 0, nr, list);
 
 	*all = nr;
-	weights = xcalloc(on_list, sizeof(*weights));
+	CALLOC_ARRAY(weights, on_list);
 
 	/* Do the real work of finding bisection commit. */
 	best = do_find_bisection(list, nr, weights, bisect_flags);
diff --git a/blame.c b/blame.c
index a5044fc..5018bb8 100644
--- a/blame.c
+++ b/blame.c
@@ -951,13 +951,13 @@
 	max_search_distance_b = ((2 * max_search_distance_a + 1) * length_b
 				 - 1) / length_a;
 
-	result = xcalloc(sizeof(int), length_b);
-	second_best_result = xcalloc(sizeof(int), length_b);
-	certainties = xcalloc(sizeof(int), length_b);
+	CALLOC_ARRAY(result, length_b);
+	CALLOC_ARRAY(second_best_result, length_b);
+	CALLOC_ARRAY(certainties, length_b);
 
 	/* See get_similarity() for details of similarities. */
 	similarity_count = length_b * (max_search_distance_a * 2 + 1);
-	similarities = xcalloc(sizeof(int), similarity_count);
+	CALLOC_ARRAY(similarities, similarity_count);
 
 	for (i = 0; i < length_b; ++i) {
 		result[i] = -1;
@@ -995,7 +995,7 @@
 		return;
 	o->num_lines = find_line_starts(&line_starts, o->file.ptr,
 					o->file.size);
-	o->fingerprints = xcalloc(sizeof(struct fingerprint), o->num_lines);
+	CALLOC_ARRAY(o->fingerprints, o->num_lines);
 	get_line_fingerprints(o->fingerprints, o->file.ptr, line_starts,
 			      0, o->num_lines);
 	free(line_starts);
@@ -1853,8 +1853,7 @@
 	diffp = NULL;
 
 	if (ignore_diffs && same - tlno > 0) {
-		line_blames = xcalloc(sizeof(struct blame_line_tracker),
-				      same - tlno);
+		CALLOC_ARRAY(line_blames, same - tlno);
 		guess_line_blames(parent, target, tlno, offset, same,
 				  parent_len, line_blames);
 	}
@@ -2216,7 +2215,7 @@
 	for (e = unblamed, num_ents = 0; e; e = e->next)
 		num_ents++;
 	if (num_ents) {
-		blame_list = xcalloc(num_ents, sizeof(struct blame_list));
+		CALLOC_ARRAY(blame_list, num_ents);
 		for (e = unblamed, i = 0; e; e = e->next)
 			blame_list[i++].ent = e;
 	}
@@ -2428,7 +2427,7 @@
 	else if (num_sg < ARRAY_SIZE(sg_buf))
 		memset(sg_buf, 0, sizeof(sg_buf));
 	else
-		sg_origin = xcalloc(num_sg, sizeof(*sg_origin));
+		CALLOC_ARRAY(sg_origin, num_sg);
 
 	/*
 	 * The first pass looks for unrenamed path to optimize for
diff --git a/block-sha1/sha1.c b/block-sha1/sha1.c
index 8681031..1bb6e7c 100644
--- a/block-sha1/sha1.c
+++ b/block-sha1/sha1.c
@@ -70,7 +70,7 @@
  * the input data, the next mix it from the 512-bit array.
  */
 #define SHA_SRC(t) get_be32((unsigned char *) block + (t)*4)
-#define SHA_MIX(t) SHA_ROL(W((t)+13) ^ W((t)+8) ^ W((t)+2) ^ W(t), 1);
+#define SHA_MIX(t) SHA_ROL(W((t)+13) ^ W((t)+8) ^ W((t)+2) ^ W(t), 1)
 
 #define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
 	unsigned int TEMP = input(t); setW(t, TEMP); \
diff --git a/bloom.c b/bloom.c
index b176f28..52b8747 100644
--- a/bloom.c
+++ b/bloom.c
@@ -277,7 +277,7 @@
 				*computed |= BLOOM_TRUNC_EMPTY;
 			filter->len = 1;
 		}
-		filter->data = xcalloc(filter->len, sizeof(unsigned char));
+		CALLOC_ARRAY(filter->data, filter->len);
 
 		hashmap_for_each_entry(&pathmap, &iter, e, entry) {
 			struct bloom_key key;
diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index d69e133..1fdb7d9 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -874,12 +874,19 @@
 	 */
 
 	for (; argc; argc--, argv++) {
+		struct commit *commit;
+
 		if (get_oid(*argv, &oid)){
 			error(_("Bad rev input: %s"), *argv);
 			oid_array_clear(&revs);
 			return BISECT_FAILED;
 		}
-		oid_array_append(&revs, &oid);
+
+		commit = lookup_commit_reference(the_repository, &oid);
+		if (!commit)
+			die(_("Bad rev input (not a commit): %s"), *argv);
+
+		oid_array_append(&revs, &commit->object.oid);
 	}
 
 	if (strbuf_read_file(&buf, git_path_bisect_expected_rev(), 0) < the_hash_algo->hexsz ||
diff --git a/builtin/checkout-index.c b/builtin/checkout-index.c
index 023e49e..c0bf4ac 100644
--- a/builtin/checkout-index.c
+++ b/builtin/checkout-index.c
@@ -11,6 +11,7 @@
 #include "quote.h"
 #include "cache-tree.h"
 #include "parse-options.h"
+#include "entry.h"
 
 #define CHECKOUT_ALL 4
 static int nul_term_line;
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 2d6550b..4c696ef 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -26,6 +26,7 @@
 #include "unpack-trees.h"
 #include "wt-status.h"
 #include "xdiff-interface.h"
+#include "entry.h"
 
 static const char * const checkout_usage[] = {
 	N_("git checkout [<options>] <branch>"),
@@ -114,7 +115,7 @@
 }
 
 static int update_some(const struct object_id *oid, struct strbuf *base,
-		const char *pathname, unsigned mode, int stage, void *context)
+		const char *pathname, unsigned mode, void *context)
 {
 	int len;
 	struct cache_entry *ce;
@@ -155,8 +156,8 @@
 
 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 {
-	read_tree_recursive(the_repository, tree, "", 0, 0,
-			    pathspec, update_some, NULL);
+	read_tree(the_repository, tree,
+		  pathspec, update_some, NULL);
 
 	/* update the index with the given tree's info
 	 * for all args, expanding wildcards, and exit
@@ -322,7 +323,7 @@
 	 * If it comes from the tree-ish, we already know it
 	 * matches the pathspec and could just stamp
 	 * CE_MATCHED to it from update_some(). But we still
-	 * need ps_matched and read_tree_recursive (and
+	 * need ps_matched and read_tree (and
 	 * eventually tree_entry_interesting) cannot fill
 	 * ps_matched yet. Once it can, we can avoid calling
 	 * match_pathspec() for _all_ entries when
diff --git a/builtin/clean.c b/builtin/clean.c
index 687ab47..995053b 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -623,7 +623,7 @@
 				nr += chosen[i];
 		}
 
-		result = xcalloc(st_add(nr, 1), sizeof(int));
+		CALLOC_ARRAY(result, st_add(nr, 1));
 		for (i = 0; i < stuff->nr && j < nr; i++) {
 			if (chosen[i])
 				result[j++] = i;
diff --git a/builtin/clone.c b/builtin/clone.c
index 51e844a..952fe3d 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -964,10 +964,10 @@
 {
 	int is_bundle = 0, is_local;
 	const char *repo_name, *repo, *work_tree, *git_dir;
-	char *path, *dir, *display_repo = NULL;
+	char *path = NULL, *dir, *display_repo = NULL;
 	int dest_exists, real_dest_exists = 0;
 	const struct ref *refs, *remote_head;
-	const struct ref *remote_head_points_at;
+	struct ref *remote_head_points_at = NULL;
 	const struct ref *our_head_points_at;
 	struct ref *mapped_refs;
 	const struct ref *ref;
@@ -1017,9 +1017,10 @@
 	repo_name = argv[0];
 
 	path = get_repo_path(repo_name, &is_bundle);
-	if (path)
+	if (path) {
+		FREE_AND_NULL(path);
 		repo = absolute_pathdup(repo_name);
-	else if (strchr(repo_name, ':')) {
+	} else if (strchr(repo_name, ':')) {
 		repo = repo_name;
 		display_repo = transport_anonymize_url(repo);
 	} else
@@ -1393,6 +1394,11 @@
 	strbuf_release(&reflog_msg);
 	strbuf_release(&branch_top);
 	strbuf_release(&key);
+	free_refs(mapped_refs);
+	free_refs(remote_head_points_at);
+	free(dir);
+	free(path);
+	UNLEAK(repo);
 	junk_mode = JUNK_LEAVE_ALL;
 
 	strvec_clear(&transport_ls_refs_options.ref_prefixes);
diff --git a/builtin/column.c b/builtin/column.c
index e815e14..40d4b3b 100644
--- a/builtin/column.c
+++ b/builtin/column.c
@@ -27,10 +27,10 @@
 		OPT_STRING(0, "command", &real_command, N_("name"), N_("lookup config vars")),
 		OPT_COLUMN(0, "mode", &colopts, N_("layout to use")),
 		OPT_INTEGER(0, "raw-mode", &colopts, N_("layout to use")),
-		OPT_INTEGER(0, "width", &copts.width, N_("Maximum width")),
-		OPT_STRING(0, "indent", &copts.indent, N_("string"), N_("Padding space on left border")),
-		OPT_INTEGER(0, "nl", &copts.nl, N_("Padding space on right border")),
-		OPT_INTEGER(0, "padding", &copts.padding, N_("Padding space between columns")),
+		OPT_INTEGER(0, "width", &copts.width, N_("maximum width")),
+		OPT_STRING(0, "indent", &copts.indent, N_("string"), N_("padding space on left border")),
+		OPT_INTEGER(0, "nl", &copts.nl, N_("padding space on right border")),
+		OPT_INTEGER(0, "padding", &copts.padding, N_("padding space between columns")),
 		OPT_END()
 	};
 
diff --git a/builtin/commit.c b/builtin/commit.c
index 739110c..55d50a8 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -105,7 +105,8 @@
  */
 static const char *author_message, *author_message_buffer;
 static char *edit_message, *use_message;
-static char *fixup_message, *squash_message;
+static char *fixup_message, *fixup_commit, *squash_message;
+static const char *fixup_prefix;
 static int all, also, interactive, patch_interactive, only, amend, signoff;
 static int edit_flag = -1; /* unspecified */
 static int quiet, verbose, no_verify, allow_empty, dry_run, renew_authorship;
@@ -113,6 +114,7 @@
 static int no_post_rewrite, allow_empty_message, pathspec_file_nul;
 static char *untracked_files_arg, *force_date, *ignore_submodule_arg, *ignored_arg;
 static char *sign_commit, *pathspec_from_file;
+static struct strvec trailer_args = STRVEC_INIT;
 
 /*
  * The default commit message cleanup mode will remove the lines
@@ -131,6 +133,14 @@
 
 static enum wt_status_format status_format = STATUS_FORMAT_UNSPECIFIED;
 
+static int opt_pass_trailer(const struct option *opt, const char *arg, int unset)
+{
+	BUG_ON_OPT_NEG(unset);
+
+	strvec_pushl(&trailer_args, "--trailer", arg, NULL);
+	return 0;
+}
+
 static int opt_parse_porcelain(const struct option *opt, const char *arg, int unset)
 {
 	enum wt_status_format *value = (enum wt_status_format *)opt->value;
@@ -357,7 +367,8 @@
 		die(_("--pathspec-file-nul requires --pathspec-from-file"));
 	}
 
-	if (!pathspec.nr && (also || (only && !amend && !allow_empty)))
+	if (!pathspec.nr && (also || (only && !allow_empty &&
+	    (!amend || (fixup_message && strcmp(fixup_prefix, "amend"))))))
 		die(_("No paths with --include/--only does not make sense."));
 
 	if (read_cache_preload(&pathspec) < 0)
@@ -681,6 +692,22 @@
 	comment_line_char = *p;
 }
 
+static void prepare_amend_commit(struct commit *commit, struct strbuf *sb,
+				struct pretty_print_context *ctx)
+{
+	const char *buffer, *subject, *fmt;
+
+	buffer = get_commit_buffer(commit, NULL);
+	find_commit_subject(buffer, &subject);
+	/*
+	 * If we amend the 'amend!' commit then we don't want to
+	 * duplicate the subject line.
+	 */
+	fmt = starts_with(subject, "amend!") ? "%b" : "%B";
+	format_commit_message(commit, fmt, sb, ctx);
+	unuse_commit_buffer(commit, buffer);
+}
+
 static int prepare_to_commit(const char *index_file, const char *prefix,
 			     struct commit *current_head,
 			     struct wt_status *s,
@@ -745,15 +772,33 @@
 	} else if (fixup_message) {
 		struct pretty_print_context ctx = {0};
 		struct commit *commit;
-		commit = lookup_commit_reference_by_name(fixup_message);
+		char *fmt;
+		commit = lookup_commit_reference_by_name(fixup_commit);
 		if (!commit)
-			die(_("could not lookup commit %s"), fixup_message);
+			die(_("could not lookup commit %s"), fixup_commit);
 		ctx.output_encoding = get_commit_output_encoding();
-		format_commit_message(commit, "fixup! %s\n\n",
-				      &sb, &ctx);
-		if (have_option_m)
-			strbuf_addbuf(&sb, &message);
+		fmt = xstrfmt("%s! %%s\n\n", fixup_prefix);
+		format_commit_message(commit, fmt, &sb, &ctx);
+		free(fmt);
 		hook_arg1 = "message";
+
+		/*
+		 * Only `-m` commit message option is checked here, as
+		 * it supports `--fixup` to append the commit message.
+		 *
+		 * The other commit message options `-c`/`-C`/`-F` are
+		 * incompatible with all the forms of `--fixup` and
+		 * have already errored out while parsing the `git commit`
+		 * options.
+		 */
+		if (have_option_m && !strcmp(fixup_prefix, "fixup"))
+			strbuf_addbuf(&sb, &message);
+
+		if (!strcmp(fixup_prefix, "amend")) {
+			if (have_option_m)
+				die(_("cannot combine -m with --fixup:%s"), fixup_message);
+			prepare_amend_commit(commit, &sb, &ctx);
+		}
 	} else if (!stat(git_path_merge_msg(the_repository), &statbuf)) {
 		size_t merge_msg_start;
 
@@ -958,6 +1003,18 @@
 
 	fclose(s->fp);
 
+	if (trailer_args.nr) {
+		struct child_process run_trailer = CHILD_PROCESS_INIT;
+
+		strvec_pushl(&run_trailer.args, "interpret-trailers",
+			     "--in-place", git_path_commit_editmsg(), NULL);
+		strvec_pushv(&run_trailer.args, trailer_args.v);
+		run_trailer.git_cmd = 1;
+		if (run_command(&run_trailer))
+			die(_("unable to pass trailers to --trailers"));
+		strvec_clear(&trailer_args);
+	}
+
 	/*
 	 * Reject an attempt to record a non-merge empty commit without
 	 * explicit --allow-empty. In the cherry-pick case, it may be
@@ -1152,6 +1209,19 @@
 		s->ahead_behind_flags = AHEAD_BEHIND_FULL;
 }
 
+static void check_fixup_reword_options(int argc, const char *argv[]) {
+	if (whence != FROM_COMMIT) {
+		if (whence == FROM_MERGE)
+			die(_("You are in the middle of a merge -- cannot reword."));
+		else if (is_from_cherry_pick(whence))
+			die(_("You are in the middle of a cherry-pick -- cannot reword."));
+	}
+	if (argc)
+		die(_("cannot combine reword option of --fixup with path '%s'"), *argv);
+	if (patch_interactive || interactive || all || also || only)
+		die(_("reword option of --fixup is mutually exclusive with --patch/--interactive/--all/--include/--only"));
+}
+
 static int parse_and_validate_options(int argc, const char *argv[],
 				      const struct option *options,
 				      const char * const usage[],
@@ -1170,7 +1240,7 @@
 	if (force_author && renew_authorship)
 		die(_("Using both --reset-author and --author does not make sense"));
 
-	if (logfile || have_option_m || use_message || fixup_message)
+	if (logfile || have_option_m || use_message)
 		use_editor = 0;
 	if (0 <= edit_flag)
 		use_editor = edit_flag;
@@ -1227,6 +1297,42 @@
 
 	if (also + only + all + interactive > 1)
 		die(_("Only one of --include/--only/--all/--interactive/--patch can be used."));
+
+	if (fixup_message) {
+		/*
+		 * We limit --fixup's suboptions to only alpha characters.
+		 * If the first character after a run of alpha is colon,
+		 * then the part before the colon may be a known suboption
+		 * name like `amend` or `reword`, or a misspelt suboption
+		 * name. In either case, we treat it as
+		 * --fixup=<suboption>:<arg>.
+		 *
+		 * Otherwise, we are dealing with --fixup=<commit>.
+		 */
+		char *p = fixup_message;
+		while (isalpha(*p))
+			p++;
+		if (p > fixup_message && *p == ':') {
+			*p = '\0';
+			fixup_commit = p + 1;
+			if (!strcmp("amend", fixup_message) ||
+			    !strcmp("reword", fixup_message)) {
+				fixup_prefix = "amend";
+				allow_empty = 1;
+				if (*fixup_message == 'r') {
+					check_fixup_reword_options(argc, argv);
+					only = 1;
+				}
+			} else {
+				die(_("unknown option: --fixup=%s:%s"), fixup_message, fixup_commit);
+			}
+		} else {
+			fixup_commit = fixup_message;
+			fixup_prefix = "fixup";
+			use_editor = 0;
+		}
+	}
+
 	cleanup_mode = get_cleanup_mode(cleanup_arg, use_editor);
 
 	handle_untracked_files_arg(s);
@@ -1504,9 +1610,14 @@
 		OPT_CALLBACK('m', "message", &message, N_("message"), N_("commit message"), opt_parse_m),
 		OPT_STRING('c', "reedit-message", &edit_message, N_("commit"), N_("reuse and edit message from specified commit")),
 		OPT_STRING('C', "reuse-message", &use_message, N_("commit"), N_("reuse message from specified commit")),
-		OPT_STRING(0, "fixup", &fixup_message, N_("commit"), N_("use autosquash formatted message to fixup specified commit")),
+		/*
+		 * TRANSLATORS: Leave "[(amend|reword):]" as-is,
+		 * and only translate <commit>.
+		 */
+		OPT_STRING(0, "fixup", &fixup_message, N_("[(amend|reword):]commit"), N_("use autosquash formatted message to fixup or amend/reword specified commit")),
 		OPT_STRING(0, "squash", &squash_message, N_("commit"), N_("use autosquash formatted message to squash specified commit")),
 		OPT_BOOL(0, "reset-author", &renew_authorship, N_("the commit is authored by me now (used with -C/-c/--amend)")),
+		OPT_CALLBACK_F(0, "trailer", NULL, N_("trailer"), N_("add custom trailer(s)"), PARSE_OPT_NONEG, opt_pass_trailer),
 		OPT_BOOL('s', "signoff", &signoff, N_("add a Signed-off-by trailer")),
 		OPT_FILENAME('t', "template", &template_file, N_("use specified template file")),
 		OPT_BOOL('e', "edit", &edit_flag, N_("force edit of commit")),
@@ -1663,6 +1774,19 @@
 		exit(1);
 	}
 
+	if (fixup_message && starts_with(sb.buf, "amend! ") &&
+	    !allow_empty_message) {
+		struct strbuf body = STRBUF_INIT;
+		size_t len = commit_subject_length(sb.buf);
+		strbuf_addstr(&body, sb.buf + len);
+		if (message_is_empty(&body, cleanup_mode)) {
+			rollback_index_files();
+			fprintf(stderr, _("Aborting commit due to empty commit message body.\n"));
+			exit(1);
+		}
+		strbuf_release(&body);
+	}
+
 	if (amend) {
 		const char *exclude_gpgsig[3] = { "gpgsig", "gpgsig-sha256", NULL };
 		extra = read_commit_extra_headers(current_head, exclude_gpgsig);
diff --git a/builtin/credential-cache--daemon.c b/builtin/credential-cache--daemon.c
index c61f123..4c6c89a 100644
--- a/builtin/credential-cache--daemon.c
+++ b/builtin/credential-cache--daemon.c
@@ -203,9 +203,10 @@
 
 static void serve_cache(const char *socket_path, int debug)
 {
+	struct unix_stream_listen_opts opts = UNIX_STREAM_LISTEN_OPTS_INIT;
 	int fd;
 
-	fd = unix_stream_listen(socket_path);
+	fd = unix_stream_listen(socket_path, &opts);
 	if (fd < 0)
 		die_errno("unable to bind to '%s'", socket_path);
 
diff --git a/builtin/credential-cache.c b/builtin/credential-cache.c
index 9b3f709..76a6ba3 100644
--- a/builtin/credential-cache.c
+++ b/builtin/credential-cache.c
@@ -14,7 +14,7 @@
 static int send_request(const char *socket, const struct strbuf *out)
 {
 	int got_data = 0;
-	int fd = unix_stream_connect(socket);
+	int fd = unix_stream_connect(socket, 0);
 
 	if (fd < 0)
 		return -1;
diff --git a/builtin/difftool.c b/builtin/difftool.c
index 6e18e62..ef25729 100644
--- a/builtin/difftool.c
+++ b/builtin/difftool.c
@@ -23,6 +23,7 @@
 #include "lockfile.h"
 #include "object-store.h"
 #include "dir.h"
+#include "entry.h"
 
 static int trust_exit_code;
 
diff --git a/builtin/fast-import.c b/builtin/fast-import.c
index dd4d09c..3afa81c 100644
--- a/builtin/fast-import.c
+++ b/builtin/fast-import.c
@@ -3322,7 +3322,7 @@
 		die(_("Expected format name:filename for submodule rewrite option"));
 	*f = '\0';
 	f++;
-	ms = xcalloc(1, sizeof(*ms));
+	CALLOC_ARRAY(ms, 1);
 
 	fp = fopen(f, "r");
 	if (!fp)
@@ -3519,9 +3519,9 @@
 
 	alloc_objects(object_entry_alloc);
 	strbuf_init(&command_buf, 0);
-	atom_table = xcalloc(atom_table_sz, sizeof(struct atom_str*));
-	branch_table = xcalloc(branch_table_sz, sizeof(struct branch*));
-	avail_tree_table = xcalloc(avail_tree_table_sz, sizeof(struct avail_tree_content*));
+	CALLOC_ARRAY(atom_table, atom_table_sz);
+	CALLOC_ARRAY(branch_table, branch_table_sz);
+	CALLOC_ARRAY(avail_tree_table, avail_tree_table_sz);
 	marks = mem_pool_calloc(&fi_mem_pool, 1, sizeof(struct mark_set));
 
 	hashmap_init(&object_table, object_entry_hashcmp, NULL, 0);
diff --git a/builtin/grep.c b/builtin/grep.c
index 4e91a25..5de725f 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -211,7 +211,7 @@
 		strbuf_init(&todo[i].out, 0);
 	}
 
-	threads = xcalloc(num_threads, sizeof(*threads));
+	CALLOC_ARRAY(threads, num_threads);
 	for (i = 0; i < num_threads; i++) {
 		int err;
 		struct grep_opt *o = grep_opt_dup(opt);
@@ -1181,6 +1181,5 @@
 		run_pager(&opt, prefix);
 	clear_pathspec(&pathspec);
 	free_grep_patterns(&opt);
-	grep_destroy();
 	return !hit;
 }
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 11f0faf..15507b5 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -185,7 +185,7 @@
 	if (show_stat)
 		pthread_mutex_init(&deepest_delta_mutex, NULL);
 	pthread_key_create(&key, NULL);
-	thread_data = xcalloc(nr_threads, sizeof(*thread_data));
+	CALLOC_ARRAY(thread_data, nr_threads);
 	for (i = 0; i < nr_threads; i++) {
 		thread_data[i].pack_fd = open(curr_pack, O_RDONLY);
 		if (thread_data[i].pack_fd == -1)
@@ -1675,7 +1675,7 @@
 	unsigned long *chain_histogram = NULL;
 
 	if (deepest_delta)
-		chain_histogram = xcalloc(deepest_delta, sizeof(unsigned long));
+		CALLOC_ARRAY(chain_histogram, deepest_delta);
 
 	for (i = 0; i < nr_objects; i++) {
 		struct object_entry *obj = &objects[i];
@@ -1897,10 +1897,10 @@
 
 	curr_pack = open_pack_file(pack_name);
 	parse_pack_header();
-	objects = xcalloc(st_add(nr_objects, 1), sizeof(struct object_entry));
+	CALLOC_ARRAY(objects, st_add(nr_objects, 1));
 	if (show_stat)
-		obj_stat = xcalloc(st_add(nr_objects, 1), sizeof(struct object_stat));
-	ofs_deltas = xcalloc(nr_objects, sizeof(struct ofs_delta_entry));
+		CALLOC_ARRAY(obj_stat, st_add(nr_objects, 1));
+	CALLOC_ARRAY(ofs_deltas, nr_objects);
 	parse_pack_objects(pack_hash);
 	if (report_end_of_input)
 		write_in_full(2, "\0", 1);
diff --git a/builtin/init-db.c b/builtin/init-db.c
index dcc45be..c19b35f 100644
--- a/builtin/init-db.c
+++ b/builtin/init-db.c
@@ -25,7 +25,6 @@
 
 static int init_is_bare_repository = 0;
 static int init_shared_repository = -1;
-static const char *init_db_template_dir;
 
 static void copy_templates_1(struct strbuf *path, struct strbuf *template_path,
 			     DIR *dir)
@@ -94,7 +93,7 @@
 	}
 }
 
-static void copy_templates(const char *template_dir)
+static void copy_templates(const char *template_dir, const char *init_template_dir)
 {
 	struct strbuf path = STRBUF_INIT;
 	struct strbuf template_path = STRBUF_INIT;
@@ -107,7 +106,7 @@
 	if (!template_dir)
 		template_dir = getenv(TEMPLATE_DIR_ENVIRONMENT);
 	if (!template_dir)
-		template_dir = init_db_template_dir;
+		template_dir = init_template_dir;
 	if (!template_dir)
 		template_dir = to_free = system_path(DEFAULT_GIT_TEMPLATE_DIR);
 	if (!template_dir[0]) {
@@ -154,17 +153,6 @@
 	clear_repository_format(&template_format);
 }
 
-static int git_init_db_config(const char *k, const char *v, void *cb)
-{
-	if (!strcmp(k, "init.templatedir"))
-		return git_config_pathname(&init_db_template_dir, k, v);
-
-	if (starts_with(k, "core."))
-		return platform_core_config(k, v, cb);
-
-	return 0;
-}
-
 /*
  * If the git_dir is not directly inside the working tree, then git will not
  * find it by default, and we need to set the worktree explicitly.
@@ -212,10 +200,8 @@
 	int reinit;
 	int filemode;
 	struct strbuf err = STRBUF_INIT;
-
-	/* Just look for `init.templatedir` */
-	init_db_template_dir = NULL; /* re-set in case it was set before */
-	git_config(git_init_db_config, NULL);
+	const char *init_template_dir = NULL;
+	const char *work_tree = get_git_work_tree();
 
 	/*
 	 * First copy the templates -- we might have the default
@@ -226,7 +212,8 @@
 	 * values (since we've just potentially changed what's available on
 	 * disk).
 	 */
-	copy_templates(template_path);
+	git_config_get_value("init.templatedir", &init_template_dir);
+	copy_templates(template_path, init_template_dir);
 	git_config_clear();
 	reset_shared_repository();
 	git_config(git_default_config, NULL);
@@ -235,7 +222,7 @@
 	 * We must make sure command-line options continue to override any
 	 * values we might have just re-read from the config.
 	 */
-	is_bare_repository_cfg = init_is_bare_repository;
+	is_bare_repository_cfg = init_is_bare_repository || !work_tree;
 	if (init_shared_repository != -1)
 		set_shared_repository(init_shared_repository);
 
@@ -299,7 +286,6 @@
 	if (is_bare_repository())
 		git_config_set("core.bare", "true");
 	else {
-		const char *work_tree = get_git_work_tree();
 		git_config_set("core.bare", "false");
 		/* allow template config file to override the default */
 		if (log_all_ref_updates == LOG_REFS_UNSET)
@@ -422,8 +408,8 @@
 	}
 	startup_info->have_repository = 1;
 
-	/* Just look for `core.hidedotfiles` */
-	git_config(git_init_db_config, NULL);
+	/* Ensure `core.hidedotfiles` is processed */
+	git_config(platform_core_config, NULL);
 
 	safe_create_dir(git_dir, 0);
 
@@ -575,8 +561,10 @@
 	if (real_git_dir && !is_absolute_path(real_git_dir))
 		real_git_dir = real_pathdup(real_git_dir, 1);
 
-	if (template_dir && *template_dir && !is_absolute_path(template_dir))
+	if (template_dir && *template_dir && !is_absolute_path(template_dir)) {
 		template_dir = absolute_pathdup(template_dir);
+		UNLEAK(template_dir);
+	}
 
 	if (argc == 1) {
 		int mkdir_tried = 0;
diff --git a/builtin/log.c b/builtin/log.c
index f67b67d..8acd285 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -599,7 +599,7 @@
 
 static int show_tree_object(const struct object_id *oid,
 		struct strbuf *base,
-		const char *pathname, unsigned mode, int stage, void *context)
+		const char *pathname, unsigned mode, void *context)
 {
 	FILE *file = context;
 	fprintf(file, "%s%s\n", pathname, S_ISDIR(mode) ? "/" : "");
@@ -681,9 +681,9 @@
 					diff_get_color_opt(&rev.diffopt, DIFF_COMMIT),
 					name,
 					diff_get_color_opt(&rev.diffopt, DIFF_RESET));
-			read_tree_recursive(the_repository, (struct tree *)o, "",
-					    0, 0, &match_all, show_tree_object,
-					    rev.diffopt.file);
+			read_tree(the_repository, (struct tree *)o,
+				  &match_all, show_tree_object,
+				  rev.diffopt.file);
 			rev.shown_one = 1;
 			break;
 		case OBJ_COMMIT:
@@ -1662,13 +1662,19 @@
 	oidclr(&bases->base_commit);
 }
 
-static const char *diff_title(struct strbuf *sb, int reroll_count,
-		       const char *generic, const char *rerolled)
+static const char *diff_title(struct strbuf *sb,
+			      const char *reroll_count,
+			      const char *generic,
+			      const char *rerolled)
 {
-	if (reroll_count <= 0)
+	int v;
+
+	/* RFC may be v0, so allow -v1 to diff against v0 */
+	if (reroll_count && !strtol_i(reroll_count, 10, &v) &&
+	    v >= 1)
+		strbuf_addf(sb, rerolled, v - 1);
+	else
 		strbuf_addstr(sb, generic);
-	else /* RFC may be v0, so allow -v1 to diff against v0 */
-		strbuf_addf(sb, rerolled, reroll_count - 1);
 	return sb->buf;
 }
 
@@ -1717,7 +1723,7 @@
 	struct strbuf buf = STRBUF_INIT;
 	int use_patch_format = 0;
 	int quiet = 0;
-	int reroll_count = -1;
+	const char *reroll_count = NULL;
 	char *cover_from_description_arg = NULL;
 	char *branch_name = NULL;
 	char *base_commit = NULL;
@@ -1751,7 +1757,7 @@
 			    N_("use <sfx> instead of '.patch'")),
 		OPT_INTEGER(0, "start-number", &start_number,
 			    N_("start numbering patches at <n> instead of 1")),
-		OPT_INTEGER('v', "reroll-count", &reroll_count,
+		OPT_STRING('v', "reroll-count", &reroll_count, N_("reroll-count"),
 			    N_("mark the series as Nth re-roll")),
 		OPT_INTEGER(0, "filename-max-length", &fmt_patch_name_max,
 			    N_("max length of output filename")),
@@ -1862,9 +1868,10 @@
 	if (cover_from_description_arg)
 		cover_from_description_mode = parse_cover_from_description(cover_from_description_arg);
 
-	if (0 < reroll_count) {
+	if (reroll_count) {
 		struct strbuf sprefix = STRBUF_INIT;
-		strbuf_addf(&sprefix, "%s v%d",
+
+		strbuf_addf(&sprefix, "%s v%s",
 			    rev.subject_prefix, reroll_count);
 		rev.reroll_count = reroll_count;
 		rev.subject_prefix = strbuf_detach(&sprefix, NULL);
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index f6f9e48..60a2913 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -12,6 +12,7 @@
 #include "dir.h"
 #include "builtin.h"
 #include "tree.h"
+#include "cache-tree.h"
 #include "parse-options.h"
 #include "resolve-undo.h"
 #include "string-list.h"
@@ -420,6 +421,53 @@
 	return common_prefix_len;
 }
 
+static int read_one_entry_opt(struct index_state *istate,
+			      const struct object_id *oid,
+			      struct strbuf *base,
+			      const char *pathname,
+			      unsigned mode, int opt)
+{
+	int len;
+	struct cache_entry *ce;
+
+	if (S_ISDIR(mode))
+		return READ_TREE_RECURSIVE;
+
+	len = strlen(pathname);
+	ce = make_empty_cache_entry(istate, base->len + len);
+
+	ce->ce_mode = create_ce_mode(mode);
+	ce->ce_flags = create_ce_flags(1);
+	ce->ce_namelen = base->len + len;
+	memcpy(ce->name, base->buf, base->len);
+	memcpy(ce->name + base->len, pathname, len+1);
+	oidcpy(&ce->oid, oid);
+	return add_index_entry(istate, ce, opt);
+}
+
+static int read_one_entry(const struct object_id *oid, struct strbuf *base,
+			  const char *pathname, unsigned mode,
+			  void *context)
+{
+	struct index_state *istate = context;
+	return read_one_entry_opt(istate, oid, base, pathname,
+				  mode,
+				  ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
+}
+
+/*
+ * This is used when the caller knows there is no existing entries at
+ * the stage that will conflict with the entry being added.
+ */
+static int read_one_entry_quick(const struct object_id *oid, struct strbuf *base,
+				const char *pathname, unsigned mode,
+				void *context)
+{
+	struct index_state *istate = context;
+	return read_one_entry_opt(istate, oid, base, pathname,
+				  mode, ADD_CACHE_JUST_APPEND);
+}
+
 /*
  * Read the tree specified with --with-tree option
  * (typically, HEAD) into stage #1 and then
@@ -436,6 +484,8 @@
 	struct pathspec pathspec;
 	struct cache_entry *last_stage0 = NULL;
 	int i;
+	read_tree_fn_t fn = NULL;
+	int err;
 
 	if (get_oid(tree_name, &oid))
 		die("tree-ish %s not found.", tree_name);
@@ -458,9 +508,32 @@
 			       PATHSPEC_PREFER_CWD, prefix, matchbuf);
 	} else
 		memset(&pathspec, 0, sizeof(pathspec));
-	if (read_tree(the_repository, tree, 1, &pathspec, istate))
+
+	/*
+	 * See if we have cache entry at the stage.  If so,
+	 * do it the original slow way, otherwise, append and then
+	 * sort at the end.
+	 */
+	for (i = 0; !fn && i < istate->cache_nr; i++) {
+		const struct cache_entry *ce = istate->cache[i];
+		if (ce_stage(ce) == 1)
+			fn = read_one_entry;
+	}
+
+	if (!fn)
+		fn = read_one_entry_quick;
+	err = read_tree(the_repository, tree, &pathspec, fn, istate);
+	if (err)
 		die("unable to read tree entries %s", tree_name);
 
+	/*
+	 * Sort the cache entry -- we need to nuke the cache tree, though.
+	 */
+	if (fn == read_one_entry_quick) {
+		cache_tree_free(&istate->cache_tree);
+		QSORT(istate->cache, istate->cache_nr, cmp_cache_name_compare);
+	}
+
 	for (i = 0; i < istate->cache_nr; i++) {
 		struct cache_entry *ce = istate->cache[i];
 		switch (ce_stage(ce)) {
diff --git a/builtin/ls-remote.c b/builtin/ls-remote.c
index ef60475..1794548 100644
--- a/builtin/ls-remote.c
+++ b/builtin/ls-remote.c
@@ -88,7 +88,7 @@
 
 	if (argc > 1) {
 		int i;
-		pattern = xcalloc(argc, sizeof(const char *));
+		CALLOC_ARRAY(pattern, argc);
 		for (i = 1; i < argc; i++) {
 			pattern[i - 1] = xstrfmt("*/%s", argv[i]);
 		}
@@ -124,8 +124,6 @@
 		int hash_algo = hash_algo_by_ptr(transport_get_hash_algo(transport));
 		repo_set_hash_algo(the_repository, hash_algo);
 	}
-	if (transport_disconnect(transport))
-		return 1;
 
 	if (!dest && !quiet)
 		fprintf(stderr, "From %s\n", *remote->url);
@@ -151,5 +149,7 @@
 	}
 
 	ref_array_clear(&ref_array);
+	if (transport_disconnect(transport))
+		return 1;
 	return status;
 }
diff --git a/builtin/ls-tree.c b/builtin/ls-tree.c
index 7cad3f2..3a44263 100644
--- a/builtin/ls-tree.c
+++ b/builtin/ls-tree.c
@@ -62,7 +62,7 @@
 }
 
 static int show_tree(const struct object_id *oid, struct strbuf *base,
-		const char *pathname, unsigned mode, int stage, void *context)
+		const char *pathname, unsigned mode, void *context)
 {
 	int retval = 0;
 	int baselen;
@@ -185,6 +185,6 @@
 	tree = parse_tree_indirect(&oid);
 	if (!tree)
 		die("not a tree object");
-	return !!read_tree_recursive(the_repository, tree, "", 0, 0,
-				     &pathspec, show_tree, NULL);
+	return !!read_tree(the_repository, tree,
+			   &pathspec, show_tree, NULL);
 }
diff --git a/builtin/merge.c b/builtin/merge.c
index eb00b27..3886195 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -210,7 +210,7 @@
 		exit(1);
 	}
 
-	ret = xcalloc(1, sizeof(struct strategy));
+	CALLOC_ARRAY(ret, 1);
 	ret->name = xstrdup(name);
 	ret->attr = NO_TRIVIAL;
 	return ret;
diff --git a/builtin/mv.c b/builtin/mv.c
index 7dac714..3fccdcb 100644
--- a/builtin/mv.c
+++ b/builtin/mv.c
@@ -221,7 +221,7 @@
 				}
 				argc += last - first;
 			}
-		} else if (!(ce = cache_file_exists(src, length, ignore_case))) {
+		} else if (!(ce = cache_file_exists(src, length, 0))) {
 			bad = _("not under version control");
 		} else if (ce_stage(ce)) {
 			bad = _("conflicted");
diff --git a/builtin/notes.c b/builtin/notes.c
index 08b8914..74bba39 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -730,7 +730,7 @@
 	else
 		oidclr(&parent_oid);
 
-	t = xcalloc(1, sizeof(struct notes_tree));
+	CALLOC_ARRAY(t, 1);
 	init_notes(t, "NOTES_MERGE_PARTIAL", combine_notes_overwrite, 0);
 
 	o->local_ref = local_ref_to_free =
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 6d62aaf..525c2d8 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -815,8 +815,8 @@
 	/* The offset of the first object of this chunk in the original
 	 * packfile. */
 	off_t original;
-	/* The offset of the first object of this chunk in the generated
-	 * packfile minus "original". */
+	/* The difference for "original" minus the offset of the first object of
+	 * this chunk in the generated packfile. */
 	off_t difference;
 } *reused_chunks;
 static int reused_chunks_nr;
@@ -1188,7 +1188,8 @@
 	return 1;
 }
 
-static int want_found_object(int exclude, struct packed_git *p)
+static int want_found_object(const struct object_id *oid, int exclude,
+			     struct packed_git *p)
 {
 	if (exclude)
 		return 1;
@@ -1204,27 +1205,82 @@
 	 * make sure no copy of this object appears in _any_ pack that makes us
 	 * to omit the object, so we need to check all the packs.
 	 *
-	 * We can however first check whether these options can possible matter;
+	 * We can however first check whether these options can possibly matter;
 	 * if they do not matter we know we want the object in generated pack.
 	 * Otherwise, we signal "-1" at the end to tell the caller that we do
 	 * not know either way, and it needs to check more packs.
 	 */
-	if (!ignore_packed_keep_on_disk &&
-	    !ignore_packed_keep_in_core &&
-	    (!local || !have_non_local_packs))
-		return 1;
 
+	/*
+	 * Objects in packs borrowed from elsewhere are discarded regardless of
+	 * if they appear in other packs that weren't borrowed.
+	 */
 	if (local && !p->pack_local)
 		return 0;
-	if (p->pack_local &&
-	    ((ignore_packed_keep_on_disk && p->pack_keep) ||
-	     (ignore_packed_keep_in_core && p->pack_keep_in_core)))
-		return 0;
+
+	/*
+	 * Then handle .keep first, as we have a fast(er) path there.
+	 */
+	if (ignore_packed_keep_on_disk || ignore_packed_keep_in_core) {
+		/*
+		 * Set the flags for the kept-pack cache to be the ones we want
+		 * to ignore.
+		 *
+		 * That is, if we are ignoring objects in on-disk keep packs,
+		 * then we want to search through the on-disk keep and ignore
+		 * the in-core ones.
+		 */
+		unsigned flags = 0;
+		if (ignore_packed_keep_on_disk)
+			flags |= ON_DISK_KEEP_PACKS;
+		if (ignore_packed_keep_in_core)
+			flags |= IN_CORE_KEEP_PACKS;
+
+		if (ignore_packed_keep_on_disk && p->pack_keep)
+			return 0;
+		if (ignore_packed_keep_in_core && p->pack_keep_in_core)
+			return 0;
+		if (has_object_kept_pack(oid, flags))
+			return 0;
+	}
+
+	/*
+	 * At this point we know definitively that either we don't care about
+	 * keep-packs, or the object is not in one. Keep checking other
+	 * conditions...
+	 */
+	if (!local || !have_non_local_packs)
+		return 1;
 
 	/* we don't know yet; keep looking for more packs */
 	return -1;
 }
 
+static int want_object_in_pack_one(struct packed_git *p,
+				   const struct object_id *oid,
+				   int exclude,
+				   struct packed_git **found_pack,
+				   off_t *found_offset)
+{
+	off_t offset;
+
+	if (p == *found_pack)
+		offset = *found_offset;
+	else
+		offset = find_pack_entry_one(oid->hash, p);
+
+	if (offset) {
+		if (!*found_pack) {
+			if (!is_pack_valid(p))
+				return -1;
+			*found_offset = offset;
+			*found_pack = p;
+		}
+		return want_found_object(oid, exclude, p);
+	}
+	return -1;
+}
+
 /*
  * Check whether we want the object in the pack (e.g., we do not want
  * objects found in non-local stores if the "--local" option was used).
@@ -1252,7 +1308,7 @@
 	 * are present we will determine the answer right now.
 	 */
 	if (*found_pack) {
-		want = want_found_object(exclude, *found_pack);
+		want = want_found_object(oid, exclude, *found_pack);
 		if (want != -1)
 			return want;
 	}
@@ -1260,51 +1316,20 @@
 	for (m = get_multi_pack_index(the_repository); m; m = m->next) {
 		struct pack_entry e;
 		if (fill_midx_entry(the_repository, oid, &e, m)) {
-			struct packed_git *p = e.p;
-			off_t offset;
-
-			if (p == *found_pack)
-				offset = *found_offset;
-			else
-				offset = find_pack_entry_one(oid->hash, p);
-
-			if (offset) {
-				if (!*found_pack) {
-					if (!is_pack_valid(p))
-						continue;
-					*found_offset = offset;
-					*found_pack = p;
-				}
-				want = want_found_object(exclude, p);
-				if (want != -1)
-					return want;
-			}
+			want = want_object_in_pack_one(e.p, oid, exclude, found_pack, found_offset);
+			if (want != -1)
+				return want;
 		}
 	}
 
 	list_for_each(pos, get_packed_git_mru(the_repository)) {
 		struct packed_git *p = list_entry(pos, struct packed_git, mru);
-		off_t offset;
-
-		if (p == *found_pack)
-			offset = *found_offset;
-		else
-			offset = find_pack_entry_one(oid->hash, p);
-
-		if (offset) {
-			if (!*found_pack) {
-				if (!is_pack_valid(p))
-					continue;
-				*found_offset = offset;
-				*found_pack = p;
-			}
-			want = want_found_object(exclude, p);
-			if (!exclude && want > 0)
-				list_move(&p->mru,
-					  get_packed_git_mru(the_repository));
-			if (want != -1)
-				return want;
-		}
+		want = want_object_in_pack_one(p, oid, exclude, found_pack, found_offset);
+		if (!exclude && want > 0)
+			list_move(&p->mru,
+				  get_packed_git_mru(the_repository));
+		if (want != -1)
+			return want;
 	}
 
 	if (uri_protocols.nr) {
@@ -1635,7 +1660,7 @@
 		}
 	}
 
-	it = xcalloc(1, sizeof(*it));
+	CALLOC_ARRAY(it, 1);
 	it->next = pbase_tree;
 	pbase_tree = it;
 
@@ -2096,7 +2121,7 @@
 		progress_state = start_progress(_("Counting objects"),
 						to_pack.nr_objects);
 
-	sorted_by_offset = xcalloc(to_pack.nr_objects, sizeof(struct object_entry *));
+	CALLOC_ARRAY(sorted_by_offset, to_pack.nr_objects);
 	for (i = 0; i < to_pack.nr_objects; i++)
 		sorted_by_offset[i] = to_pack.objects + i;
 	QSORT(sorted_by_offset, to_pack.nr_objects, pack_offset_sort);
@@ -2428,7 +2453,7 @@
 	struct unpacked *array;
 	unsigned long mem_usage = 0;
 
-	array = xcalloc(window, sizeof(struct unpacked));
+	CALLOC_ARRAY(array, window);
 
 	for (;;) {
 		struct object_entry *entry;
@@ -2665,7 +2690,7 @@
 	if (progress > pack_to_stdout)
 		fprintf_ln(stderr, _("Delta compression using up to %d threads"),
 			   delta_search_threads);
-	p = xcalloc(delta_search_threads, sizeof(*p));
+	CALLOC_ARRAY(p, delta_search_threads);
 
 	/* Partition the work amongst work threads. */
 	for (i = 0; i < delta_search_threads; i++) {
@@ -2986,6 +3011,191 @@
 	return git_default_config(k, v, cb);
 }
 
+/* Counters for trace2 output when in --stdin-packs mode. */
+static int stdin_packs_found_nr;
+static int stdin_packs_hints_nr;
+
+static int add_object_entry_from_pack(const struct object_id *oid,
+				      struct packed_git *p,
+				      uint32_t pos,
+				      void *_data)
+{
+	struct rev_info *revs = _data;
+	struct object_info oi = OBJECT_INFO_INIT;
+	off_t ofs;
+	enum object_type type;
+
+	display_progress(progress_state, ++nr_seen);
+
+	if (have_duplicate_entry(oid, 0))
+		return 0;
+
+	ofs = nth_packed_object_offset(p, pos);
+	if (!want_object_in_pack(oid, 0, &p, &ofs))
+		return 0;
+
+	oi.typep = &type;
+	if (packed_object_info(the_repository, p, ofs, &oi) < 0)
+		die(_("could not get type of object %s in pack %s"),
+		    oid_to_hex(oid), p->pack_name);
+	else if (type == OBJ_COMMIT) {
+		/*
+		 * commits in included packs are used as starting points for the
+		 * subsequent revision walk
+		 */
+		add_pending_oid(revs, NULL, oid, 0);
+	}
+
+	stdin_packs_found_nr++;
+
+	create_object_entry(oid, type, 0, 0, 0, p, ofs);
+
+	return 0;
+}
+
+static void show_commit_pack_hint(struct commit *commit, void *_data)
+{
+	/* nothing to do; commits don't have a namehash */
+}
+
+static void show_object_pack_hint(struct object *object, const char *name,
+				  void *_data)
+{
+	struct object_entry *oe = packlist_find(&to_pack, &object->oid);
+	if (!oe)
+		return;
+
+	/*
+	 * Our 'to_pack' list was constructed by iterating all objects packed in
+	 * included packs, and so doesn't have a non-zero hash field that you
+	 * would typically pick up during a reachability traversal.
+	 *
+	 * Make a best-effort attempt to fill in the ->hash and ->no_try_delta
+	 * here using a now in order to perhaps improve the delta selection
+	 * process.
+	 */
+	oe->hash = pack_name_hash(name);
+	oe->no_try_delta = name && no_try_delta(name);
+
+	stdin_packs_hints_nr++;
+}
+
+static int pack_mtime_cmp(const void *_a, const void *_b)
+{
+	struct packed_git *a = ((const struct string_list_item*)_a)->util;
+	struct packed_git *b = ((const struct string_list_item*)_b)->util;
+
+	/*
+	 * order packs by descending mtime so that objects are laid out
+	 * roughly as newest-to-oldest
+	 */
+	if (a->mtime < b->mtime)
+		return 1;
+	else if (b->mtime < a->mtime)
+		return -1;
+	else
+		return 0;
+}
+
+static void read_packs_list_from_stdin(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct string_list include_packs = STRING_LIST_INIT_DUP;
+	struct string_list exclude_packs = STRING_LIST_INIT_DUP;
+	struct string_list_item *item = NULL;
+
+	struct packed_git *p;
+	struct rev_info revs;
+
+	repo_init_revisions(the_repository, &revs, NULL);
+	/*
+	 * Use a revision walk to fill in the namehash of objects in the include
+	 * packs. To save time, we'll avoid traversing through objects that are
+	 * in excluded packs.
+	 *
+	 * That may cause us to avoid populating all of the namehash fields of
+	 * all included objects, but our goal is best-effort, since this is only
+	 * an optimization during delta selection.
+	 */
+	revs.no_kept_objects = 1;
+	revs.keep_pack_cache_flags |= IN_CORE_KEEP_PACKS;
+	revs.blob_objects = 1;
+	revs.tree_objects = 1;
+	revs.tag_objects = 1;
+	revs.ignore_missing_links = 1;
+
+	while (strbuf_getline(&buf, stdin) != EOF) {
+		if (!buf.len)
+			continue;
+
+		if (*buf.buf == '^')
+			string_list_append(&exclude_packs, buf.buf + 1);
+		else
+			string_list_append(&include_packs, buf.buf);
+
+		strbuf_reset(&buf);
+	}
+
+	string_list_sort(&include_packs);
+	string_list_sort(&exclude_packs);
+
+	for (p = get_all_packs(the_repository); p; p = p->next) {
+		const char *pack_name = pack_basename(p);
+
+		item = string_list_lookup(&include_packs, pack_name);
+		if (!item)
+			item = string_list_lookup(&exclude_packs, pack_name);
+
+		if (item)
+			item->util = p;
+	}
+
+	/*
+	 * First handle all of the excluded packs, marking them as kept in-core
+	 * so that later calls to add_object_entry() discards any objects that
+	 * are also found in excluded packs.
+	 */
+	for_each_string_list_item(item, &exclude_packs) {
+		struct packed_git *p = item->util;
+		if (!p)
+			die(_("could not find pack '%s'"), item->string);
+		p->pack_keep_in_core = 1;
+	}
+
+	/*
+	 * Order packs by ascending mtime; use QSORT directly to access the
+	 * string_list_item's ->util pointer, which string_list_sort() does not
+	 * provide.
+	 */
+	QSORT(include_packs.items, include_packs.nr, pack_mtime_cmp);
+
+	for_each_string_list_item(item, &include_packs) {
+		struct packed_git *p = item->util;
+		if (!p)
+			die(_("could not find pack '%s'"), item->string);
+		for_each_object_in_pack(p,
+					add_object_entry_from_pack,
+					&revs,
+					FOR_EACH_OBJECT_PACK_ORDER);
+	}
+
+	if (prepare_revision_walk(&revs))
+		die(_("revision walk setup failed"));
+	traverse_commit_list(&revs,
+			     show_commit_pack_hint,
+			     show_object_pack_hint,
+			     NULL);
+
+	trace2_data_intmax("pack-objects", the_repository, "stdin_packs_found",
+			   stdin_packs_found_nr);
+	trace2_data_intmax("pack-objects", the_repository, "stdin_packs_hints",
+			   stdin_packs_hints_nr);
+
+	strbuf_release(&buf);
+	string_list_clear(&include_packs, 0);
+	string_list_clear(&exclude_packs, 0);
+}
+
 static void read_object_list_from_stdin(void)
 {
 	char line[GIT_MAX_HEXSZ + 1 + PATH_MAX + 2];
@@ -3489,6 +3699,7 @@
 	struct strvec rp = STRVEC_INIT;
 	int rev_list_unpacked = 0, rev_list_all = 0, rev_list_reflog = 0;
 	int rev_list_index = 0;
+	int stdin_packs = 0;
 	struct string_list keep_pack_list = STRING_LIST_INIT_NODUP;
 	struct option pack_objects_options[] = {
 		OPT_SET_INT('q', "quiet", &progress,
@@ -3539,6 +3750,8 @@
 		OPT_SET_INT_F(0, "indexed-objects", &rev_list_index,
 			      N_("include objects referred to by the index"),
 			      1, PARSE_OPT_NONEG),
+		OPT_BOOL(0, "stdin-packs", &stdin_packs,
+			 N_("read packs from stdin")),
 		OPT_BOOL(0, "stdout", &pack_to_stdout,
 			 N_("output pack to stdout")),
 		OPT_BOOL(0, "include-tag", &include_tag,
@@ -3645,7 +3858,7 @@
 		use_internal_rev_list = 1;
 		strvec_push(&rp, "--indexed-objects");
 	}
-	if (rev_list_unpacked) {
+	if (rev_list_unpacked && !stdin_packs) {
 		use_internal_rev_list = 1;
 		strvec_push(&rp, "--unpacked");
 	}
@@ -3690,8 +3903,13 @@
 	if (filter_options.choice) {
 		if (!pack_to_stdout)
 			die(_("cannot use --filter without --stdout"));
+		if (stdin_packs)
+			die(_("cannot use --filter with --stdin-packs"));
 	}
 
+	if (stdin_packs && use_internal_rev_list)
+		die(_("cannot use internal rev list with --stdin-packs"));
+
 	/*
 	 * "soft" reasons not to use bitmaps - for on-disk repack by default we want
 	 *
@@ -3750,7 +3968,13 @@
 
 	if (progress)
 		progress_state = start_progress(_("Enumerating objects"), 0);
-	if (!use_internal_rev_list)
+	if (stdin_packs) {
+		/* avoids adding objects in excluded packs */
+		ignore_packed_keep_in_core = 1;
+		read_packs_list_from_stdin();
+		if (rev_list_unpacked)
+			add_unreachable_loose_objects();
+	} else if (!use_internal_rev_list)
 		read_object_list_from_stdin();
 	else {
 		get_object_list(rp.nr, rp.v);
diff --git a/builtin/pack-redundant.c b/builtin/pack-redundant.c
index 6e115a8..7102996 100644
--- a/builtin/pack-redundant.c
+++ b/builtin/pack-redundant.c
@@ -373,7 +373,7 @@
 		return;
 
 	/* prepare an array of packed_list for easier sorting */
-	ary = xcalloc(n, sizeof(struct pack_list *));
+	CALLOC_ARRAY(ary, n);
 	for (n = 0, p = *pl; p; p = p->next)
 		ary[n++] = p;
 
diff --git a/builtin/range-diff.c b/builtin/range-diff.c
index 78bc9fa..5031884 100644
--- a/builtin/range-diff.c
+++ b/builtin/range-diff.c
@@ -25,7 +25,7 @@
 	struct option range_diff_options[] = {
 		OPT_INTEGER(0, "creation-factor",
 			    &range_diff_opts.creation_factor,
-			    N_("Percentage by which creation is weighted")),
+			    N_("percentage by which creation is weighted")),
 		OPT_BOOL(0, "no-dual-color", &simple_color,
 			    N_("use simple diff colors")),
 		OPT_PASSTHRU_ARGV(0, "notes", &other_arg,
diff --git a/builtin/rebase.c b/builtin/rebase.c
index de400f9..783b526 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -100,7 +100,6 @@
 	char *strategy, *strategy_opts;
 	struct strbuf git_format_patch_opt;
 	int reschedule_failed_exec;
-	int use_legacy_rebase;
 	int reapply_cherry_picks;
 	int fork_point;
 };
@@ -1102,11 +1101,6 @@
 		return 0;
 	}
 
-	if (!strcmp(var, "rebase.usebuiltin")) {
-		opts->use_legacy_rebase = !git_config_bool(var, value);
-		return 0;
-	}
-
 	if (!strcmp(var, "rebase.backend")) {
 		return git_config_string(&opts->default_backend, var, value);
 	}
@@ -1441,11 +1435,6 @@
 	gpg_sign = options.gpg_sign_opt ? "" : NULL;
 	FREE_AND_NULL(options.gpg_sign_opt);
 
-	if (options.use_legacy_rebase ||
-	    !git_env_bool("GIT_TEST_REBASE_USE_BUILTIN", -1))
-		warning(_("the rebase.useBuiltin support has been removed!\n"
-			  "See its entry in 'git help config' for details."));
-
 	strbuf_reset(&buf);
 	strbuf_addf(&buf, "%s/applying", apply_dir());
 	if(file_exists(buf.buf))
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index d26040c..6bc12c8 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -358,7 +358,7 @@
 	char *p;
 	int len;
 
-	ref_pattern = xcalloc(1, sizeof(struct proc_receive_ref));
+	CALLOC_ARRAY(ref_pattern, 1);
 	p = strchr(prefix, ':');
 	if (p) {
 		while (prefix < p) {
@@ -1024,7 +1024,7 @@
 			}
 			if (new_report) {
 				if (!hint->report) {
-					hint->report = xcalloc(1, sizeof(struct ref_push_report));
+					CALLOC_ARRAY(hint->report, 1);
 					report = hint->report;
 				} else {
 					report = hint->report;
@@ -2313,11 +2313,9 @@
 	ALLOC_ARRAY(si->used_shallow, si->shallow->nr);
 	assign_shallow_commits_to_refs(si, si->used_shallow, NULL);
 
-	si->need_reachability_test =
-		xcalloc(si->shallow->nr, sizeof(*si->need_reachability_test));
-	si->reachable =
-		xcalloc(si->shallow->nr, sizeof(*si->reachable));
-	si->shallow_ref = xcalloc(si->ref->nr, sizeof(*si->shallow_ref));
+	CALLOC_ARRAY(si->need_reachability_test, si->shallow->nr);
+	CALLOC_ARRAY(si->reachable, si->shallow->nr);
+	CALLOC_ARRAY(si->shallow_ref, si->ref->nr);
 
 	for (i = 0; i < si->nr_ours; i++)
 		si->need_reachability_test[si->ours[i]] = 1;
diff --git a/builtin/remote.c b/builtin/remote.c
index d11a558..7f88e6c 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -221,7 +221,7 @@
 
 	if (fetch_tags != TAGS_DEFAULT) {
 		strbuf_reset(&buf);
-		strbuf_addf(&buf, "remote.%s.tagopt", name);
+		strbuf_addf(&buf, "remote.%s.tagOpt", name);
 		git_config_set(buf.buf,
 			       fetch_tags == TAGS_SET ? "--tags" : "--no-tags");
 	}
@@ -746,7 +746,7 @@
 		}
 		if (info->push_remote_name && !strcmp(info->push_remote_name, rename.old_name)) {
 			strbuf_reset(&buf);
-			strbuf_addf(&buf, "branch.%s.pushremote", item->string);
+			strbuf_addf(&buf, "branch.%s.pushRemote", item->string);
 			git_config_set(buf.buf, rename.new_name);
 		}
 	}
@@ -938,9 +938,6 @@
 				 struct ref_states *states,
 				 int query)
 {
-	struct transport *transport;
-	const struct ref *remote_refs;
-
 	states->remote = remote_get(name);
 	if (!states->remote)
 		return error(_("No such remote: '%s'"), name);
@@ -948,10 +945,12 @@
 	read_branches();
 
 	if (query) {
+		struct transport *transport;
+		const struct ref *remote_refs;
+
 		transport = transport_get(states->remote, states->remote->url_nr > 0 ?
 			states->remote->url[0] : NULL);
 		remote_refs = transport_get_remote_refs(transport, NULL);
-		transport_disconnect(transport);
 
 		states->queried = 1;
 		if (query & GET_REF_STATES)
@@ -960,6 +959,7 @@
 			get_head_names(remote_refs, states);
 		if (query & GET_PUSH_REF_STATES)
 			get_push_ref_states(remote_refs, states);
+		transport_disconnect(transport);
 	} else {
 		for_each_ref(append_ref_to_tracked_list, states);
 		string_list_sort(&states->tracked);
diff --git a/builtin/repack.c b/builtin/repack.c
index 01440de..6ce2556 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -297,6 +297,142 @@
 #define ALL_INTO_ONE 1
 #define LOOSEN_UNREACHABLE 2
 
+struct pack_geometry {
+	struct packed_git **pack;
+	uint32_t pack_nr, pack_alloc;
+	uint32_t split;
+};
+
+static uint32_t geometry_pack_weight(struct packed_git *p)
+{
+	if (open_pack_index(p))
+		die(_("cannot open index for %s"), p->pack_name);
+	return p->num_objects;
+}
+
+static int geometry_cmp(const void *va, const void *vb)
+{
+	uint32_t aw = geometry_pack_weight(*(struct packed_git **)va),
+		 bw = geometry_pack_weight(*(struct packed_git **)vb);
+
+	if (aw < bw)
+		return -1;
+	if (aw > bw)
+		return 1;
+	return 0;
+}
+
+static void init_pack_geometry(struct pack_geometry **geometry_p)
+{
+	struct packed_git *p;
+	struct pack_geometry *geometry;
+
+	*geometry_p = xcalloc(1, sizeof(struct pack_geometry));
+	geometry = *geometry_p;
+
+	for (p = get_all_packs(the_repository); p; p = p->next) {
+		if (!pack_kept_objects && p->pack_keep)
+			continue;
+
+		ALLOC_GROW(geometry->pack,
+			   geometry->pack_nr + 1,
+			   geometry->pack_alloc);
+
+		geometry->pack[geometry->pack_nr] = p;
+		geometry->pack_nr++;
+	}
+
+	QSORT(geometry->pack, geometry->pack_nr, geometry_cmp);
+}
+
+static void split_pack_geometry(struct pack_geometry *geometry, int factor)
+{
+	uint32_t i;
+	uint32_t split;
+	off_t total_size = 0;
+
+	if (!geometry->pack_nr) {
+		geometry->split = geometry->pack_nr;
+		return;
+	}
+
+	/*
+	 * First, count the number of packs (in descending order of size) which
+	 * already form a geometric progression.
+	 */
+	for (i = geometry->pack_nr - 1; i > 0; i--) {
+		struct packed_git *ours = geometry->pack[i];
+		struct packed_git *prev = geometry->pack[i - 1];
+
+		if (unsigned_mult_overflows(factor, geometry_pack_weight(prev)))
+			die(_("pack %s too large to consider in geometric "
+			      "progression"),
+			    prev->pack_name);
+
+		if (geometry_pack_weight(ours) < factor * geometry_pack_weight(prev))
+			break;
+	}
+
+	split = i;
+
+	if (split) {
+		/*
+		 * Move the split one to the right, since the top element in the
+		 * last-compared pair can't be in the progression. Only do this
+		 * when we split in the middle of the array (otherwise if we got
+		 * to the end, then the split is in the right place).
+		 */
+		split++;
+	}
+
+	/*
+	 * Then, anything to the left of 'split' must be in a new pack. But,
+	 * creating that new pack may cause packs in the heavy half to no longer
+	 * form a geometric progression.
+	 *
+	 * Compute an expected size of the new pack, and then determine how many
+	 * packs in the heavy half need to be joined into it (if any) to restore
+	 * the geometric progression.
+	 */
+	for (i = 0; i < split; i++) {
+		struct packed_git *p = geometry->pack[i];
+
+		if (unsigned_add_overflows(total_size, geometry_pack_weight(p)))
+			die(_("pack %s too large to roll up"), p->pack_name);
+		total_size += geometry_pack_weight(p);
+	}
+	for (i = split; i < geometry->pack_nr; i++) {
+		struct packed_git *ours = geometry->pack[i];
+
+		if (unsigned_mult_overflows(factor, total_size))
+			die(_("pack %s too large to roll up"), ours->pack_name);
+
+		if (geometry_pack_weight(ours) < factor * total_size) {
+			if (unsigned_add_overflows(total_size,
+						   geometry_pack_weight(ours)))
+				die(_("pack %s too large to roll up"),
+				    ours->pack_name);
+
+			split++;
+			total_size += geometry_pack_weight(ours);
+		} else
+			break;
+	}
+
+	geometry->split = split;
+}
+
+static void clear_pack_geometry(struct pack_geometry *geometry)
+{
+	if (!geometry)
+		return;
+
+	free(geometry->pack);
+	geometry->pack_nr = 0;
+	geometry->pack_alloc = 0;
+	geometry->split = 0;
+}
+
 int cmd_repack(int argc, const char **argv, const char *prefix)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
@@ -304,6 +440,7 @@
 	struct string_list names = STRING_LIST_INIT_DUP;
 	struct string_list rollback = STRING_LIST_INIT_NODUP;
 	struct string_list existing_packs = STRING_LIST_INIT_DUP;
+	struct pack_geometry *geometry = NULL;
 	struct strbuf line = STRBUF_INIT;
 	int i, ext, ret;
 	FILE *out;
@@ -316,6 +453,7 @@
 	struct string_list keep_pack_list = STRING_LIST_INIT_NODUP;
 	int no_update_server_info = 0;
 	struct pack_objects_args po_args = {NULL};
+	int geometric_factor = 0;
 
 	struct option builtin_repack_options[] = {
 		OPT_BIT('a', NULL, &pack_everything,
@@ -356,6 +494,8 @@
 				N_("repack objects in packs marked with .keep")),
 		OPT_STRING_LIST(0, "keep-pack", &keep_pack_list, N_("name"),
 				N_("do not repack this pack")),
+		OPT_INTEGER('g', "geometric", &geometric_factor,
+			    N_("find a geometric progression with factor <N>")),
 		OPT_END()
 	};
 
@@ -382,6 +522,13 @@
 	if (write_bitmaps && !(pack_everything & ALL_INTO_ONE))
 		die(_(incremental_bitmap_conflict_error));
 
+	if (geometric_factor) {
+		if (pack_everything)
+			die(_("--geometric is incompatible with -A, -a"));
+		init_pack_geometry(&geometry);
+		split_pack_geometry(geometry, geometric_factor);
+	}
+
 	packdir = mkpathdup("%s/pack", get_object_directory());
 	packtmp = mkpathdup("%s/.tmp-%d-pack", packdir, (int)getpid());
 
@@ -396,9 +543,21 @@
 		strvec_pushf(&cmd.args, "--keep-pack=%s",
 			     keep_pack_list.items[i].string);
 	strvec_push(&cmd.args, "--non-empty");
-	strvec_push(&cmd.args, "--all");
-	strvec_push(&cmd.args, "--reflog");
-	strvec_push(&cmd.args, "--indexed-objects");
+	if (!geometry) {
+		/*
+		 * We need to grab all reachable objects, including those that
+		 * are reachable from reflogs and the index.
+		 *
+		 * When repacking into a geometric progression of packs,
+		 * however, we ask 'git pack-objects --stdin-packs', and it is
+		 * not about packing objects based on reachability but about
+		 * repacking all the objects in specified packs and loose ones
+		 * (indeed, --stdin-packs is incompatible with these options).
+		 */
+		strvec_push(&cmd.args, "--all");
+		strvec_push(&cmd.args, "--reflog");
+		strvec_push(&cmd.args, "--indexed-objects");
+	}
 	if (has_promisor_remote())
 		strvec_push(&cmd.args, "--exclude-promisor-objects");
 	if (write_bitmaps > 0)
@@ -429,17 +588,37 @@
 				strvec_push(&cmd.env_array, "GIT_REF_PARANOIA=1");
 			}
 		}
+	} else if (geometry) {
+		strvec_push(&cmd.args, "--stdin-packs");
+		strvec_push(&cmd.args, "--unpacked");
 	} else {
 		strvec_push(&cmd.args, "--unpacked");
 		strvec_push(&cmd.args, "--incremental");
 	}
 
-	cmd.no_stdin = 1;
+	if (geometry)
+		cmd.in = -1;
+	else
+		cmd.no_stdin = 1;
 
 	ret = start_command(&cmd);
 	if (ret)
 		return ret;
 
+	if (geometry) {
+		FILE *in = xfdopen(cmd.in, "w");
+		/*
+		 * The resulting pack should contain all objects in packs that
+		 * are going to be rolled up, but exclude objects in packs which
+		 * are being left alone.
+		 */
+		for (i = 0; i < geometry->split; i++)
+			fprintf(in, "%s\n", pack_basename(geometry->pack[i]));
+		for (i = geometry->split; i < geometry->pack_nr; i++)
+			fprintf(in, "^%s\n", pack_basename(geometry->pack[i]));
+		fclose(in);
+	}
+
 	out = xfdopen(cmd.out, "r");
 	while (strbuf_getline_lf(&line, out) != EOF) {
 		if (line.len != the_hash_algo->hexsz)
@@ -507,6 +686,25 @@
 			if (!string_list_has_string(&names, sha1))
 				remove_redundant_pack(packdir, item->string);
 		}
+
+		if (geometry) {
+			struct strbuf buf = STRBUF_INIT;
+
+			uint32_t i;
+			for (i = 0; i < geometry->split; i++) {
+				struct packed_git *p = geometry->pack[i];
+				if (string_list_has_string(&names,
+							   hash_to_hex(p->hash)))
+					continue;
+
+				strbuf_reset(&buf);
+				strbuf_addstr(&buf, pack_basename(p));
+				strbuf_strip_suffix(&buf, ".pack");
+
+				remove_redundant_pack(packdir, buf.buf);
+			}
+			strbuf_release(&buf);
+		}
 		if (!po_args.quiet && isatty(2))
 			opts |= PRUNE_PACKED_VERBOSE;
 		prune_packed_objects(opts);
@@ -528,6 +726,7 @@
 	string_list_clear(&names, 0);
 	string_list_clear(&rollback, 0);
 	string_list_clear(&existing_packs, 0);
+	clear_pack_geometry(geometry);
 	strbuf_release(&line);
 
 	return 0;
diff --git a/builtin/reset.c b/builtin/reset.c
index c635b06..43e855c 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -425,7 +425,7 @@
 
 			dwim_ref(rev, strlen(rev), &dummy, &ref, 0);
 			if (ref && !starts_with(ref, "refs/"))
-				ref = NULL;
+				FREE_AND_NULL(ref);
 
 			err = reset_index(ref, &oid, reset_type, quiet);
 			if (reset_type == KEEP && !err)
diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index 2306a9a..d7da50a 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -64,7 +64,7 @@
 	pl.use_cone_patterns = core_sparse_checkout_cone;
 
 	sparse_filename = get_sparse_checkout_filename();
-	res = add_patterns_from_file_to_list(sparse_filename, "", 0, &pl, NULL);
+	res = add_patterns_from_file_to_list(sparse_filename, "", 0, &pl, NULL, 0);
 	free(sparse_filename);
 
 	if (res < 0) {
@@ -321,7 +321,7 @@
 	memset(&pl, 0, sizeof(pl));
 
 	sparse_filename = get_sparse_checkout_filename();
-	res = add_patterns_from_file_to_list(sparse_filename, "", 0, &pl, NULL);
+	res = add_patterns_from_file_to_list(sparse_filename, "", 0, &pl, NULL, 0);
 
 	/* If we already have a sparse-checkout file, use it. */
 	if (res >= 0) {
@@ -483,7 +483,7 @@
 	existing.use_cone_patterns = core_sparse_checkout_cone;
 
 	if (add_patterns_from_file_to_list(sparse_filename, "", 0,
-					   &existing, NULL))
+					   &existing, NULL, 0))
 		die(_("unable to load existing sparse-checkout patterns"));
 	free(sparse_filename);
 
@@ -507,7 +507,7 @@
 {
 	char *sparse_filename = get_sparse_checkout_filename();
 	if (add_patterns_from_file_to_list(sparse_filename, "", 0,
-					   pl, NULL))
+					   pl, NULL, 0))
 		die(_("unable to load existing sparse-checkout patterns"));
 	free(sparse_filename);
 	add_patterns_from_input(pl, argc, argv);
diff --git a/builtin/stash.c b/builtin/stash.c
index ba774cc..c56fed3 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -10,11 +10,13 @@
 #include "strvec.h"
 #include "run-command.h"
 #include "dir.h"
+#include "entry.h"
 #include "rerere.h"
 #include "revision.h"
 #include "log-tree.h"
 #include "diffcore.h"
 #include "exec-cmd.h"
+#include "entry.h"
 
 #define INCLUDE_ALL_FILES 2
 
@@ -768,6 +770,7 @@
 
 static int show_stat = 1;
 static int show_patch;
+static int show_include_untracked;
 static int use_legacy_stash;
 
 static int git_stash_config(const char *var, const char *value, void *cb)
@@ -780,6 +783,10 @@
 		show_patch = git_config_bool(var, value);
 		return 0;
 	}
+	if (!strcmp(var, "stash.showincludeuntracked")) {
+		show_include_untracked = git_config_bool(var, value);
+		return 0;
+	}
 	if (!strcmp(var, "stash.usebuiltin")) {
 		use_legacy_stash = !git_config_bool(var, value);
 		return 0;
@@ -787,6 +794,33 @@
 	return git_diff_basic_config(var, value, cb);
 }
 
+static void diff_include_untracked(const struct stash_info *info, struct diff_options *diff_opt)
+{
+	const struct object_id *oid[] = { &info->w_commit, &info->u_tree };
+	struct tree *tree[ARRAY_SIZE(oid)];
+	struct tree_desc tree_desc[ARRAY_SIZE(oid)];
+	struct unpack_trees_options unpack_tree_opt = { 0 };
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(oid); i++) {
+		tree[i] = parse_tree_indirect(oid[i]);
+		if (parse_tree(tree[i]) < 0)
+			die(_("failed to parse tree"));
+		init_tree_desc(&tree_desc[i], tree[i]->buffer, tree[i]->size);
+	}
+
+	unpack_tree_opt.head_idx = -1;
+	unpack_tree_opt.src_index = &the_index;
+	unpack_tree_opt.dst_index = &the_index;
+	unpack_tree_opt.merge = 1;
+	unpack_tree_opt.fn = stash_worktree_untracked_merge;
+
+	if (unpack_trees(ARRAY_SIZE(tree_desc), tree_desc, &unpack_tree_opt))
+		die(_("failed to unpack trees"));
+
+	do_diff_cache(&info->b_commit, diff_opt);
+}
+
 static int show_stash(int argc, const char **argv, const char *prefix)
 {
 	int i;
@@ -795,7 +829,18 @@
 	struct rev_info rev;
 	struct strvec stash_args = STRVEC_INIT;
 	struct strvec revision_args = STRVEC_INIT;
+	enum {
+		UNTRACKED_NONE,
+		UNTRACKED_INCLUDE,
+		UNTRACKED_ONLY
+	} show_untracked = UNTRACKED_NONE;
 	struct option options[] = {
+		OPT_SET_INT('u', "include-untracked", &show_untracked,
+			    N_("include untracked files in the stash"),
+			    UNTRACKED_INCLUDE),
+		OPT_SET_INT_F(0, "only-untracked", &show_untracked,
+			      N_("only show untracked files in the stash"),
+			      UNTRACKED_ONLY, PARSE_OPT_NONEG),
 		OPT_END()
 	};
 
@@ -803,6 +848,10 @@
 	git_config(git_diff_ui_config, NULL);
 	init_revisions(&rev, prefix);
 
+	argc = parse_options(argc, argv, prefix, options, git_stash_show_usage,
+			     PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN |
+			     PARSE_OPT_KEEP_DASHDASH);
+
 	strvec_push(&revision_args, argv[0]);
 	for (i = 1; i < argc; i++) {
 		if (argv[i][0] != '-')
@@ -827,6 +876,9 @@
 		if (show_patch)
 			rev.diffopt.output_format |= DIFF_FORMAT_PATCH;
 
+		if (show_include_untracked)
+			show_untracked = UNTRACKED_INCLUDE;
+
 		if (!show_stat && !show_patch) {
 			free_stash_info(&info);
 			return 0;
@@ -845,7 +897,17 @@
 
 	rev.diffopt.flags.recursive = 1;
 	setup_diff_pager(&rev.diffopt);
-	diff_tree_oid(&info.b_commit, &info.w_commit, "", &rev.diffopt);
+	switch (show_untracked) {
+	case UNTRACKED_NONE:
+		diff_tree_oid(&info.b_commit, &info.w_commit, "", &rev.diffopt);
+		break;
+	case UNTRACKED_ONLY:
+		diff_root_tree_oid(&info.u_tree, "", &rev.diffopt);
+		break;
+	case UNTRACKED_INCLUDE:
+		diff_include_untracked(&info, &rev.diffopt);
+		break;
+	}
 	log_tree_diff_flush(&rev);
 
 	free_stash_info(&info);
diff --git a/builtin/symbolic-ref.c b/builtin/symbolic-ref.c
index 80237f0..e547a08 100644
--- a/builtin/symbolic-ref.c
+++ b/builtin/symbolic-ref.c
@@ -24,9 +24,11 @@
 			return 1;
 	}
 	if (print) {
+		char *to_free = NULL;
 		if (shorten)
-			refname = shorten_unambiguous_ref(refname, 0);
+			refname = to_free = shorten_unambiguous_ref(refname, 0);
 		puts(refname);
+		free(to_free);
 	}
 	return 0;
 }
diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
index ca54fd1..4a70b17 100644
--- a/builtin/unpack-objects.c
+++ b/builtin/unpack-objects.c
@@ -46,7 +46,7 @@
 static void add_object_buffer(struct object *object, char *buffer, unsigned long size)
 {
 	struct obj_buffer *obj;
-	obj = xcalloc(1, sizeof(struct obj_buffer));
+	CALLOC_ARRAY(obj, 1);
 	obj->buffer = buffer;
 	obj->size = size;
 	if (add_decoration(&obj_decorate, object, obj))
@@ -501,7 +501,7 @@
 
 	if (!quiet)
 		progress = start_progress(_("Unpacking objects"), nr_objects);
-	obj_list = xcalloc(nr_objects, sizeof(*obj_list));
+	CALLOC_ARRAY(obj_list, nr_objects);
 	for (i = 0; i < nr_objects; i++) {
 		unpack_one(i);
 		display_progress(progress, i + 1);
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 1cd5c20..8771453 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -446,16 +446,18 @@
 static const char *dwim_branch(const char *path, const char **new_branch)
 {
 	int n;
+	int branch_exists;
 	const char *s = worktree_basename(path, &n);
 	const char *branchname = xstrndup(s, n);
 	struct strbuf ref = STRBUF_INIT;
 
 	UNLEAK(branchname);
-	if (!strbuf_check_branch_ref(&ref, branchname) &&
-	    ref_exists(ref.buf)) {
-		strbuf_release(&ref);
+
+	branch_exists = !strbuf_check_branch_ref(&ref, branchname) &&
+			ref_exists(ref.buf);
+	strbuf_release(&ref);
+	if (branch_exists)
 		return branchname;
-	}
 
 	*new_branch = branchname;
 	if (guess_remote) {
diff --git a/bulk-checkin.c b/bulk-checkin.c
index 583aacb..6f3c97c 100644
--- a/bulk-checkin.c
+++ b/bulk-checkin.c
@@ -211,7 +211,7 @@
 
 	/* Note: idx is non-NULL when we are writing */
 	if ((flags & HASH_WRITE_OBJECT) != 0)
-		idx = xcalloc(1, sizeof(*idx));
+		CALLOC_ARRAY(idx, 1);
 
 	already_hashed_to = 0;
 
diff --git a/cache-tree.c b/cache-tree.c
index 2fb483d..add1f07 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -564,7 +564,7 @@
 	 * hence +2.
 	 */
 	it->subtree_alloc = subtree_nr + 2;
-	it->down = xcalloc(it->subtree_alloc, sizeof(struct cache_tree_sub *));
+	CALLOC_ARRAY(it->down, it->subtree_alloc);
 	for (i = 0; i < subtree_nr; i++) {
 		/* read each subtree */
 		struct cache_tree *sub;
diff --git a/cache.h b/cache.h
index 6fda809..148d9ab 100644
--- a/cache.h
+++ b/cache.h
@@ -803,7 +803,7 @@
 #define ADD_CACHE_OK_TO_ADD 1		/* Ok to add */
 #define ADD_CACHE_OK_TO_REPLACE 2	/* Ok to replace file/directory */
 #define ADD_CACHE_SKIP_DFCHECK 4	/* Ok to skip DF conflict checks */
-#define ADD_CACHE_JUST_APPEND 8		/* Append only; tree.c::read_tree() */
+#define ADD_CACHE_JUST_APPEND 8		/* Append only */
 #define ADD_CACHE_NEW_ONLY 16		/* Do not replace existing ones */
 #define ADD_CACHE_KEEP_CACHE_TREE 32	/* Do not invalidate cache-tree */
 #define ADD_CACHE_RENORMALIZE 64        /* Pass along HASH_RENORMALIZE */
@@ -1621,30 +1621,6 @@
  */
 int ident_cmp(const struct ident_split *, const struct ident_split *);
 
-struct checkout {
-	struct index_state *istate;
-	const char *base_dir;
-	int base_dir_len;
-	struct delayed_checkout *delayed_checkout;
-	struct checkout_metadata meta;
-	unsigned force:1,
-		 quiet:1,
-		 not_new:1,
-		 clone:1,
-		 refresh_cache:1;
-};
-#define CHECKOUT_INIT { NULL, "" }
-
-#define TEMPORARY_FILENAME_LENGTH 25
-int checkout_entry(struct cache_entry *ce, const struct checkout *state, char *topath, int *nr_checkouts);
-void enable_delayed_checkout(struct checkout *state);
-int finish_delayed_checkout(struct checkout *state, int *nr_checkouts);
-/*
- * Unlink the last component and schedule the leading directories for
- * removal, such that empty directories get removed.
- */
-void unlink_entry(const struct cache_entry *ce);
-
 struct cache_def {
 	struct strbuf path;
 	int flags;
@@ -1659,7 +1635,7 @@
 
 int has_symlink_leading_path(const char *name, int len);
 int threaded_has_symlink_leading_path(struct cache_def *, const char *, int);
-int check_leading_path(const char *name, int len);
+int check_leading_path(const char *name, int len, int warn_on_lstat_err);
 int has_dirs_only_path(const char *name, int len, int prefix_len);
 void invalidate_lstat_cache(void);
 void schedule_dir_for_removal(const char *name, int len);
diff --git a/combine-diff.c b/combine-diff.c
index 9228aeb..06635f9 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -214,11 +214,11 @@
 	 *   - Else if we have NEW, insert newend lline into base and
 	 *   consume newend
 	 */
-	lcs = xcalloc(st_add(origbaselen, 1), sizeof(int*));
-	directions = xcalloc(st_add(origbaselen, 1), sizeof(enum coalesce_direction*));
+	CALLOC_ARRAY(lcs, st_add(origbaselen, 1));
+	CALLOC_ARRAY(directions, st_add(origbaselen, 1));
 	for (i = 0; i < origbaselen + 1; i++) {
-		lcs[i] = xcalloc(st_add(lennew, 1), sizeof(int));
-		directions[i] = xcalloc(st_add(lennew, 1), sizeof(enum coalesce_direction));
+		CALLOC_ARRAY(lcs[i], st_add(lennew, 1));
+		CALLOC_ARRAY(directions[i], st_add(lennew, 1));
 		directions[i][0] = BASE;
 	}
 	for (j = 1; j < lennew + 1; j++)
@@ -398,8 +398,8 @@
 		state->lost_bucket = &state->sline[state->nb-1];
 	}
 	if (!state->sline[state->nb-1].p_lno)
-		state->sline[state->nb-1].p_lno =
-			xcalloc(state->num_parent, sizeof(unsigned long));
+		CALLOC_ARRAY(state->sline[state->nb - 1].p_lno,
+			     state->num_parent);
 	state->sline[state->nb-1].p_lno[state->n] = state->ob;
 }
 
@@ -1159,7 +1159,7 @@
 	if (result_size && result[result_size-1] != '\n')
 		cnt++; /* incomplete line */
 
-	sline = xcalloc(st_add(cnt, 2), sizeof(*sline));
+	CALLOC_ARRAY(sline, st_add(cnt, 2));
 	sline[0].bol = result;
 	for (lno = 0, cp = result; cp < result + result_size; cp++) {
 		if (*cp == '\n') {
@@ -1178,7 +1178,7 @@
 	/* Even p_lno[cnt+1] is valid -- that is for the end line number
 	 * for deletion hunk at the end.
 	 */
-	sline[0].p_lno = xcalloc(st_mult(st_add(cnt, 2), num_parent), sizeof(unsigned long));
+	CALLOC_ARRAY(sline[0].p_lno, st_mult(st_add(cnt, 2), num_parent));
 	for (lno = 0; lno <= cnt; lno++)
 		sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
 
@@ -1319,7 +1319,7 @@
 	struct diff_filespec *pool;
 
 	pair = xmalloc(sizeof(*pair));
-	pool = xcalloc(st_add(num_parent, 1), sizeof(struct diff_filespec));
+	CALLOC_ARRAY(pool, st_add(num_parent, 1));
 	pair->one = pool + 1;
 	pair->two = pool;
 
@@ -1348,7 +1348,7 @@
 	struct diff_queue_struct q;
 	int i;
 
-	q.queue = xcalloc(num_paths, sizeof(struct diff_filepair *));
+	CALLOC_ARRAY(q.queue, num_paths);
 	q.alloc = num_paths;
 	q.nr = num_paths;
 	for (i = 0, p = paths; p; p = p->next)
diff --git a/commit-graph.c b/commit-graph.c
index ca025ce..f18380b 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -96,6 +96,13 @@
 static struct commit_graph_data_slab commit_graph_data_slab =
 	COMMIT_SLAB_INIT(1, commit_graph_data_slab);
 
+static int get_configured_generation_version(struct repository *r)
+{
+	int version = 2;
+	repo_config_get_int(r, "commitgraph.generationversion", &version);
+	return version;
+}
+
 uint32_t commit_graph_position(const struct commit *c)
 {
 	struct commit_graph_data *data =
@@ -394,10 +401,13 @@
 	pair_chunk(cf, GRAPH_CHUNKID_DATA, &graph->chunk_commit_data);
 	pair_chunk(cf, GRAPH_CHUNKID_EXTRAEDGES, &graph->chunk_extra_edges);
 	pair_chunk(cf, GRAPH_CHUNKID_BASE, &graph->chunk_base_graphs);
-	pair_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA,
-		   &graph->chunk_generation_data);
-	pair_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA_OVERFLOW,
-		   &graph->chunk_generation_data_overflow);
+
+	if (get_configured_generation_version(r) >= 2) {
+		pair_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA,
+			&graph->chunk_generation_data);
+		pair_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA_OVERFLOW,
+			&graph->chunk_generation_data_overflow);
+	}
 
 	if (r->settings.commit_graph_read_changed_paths) {
 		pair_chunk(cf, GRAPH_CHUNKID_BLOOMINDEXES,
@@ -516,7 +526,7 @@
 		return NULL;
 
 	count = st.st_size / (the_hash_algo->hexsz + 1);
-	oids = xcalloc(count, sizeof(struct object_id));
+	CALLOC_ARRAY(oids, count);
 
 	prepare_alt_odb(r);
 
@@ -1839,8 +1849,6 @@
 	add_chunk(cf, GRAPH_CHUNKID_DATA, (hashsz + 16) * ctx->commits.nr,
 		  write_graph_chunk_data);
 
-	if (git_env_bool(GIT_TEST_COMMIT_GRAPH_NO_GDAT, 0))
-		ctx->write_generation_data = 0;
 	if (ctx->write_generation_data)
 		add_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA,
 			  sizeof(uint32_t) * ctx->commits.nr,
@@ -2223,6 +2231,7 @@
 		       enum commit_graph_write_flags flags,
 		       const struct commit_graph_opts *opts)
 {
+	struct repository *r = the_repository;
 	struct write_commit_graph_context *ctx;
 	uint32_t i;
 	int res = 0;
@@ -2230,23 +2239,23 @@
 	struct bloom_filter_settings bloom_settings = DEFAULT_BLOOM_FILTER_SETTINGS;
 	struct topo_level_slab topo_levels;
 
-	prepare_repo_settings(the_repository);
-	if (!the_repository->settings.core_commit_graph) {
+	prepare_repo_settings(r);
+	if (!r->settings.core_commit_graph) {
 		warning(_("attempting to write a commit-graph, but 'core.commitGraph' is disabled"));
 		return 0;
 	}
-	if (!commit_graph_compatible(the_repository))
+	if (!commit_graph_compatible(r))
 		return 0;
 
-	ctx = xcalloc(1, sizeof(struct write_commit_graph_context));
-	ctx->r = the_repository;
+	CALLOC_ARRAY(ctx, 1);
+	ctx->r = r;
 	ctx->odb = odb;
 	ctx->append = flags & COMMIT_GRAPH_WRITE_APPEND ? 1 : 0;
 	ctx->report_progress = flags & COMMIT_GRAPH_WRITE_PROGRESS ? 1 : 0;
 	ctx->split = flags & COMMIT_GRAPH_WRITE_SPLIT ? 1 : 0;
 	ctx->opts = opts;
 	ctx->total_bloom_filter_data_size = 0;
-	ctx->write_generation_data = 1;
+	ctx->write_generation_data = (get_configured_generation_version(r) == 2);
 	ctx->num_generation_data_overflows = 0;
 
 	bloom_settings.bits_per_entry = git_env_ulong("GIT_TEST_BLOOM_SETTINGS_BITS_PER_ENTRY",
diff --git a/commit-graph.h b/commit-graph.h
index 97f3497..96c24fb 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -6,7 +6,6 @@
 #include "oidset.h"
 
 #define GIT_TEST_COMMIT_GRAPH "GIT_TEST_COMMIT_GRAPH"
-#define GIT_TEST_COMMIT_GRAPH_NO_GDAT "GIT_TEST_COMMIT_GRAPH_NO_GDAT"
 #define GIT_TEST_COMMIT_GRAPH_DIE_ON_PARSE "GIT_TEST_COMMIT_GRAPH_DIE_ON_PARSE"
 #define GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS "GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS"
 
diff --git a/commit-reach.c b/commit-reach.c
index 2ea84d3..c226ee3 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -183,7 +183,7 @@
 	int *filled_index;
 	int i, j, filled;
 
-	work = xcalloc(cnt, sizeof(*work));
+	CALLOC_ARRAY(work, cnt);
 	redundant = xcalloc(cnt, 1);
 	ALLOC_ARRAY(filled_index, cnt - 1);
 
@@ -399,7 +399,7 @@
 
 	/* There are more than one */
 	cnt = commit_list_count(result);
-	rslt = xcalloc(cnt, sizeof(*rslt));
+	CALLOC_ARRAY(rslt, cnt);
 	for (list = result, i = 0; list; list = list->next)
 		rslt[i++] = list->item;
 	free_commit_list(result);
@@ -541,7 +541,7 @@
 		p->item->object.flags |= STALE;
 		num_head++;
 	}
-	array = xcalloc(num_head, sizeof(*array));
+	CALLOC_ARRAY(array, num_head);
 	for (p = heads, i = 0; p; p = p->next) {
 		if (p->item->object.flags & STALE) {
 			array[i++] = p->item;
diff --git a/commit.c b/commit.c
index 6ccd774..8ea55a4 100644
--- a/commit.c
+++ b/commit.c
@@ -535,6 +535,20 @@
 	return eol - p;
 }
 
+size_t commit_subject_length(const char *body)
+{
+	const char *p = body;
+	while (*p) {
+		const char *next = skip_blank_lines(p);
+		if (next != p)
+			break;
+		p = strchrnul(p, '\n');
+		if (*p)
+			p++;
+	}
+	return p - body;
+}
+
 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 {
 	struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
@@ -1171,7 +1185,7 @@
 	 * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
 	 *	warn("warning: signed tag unverified.");
 	 */
-	mergetag = xcalloc(1, sizeof(*mergetag));
+	CALLOC_ARRAY(mergetag, 1);
 	mergetag->key = xstrdup("mergetag");
 	mergetag->value = buf;
 	mergetag->len = size;
@@ -1336,7 +1350,7 @@
 			 excluded_header_field(line, eof - line, exclude))
 			continue;
 
-		it = xcalloc(1, sizeof(*it));
+		CALLOC_ARRAY(it, 1);
 		it->key = xmemdupz(line, eof-line);
 		*tail = it;
 		tail = &it->next;
diff --git a/commit.h b/commit.h
index 49c0f50..df42eb4 100644
--- a/commit.h
+++ b/commit.h
@@ -167,6 +167,9 @@
 /* Find beginning and length of commit subject. */
 int find_commit_subject(const char *commit_buffer, const char **subject);
 
+/* Return length of the commit subject from commit log message. */
+size_t commit_subject_length(const char *body);
+
 struct commit_list *commit_list_insert(struct commit *item,
 					struct commit_list **list);
 int commit_list_contains(struct commit *item,
diff --git a/compat/simple-ipc/ipc-shared.c b/compat/simple-ipc/ipc-shared.c
new file mode 100644
index 0000000..1edec81
--- /dev/null
+++ b/compat/simple-ipc/ipc-shared.c
@@ -0,0 +1,28 @@
+#include "cache.h"
+#include "simple-ipc.h"
+#include "strbuf.h"
+#include "pkt-line.h"
+#include "thread-utils.h"
+
+#ifdef SUPPORTS_SIMPLE_IPC
+
+int ipc_server_run(const char *path, const struct ipc_server_opts *opts,
+		   ipc_server_application_cb *application_cb,
+		   void *application_data)
+{
+	struct ipc_server_data *server_data = NULL;
+	int ret;
+
+	ret = ipc_server_run_async(&server_data, path, opts,
+				   application_cb, application_data);
+	if (ret)
+		return ret;
+
+	ret = ipc_server_await(server_data);
+
+	ipc_server_free(server_data);
+
+	return ret;
+}
+
+#endif /* SUPPORTS_SIMPLE_IPC */
diff --git a/compat/simple-ipc/ipc-unix-socket.c b/compat/simple-ipc/ipc-unix-socket.c
new file mode 100644
index 0000000..38689b2
--- /dev/null
+++ b/compat/simple-ipc/ipc-unix-socket.c
@@ -0,0 +1,999 @@
+#include "cache.h"
+#include "simple-ipc.h"
+#include "strbuf.h"
+#include "pkt-line.h"
+#include "thread-utils.h"
+#include "unix-socket.h"
+#include "unix-stream-server.h"
+
+#ifdef NO_UNIX_SOCKETS
+#error compat/simple-ipc/ipc-unix-socket.c requires Unix sockets
+#endif
+
+enum ipc_active_state ipc_get_active_state(const char *path)
+{
+	enum ipc_active_state state = IPC_STATE__OTHER_ERROR;
+	struct ipc_client_connect_options options
+		= IPC_CLIENT_CONNECT_OPTIONS_INIT;
+	struct stat st;
+	struct ipc_client_connection *connection_test = NULL;
+
+	options.wait_if_busy = 0;
+	options.wait_if_not_found = 0;
+
+	if (lstat(path, &st) == -1) {
+		switch (errno) {
+		case ENOENT:
+		case ENOTDIR:
+			return IPC_STATE__NOT_LISTENING;
+		default:
+			return IPC_STATE__INVALID_PATH;
+		}
+	}
+
+	/* also complain if a plain file is in the way */
+	if ((st.st_mode & S_IFMT) != S_IFSOCK)
+		return IPC_STATE__INVALID_PATH;
+
+	/*
+	 * Just because the filesystem has a S_IFSOCK type inode
+	 * at `path`, doesn't mean it that there is a server listening.
+	 * Ping it to be sure.
+	 */
+	state = ipc_client_try_connect(path, &options, &connection_test);
+	ipc_client_close_connection(connection_test);
+
+	return state;
+}
+
+/*
+ * Retry frequency when trying to connect to a server.
+ *
+ * This value should be short enough that we don't seriously delay our
+ * caller, but not fast enough that our spinning puts pressure on the
+ * system.
+ */
+#define WAIT_STEP_MS (50)
+
+/*
+ * Try to connect to the server.  If the server is just starting up or
+ * is very busy, we may not get a connection the first time.
+ */
+static enum ipc_active_state connect_to_server(
+	const char *path,
+	int timeout_ms,
+	const struct ipc_client_connect_options *options,
+	int *pfd)
+{
+	int k;
+
+	*pfd = -1;
+
+	for (k = 0; k < timeout_ms; k += WAIT_STEP_MS) {
+		int fd = unix_stream_connect(path, options->uds_disallow_chdir);
+
+		if (fd != -1) {
+			*pfd = fd;
+			return IPC_STATE__LISTENING;
+		}
+
+		if (errno == ENOENT) {
+			if (!options->wait_if_not_found)
+				return IPC_STATE__PATH_NOT_FOUND;
+
+			goto sleep_and_try_again;
+		}
+
+		if (errno == ETIMEDOUT) {
+			if (!options->wait_if_busy)
+				return IPC_STATE__NOT_LISTENING;
+
+			goto sleep_and_try_again;
+		}
+
+		if (errno == ECONNREFUSED) {
+			if (!options->wait_if_busy)
+				return IPC_STATE__NOT_LISTENING;
+
+			goto sleep_and_try_again;
+		}
+
+		return IPC_STATE__OTHER_ERROR;
+
+	sleep_and_try_again:
+		sleep_millisec(WAIT_STEP_MS);
+	}
+
+	return IPC_STATE__NOT_LISTENING;
+}
+
+/*
+ * The total amount of time that we are willing to wait when trying to
+ * connect to a server.
+ *
+ * When the server is first started, it might take a little while for
+ * it to become ready to service requests.  Likewise, the server may
+ * be very (temporarily) busy and not respond to our connections.
+ *
+ * We should gracefully and silently handle those conditions and try
+ * again for a reasonable time period.
+ *
+ * The value chosen here should be long enough for the server
+ * to reliably heal from the above conditions.
+ */
+#define MY_CONNECTION_TIMEOUT_MS (1000)
+
+enum ipc_active_state ipc_client_try_connect(
+	const char *path,
+	const struct ipc_client_connect_options *options,
+	struct ipc_client_connection **p_connection)
+{
+	enum ipc_active_state state = IPC_STATE__OTHER_ERROR;
+	int fd = -1;
+
+	*p_connection = NULL;
+
+	trace2_region_enter("ipc-client", "try-connect", NULL);
+	trace2_data_string("ipc-client", NULL, "try-connect/path", path);
+
+	state = connect_to_server(path, MY_CONNECTION_TIMEOUT_MS,
+				  options, &fd);
+
+	trace2_data_intmax("ipc-client", NULL, "try-connect/state",
+			   (intmax_t)state);
+	trace2_region_leave("ipc-client", "try-connect", NULL);
+
+	if (state == IPC_STATE__LISTENING) {
+		(*p_connection) = xcalloc(1, sizeof(struct ipc_client_connection));
+		(*p_connection)->fd = fd;
+	}
+
+	return state;
+}
+
+void ipc_client_close_connection(struct ipc_client_connection *connection)
+{
+	if (!connection)
+		return;
+
+	if (connection->fd != -1)
+		close(connection->fd);
+
+	free(connection);
+}
+
+int ipc_client_send_command_to_connection(
+	struct ipc_client_connection *connection,
+	const char *message, struct strbuf *answer)
+{
+	int ret = 0;
+
+	strbuf_setlen(answer, 0);
+
+	trace2_region_enter("ipc-client", "send-command", NULL);
+
+	if (write_packetized_from_buf_no_flush(message, strlen(message),
+					       connection->fd) < 0 ||
+	    packet_flush_gently(connection->fd) < 0) {
+		ret = error(_("could not send IPC command"));
+		goto done;
+	}
+
+	if (read_packetized_to_strbuf(
+		    connection->fd, answer,
+		    PACKET_READ_GENTLE_ON_EOF | PACKET_READ_GENTLE_ON_READ_ERROR) < 0) {
+		ret = error(_("could not read IPC response"));
+		goto done;
+	}
+
+done:
+	trace2_region_leave("ipc-client", "send-command", NULL);
+	return ret;
+}
+
+int ipc_client_send_command(const char *path,
+			    const struct ipc_client_connect_options *options,
+			    const char *message, struct strbuf *answer)
+{
+	int ret = -1;
+	enum ipc_active_state state;
+	struct ipc_client_connection *connection = NULL;
+
+	state = ipc_client_try_connect(path, options, &connection);
+
+	if (state != IPC_STATE__LISTENING)
+		return ret;
+
+	ret = ipc_client_send_command_to_connection(connection, message, answer);
+
+	ipc_client_close_connection(connection);
+
+	return ret;
+}
+
+static int set_socket_blocking_flag(int fd, int make_nonblocking)
+{
+	int flags;
+
+	flags = fcntl(fd, F_GETFL, NULL);
+
+	if (flags < 0)
+		return -1;
+
+	if (make_nonblocking)
+		flags |= O_NONBLOCK;
+	else
+		flags &= ~O_NONBLOCK;
+
+	return fcntl(fd, F_SETFL, flags);
+}
+
+/*
+ * Magic numbers used to annotate callback instance data.
+ * These are used to help guard against accidentally passing the
+ * wrong instance data across multiple levels of callbacks (which
+ * is easy to do if there are `void*` arguments).
+ */
+enum magic {
+	MAGIC_SERVER_REPLY_DATA,
+	MAGIC_WORKER_THREAD_DATA,
+	MAGIC_ACCEPT_THREAD_DATA,
+	MAGIC_SERVER_DATA,
+};
+
+struct ipc_server_reply_data {
+	enum magic magic;
+	int fd;
+	struct ipc_worker_thread_data *worker_thread_data;
+};
+
+struct ipc_worker_thread_data {
+	enum magic magic;
+	struct ipc_worker_thread_data *next_thread;
+	struct ipc_server_data *server_data;
+	pthread_t pthread_id;
+};
+
+struct ipc_accept_thread_data {
+	enum magic magic;
+	struct ipc_server_data *server_data;
+
+	struct unix_ss_socket *server_socket;
+
+	int fd_send_shutdown;
+	int fd_wait_shutdown;
+	pthread_t pthread_id;
+};
+
+/*
+ * With unix-sockets, the conceptual "ipc-server" is implemented as a single
+ * controller "accept-thread" thread and a pool of "worker-thread" threads.
+ * The former does the usual `accept()` loop and dispatches connections
+ * to an idle worker thread.  The worker threads wait in an idle loop for
+ * a new connection, communicate with the client and relay data to/from
+ * the `application_cb` and then wait for another connection from the
+ * server thread.  This avoids the overhead of constantly creating and
+ * destroying threads.
+ */
+struct ipc_server_data {
+	enum magic magic;
+	ipc_server_application_cb *application_cb;
+	void *application_data;
+	struct strbuf buf_path;
+
+	struct ipc_accept_thread_data *accept_thread;
+	struct ipc_worker_thread_data *worker_thread_list;
+
+	pthread_mutex_t work_available_mutex;
+	pthread_cond_t work_available_cond;
+
+	/*
+	 * Accepted but not yet processed client connections are kept
+	 * in a circular buffer FIFO.  The queue is empty when the
+	 * positions are equal.
+	 */
+	int *fifo_fds;
+	int queue_size;
+	int back_pos;
+	int front_pos;
+
+	int shutdown_requested;
+	int is_stopped;
+};
+
+/*
+ * Remove and return the oldest queued connection.
+ *
+ * Returns -1 if empty.
+ */
+static int fifo_dequeue(struct ipc_server_data *server_data)
+{
+	/* ASSERT holding mutex */
+
+	int fd;
+
+	if (server_data->back_pos == server_data->front_pos)
+		return -1;
+
+	fd = server_data->fifo_fds[server_data->front_pos];
+	server_data->fifo_fds[server_data->front_pos] = -1;
+
+	server_data->front_pos++;
+	if (server_data->front_pos == server_data->queue_size)
+		server_data->front_pos = 0;
+
+	return fd;
+}
+
+/*
+ * Push a new fd onto the back of the queue.
+ *
+ * Drop it and return -1 if queue is already full.
+ */
+static int fifo_enqueue(struct ipc_server_data *server_data, int fd)
+{
+	/* ASSERT holding mutex */
+
+	int next_back_pos;
+
+	next_back_pos = server_data->back_pos + 1;
+	if (next_back_pos == server_data->queue_size)
+		next_back_pos = 0;
+
+	if (next_back_pos == server_data->front_pos) {
+		/* Queue is full. Just drop it. */
+		close(fd);
+		return -1;
+	}
+
+	server_data->fifo_fds[server_data->back_pos] = fd;
+	server_data->back_pos = next_back_pos;
+
+	return fd;
+}
+
+/*
+ * Wait for a connection to be queued to the FIFO and return it.
+ *
+ * Returns -1 if someone has already requested a shutdown.
+ */
+static int worker_thread__wait_for_connection(
+	struct ipc_worker_thread_data *worker_thread_data)
+{
+	/* ASSERT NOT holding mutex */
+
+	struct ipc_server_data *server_data = worker_thread_data->server_data;
+	int fd = -1;
+
+	pthread_mutex_lock(&server_data->work_available_mutex);
+	for (;;) {
+		if (server_data->shutdown_requested)
+			break;
+
+		fd = fifo_dequeue(server_data);
+		if (fd >= 0)
+			break;
+
+		pthread_cond_wait(&server_data->work_available_cond,
+				  &server_data->work_available_mutex);
+	}
+	pthread_mutex_unlock(&server_data->work_available_mutex);
+
+	return fd;
+}
+
+/*
+ * Forward declare our reply callback function so that any compiler
+ * errors are reported when we actually define the function (in addition
+ * to any errors reported when we try to pass this callback function as
+ * a parameter in a function call).  The former are easier to understand.
+ */
+static ipc_server_reply_cb do_io_reply_callback;
+
+/*
+ * Relay application's response message to the client process.
+ * (We do not flush at this point because we allow the caller
+ * to chunk data to the client thru us.)
+ */
+static int do_io_reply_callback(struct ipc_server_reply_data *reply_data,
+		       const char *response, size_t response_len)
+{
+	if (reply_data->magic != MAGIC_SERVER_REPLY_DATA)
+		BUG("reply_cb called with wrong instance data");
+
+	return write_packetized_from_buf_no_flush(response, response_len,
+						  reply_data->fd);
+}
+
+/* A randomly chosen value. */
+#define MY_WAIT_POLL_TIMEOUT_MS (10)
+
+/*
+ * If the client hangs up without sending any data on the wire, just
+ * quietly close the socket and ignore this client.
+ *
+ * This worker thread is committed to reading the IPC request data
+ * from the client at the other end of this fd.  Wait here for the
+ * client to actually put something on the wire -- because if the
+ * client just does a ping (connect and hangup without sending any
+ * data), our use of the pkt-line read routines will spew an error
+ * message.
+ *
+ * Return -1 if the client hung up.
+ * Return 0 if data (possibly incomplete) is ready.
+ */
+static int worker_thread__wait_for_io_start(
+	struct ipc_worker_thread_data *worker_thread_data,
+	int fd)
+{
+	struct ipc_server_data *server_data = worker_thread_data->server_data;
+	struct pollfd pollfd[1];
+	int result;
+
+	for (;;) {
+		pollfd[0].fd = fd;
+		pollfd[0].events = POLLIN;
+
+		result = poll(pollfd, 1, MY_WAIT_POLL_TIMEOUT_MS);
+		if (result < 0) {
+			if (errno == EINTR)
+				continue;
+			goto cleanup;
+		}
+
+		if (result == 0) {
+			/* a timeout */
+
+			int in_shutdown;
+
+			pthread_mutex_lock(&server_data->work_available_mutex);
+			in_shutdown = server_data->shutdown_requested;
+			pthread_mutex_unlock(&server_data->work_available_mutex);
+
+			/*
+			 * If a shutdown is already in progress and this
+			 * client has not started talking yet, just drop it.
+			 */
+			if (in_shutdown)
+				goto cleanup;
+			continue;
+		}
+
+		if (pollfd[0].revents & POLLHUP)
+			goto cleanup;
+
+		if (pollfd[0].revents & POLLIN)
+			return 0;
+
+		goto cleanup;
+	}
+
+cleanup:
+	close(fd);
+	return -1;
+}
+
+/*
+ * Receive the request/command from the client and pass it to the
+ * registered request-callback.  The request-callback will compose
+ * a response and call our reply-callback to send it to the client.
+ */
+static int worker_thread__do_io(
+	struct ipc_worker_thread_data *worker_thread_data,
+	int fd)
+{
+	/* ASSERT NOT holding lock */
+
+	struct strbuf buf = STRBUF_INIT;
+	struct ipc_server_reply_data reply_data;
+	int ret = 0;
+
+	reply_data.magic = MAGIC_SERVER_REPLY_DATA;
+	reply_data.worker_thread_data = worker_thread_data;
+
+	reply_data.fd = fd;
+
+	ret = read_packetized_to_strbuf(
+		reply_data.fd, &buf,
+		PACKET_READ_GENTLE_ON_EOF | PACKET_READ_GENTLE_ON_READ_ERROR);
+	if (ret >= 0) {
+		ret = worker_thread_data->server_data->application_cb(
+			worker_thread_data->server_data->application_data,
+			buf.buf, do_io_reply_callback, &reply_data);
+
+		packet_flush_gently(reply_data.fd);
+	}
+	else {
+		/*
+		 * The client probably disconnected/shutdown before it
+		 * could send a well-formed message.  Ignore it.
+		 */
+	}
+
+	strbuf_release(&buf);
+	close(reply_data.fd);
+
+	return ret;
+}
+
+/*
+ * Block SIGPIPE on the current thread (so that we get EPIPE from
+ * write() rather than an actual signal).
+ *
+ * Note that using sigchain_push() and _pop() to control SIGPIPE
+ * around our IO calls is not thread safe:
+ * [] It uses a global stack of handler frames.
+ * [] It uses ALLOC_GROW() to resize it.
+ * [] Finally, according to the `signal(2)` man-page:
+ *    "The effects of `signal()` in a multithreaded process are unspecified."
+ */
+static void thread_block_sigpipe(sigset_t *old_set)
+{
+	sigset_t new_set;
+
+	sigemptyset(&new_set);
+	sigaddset(&new_set, SIGPIPE);
+
+	sigemptyset(old_set);
+	pthread_sigmask(SIG_BLOCK, &new_set, old_set);
+}
+
+/*
+ * Thread proc for an IPC worker thread.  It handles a series of
+ * connections from clients.  It pulls the next fd from the queue
+ * processes it, and then waits for the next client.
+ *
+ * Block SIGPIPE in this worker thread for the life of the thread.
+ * This avoids stray (and sometimes delayed) SIGPIPE signals caused
+ * by client errors and/or when we are under extremely heavy IO load.
+ *
+ * This means that the application callback will have SIGPIPE blocked.
+ * The callback should not change it.
+ */
+static void *worker_thread_proc(void *_worker_thread_data)
+{
+	struct ipc_worker_thread_data *worker_thread_data = _worker_thread_data;
+	struct ipc_server_data *server_data = worker_thread_data->server_data;
+	sigset_t old_set;
+	int fd, io;
+	int ret;
+
+	trace2_thread_start("ipc-worker");
+
+	thread_block_sigpipe(&old_set);
+
+	for (;;) {
+		fd = worker_thread__wait_for_connection(worker_thread_data);
+		if (fd == -1)
+			break; /* in shutdown */
+
+		io = worker_thread__wait_for_io_start(worker_thread_data, fd);
+		if (io == -1)
+			continue; /* client hung up without sending anything */
+
+		ret = worker_thread__do_io(worker_thread_data, fd);
+
+		if (ret == SIMPLE_IPC_QUIT) {
+			trace2_data_string("ipc-worker", NULL, "queue_stop_async",
+					   "application_quit");
+			/*
+			 * The application layer is telling the ipc-server
+			 * layer to shutdown.
+			 *
+			 * We DO NOT have a response to send to the client.
+			 *
+			 * Queue an async stop (to stop the other threads) and
+			 * allow this worker thread to exit now (no sense waiting
+			 * for the thread-pool shutdown signal).
+			 *
+			 * Other non-idle worker threads are allowed to finish
+			 * responding to their current clients.
+			 */
+			ipc_server_stop_async(server_data);
+			break;
+		}
+	}
+
+	trace2_thread_exit();
+	return NULL;
+}
+
+/* A randomly chosen value. */
+#define MY_ACCEPT_POLL_TIMEOUT_MS (60 * 1000)
+
+/*
+ * Accept a new client connection on our socket.  This uses non-blocking
+ * IO so that we can also wait for shutdown requests on our socket-pair
+ * without actually spinning on a fast timeout.
+ */
+static int accept_thread__wait_for_connection(
+	struct ipc_accept_thread_data *accept_thread_data)
+{
+	struct pollfd pollfd[2];
+	int result;
+
+	for (;;) {
+		pollfd[0].fd = accept_thread_data->fd_wait_shutdown;
+		pollfd[0].events = POLLIN;
+
+		pollfd[1].fd = accept_thread_data->server_socket->fd_socket;
+		pollfd[1].events = POLLIN;
+
+		result = poll(pollfd, 2, MY_ACCEPT_POLL_TIMEOUT_MS);
+		if (result < 0) {
+			if (errno == EINTR)
+				continue;
+			return result;
+		}
+
+		if (result == 0) {
+			/* a timeout */
+
+			/*
+			 * If someone deletes or force-creates a new unix
+			 * domain socket at our path, all future clients
+			 * will be routed elsewhere and we silently starve.
+			 * If that happens, just queue a shutdown.
+			 */
+			if (unix_ss_was_stolen(
+				    accept_thread_data->server_socket)) {
+				trace2_data_string("ipc-accept", NULL,
+						   "queue_stop_async",
+						   "socket_stolen");
+				ipc_server_stop_async(
+					accept_thread_data->server_data);
+			}
+			continue;
+		}
+
+		if (pollfd[0].revents & POLLIN) {
+			/* shutdown message queued to socketpair */
+			return -1;
+		}
+
+		if (pollfd[1].revents & POLLIN) {
+			/* a connection is available on server_socket */
+
+			int client_fd =
+				accept(accept_thread_data->server_socket->fd_socket,
+				       NULL, NULL);
+			if (client_fd >= 0)
+				return client_fd;
+
+			/*
+			 * An error here is unlikely -- it probably
+			 * indicates that the connecting process has
+			 * already dropped the connection.
+			 */
+			continue;
+		}
+
+		BUG("unandled poll result errno=%d r[0]=%d r[1]=%d",
+		    errno, pollfd[0].revents, pollfd[1].revents);
+	}
+}
+
+/*
+ * Thread proc for the IPC server "accept thread".  This waits for
+ * an incoming socket connection, appends it to the queue of available
+ * connections, and notifies a worker thread to process it.
+ *
+ * Block SIGPIPE in this thread for the life of the thread.  This
+ * avoids any stray SIGPIPE signals when closing pipe fds under
+ * extremely heavy loads (such as when the fifo queue is full and we
+ * drop incomming connections).
+ */
+static void *accept_thread_proc(void *_accept_thread_data)
+{
+	struct ipc_accept_thread_data *accept_thread_data = _accept_thread_data;
+	struct ipc_server_data *server_data = accept_thread_data->server_data;
+	sigset_t old_set;
+
+	trace2_thread_start("ipc-accept");
+
+	thread_block_sigpipe(&old_set);
+
+	for (;;) {
+		int client_fd = accept_thread__wait_for_connection(
+			accept_thread_data);
+
+		pthread_mutex_lock(&server_data->work_available_mutex);
+		if (server_data->shutdown_requested) {
+			pthread_mutex_unlock(&server_data->work_available_mutex);
+			if (client_fd >= 0)
+				close(client_fd);
+			break;
+		}
+
+		if (client_fd < 0) {
+			/* ignore transient accept() errors */
+		}
+		else {
+			fifo_enqueue(server_data, client_fd);
+			pthread_cond_broadcast(&server_data->work_available_cond);
+		}
+		pthread_mutex_unlock(&server_data->work_available_mutex);
+	}
+
+	trace2_thread_exit();
+	return NULL;
+}
+
+/*
+ * We can't predict the connection arrival rate relative to the worker
+ * processing rate, therefore we allow the "accept-thread" to queue up
+ * a generous number of connections, since we'd rather have the client
+ * not unnecessarily timeout if we can avoid it.  (The assumption is
+ * that this will be used for FSMonitor and a few second wait on a
+ * connection is better than having the client timeout and do the full
+ * computation itself.)
+ *
+ * The FIFO queue size is set to a multiple of the worker pool size.
+ * This value chosen at random.
+ */
+#define FIFO_SCALE (100)
+
+/*
+ * The backlog value for `listen(2)`.  This doesn't need to huge,
+ * rather just large enough for our "accept-thread" to wake up and
+ * queue incoming connections onto the FIFO without the kernel
+ * dropping any.
+ *
+ * This value chosen at random.
+ */
+#define LISTEN_BACKLOG (50)
+
+static int create_listener_socket(
+	const char *path,
+	const struct ipc_server_opts *ipc_opts,
+	struct unix_ss_socket **new_server_socket)
+{
+	struct unix_ss_socket *server_socket = NULL;
+	struct unix_stream_listen_opts uslg_opts = UNIX_STREAM_LISTEN_OPTS_INIT;
+	int ret;
+
+	uslg_opts.listen_backlog_size = LISTEN_BACKLOG;
+	uslg_opts.disallow_chdir = ipc_opts->uds_disallow_chdir;
+
+	ret = unix_ss_create(path, &uslg_opts, -1, &server_socket);
+	if (ret)
+		return ret;
+
+	if (set_socket_blocking_flag(server_socket->fd_socket, 1)) {
+		int saved_errno = errno;
+		unix_ss_free(server_socket);
+		errno = saved_errno;
+		return -1;
+	}
+
+	*new_server_socket = server_socket;
+
+	trace2_data_string("ipc-server", NULL, "listen-with-lock", path);
+	return 0;
+}
+
+static int setup_listener_socket(
+	const char *path,
+	const struct ipc_server_opts *ipc_opts,
+	struct unix_ss_socket **new_server_socket)
+{
+	int ret, saved_errno;
+
+	trace2_region_enter("ipc-server", "create-listener_socket", NULL);
+
+	ret = create_listener_socket(path, ipc_opts, new_server_socket);
+
+	saved_errno = errno;
+	trace2_region_leave("ipc-server", "create-listener_socket", NULL);
+	errno = saved_errno;
+
+	return ret;
+}
+
+/*
+ * Start IPC server in a pool of background threads.
+ */
+int ipc_server_run_async(struct ipc_server_data **returned_server_data,
+			 const char *path, const struct ipc_server_opts *opts,
+			 ipc_server_application_cb *application_cb,
+			 void *application_data)
+{
+	struct unix_ss_socket *server_socket = NULL;
+	struct ipc_server_data *server_data;
+	int sv[2];
+	int k;
+	int ret;
+	int nr_threads = opts->nr_threads;
+
+	*returned_server_data = NULL;
+
+	/*
+	 * Create a socketpair and set sv[1] to non-blocking.  This
+	 * will used to send a shutdown message to the accept-thread
+	 * and allows the accept-thread to wait on EITHER a client
+	 * connection or a shutdown request without spinning.
+	 */
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv) < 0)
+		return -1;
+
+	if (set_socket_blocking_flag(sv[1], 1)) {
+		int saved_errno = errno;
+		close(sv[0]);
+		close(sv[1]);
+		errno = saved_errno;
+		return -1;
+	}
+
+	ret = setup_listener_socket(path, opts, &server_socket);
+	if (ret) {
+		int saved_errno = errno;
+		close(sv[0]);
+		close(sv[1]);
+		errno = saved_errno;
+		return ret;
+	}
+
+	server_data = xcalloc(1, sizeof(*server_data));
+	server_data->magic = MAGIC_SERVER_DATA;
+	server_data->application_cb = application_cb;
+	server_data->application_data = application_data;
+	strbuf_init(&server_data->buf_path, 0);
+	strbuf_addstr(&server_data->buf_path, path);
+
+	if (nr_threads < 1)
+		nr_threads = 1;
+
+	pthread_mutex_init(&server_data->work_available_mutex, NULL);
+	pthread_cond_init(&server_data->work_available_cond, NULL);
+
+	server_data->queue_size = nr_threads * FIFO_SCALE;
+	CALLOC_ARRAY(server_data->fifo_fds, server_data->queue_size);
+
+	server_data->accept_thread =
+		xcalloc(1, sizeof(*server_data->accept_thread));
+	server_data->accept_thread->magic = MAGIC_ACCEPT_THREAD_DATA;
+	server_data->accept_thread->server_data = server_data;
+	server_data->accept_thread->server_socket = server_socket;
+	server_data->accept_thread->fd_send_shutdown = sv[0];
+	server_data->accept_thread->fd_wait_shutdown = sv[1];
+
+	if (pthread_create(&server_data->accept_thread->pthread_id, NULL,
+			   accept_thread_proc, server_data->accept_thread))
+		die_errno(_("could not start accept_thread '%s'"), path);
+
+	for (k = 0; k < nr_threads; k++) {
+		struct ipc_worker_thread_data *wtd;
+
+		wtd = xcalloc(1, sizeof(*wtd));
+		wtd->magic = MAGIC_WORKER_THREAD_DATA;
+		wtd->server_data = server_data;
+
+		if (pthread_create(&wtd->pthread_id, NULL, worker_thread_proc,
+				   wtd)) {
+			if (k == 0)
+				die(_("could not start worker[0] for '%s'"),
+				    path);
+			/*
+			 * Limp along with the thread pool that we have.
+			 */
+			break;
+		}
+
+		wtd->next_thread = server_data->worker_thread_list;
+		server_data->worker_thread_list = wtd;
+	}
+
+	*returned_server_data = server_data;
+	return 0;
+}
+
+/*
+ * Gently tell the IPC server treads to shutdown.
+ * Can be run on any thread.
+ */
+int ipc_server_stop_async(struct ipc_server_data *server_data)
+{
+	/* ASSERT NOT holding mutex */
+
+	int fd;
+
+	if (!server_data)
+		return 0;
+
+	trace2_region_enter("ipc-server", "server-stop-async", NULL);
+
+	pthread_mutex_lock(&server_data->work_available_mutex);
+
+	server_data->shutdown_requested = 1;
+
+	/*
+	 * Write a byte to the shutdown socket pair to wake up the
+	 * accept-thread.
+	 */
+	if (write(server_data->accept_thread->fd_send_shutdown, "Q", 1) < 0)
+		error_errno("could not write to fd_send_shutdown");
+
+	/*
+	 * Drain the queue of existing connections.
+	 */
+	while ((fd = fifo_dequeue(server_data)) != -1)
+		close(fd);
+
+	/*
+	 * Gently tell worker threads to stop processing new connections
+	 * and exit.  (This does not abort in-process conversations.)
+	 */
+	pthread_cond_broadcast(&server_data->work_available_cond);
+
+	pthread_mutex_unlock(&server_data->work_available_mutex);
+
+	trace2_region_leave("ipc-server", "server-stop-async", NULL);
+
+	return 0;
+}
+
+/*
+ * Wait for all IPC server threads to stop.
+ */
+int ipc_server_await(struct ipc_server_data *server_data)
+{
+	pthread_join(server_data->accept_thread->pthread_id, NULL);
+
+	if (!server_data->shutdown_requested)
+		BUG("ipc-server: accept-thread stopped for '%s'",
+		    server_data->buf_path.buf);
+
+	while (server_data->worker_thread_list) {
+		struct ipc_worker_thread_data *wtd =
+			server_data->worker_thread_list;
+
+		pthread_join(wtd->pthread_id, NULL);
+
+		server_data->worker_thread_list = wtd->next_thread;
+		free(wtd);
+	}
+
+	server_data->is_stopped = 1;
+
+	return 0;
+}
+
+void ipc_server_free(struct ipc_server_data *server_data)
+{
+	struct ipc_accept_thread_data * accept_thread_data;
+
+	if (!server_data)
+		return;
+
+	if (!server_data->is_stopped)
+		BUG("cannot free ipc-server while running for '%s'",
+		    server_data->buf_path.buf);
+
+	accept_thread_data = server_data->accept_thread;
+	if (accept_thread_data) {
+		unix_ss_free(accept_thread_data->server_socket);
+
+		if (accept_thread_data->fd_send_shutdown != -1)
+			close(accept_thread_data->fd_send_shutdown);
+		if (accept_thread_data->fd_wait_shutdown != -1)
+			close(accept_thread_data->fd_wait_shutdown);
+
+		free(server_data->accept_thread);
+	}
+
+	while (server_data->worker_thread_list) {
+		struct ipc_worker_thread_data *wtd =
+			server_data->worker_thread_list;
+
+		server_data->worker_thread_list = wtd->next_thread;
+		free(wtd);
+	}
+
+	pthread_cond_destroy(&server_data->work_available_cond);
+	pthread_mutex_destroy(&server_data->work_available_mutex);
+
+	strbuf_release(&server_data->buf_path);
+
+	free(server_data->fifo_fds);
+	free(server_data);
+}
diff --git a/compat/simple-ipc/ipc-win32.c b/compat/simple-ipc/ipc-win32.c
new file mode 100644
index 0000000..8f89c02
--- /dev/null
+++ b/compat/simple-ipc/ipc-win32.c
@@ -0,0 +1,751 @@
+#include "cache.h"
+#include "simple-ipc.h"
+#include "strbuf.h"
+#include "pkt-line.h"
+#include "thread-utils.h"
+
+#ifndef GIT_WINDOWS_NATIVE
+#error This file can only be compiled on Windows
+#endif
+
+static int initialize_pipe_name(const char *path, wchar_t *wpath, size_t alloc)
+{
+	int off = 0;
+	struct strbuf realpath = STRBUF_INIT;
+
+	if (!strbuf_realpath(&realpath, path, 0))
+		return -1;
+
+	off = swprintf(wpath, alloc, L"\\\\.\\pipe\\");
+	if (xutftowcs(wpath + off, realpath.buf, alloc - off) < 0)
+		return -1;
+
+	/* Handle drive prefix */
+	if (wpath[off] && wpath[off + 1] == L':') {
+		wpath[off + 1] = L'_';
+		off += 2;
+	}
+
+	for (; wpath[off]; off++)
+		if (wpath[off] == L'/')
+			wpath[off] = L'\\';
+
+	strbuf_release(&realpath);
+	return 0;
+}
+
+static enum ipc_active_state get_active_state(wchar_t *pipe_path)
+{
+	if (WaitNamedPipeW(pipe_path, NMPWAIT_USE_DEFAULT_WAIT))
+		return IPC_STATE__LISTENING;
+
+	if (GetLastError() == ERROR_SEM_TIMEOUT)
+		return IPC_STATE__NOT_LISTENING;
+
+	if (GetLastError() == ERROR_FILE_NOT_FOUND)
+		return IPC_STATE__PATH_NOT_FOUND;
+
+	return IPC_STATE__OTHER_ERROR;
+}
+
+enum ipc_active_state ipc_get_active_state(const char *path)
+{
+	wchar_t pipe_path[MAX_PATH];
+
+	if (initialize_pipe_name(path, pipe_path, ARRAY_SIZE(pipe_path)) < 0)
+		return IPC_STATE__INVALID_PATH;
+
+	return get_active_state(pipe_path);
+}
+
+#define WAIT_STEP_MS (50)
+
+static enum ipc_active_state connect_to_server(
+	const wchar_t *wpath,
+	DWORD timeout_ms,
+	const struct ipc_client_connect_options *options,
+	int *pfd)
+{
+	DWORD t_start_ms, t_waited_ms;
+	DWORD step_ms;
+	HANDLE hPipe = INVALID_HANDLE_VALUE;
+	DWORD mode = PIPE_READMODE_BYTE;
+	DWORD gle;
+
+	*pfd = -1;
+
+	for (;;) {
+		hPipe = CreateFileW(wpath, GENERIC_READ | GENERIC_WRITE,
+				    0, NULL, OPEN_EXISTING, 0, NULL);
+		if (hPipe != INVALID_HANDLE_VALUE)
+			break;
+
+		gle = GetLastError();
+
+		switch (gle) {
+		case ERROR_FILE_NOT_FOUND:
+			if (!options->wait_if_not_found)
+				return IPC_STATE__PATH_NOT_FOUND;
+			if (!timeout_ms)
+				return IPC_STATE__PATH_NOT_FOUND;
+
+			step_ms = (timeout_ms < WAIT_STEP_MS) ?
+				timeout_ms : WAIT_STEP_MS;
+			sleep_millisec(step_ms);
+
+			timeout_ms -= step_ms;
+			break; /* try again */
+
+		case ERROR_PIPE_BUSY:
+			if (!options->wait_if_busy)
+				return IPC_STATE__NOT_LISTENING;
+			if (!timeout_ms)
+				return IPC_STATE__NOT_LISTENING;
+
+			t_start_ms = (DWORD)(getnanotime() / 1000000);
+
+			if (!WaitNamedPipeW(wpath, timeout_ms)) {
+				if (GetLastError() == ERROR_SEM_TIMEOUT)
+					return IPC_STATE__NOT_LISTENING;
+
+				return IPC_STATE__OTHER_ERROR;
+			}
+
+			/*
+			 * A pipe server instance became available.
+			 * Race other client processes to connect to
+			 * it.
+			 *
+			 * But first decrement our overall timeout so
+			 * that we don't starve if we keep losing the
+			 * race.  But also guard against special
+			 * NPMWAIT_ values (0 and -1).
+			 */
+			t_waited_ms = (DWORD)(getnanotime() / 1000000) - t_start_ms;
+			if (t_waited_ms < timeout_ms)
+				timeout_ms -= t_waited_ms;
+			else
+				timeout_ms = 1;
+			break; /* try again */
+
+		default:
+			return IPC_STATE__OTHER_ERROR;
+		}
+	}
+
+	if (!SetNamedPipeHandleState(hPipe, &mode, NULL, NULL)) {
+		CloseHandle(hPipe);
+		return IPC_STATE__OTHER_ERROR;
+	}
+
+	*pfd = _open_osfhandle((intptr_t)hPipe, O_RDWR|O_BINARY);
+	if (*pfd < 0) {
+		CloseHandle(hPipe);
+		return IPC_STATE__OTHER_ERROR;
+	}
+
+	/* fd now owns hPipe */
+
+	return IPC_STATE__LISTENING;
+}
+
+/*
+ * The default connection timeout for Windows clients.
+ *
+ * This is not currently part of the ipc_ API (nor the config settings)
+ * because of differences between Windows and other platforms.
+ *
+ * This value was chosen at random.
+ */
+#define WINDOWS_CONNECTION_TIMEOUT_MS (30000)
+
+enum ipc_active_state ipc_client_try_connect(
+	const char *path,
+	const struct ipc_client_connect_options *options,
+	struct ipc_client_connection **p_connection)
+{
+	wchar_t wpath[MAX_PATH];
+	enum ipc_active_state state = IPC_STATE__OTHER_ERROR;
+	int fd = -1;
+
+	*p_connection = NULL;
+
+	trace2_region_enter("ipc-client", "try-connect", NULL);
+	trace2_data_string("ipc-client", NULL, "try-connect/path", path);
+
+	if (initialize_pipe_name(path, wpath, ARRAY_SIZE(wpath)) < 0)
+		state = IPC_STATE__INVALID_PATH;
+	else
+		state = connect_to_server(wpath, WINDOWS_CONNECTION_TIMEOUT_MS,
+					  options, &fd);
+
+	trace2_data_intmax("ipc-client", NULL, "try-connect/state",
+			   (intmax_t)state);
+	trace2_region_leave("ipc-client", "try-connect", NULL);
+
+	if (state == IPC_STATE__LISTENING) {
+		(*p_connection) = xcalloc(1, sizeof(struct ipc_client_connection));
+		(*p_connection)->fd = fd;
+	}
+
+	return state;
+}
+
+void ipc_client_close_connection(struct ipc_client_connection *connection)
+{
+	if (!connection)
+		return;
+
+	if (connection->fd != -1)
+		close(connection->fd);
+
+	free(connection);
+}
+
+int ipc_client_send_command_to_connection(
+	struct ipc_client_connection *connection,
+	const char *message, struct strbuf *answer)
+{
+	int ret = 0;
+
+	strbuf_setlen(answer, 0);
+
+	trace2_region_enter("ipc-client", "send-command", NULL);
+
+	if (write_packetized_from_buf_no_flush(message, strlen(message),
+					       connection->fd) < 0 ||
+	    packet_flush_gently(connection->fd) < 0) {
+		ret = error(_("could not send IPC command"));
+		goto done;
+	}
+
+	FlushFileBuffers((HANDLE)_get_osfhandle(connection->fd));
+
+	if (read_packetized_to_strbuf(
+		    connection->fd, answer,
+		    PACKET_READ_GENTLE_ON_EOF | PACKET_READ_GENTLE_ON_READ_ERROR) < 0) {
+		ret = error(_("could not read IPC response"));
+		goto done;
+	}
+
+done:
+	trace2_region_leave("ipc-client", "send-command", NULL);
+	return ret;
+}
+
+int ipc_client_send_command(const char *path,
+			    const struct ipc_client_connect_options *options,
+			    const char *message, struct strbuf *response)
+{
+	int ret = -1;
+	enum ipc_active_state state;
+	struct ipc_client_connection *connection = NULL;
+
+	state = ipc_client_try_connect(path, options, &connection);
+
+	if (state != IPC_STATE__LISTENING)
+		return ret;
+
+	ret = ipc_client_send_command_to_connection(connection, message, response);
+
+	ipc_client_close_connection(connection);
+
+	return ret;
+}
+
+/*
+ * Duplicate the given pipe handle and wrap it in a file descriptor so
+ * that we can use pkt-line on it.
+ */
+static int dup_fd_from_pipe(const HANDLE pipe)
+{
+	HANDLE process = GetCurrentProcess();
+	HANDLE handle;
+	int fd;
+
+	if (!DuplicateHandle(process, pipe, process, &handle, 0, FALSE,
+			     DUPLICATE_SAME_ACCESS)) {
+		errno = err_win_to_posix(GetLastError());
+		return -1;
+	}
+
+	fd = _open_osfhandle((intptr_t)handle, O_RDWR|O_BINARY);
+	if (fd < 0) {
+		errno = err_win_to_posix(GetLastError());
+		CloseHandle(handle);
+		return -1;
+	}
+
+	/*
+	 * `handle` is now owned by `fd` and will be automatically closed
+	 * when the descriptor is closed.
+	 */
+
+	return fd;
+}
+
+/*
+ * Magic numbers used to annotate callback instance data.
+ * These are used to help guard against accidentally passing the
+ * wrong instance data across multiple levels of callbacks (which
+ * is easy to do if there are `void*` arguments).
+ */
+enum magic {
+	MAGIC_SERVER_REPLY_DATA,
+	MAGIC_SERVER_THREAD_DATA,
+	MAGIC_SERVER_DATA,
+};
+
+struct ipc_server_reply_data {
+	enum magic magic;
+	int fd;
+	struct ipc_server_thread_data *server_thread_data;
+};
+
+struct ipc_server_thread_data {
+	enum magic magic;
+	struct ipc_server_thread_data *next_thread;
+	struct ipc_server_data *server_data;
+	pthread_t pthread_id;
+	HANDLE hPipe;
+};
+
+/*
+ * On Windows, the conceptual "ipc-server" is implemented as a pool of
+ * n idential/peer "server-thread" threads.  That is, there is no
+ * hierarchy of threads; and therefore no controller thread managing
+ * the pool.  Each thread has an independent handle to the named pipe,
+ * receives incoming connections, processes the client, and re-uses
+ * the pipe for the next client connection.
+ *
+ * Therefore, the "ipc-server" only needs to maintain a list of the
+ * spawned threads for eventual "join" purposes.
+ *
+ * A single "stop-event" is visible to all of the server threads to
+ * tell them to shutdown (when idle).
+ */
+struct ipc_server_data {
+	enum magic magic;
+	ipc_server_application_cb *application_cb;
+	void *application_data;
+	struct strbuf buf_path;
+	wchar_t wpath[MAX_PATH];
+
+	HANDLE hEventStopRequested;
+	struct ipc_server_thread_data *thread_list;
+	int is_stopped;
+};
+
+enum connect_result {
+	CR_CONNECTED = 0,
+	CR_CONNECT_PENDING,
+	CR_CONNECT_ERROR,
+	CR_WAIT_ERROR,
+	CR_SHUTDOWN,
+};
+
+static enum connect_result queue_overlapped_connect(
+	struct ipc_server_thread_data *server_thread_data,
+	OVERLAPPED *lpo)
+{
+	if (ConnectNamedPipe(server_thread_data->hPipe, lpo))
+		goto failed;
+
+	switch (GetLastError()) {
+	case ERROR_IO_PENDING:
+		return CR_CONNECT_PENDING;
+
+	case ERROR_PIPE_CONNECTED:
+		SetEvent(lpo->hEvent);
+		return CR_CONNECTED;
+
+	default:
+		break;
+	}
+
+failed:
+	error(_("ConnectNamedPipe failed for '%s' (%lu)"),
+	      server_thread_data->server_data->buf_path.buf,
+	      GetLastError());
+	return CR_CONNECT_ERROR;
+}
+
+/*
+ * Use Windows Overlapped IO to wait for a connection or for our event
+ * to be signalled.
+ */
+static enum connect_result wait_for_connection(
+	struct ipc_server_thread_data *server_thread_data,
+	OVERLAPPED *lpo)
+{
+	enum connect_result r;
+	HANDLE waitHandles[2];
+	DWORD dwWaitResult;
+
+	r = queue_overlapped_connect(server_thread_data, lpo);
+	if (r != CR_CONNECT_PENDING)
+		return r;
+
+	waitHandles[0] = server_thread_data->server_data->hEventStopRequested;
+	waitHandles[1] = lpo->hEvent;
+
+	dwWaitResult = WaitForMultipleObjects(2, waitHandles, FALSE, INFINITE);
+	switch (dwWaitResult) {
+	case WAIT_OBJECT_0 + 0:
+		return CR_SHUTDOWN;
+
+	case WAIT_OBJECT_0 + 1:
+		ResetEvent(lpo->hEvent);
+		return CR_CONNECTED;
+
+	default:
+		return CR_WAIT_ERROR;
+	}
+}
+
+/*
+ * Forward declare our reply callback function so that any compiler
+ * errors are reported when we actually define the function (in addition
+ * to any errors reported when we try to pass this callback function as
+ * a parameter in a function call).  The former are easier to understand.
+ */
+static ipc_server_reply_cb do_io_reply_callback;
+
+/*
+ * Relay application's response message to the client process.
+ * (We do not flush at this point because we allow the caller
+ * to chunk data to the client thru us.)
+ */
+static int do_io_reply_callback(struct ipc_server_reply_data *reply_data,
+		       const char *response, size_t response_len)
+{
+	if (reply_data->magic != MAGIC_SERVER_REPLY_DATA)
+		BUG("reply_cb called with wrong instance data");
+
+	return write_packetized_from_buf_no_flush(response, response_len,
+						  reply_data->fd);
+}
+
+/*
+ * Receive the request/command from the client and pass it to the
+ * registered request-callback.  The request-callback will compose
+ * a response and call our reply-callback to send it to the client.
+ *
+ * Simple-IPC only contains one round trip, so we flush and close
+ * here after the response.
+ */
+static int do_io(struct ipc_server_thread_data *server_thread_data)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct ipc_server_reply_data reply_data;
+	int ret = 0;
+
+	reply_data.magic = MAGIC_SERVER_REPLY_DATA;
+	reply_data.server_thread_data = server_thread_data;
+
+	reply_data.fd = dup_fd_from_pipe(server_thread_data->hPipe);
+	if (reply_data.fd < 0)
+		return error(_("could not create fd from pipe for '%s'"),
+			     server_thread_data->server_data->buf_path.buf);
+
+	ret = read_packetized_to_strbuf(
+		reply_data.fd, &buf,
+		PACKET_READ_GENTLE_ON_EOF | PACKET_READ_GENTLE_ON_READ_ERROR);
+	if (ret >= 0) {
+		ret = server_thread_data->server_data->application_cb(
+			server_thread_data->server_data->application_data,
+			buf.buf, do_io_reply_callback, &reply_data);
+
+		packet_flush_gently(reply_data.fd);
+
+		FlushFileBuffers((HANDLE)_get_osfhandle((reply_data.fd)));
+	}
+	else {
+		/*
+		 * The client probably disconnected/shutdown before it
+		 * could send a well-formed message.  Ignore it.
+		 */
+	}
+
+	strbuf_release(&buf);
+	close(reply_data.fd);
+
+	return ret;
+}
+
+/*
+ * Handle IPC request and response with this connected client.  And reset
+ * the pipe to prepare for the next client.
+ */
+static int use_connection(struct ipc_server_thread_data *server_thread_data)
+{
+	int ret;
+
+	ret = do_io(server_thread_data);
+
+	FlushFileBuffers(server_thread_data->hPipe);
+	DisconnectNamedPipe(server_thread_data->hPipe);
+
+	return ret;
+}
+
+/*
+ * Thread proc for an IPC server worker thread.  It handles a series of
+ * connections from clients.  It cleans and reuses the hPipe between each
+ * client.
+ */
+static void *server_thread_proc(void *_server_thread_data)
+{
+	struct ipc_server_thread_data *server_thread_data = _server_thread_data;
+	HANDLE hEventConnected = INVALID_HANDLE_VALUE;
+	OVERLAPPED oConnect;
+	enum connect_result cr;
+	int ret;
+
+	assert(server_thread_data->hPipe != INVALID_HANDLE_VALUE);
+
+	trace2_thread_start("ipc-server");
+	trace2_data_string("ipc-server", NULL, "pipe",
+			   server_thread_data->server_data->buf_path.buf);
+
+	hEventConnected = CreateEventW(NULL, TRUE, FALSE, NULL);
+
+	memset(&oConnect, 0, sizeof(oConnect));
+	oConnect.hEvent = hEventConnected;
+
+	for (;;) {
+		cr = wait_for_connection(server_thread_data, &oConnect);
+
+		switch (cr) {
+		case CR_SHUTDOWN:
+			goto finished;
+
+		case CR_CONNECTED:
+			ret = use_connection(server_thread_data);
+			if (ret == SIMPLE_IPC_QUIT) {
+				ipc_server_stop_async(
+					server_thread_data->server_data);
+				goto finished;
+			}
+			if (ret > 0) {
+				/*
+				 * Ignore (transient) IO errors with this
+				 * client and reset for the next client.
+				 */
+			}
+			break;
+
+		case CR_CONNECT_PENDING:
+			/* By construction, this should not happen. */
+			BUG("ipc-server[%s]: unexpeced CR_CONNECT_PENDING",
+			    server_thread_data->server_data->buf_path.buf);
+
+		case CR_CONNECT_ERROR:
+		case CR_WAIT_ERROR:
+			/*
+			 * Ignore these theoretical errors.
+			 */
+			DisconnectNamedPipe(server_thread_data->hPipe);
+			break;
+
+		default:
+			BUG("unandled case after wait_for_connection");
+		}
+	}
+
+finished:
+	CloseHandle(server_thread_data->hPipe);
+	CloseHandle(hEventConnected);
+
+	trace2_thread_exit();
+	return NULL;
+}
+
+static HANDLE create_new_pipe(wchar_t *wpath, int is_first)
+{
+	HANDLE hPipe;
+	DWORD dwOpenMode, dwPipeMode;
+	LPSECURITY_ATTRIBUTES lpsa = NULL;
+
+	dwOpenMode = PIPE_ACCESS_INBOUND | PIPE_ACCESS_OUTBOUND |
+		FILE_FLAG_OVERLAPPED;
+
+	dwPipeMode = PIPE_TYPE_MESSAGE | PIPE_READMODE_BYTE | PIPE_WAIT |
+		PIPE_REJECT_REMOTE_CLIENTS;
+
+	if (is_first) {
+		dwOpenMode |= FILE_FLAG_FIRST_PIPE_INSTANCE;
+
+		/*
+		 * On Windows, the first server pipe instance gets to
+		 * set the ACL / Security Attributes on the named
+		 * pipe; subsequent instances inherit and cannot
+		 * change them.
+		 *
+		 * TODO Should we allow the application layer to
+		 * specify security attributes, such as `LocalService`
+		 * or `LocalSystem`, when we create the named pipe?
+		 * This question is probably not important when the
+		 * daemon is started by a foreground user process and
+		 * only needs to talk to the current user, but may be
+		 * if the daemon is run via the Control Panel as a
+		 * System Service.
+		 */
+	}
+
+	hPipe = CreateNamedPipeW(wpath, dwOpenMode, dwPipeMode,
+				 PIPE_UNLIMITED_INSTANCES, 1024, 1024, 0, lpsa);
+
+	return hPipe;
+}
+
+int ipc_server_run_async(struct ipc_server_data **returned_server_data,
+			 const char *path, const struct ipc_server_opts *opts,
+			 ipc_server_application_cb *application_cb,
+			 void *application_data)
+{
+	struct ipc_server_data *server_data;
+	wchar_t wpath[MAX_PATH];
+	HANDLE hPipeFirst = INVALID_HANDLE_VALUE;
+	int k;
+	int ret = 0;
+	int nr_threads = opts->nr_threads;
+
+	*returned_server_data = NULL;
+
+	ret = initialize_pipe_name(path, wpath, ARRAY_SIZE(wpath));
+	if (ret < 0) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	hPipeFirst = create_new_pipe(wpath, 1);
+	if (hPipeFirst == INVALID_HANDLE_VALUE) {
+		errno = EADDRINUSE;
+		return -2;
+	}
+
+	server_data = xcalloc(1, sizeof(*server_data));
+	server_data->magic = MAGIC_SERVER_DATA;
+	server_data->application_cb = application_cb;
+	server_data->application_data = application_data;
+	server_data->hEventStopRequested = CreateEvent(NULL, TRUE, FALSE, NULL);
+	strbuf_init(&server_data->buf_path, 0);
+	strbuf_addstr(&server_data->buf_path, path);
+	wcscpy(server_data->wpath, wpath);
+
+	if (nr_threads < 1)
+		nr_threads = 1;
+
+	for (k = 0; k < nr_threads; k++) {
+		struct ipc_server_thread_data *std;
+
+		std = xcalloc(1, sizeof(*std));
+		std->magic = MAGIC_SERVER_THREAD_DATA;
+		std->server_data = server_data;
+		std->hPipe = INVALID_HANDLE_VALUE;
+
+		std->hPipe = (k == 0)
+			? hPipeFirst
+			: create_new_pipe(server_data->wpath, 0);
+
+		if (std->hPipe == INVALID_HANDLE_VALUE) {
+			/*
+			 * If we've reached a pipe instance limit for
+			 * this path, just use fewer threads.
+			 */
+			free(std);
+			break;
+		}
+
+		if (pthread_create(&std->pthread_id, NULL,
+				   server_thread_proc, std)) {
+			/*
+			 * Likewise, if we're out of threads, just use
+			 * fewer threads than requested.
+			 *
+			 * However, we just give up if we can't even get
+			 * one thread.  This should not happen.
+			 */
+			if (k == 0)
+				die(_("could not start thread[0] for '%s'"),
+				    path);
+
+			CloseHandle(std->hPipe);
+			free(std);
+			break;
+		}
+
+		std->next_thread = server_data->thread_list;
+		server_data->thread_list = std;
+	}
+
+	*returned_server_data = server_data;
+	return 0;
+}
+
+int ipc_server_stop_async(struct ipc_server_data *server_data)
+{
+	if (!server_data)
+		return 0;
+
+	/*
+	 * Gently tell all of the ipc_server threads to shutdown.
+	 * This will be seen the next time they are idle (and waiting
+	 * for a connection).
+	 *
+	 * We DO NOT attempt to force them to drop an active connection.
+	 */
+	SetEvent(server_data->hEventStopRequested);
+	return 0;
+}
+
+int ipc_server_await(struct ipc_server_data *server_data)
+{
+	DWORD dwWaitResult;
+
+	if (!server_data)
+		return 0;
+
+	dwWaitResult = WaitForSingleObject(server_data->hEventStopRequested, INFINITE);
+	if (dwWaitResult != WAIT_OBJECT_0)
+		return error(_("wait for hEvent failed for '%s'"),
+			     server_data->buf_path.buf);
+
+	while (server_data->thread_list) {
+		struct ipc_server_thread_data *std = server_data->thread_list;
+
+		pthread_join(std->pthread_id, NULL);
+
+		server_data->thread_list = std->next_thread;
+		free(std);
+	}
+
+	server_data->is_stopped = 1;
+
+	return 0;
+}
+
+void ipc_server_free(struct ipc_server_data *server_data)
+{
+	if (!server_data)
+		return;
+
+	if (!server_data->is_stopped)
+		BUG("cannot free ipc-server while running for '%s'",
+		    server_data->buf_path.buf);
+
+	strbuf_release(&server_data->buf_path);
+
+	if (server_data->hEventStopRequested != INVALID_HANDLE_VALUE)
+		CloseHandle(server_data->hEventStopRequested);
+
+	while (server_data->thread_list) {
+		struct ipc_server_thread_data *std = server_data->thread_list;
+
+		server_data->thread_list = std->next_thread;
+		free(std);
+	}
+
+	free(server_data);
+}
diff --git a/config.c b/config.c
index f90b633..6428393 100644
--- a/config.c
+++ b/config.c
@@ -2269,7 +2269,7 @@
 	opts.git_dir = repo->gitdir;
 
 	if (!repo->config)
-		repo->config = xcalloc(1, sizeof(struct config_set));
+		CALLOC_ARRAY(repo->config, 1);
 	else
 		git_configset_clear(repo->config);
 
diff --git a/config.mak.uname b/config.mak.uname
index d204c20..cb443b4 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -424,6 +424,7 @@
 	RUNTIME_PREFIX = YesPlease
 	HAVE_WPGMPTR = YesWeDo
 	NO_ST_BLOCKS_IN_STRUCT_STAT = YesPlease
+	USE_WIN32_IPC = YesPlease
 	USE_WIN32_MMAP = YesPlease
 	MMAP_PREVENTS_DELETE = UnfortunatelyYes
 	# USE_NED_ALLOCATOR = YesPlease
@@ -600,6 +601,7 @@
 	RUNTIME_PREFIX = YesPlease
 	HAVE_WPGMPTR = YesWeDo
 	NO_ST_BLOCKS_IN_STRUCT_STAT = YesPlease
+	USE_WIN32_IPC = YesPlease
 	USE_WIN32_MMAP = YesPlease
 	MMAP_PREVENTS_DELETE = UnfortunatelyYes
 	USE_NED_ALLOCATOR = YesPlease
diff --git a/contrib/buildsystems/CMakeLists.txt b/contrib/buildsystems/CMakeLists.txt
index ac3dbc0..75ed198 100644
--- a/contrib/buildsystems/CMakeLists.txt
+++ b/contrib/buildsystems/CMakeLists.txt
@@ -58,6 +58,10 @@
 
 	# In the vcpkg edition, we need this to be able to link to libcurl
 	set(CURL_NO_CURL_CMAKE ON)
+
+	# Copy the necessary vcpkg DLLs (like iconv) to the install dir
+	set(X_VCPKG_APPLOCAL_DEPS_INSTALL ON)
+	set(CMAKE_TOOLCHAIN_FILE ${VCPKG_DIR}/scripts/buildsystems/vcpkg.cmake CACHE STRING "Vcpkg toolchain file")
 endif()
 
 find_program(SH_EXE sh PATHS "C:/Program Files/Git/bin")
@@ -243,7 +247,13 @@
 
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
 	add_compile_definitions(PROCFS_EXECUTABLE_PATH="/proc/self/exe" HAVE_DEV_TTY )
-	list(APPEND compat_SOURCES unix-socket.c)
+	list(APPEND compat_SOURCES unix-socket.c unix-stream-server.c)
+endif()
+
+if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
+	list(APPEND compat_SOURCES compat/simple-ipc/ipc-shared.c compat/simple-ipc/ipc-win32.c)
+else()
+	list(APPEND compat_SOURCES compat/simple-ipc/ipc-shared.c compat/simple-ipc/ipc-unix-socket.c)
 endif()
 
 set(EXE_EXTENSION ${CMAKE_EXECUTABLE_SUFFIX})
@@ -685,13 +695,17 @@
 
 parse_makefile_for_executables(git_builtin_extra "BUILT_INS")
 
+option(SKIP_DASHED_BUILT_INS "Skip hardlinking the dashed versions of the built-ins")
+
 #Creating hardlinks
+if(NOT SKIP_DASHED_BUILT_INS)
 foreach(s ${git_SOURCES} ${git_builtin_extra})
 	string(REPLACE "${CMAKE_SOURCE_DIR}/builtin/" "" s ${s})
 	string(REPLACE ".c" "" s ${s})
 	file(APPEND ${CMAKE_BINARY_DIR}/CreateLinks.cmake "file(CREATE_LINK git${EXE_EXTENSION} git-${s}${EXE_EXTENSION})\n")
 	list(APPEND git_links ${CMAKE_BINARY_DIR}/git-${s}${EXE_EXTENSION})
 endforeach()
+endif()
 
 if(CURL_FOUND)
 	set(remote_exes
@@ -807,15 +821,19 @@
 list(TRANSFORM git_perl_scripts PREPEND "${CMAKE_BINARY_DIR}/")
 
 #install
-install(TARGETS git git-shell
+foreach(program ${PROGRAMS_BUILT})
+if(program STREQUAL "git" OR program STREQUAL "git-shell")
+install(TARGETS ${program}
 	RUNTIME DESTINATION bin)
+else()
+install(TARGETS ${program}
+	RUNTIME DESTINATION libexec/git-core)
+endif()
+endforeach()
+
 install(PROGRAMS ${CMAKE_BINARY_DIR}/git-cvsserver
 	DESTINATION bin)
 
-list(REMOVE_ITEM PROGRAMS_BUILT git git-shell)
-install(TARGETS ${PROGRAMS_BUILT}
-	RUNTIME DESTINATION libexec/git-core)
-
 set(bin_links
 	git-receive-pack git-upload-archive git-upload-pack)
 
@@ -828,12 +846,12 @@
 
 foreach(b ${git_links})
 	string(REPLACE "${CMAKE_BINARY_DIR}" "" b ${b})
-	install(CODE "file(CREATE_LINK ${CMAKE_INSTALL_PREFIX}/bin/git${EXE_EXTENSION} ${CMAKE_INSTALL_PREFIX}/libexec/git-core/${b}${EXE_EXTENSION})")
+	install(CODE "file(CREATE_LINK ${CMAKE_INSTALL_PREFIX}/bin/git${EXE_EXTENSION} ${CMAKE_INSTALL_PREFIX}/libexec/git-core/${b})")
 endforeach()
 
 foreach(b ${git_http_links})
 	string(REPLACE "${CMAKE_BINARY_DIR}" "" b ${b})
-	install(CODE "file(CREATE_LINK  ${CMAKE_INSTALL_PREFIX}/libexec/git-core/git-remote-http${EXE_EXTENSION} ${CMAKE_INSTALL_PREFIX}/libexec/git-core/${b}${EXE_EXTENSION})")
+	install(CODE "file(CREATE_LINK  ${CMAKE_INSTALL_PREFIX}/libexec/git-core/git-remote-http${EXE_EXTENSION} ${CMAKE_INSTALL_PREFIX}/libexec/git-core/${b})")
 endforeach()
 
 install(PROGRAMS ${git_shell_scripts} ${git_perl_scripts} ${CMAKE_BINARY_DIR}/git-p4
diff --git a/contrib/coccinelle/array.cocci b/contrib/coccinelle/array.cocci
index 46b8d2e..9a4f00c 100644
--- a/contrib/coccinelle/array.cocci
+++ b/contrib/coccinelle/array.cocci
@@ -88,3 +88,11 @@
 @@
 - ptr = xmalloc((n) * sizeof(T));
 + ALLOC_ARRAY(ptr, n);
+
+@@
+type T;
+T *ptr;
+expression n != 1;
+@@
+- ptr = xcalloc(n, \( sizeof(*ptr) \| sizeof(T) \) )
++ CALLOC_ARRAY(ptr, n)
diff --git a/contrib/coccinelle/xcalloc.cocci b/contrib/coccinelle/xcalloc.cocci
new file mode 100644
index 0000000..c291011
--- /dev/null
+++ b/contrib/coccinelle/xcalloc.cocci
@@ -0,0 +1,10 @@
+@@
+type T;
+T *ptr;
+expression n;
+@@
+  xcalloc(
++ n,
+  \( sizeof(T) \| sizeof(*ptr) \)
+- , n
+  )
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 7dc6cd8..e1a6695 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -3053,7 +3053,7 @@
 			__gitcomp "--name-status --oneline --patch-with-stat"
 			;;
 		show,--*)
-			__gitcomp "$__git_diff_common_options"
+			__gitcomp "--include-untracked --only-untracked $__git_diff_common_options"
 			;;
 		branch,--*)
 			;;
diff --git a/convert.c b/convert.c
index ee360c2..45ac75f 100644
--- a/convert.c
+++ b/convert.c
@@ -24,17 +24,6 @@
 #define CONVERT_STAT_BITS_TXT_CRLF  0x2
 #define CONVERT_STAT_BITS_BIN       0x4
 
-enum crlf_action {
-	CRLF_UNDEFINED,
-	CRLF_BINARY,
-	CRLF_TEXT,
-	CRLF_TEXT_INPUT,
-	CRLF_TEXT_CRLF,
-	CRLF_AUTO,
-	CRLF_AUTO_INPUT,
-	CRLF_AUTO_CRLF
-};
-
 struct text_stat {
 	/* NUL, CR, LF and CRLF counts */
 	unsigned nul, lonecr, lonelf, crlf;
@@ -172,7 +161,7 @@
 	return 0;
 }
 
-static enum eol output_eol(enum crlf_action crlf_action)
+static enum eol output_eol(enum convert_crlf_action crlf_action)
 {
 	switch (crlf_action) {
 	case CRLF_BINARY:
@@ -246,7 +235,7 @@
 }
 
 static int will_convert_lf_to_crlf(struct text_stat *stats,
-				   enum crlf_action crlf_action)
+				   enum convert_crlf_action crlf_action)
 {
 	if (output_eol(crlf_action) != EOL_CRLF)
 		return 0;
@@ -499,7 +488,7 @@
 static int crlf_to_git(const struct index_state *istate,
 		       const char *path, const char *src, size_t len,
 		       struct strbuf *buf,
-		       enum crlf_action crlf_action, int conv_flags)
+		       enum convert_crlf_action crlf_action, int conv_flags)
 {
 	struct text_stat stats;
 	char *dst;
@@ -585,8 +574,8 @@
 	return 1;
 }
 
-static int crlf_to_worktree(const char *src, size_t len,
-			    struct strbuf *buf, enum crlf_action crlf_action)
+static int crlf_to_worktree(const char *src, size_t len, struct strbuf *buf,
+			    enum convert_crlf_action crlf_action)
 {
 	char *to_free = NULL;
 	struct text_stat stats;
@@ -884,9 +873,13 @@
 		goto done;
 
 	if (fd >= 0)
-		err = write_packetized_from_fd(fd, process->in);
+		err = write_packetized_from_fd_no_flush(fd, process->in);
 	else
-		err = write_packetized_from_buf(src, len, process->in);
+		err = write_packetized_from_buf_no_flush(src, len, process->in);
+	if (err)
+		goto done;
+
+	err = packet_flush_gently(process->in);
 	if (err)
 		goto done;
 
@@ -903,7 +896,8 @@
 		if (err)
 			goto done;
 
-		err = read_packetized_to_strbuf(process->out, &nbuf) < 0;
+		err = read_packetized_to_strbuf(process->out, &nbuf,
+						PACKET_READ_GENTLE_ON_EOF) < 0;
 		if (err)
 			goto done;
 
@@ -1028,7 +1022,7 @@
 		if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 			break;
 	if (!drv) {
-		drv = xcalloc(1, sizeof(struct convert_driver));
+		CALLOC_ARRAY(drv, 1);
 		drv->name = xmemdupz(name, namelen);
 		*user_convert_tail = drv;
 		user_convert_tail = &(drv->next);
@@ -1247,7 +1241,7 @@
 	return value;
 }
 
-static enum crlf_action git_path_check_crlf(struct attr_check_item *check)
+static enum convert_crlf_action git_path_check_crlf(struct attr_check_item *check)
 {
 	const char *value = check->value;
 
@@ -1297,18 +1291,10 @@
 	return !!ATTR_TRUE(value);
 }
 
-struct conv_attrs {
-	struct convert_driver *drv;
-	enum crlf_action attr_action; /* What attr says */
-	enum crlf_action crlf_action; /* When no attr is set, use core.autocrlf */
-	int ident;
-	const char *working_tree_encoding; /* Supported encoding or default encoding if NULL */
-};
-
 static struct attr_check *check;
 
-static void convert_attrs(const struct index_state *istate,
-			  struct conv_attrs *ca, const char *path)
+void convert_attrs(const struct index_state *istate,
+		   struct conv_attrs *ca, const char *path)
 {
 	struct attr_check_item *ccheck = NULL;
 
@@ -1456,7 +1442,6 @@
 	convert_attrs(istate, &ca, path);
 
 	assert(ca.drv);
-	assert(ca.drv->clean || ca.drv->process);
 
 	if (!apply_filter(path, NULL, 0, fd, dst, ca.drv, CAP_CLEAN, NULL, NULL))
 		die(_("%s: clean filter '%s' failed"), path, ca.drv->name);
@@ -1466,19 +1451,16 @@
 	ident_to_git(dst->buf, dst->len, dst, ca.ident);
 }
 
-static int convert_to_working_tree_internal(const struct index_state *istate,
-					    const char *path, const char *src,
-					    size_t len, struct strbuf *dst,
-					    int normalizing,
-					    const struct checkout_metadata *meta,
-					    struct delayed_checkout *dco)
+static int convert_to_working_tree_ca_internal(const struct conv_attrs *ca,
+					       const char *path, const char *src,
+					       size_t len, struct strbuf *dst,
+					       int normalizing,
+					       const struct checkout_metadata *meta,
+					       struct delayed_checkout *dco)
 {
 	int ret = 0, ret_filter = 0;
-	struct conv_attrs ca;
 
-	convert_attrs(istate, &ca, path);
-
-	ret |= ident_to_worktree(src, len, dst, ca.ident);
+	ret |= ident_to_worktree(src, len, dst, ca->ident);
 	if (ret) {
 		src = dst->buf;
 		len = dst->len;
@@ -1488,49 +1470,56 @@
 	 * is a smudge or process filter (even if the process filter doesn't
 	 * support smudge).  The filters might expect CRLFs.
 	 */
-	if ((ca.drv && (ca.drv->smudge || ca.drv->process)) || !normalizing) {
-		ret |= crlf_to_worktree(src, len, dst, ca.crlf_action);
+	if ((ca->drv && (ca->drv->smudge || ca->drv->process)) || !normalizing) {
+		ret |= crlf_to_worktree(src, len, dst, ca->crlf_action);
 		if (ret) {
 			src = dst->buf;
 			len = dst->len;
 		}
 	}
 
-	ret |= encode_to_worktree(path, src, len, dst, ca.working_tree_encoding);
+	ret |= encode_to_worktree(path, src, len, dst, ca->working_tree_encoding);
 	if (ret) {
 		src = dst->buf;
 		len = dst->len;
 	}
 
 	ret_filter = apply_filter(
-		path, src, len, -1, dst, ca.drv, CAP_SMUDGE, meta, dco);
-	if (!ret_filter && ca.drv && ca.drv->required)
-		die(_("%s: smudge filter %s failed"), path, ca.drv->name);
+		path, src, len, -1, dst, ca->drv, CAP_SMUDGE, meta, dco);
+	if (!ret_filter && ca->drv && ca->drv->required)
+		die(_("%s: smudge filter %s failed"), path, ca->drv->name);
 
 	return ret | ret_filter;
 }
 
-int async_convert_to_working_tree(const struct index_state *istate,
-				  const char *path, const char *src,
-				  size_t len, struct strbuf *dst,
-				  const struct checkout_metadata *meta,
-				  void *dco)
+int async_convert_to_working_tree_ca(const struct conv_attrs *ca,
+				     const char *path, const char *src,
+				     size_t len, struct strbuf *dst,
+				     const struct checkout_metadata *meta,
+				     void *dco)
 {
-	return convert_to_working_tree_internal(istate, path, src, len, dst, 0, meta, dco);
+	return convert_to_working_tree_ca_internal(ca, path, src, len, dst, 0,
+						   meta, dco);
 }
 
-int convert_to_working_tree(const struct index_state *istate,
-			    const char *path, const char *src,
-			    size_t len, struct strbuf *dst,
-			    const struct checkout_metadata *meta)
+int convert_to_working_tree_ca(const struct conv_attrs *ca,
+			       const char *path, const char *src,
+			       size_t len, struct strbuf *dst,
+			       const struct checkout_metadata *meta)
 {
-	return convert_to_working_tree_internal(istate, path, src, len, dst, 0, meta, NULL);
+	return convert_to_working_tree_ca_internal(ca, path, src, len, dst, 0,
+						   meta, NULL);
 }
 
 int renormalize_buffer(const struct index_state *istate, const char *path,
 		       const char *src, size_t len, struct strbuf *dst)
 {
-	int ret = convert_to_working_tree_internal(istate, path, src, len, dst, 1, NULL, NULL);
+	struct conv_attrs ca;
+	int ret;
+
+	convert_attrs(istate, &ca, path);
+	ret = convert_to_working_tree_ca_internal(&ca, path, src, len, dst, 1,
+						  NULL, NULL);
 	if (ret) {
 		src = dst->buf;
 		len = dst->len;
@@ -1957,34 +1946,25 @@
 }
 
 /*
- * Return an appropriately constructed filter for the path, or NULL if
+ * Return an appropriately constructed filter for the given ca, or NULL if
  * the contents cannot be filtered without reading the whole thing
  * in-core.
  *
  * Note that you would be crazy to set CRLF, smudge/clean or ident to a
  * large binary blob you would want us not to slurp into the memory!
  */
-struct stream_filter *get_stream_filter(const struct index_state *istate,
-					const char *path,
-					const struct object_id *oid)
+struct stream_filter *get_stream_filter_ca(const struct conv_attrs *ca,
+					   const struct object_id *oid)
 {
-	struct conv_attrs ca;
 	struct stream_filter *filter = NULL;
 
-	convert_attrs(istate, &ca, path);
-	if (ca.drv && (ca.drv->process || ca.drv->smudge || ca.drv->clean))
+	if (classify_conv_attrs(ca) != CA_CLASS_STREAMABLE)
 		return NULL;
 
-	if (ca.working_tree_encoding)
-		return NULL;
-
-	if (ca.crlf_action == CRLF_AUTO || ca.crlf_action == CRLF_AUTO_CRLF)
-		return NULL;
-
-	if (ca.ident)
+	if (ca->ident)
 		filter = ident_filter(oid);
 
-	if (output_eol(ca.crlf_action) == EOL_CRLF)
+	if (output_eol(ca->crlf_action) == EOL_CRLF)
 		filter = cascade_filter(filter, lf_to_crlf_filter());
 	else
 		filter = cascade_filter(filter, &null_filter_singleton);
@@ -1992,6 +1972,15 @@
 	return filter;
 }
 
+struct stream_filter *get_stream_filter(const struct index_state *istate,
+					const char *path,
+					const struct object_id *oid)
+{
+	struct conv_attrs ca;
+	convert_attrs(istate, &ca, path);
+	return get_stream_filter_ca(&ca, oid);
+}
+
 void free_stream_filter(struct stream_filter *filter)
 {
 	filter->vtbl->free(filter);
@@ -2025,3 +2014,21 @@
 	if (blob)
 		oidcpy(&dst->blob, blob);
 }
+
+enum conv_attrs_classification classify_conv_attrs(const struct conv_attrs *ca)
+{
+	if (ca->drv) {
+		if (ca->drv->process)
+			return CA_CLASS_INCORE_PROCESS;
+		if (ca->drv->smudge || ca->drv->clean)
+			return CA_CLASS_INCORE_FILTER;
+	}
+
+	if (ca->working_tree_encoding)
+		return CA_CLASS_INCORE;
+
+	if (ca->crlf_action == CRLF_AUTO || ca->crlf_action == CRLF_AUTO_CRLF)
+		return CA_CLASS_INCORE;
+
+	return CA_CLASS_STREAMABLE;
+}
diff --git a/convert.h b/convert.h
index e29d102..43e567a 100644
--- a/convert.h
+++ b/convert.h
@@ -63,6 +63,30 @@
 	struct object_id blob;
 };
 
+enum convert_crlf_action {
+	CRLF_UNDEFINED,
+	CRLF_BINARY,
+	CRLF_TEXT,
+	CRLF_TEXT_INPUT,
+	CRLF_TEXT_CRLF,
+	CRLF_AUTO,
+	CRLF_AUTO_INPUT,
+	CRLF_AUTO_CRLF
+};
+
+struct convert_driver;
+
+struct conv_attrs {
+	struct convert_driver *drv;
+	enum convert_crlf_action attr_action; /* What attr says */
+	enum convert_crlf_action crlf_action; /* When no attr is set, use core.autocrlf */
+	int ident;
+	const char *working_tree_encoding; /* Supported encoding or default encoding if NULL */
+};
+
+void convert_attrs(const struct index_state *istate,
+		   struct conv_attrs *ca, const char *path);
+
 extern enum eol core_eol;
 extern char *check_roundtrip_encoding;
 const char *get_cached_convert_stats_ascii(const struct index_state *istate,
@@ -75,15 +99,34 @@
 int convert_to_git(const struct index_state *istate,
 		   const char *path, const char *src, size_t len,
 		   struct strbuf *dst, int conv_flags);
-int convert_to_working_tree(const struct index_state *istate,
-			    const char *path, const char *src,
-			    size_t len, struct strbuf *dst,
-			    const struct checkout_metadata *meta);
-int async_convert_to_working_tree(const struct index_state *istate,
-				  const char *path, const char *src,
-				  size_t len, struct strbuf *dst,
-				  const struct checkout_metadata *meta,
-				  void *dco);
+int convert_to_working_tree_ca(const struct conv_attrs *ca,
+			       const char *path, const char *src,
+			       size_t len, struct strbuf *dst,
+			       const struct checkout_metadata *meta);
+int async_convert_to_working_tree_ca(const struct conv_attrs *ca,
+				     const char *path, const char *src,
+				     size_t len, struct strbuf *dst,
+				     const struct checkout_metadata *meta,
+				     void *dco);
+static inline int convert_to_working_tree(const struct index_state *istate,
+					  const char *path, const char *src,
+					  size_t len, struct strbuf *dst,
+					  const struct checkout_metadata *meta)
+{
+	struct conv_attrs ca;
+	convert_attrs(istate, &ca, path);
+	return convert_to_working_tree_ca(&ca, path, src, len, dst, meta);
+}
+static inline int async_convert_to_working_tree(const struct index_state *istate,
+						const char *path, const char *src,
+						size_t len, struct strbuf *dst,
+						const struct checkout_metadata *meta,
+						void *dco)
+{
+	struct conv_attrs ca;
+	convert_attrs(istate, &ca, path);
+	return async_convert_to_working_tree_ca(&ca, path, src, len, dst, meta, dco);
+}
 int async_query_available_blobs(const char *cmd,
 				struct string_list *available_paths);
 int renormalize_buffer(const struct index_state *istate,
@@ -136,6 +179,8 @@
 struct stream_filter *get_stream_filter(const struct index_state *istate,
 					const char *path,
 					const struct object_id *);
+struct stream_filter *get_stream_filter_ca(const struct conv_attrs *ca,
+					   const struct object_id *oid);
 void free_stream_filter(struct stream_filter *);
 int is_null_stream_filter(struct stream_filter *);
 
@@ -155,4 +200,37 @@
 		  const char *input, size_t *isize_p,
 		  char *output, size_t *osize_p);
 
+enum conv_attrs_classification {
+	/*
+	 * The blob must be loaded into a buffer before it can be
+	 * smudged. All smudging is done in-proc.
+	 */
+	CA_CLASS_INCORE,
+
+	/*
+	 * The blob must be loaded into a buffer, but uses a
+	 * single-file driver filter, such as rot13.
+	 */
+	CA_CLASS_INCORE_FILTER,
+
+	/*
+	 * The blob must be loaded into a buffer, but uses a
+	 * long-running driver process, such as LFS. This might or
+	 * might not use delayed operations. (The important thing is
+	 * that there is a single subordinate long-running process
+	 * handling all associated blobs and in case of delayed
+	 * operations, may hold per-blob state.)
+	 */
+	CA_CLASS_INCORE_PROCESS,
+
+	/*
+	 * The blob can be streamed and smudged without needing to
+	 * completely read it into a buffer.
+	 */
+	CA_CLASS_STREAMABLE,
+};
+
+enum conv_attrs_classification classify_conv_attrs(
+	const struct conv_attrs *ca);
+
 #endif /* CONVERT_H */
diff --git a/csum-file.c b/csum-file.c
index 0f35fa5..7510950 100644
--- a/csum-file.c
+++ b/csum-file.c
@@ -89,32 +89,35 @@
 void hashwrite(struct hashfile *f, const void *buf, unsigned int count)
 {
 	while (count) {
-		unsigned offset = f->offset;
-		unsigned left = sizeof(f->buffer) - offset;
+		unsigned left = sizeof(f->buffer) - f->offset;
 		unsigned nr = count > left ? left : count;
-		const void *data;
 
 		if (f->do_crc)
 			f->crc32 = crc32(f->crc32, buf, nr);
 
 		if (nr == sizeof(f->buffer)) {
-			/* process full buffer directly without copy */
-			data = buf;
+			/*
+			 * Flush a full batch worth of data directly
+			 * from the input, skipping the memcpy() to
+			 * the hashfile's buffer. In this block,
+			 * f->offset is necessarily zero.
+			 */
+			the_hash_algo->update_fn(&f->ctx, buf, nr);
+			flush(f, buf, nr);
 		} else {
-			memcpy(f->buffer + offset, buf, nr);
-			data = f->buffer;
+			/*
+			 * Copy to the hashfile's buffer, flushing only
+			 * if it became full.
+			 */
+			memcpy(f->buffer + f->offset, buf, nr);
+			f->offset += nr;
+			left -= nr;
+			if (!left)
+				hashflush(f);
 		}
 
 		count -= nr;
-		offset += nr;
 		buf = (char *) buf + nr;
-		left -= nr;
-		if (!left) {
-			the_hash_algo->update_fn(&f->ctx, data, offset);
-			flush(f, data, offset);
-			offset = 0;
-		}
-		f->offset = offset;
 	}
 }
 
diff --git a/daemon.c b/daemon.c
index 2ab7ea8..3435319 100644
--- a/daemon.c
+++ b/daemon.c
@@ -840,7 +840,7 @@
 {
 	struct child *newborn, **cradle;
 
-	newborn = xcalloc(1, sizeof(*newborn));
+	CALLOC_ARRAY(newborn, 1);
 	live_children++;
 	memcpy(&newborn->cld, cld, sizeof(*cld));
 	memcpy(&newborn->address, addr, addrlen);
@@ -1148,7 +1148,7 @@
 	struct pollfd *pfd;
 	int i;
 
-	pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
+	CALLOC_ARRAY(pfd, socklist->nr);
 
 	for (i = 0; i < socklist->nr; i++) {
 		pfd[i].fd = socklist->list[i];
diff --git a/decorate.c b/decorate.c
index a605b1b..2036d15 100644
--- a/decorate.c
+++ b/decorate.c
@@ -39,7 +39,7 @@
 	struct decoration_entry *old_entries = n->entries;
 
 	n->size = (old_size + 1000) * 3 / 2;
-	n->entries = xcalloc(n->size, sizeof(struct decoration_entry));
+	CALLOC_ARRAY(n->entries, n->size);
 	n->nr = 0;
 
 	for (i = 0; i < old_size; i++) {
diff --git a/diff-lib.c b/diff-lib.c
index b73cc18..e5a58c9 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -28,9 +28,10 @@
  * exists for ce that is a submodule -- it is a submodule that is not
  * checked out).  Return negative for an error.
  */
-static int check_removed(const struct cache_entry *ce, struct stat *st)
+static int check_removed(const struct index_state *istate, const struct cache_entry *ce, struct stat *st)
 {
-	if (lstat(ce->name, st) < 0) {
+	assert(is_fsmonitor_refreshed(istate));
+	if (!(ce->ce_flags & CE_FSMONITOR_VALID) && lstat(ce->name, st) < 0) {
 		if (!is_missing_file_error(errno))
 			return -1;
 		return 1;
@@ -136,7 +137,7 @@
 			memset(&(dpath->parent[0]), 0,
 			       sizeof(struct combine_diff_parent)*5);
 
-			changed = check_removed(ce, &st);
+			changed = check_removed(istate, ce, &st);
 			if (!changed)
 				wt_mode = ce_mode_from_stat(ce, st.st_mode);
 			else {
@@ -216,7 +217,7 @@
 		} else {
 			struct stat st;
 
-			changed = check_removed(ce, &st);
+			changed = check_removed(istate, ce, &st);
 			if (changed) {
 				if (changed < 0) {
 					perror(ce->name);
@@ -278,7 +279,8 @@
 		       oid, oid_valid, ce->name, dirty_submodule);
 }
 
-static int get_stat_data(const struct cache_entry *ce,
+static int get_stat_data(const struct index_state *istate,
+			 const struct cache_entry *ce,
 			 const struct object_id **oidp,
 			 unsigned int *modep,
 			 int cached, int match_missing,
@@ -290,7 +292,7 @@
 	if (!cached && !ce_uptodate(ce)) {
 		int changed;
 		struct stat st;
-		changed = check_removed(ce, &st);
+		changed = check_removed(istate, ce, &st);
 		if (changed < 0)
 			return -1;
 		else if (changed) {
@@ -321,12 +323,13 @@
 	const struct object_id *oid;
 	unsigned int mode;
 	unsigned dirty_submodule = 0;
+	struct index_state *istate = revs->diffopt.repo->index;
 
 	/*
 	 * New file in the index: it might actually be different in
 	 * the working tree.
 	 */
-	if (get_stat_data(new_file, &oid, &mode, cached, match_missing,
+	if (get_stat_data(istate, new_file, &oid, &mode, cached, match_missing,
 	    &dirty_submodule, &revs->diffopt) < 0)
 		return;
 
@@ -342,8 +345,9 @@
 	unsigned int mode, oldmode;
 	const struct object_id *oid;
 	unsigned dirty_submodule = 0;
+	struct index_state *istate = revs->diffopt.repo->index;
 
-	if (get_stat_data(new_entry, &oid, &mode, cached, match_missing,
+	if (get_stat_data(istate, new_entry, &oid, &mode, cached, match_missing,
 			  &dirty_submodule, &revs->diffopt) < 0) {
 		if (report_missing)
 			diff_index_show_file(revs, "-", old_entry,
@@ -574,6 +578,7 @@
 	struct object_id oid;
 	const char *name;
 	char merge_base_hex[GIT_MAX_HEXSZ + 1];
+	struct index_state *istate = revs->diffopt.repo->index;
 
 	if (revs->pending.nr != 1)
 		BUG("run_diff_index must be passed exactly one tree");
@@ -581,6 +586,8 @@
 	trace_performance_enter();
 	ent = revs->pending.objects;
 
+	refresh_fsmonitor(istate);
+
 	if (merge_base) {
 		diff_get_merge_base(revs, &oid);
 		name = oid_to_hex_r(merge_base_hex, &oid);
diff --git a/diff.c b/diff.c
index 6956f5e..4acccd9 100644
--- a/diff.c
+++ b/diff.c
@@ -2233,14 +2233,12 @@
 	struct diff_options *o = xmalloc(sizeof(struct diff_options));
 	memcpy(o, orig_opts, sizeof(struct diff_options));
 
-	ecbdata->diff_words =
-		xcalloc(1, sizeof(struct diff_words_data));
+	CALLOC_ARRAY(ecbdata->diff_words, 1);
 	ecbdata->diff_words->type = o->word_diff;
 	ecbdata->diff_words->opt = o;
 
 	if (orig_opts->emitted_symbols)
-		o->emitted_symbols =
-			xcalloc(1, sizeof(struct emitted_diff_symbols));
+		CALLOC_ARRAY(o->emitted_symbols, 1);
 
 	if (!o->word_regex)
 		o->word_regex = userdiff_word_regex(one, o->repo->index);
@@ -2509,7 +2507,7 @@
 					  const char *name_b)
 {
 	struct diffstat_file *x;
-	x = xcalloc(1, sizeof(*x));
+	CALLOC_ARRAY(x, 1);
 	ALLOC_GROW(diffstat->files, diffstat->nr + 1, diffstat->alloc);
 	diffstat->files[diffstat->nr++] = x;
 	if (name_b) {
@@ -4918,7 +4916,7 @@
 		return error(_("unable to resolve '%s'"), arg);
 
 	if (!opt->objfind)
-		opt->objfind = xcalloc(1, sizeof(*opt->objfind));
+		CALLOC_ARRAY(opt->objfind, 1);
 
 	opt->pickaxe_opts |= DIFF_PICKAXE_KIND_OBJFIND;
 	opt->flags.recursive = 1;
diff --git a/diffcore-rename.c b/diffcore-rename.c
index 4155818..e2ed648 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -367,6 +367,296 @@
 	return renames;
 }
 
+struct dir_rename_info {
+	struct strintmap idx_map;
+	struct strmap dir_rename_guess;
+	struct strmap *dir_rename_count;
+	struct strset *relevant_source_dirs;
+	unsigned setup;
+};
+
+static char *get_dirname(const char *filename)
+{
+	char *slash = strrchr(filename, '/');
+	return slash ? xstrndup(filename, slash - filename) : xstrdup("");
+}
+
+static void dirname_munge(char *filename)
+{
+	char *slash = strrchr(filename, '/');
+	if (!slash)
+		slash = filename;
+	*slash = '\0';
+}
+
+static const char *get_highest_rename_path(struct strintmap *counts)
+{
+	int highest_count = 0;
+	const char *highest_destination_dir = NULL;
+	struct hashmap_iter iter;
+	struct strmap_entry *entry;
+
+	strintmap_for_each_entry(counts, &iter, entry) {
+		const char *destination_dir = entry->key;
+		intptr_t count = (intptr_t)entry->value;
+		if (count > highest_count) {
+			highest_count = count;
+			highest_destination_dir = destination_dir;
+		}
+	}
+	return highest_destination_dir;
+}
+
+static void increment_count(struct dir_rename_info *info,
+			    char *old_dir,
+			    char *new_dir)
+{
+	struct strintmap *counts;
+	struct strmap_entry *e;
+
+	/* Get the {new_dirs -> counts} mapping using old_dir */
+	e = strmap_get_entry(info->dir_rename_count, old_dir);
+	if (e) {
+		counts = e->value;
+	} else {
+		counts = xmalloc(sizeof(*counts));
+		strintmap_init_with_options(counts, 0, NULL, 1);
+		strmap_put(info->dir_rename_count, old_dir, counts);
+	}
+
+	/* Increment the count for new_dir */
+	strintmap_incr(counts, new_dir, 1);
+}
+
+static void update_dir_rename_counts(struct dir_rename_info *info,
+				     struct strset *dirs_removed,
+				     const char *oldname,
+				     const char *newname)
+{
+	char *old_dir = xstrdup(oldname);
+	char *new_dir = xstrdup(newname);
+	char new_dir_first_char = new_dir[0];
+	int first_time_in_loop = 1;
+
+	if (!info->setup)
+		/*
+		 * info->setup is 0 here in two cases: (1) all auxiliary
+		 * vars (like dirs_removed) were NULL so
+		 * initialize_dir_rename_info() returned early, or (2)
+		 * either break detection or copy detection are active so
+		 * that we never called initialize_dir_rename_info().  In
+		 * the former case, we don't have enough info to know if
+		 * directories were renamed (because dirs_removed lets us
+		 * know about a necessary prerequisite, namely if they were
+		 * removed), and in the latter, we don't care about
+		 * directory renames or find_basename_matches.
+		 *
+		 * This matters because both basename and inexact matching
+		 * will also call update_dir_rename_counts().  In either of
+		 * the above two cases info->dir_rename_counts will not
+		 * have been properly initialized which prevents us from
+		 * updating it, but in these two cases we don't care about
+		 * dir_rename_counts anyway, so we can just exit early.
+		 */
+		return;
+
+	while (1) {
+		/* Get old_dir, skip if its directory isn't relevant. */
+		dirname_munge(old_dir);
+		if (info->relevant_source_dirs &&
+		    !strset_contains(info->relevant_source_dirs, old_dir))
+			break;
+
+		/* Get new_dir */
+		dirname_munge(new_dir);
+
+		/*
+		 * When renaming
+		 *   "a/b/c/d/e/foo.c" -> "a/b/some/thing/else/e/foo.c"
+		 * then this suggests that both
+		 *   a/b/c/d/e/ => a/b/some/thing/else/e/
+		 *   a/b/c/d/   => a/b/some/thing/else/
+		 * so we want to increment counters for both.  We do NOT,
+		 * however, also want to suggest that there was the following
+		 * rename:
+		 *   a/b/c/ => a/b/some/thing/
+		 * so we need to quit at that point.
+		 *
+		 * Note the when first_time_in_loop, we only strip off the
+		 * basename, and we don't care if that's different.
+		 */
+		if (!first_time_in_loop) {
+			char *old_sub_dir = strchr(old_dir, '\0')+1;
+			char *new_sub_dir = strchr(new_dir, '\0')+1;
+			if (!*new_dir) {
+				/*
+				 * Special case when renaming to root directory,
+				 * i.e. when new_dir == "".  In this case, we had
+				 * something like
+				 *    a/b/subdir => subdir
+				 * and so dirname_munge() sets things up so that
+				 *    old_dir = "a/b\0subdir\0"
+				 *    new_dir = "\0ubdir\0"
+				 * We didn't have a '/' to overwrite a '\0' onto
+				 * in new_dir, so we have to compare differently.
+				 */
+				if (new_dir_first_char != old_sub_dir[0] ||
+				    strcmp(old_sub_dir+1, new_sub_dir))
+					break;
+			} else {
+				if (strcmp(old_sub_dir, new_sub_dir))
+					break;
+			}
+		}
+
+		if (strset_contains(dirs_removed, old_dir))
+			increment_count(info, old_dir, new_dir);
+		else
+			break;
+
+		/* If we hit toplevel directory ("") for old or new dir, quit */
+		if (!*old_dir || !*new_dir)
+			break;
+
+		first_time_in_loop = 0;
+	}
+
+	/* Free resources we don't need anymore */
+	free(old_dir);
+	free(new_dir);
+}
+
+static void initialize_dir_rename_info(struct dir_rename_info *info,
+				       struct strset *dirs_removed,
+				       struct strmap *dir_rename_count)
+{
+	struct hashmap_iter iter;
+	struct strmap_entry *entry;
+	int i;
+
+	if (!dirs_removed) {
+		info->setup = 0;
+		return;
+	}
+	info->setup = 1;
+
+	info->dir_rename_count = dir_rename_count;
+	if (!info->dir_rename_count) {
+		info->dir_rename_count = xmalloc(sizeof(*dir_rename_count));
+		strmap_init(info->dir_rename_count);
+	}
+	strintmap_init_with_options(&info->idx_map, -1, NULL, 0);
+	strmap_init_with_options(&info->dir_rename_guess, NULL, 0);
+
+	/* Setup info->relevant_source_dirs */
+	info->relevant_source_dirs = dirs_removed;
+
+	/*
+	 * Loop setting up both info->idx_map, and doing setup of
+	 * info->dir_rename_count.
+	 */
+	for (i = 0; i < rename_dst_nr; ++i) {
+		/*
+		 * For non-renamed files, make idx_map contain mapping of
+		 *   filename -> index (index within rename_dst, that is)
+		 */
+		if (!rename_dst[i].is_rename) {
+			char *filename = rename_dst[i].p->two->path;
+			strintmap_set(&info->idx_map, filename, i);
+			continue;
+		}
+
+		/*
+		 * For everything else (i.e. renamed files), make
+		 * dir_rename_count contain a map of a map:
+		 *   old_directory -> {new_directory -> count}
+		 * In other words, for every pair look at the directories for
+		 * the old filename and the new filename and count how many
+		 * times that pairing occurs.
+		 */
+		update_dir_rename_counts(info, dirs_removed,
+					 rename_dst[i].p->one->path,
+					 rename_dst[i].p->two->path);
+	}
+
+	/*
+	 * Now we collapse
+	 *    dir_rename_count: old_directory -> {new_directory -> count}
+	 * down to
+	 *    dir_rename_guess: old_directory -> best_new_directory
+	 * where best_new_directory is the one with the highest count.
+	 */
+	strmap_for_each_entry(info->dir_rename_count, &iter, entry) {
+		/* entry->key is source_dir */
+		struct strintmap *counts = entry->value;
+		char *best_newdir;
+
+		best_newdir = xstrdup(get_highest_rename_path(counts));
+		strmap_put(&info->dir_rename_guess, entry->key,
+			   best_newdir);
+	}
+}
+
+void partial_clear_dir_rename_count(struct strmap *dir_rename_count)
+{
+	struct hashmap_iter iter;
+	struct strmap_entry *entry;
+
+	strmap_for_each_entry(dir_rename_count, &iter, entry) {
+		struct strintmap *counts = entry->value;
+		strintmap_clear(counts);
+	}
+	strmap_partial_clear(dir_rename_count, 1);
+}
+
+static void cleanup_dir_rename_info(struct dir_rename_info *info,
+				    struct strset *dirs_removed,
+				    int keep_dir_rename_count)
+{
+	struct hashmap_iter iter;
+	struct strmap_entry *entry;
+	struct string_list to_remove = STRING_LIST_INIT_NODUP;
+	int i;
+
+	if (!info->setup)
+		return;
+
+	/* idx_map */
+	strintmap_clear(&info->idx_map);
+
+	/* dir_rename_guess */
+	strmap_clear(&info->dir_rename_guess, 1);
+
+	/* dir_rename_count */
+	if (!keep_dir_rename_count) {
+		partial_clear_dir_rename_count(info->dir_rename_count);
+		strmap_clear(info->dir_rename_count, 1);
+		FREE_AND_NULL(info->dir_rename_count);
+		return;
+	}
+
+	/*
+	 * Although dir_rename_count was passed in
+	 * diffcore_rename_extended() and we want to keep it around and
+	 * return it to that caller, we first want to remove any data
+	 * associated with directories that weren't renamed.
+	 */
+	strmap_for_each_entry(info->dir_rename_count, &iter, entry) {
+		const char *source_dir = entry->key;
+		struct strintmap *counts = entry->value;
+
+		if (!strset_contains(dirs_removed, source_dir)) {
+			string_list_append(&to_remove, source_dir);
+			strintmap_clear(counts);
+			continue;
+		}
+	}
+	for (i = 0; i < to_remove.nr; ++i)
+		strmap_remove(info->dir_rename_count,
+			      to_remove.items[i].string, 1);
+	string_list_clear(&to_remove, 0);
+}
+
 static const char *get_basename(const char *filename)
 {
 	/*
@@ -379,8 +669,87 @@
 	return base ? base + 1 : filename;
 }
 
+static int idx_possible_rename(char *filename, struct dir_rename_info *info)
+{
+	/*
+	 * Our comparison of files with the same basename (see
+	 * find_basename_matches() below), is only helpful when after exact
+	 * rename detection we have exactly one file with a given basename
+	 * among the rename sources and also only exactly one file with
+	 * that basename among the rename destinations.  When we have
+	 * multiple files with the same basename in either set, we do not
+	 * know which to compare against.  However, there are some
+	 * filenames that occur in large numbers (particularly
+	 * build-related filenames such as 'Makefile', '.gitignore', or
+	 * 'build.gradle' that potentially exist within every single
+	 * subdirectory), and for performance we want to be able to quickly
+	 * find renames for these files too.
+	 *
+	 * The reason basename comparisons are a useful heuristic was that it
+	 * is common for people to move files across directories while keeping
+	 * their filename the same.  If we had a way of determining or even
+	 * making a good educated guess about which directory these non-unique
+	 * basename files had moved the file to, we could check it.
+	 * Luckily...
+	 *
+	 * When an entire directory is in fact renamed, we have two factors
+	 * helping us out:
+	 *   (a) the original directory disappeared giving us a hint
+	 *       about when we can apply an extra heuristic.
+	 *   (a) we often have several files within that directory and
+	 *       subdirectories that are renamed without changes
+	 * So, rules for a heuristic:
+	 *   (0) If there basename matches are non-unique (the condition under
+	 *       which this function is called) AND
+	 *   (1) the directory in which the file was found has disappeared
+	 *       (i.e. dirs_removed is non-NULL and has a relevant entry) THEN
+	 *   (2) use exact renames of files within the directory to determine
+	 *       where the directory is likely to have been renamed to.  IF
+	 *       there is at least one exact rename from within that
+	 *       directory, we can proceed.
+	 *   (3) If there are multiple places the directory could have been
+	 *       renamed to based on exact renames, ignore all but one of them.
+	 *       Just use the destination with the most renames going to it.
+	 *   (4) Check if applying that directory rename to the original file
+	 *       would result in a destination filename that is in the
+	 *       potential rename set.  If so, return the index of the
+	 *       destination file (the index within rename_dst).
+	 *   (5) Compare the original file and returned destination for
+	 *       similarity, and if they are sufficiently similar, record the
+	 *       rename.
+	 *
+	 * This function, idx_possible_rename(), is only responsible for (4).
+	 * The conditions/steps in (1)-(3) are handled via setting up
+	 * dir_rename_count and dir_rename_guess in
+	 * initialize_dir_rename_info().  Steps (0) and (5) are handled by
+	 * the caller of this function.
+	 */
+	char *old_dir, *new_dir;
+	struct strbuf new_path = STRBUF_INIT;
+	int idx;
+
+	if (!info->setup)
+		return -1;
+
+	old_dir = get_dirname(filename);
+	new_dir = strmap_get(&info->dir_rename_guess, old_dir);
+	free(old_dir);
+	if (!new_dir)
+		return -1;
+
+	strbuf_addstr(&new_path, new_dir);
+	strbuf_addch(&new_path, '/');
+	strbuf_addstr(&new_path, get_basename(filename));
+
+	idx = strintmap_get(&info->idx_map, new_path.buf);
+	strbuf_release(&new_path);
+	return idx;
+}
+
 static int find_basename_matches(struct diff_options *options,
-				 int minimum_score)
+				 int minimum_score,
+				 struct dir_rename_info *info,
+				 struct strset *dirs_removed)
 {
 	/*
 	 * When I checked in early 2020, over 76% of file renames in linux
@@ -415,8 +784,6 @@
 	int i, renames = 0;
 	struct strintmap sources;
 	struct strintmap dests;
-	struct hashmap_iter iter;
-	struct strmap_entry *entry;
 
 	/*
 	 * The prefeteching stuff wants to know if it can skip prefetching
@@ -466,17 +833,39 @@
 	}
 
 	/* Now look for basename matchups and do similarity estimation */
-	strintmap_for_each_entry(&sources, &iter, entry) {
-		const char *base = entry->key;
-		intptr_t src_index = (intptr_t)entry->value;
+	for (i = 0; i < rename_src_nr; ++i) {
+		char *filename = rename_src[i].p->one->path;
+		const char *base = NULL;
+		intptr_t src_index;
 		intptr_t dst_index;
-		if (src_index == -1)
-			continue;
 
-		if (0 <= (dst_index = strintmap_get(&dests, base))) {
+		/*
+		 * If the basename is unique among remaining sources, then
+		 * src_index will equal 'i' and we can attempt to match it
+		 * to a unique basename in the destinations.  Otherwise,
+		 * use directory rename heuristics, if possible.
+		 */
+		base = get_basename(filename);
+		src_index = strintmap_get(&sources, base);
+		assert(src_index == -1 || src_index == i);
+
+		if (strintmap_contains(&dests, base)) {
 			struct diff_filespec *one, *two;
 			int score;
 
+			/* Find a matching destination, if possible */
+			dst_index = strintmap_get(&dests, base);
+			if (src_index == -1 || dst_index == -1) {
+				src_index = i;
+				dst_index = idx_possible_rename(filename, info);
+			}
+			if (dst_index == -1)
+				continue;
+
+			/* Ignore this dest if already used in a rename */
+			if (rename_dst[dst_index].is_rename)
+				continue; /* already used previously */
+
 			/* Estimate the similarity */
 			one = rename_src[src_index].p->one;
 			two = rename_dst[dst_index].p->two;
@@ -488,6 +877,8 @@
 				continue;
 			record_rename_pair(dst_index, src_index, score);
 			renames++;
+			update_dir_rename_counts(info, dirs_removed,
+						 one->path, two->path);
 
 			/*
 			 * Found a rename so don't need text anymore; if we
@@ -571,7 +962,12 @@
 	return 1;
 }
 
-static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
+static int find_renames(struct diff_score *mx,
+			int dst_cnt,
+			int minimum_score,
+			int copies,
+			struct dir_rename_info *info,
+			struct strset *dirs_removed)
 {
 	int count = 0, i;
 
@@ -588,6 +984,9 @@
 			continue;
 		record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 		count++;
+		update_dir_rename_counts(info, dirs_removed,
+					 rename_src[mx[i].src].p->one->path,
+					 rename_dst[mx[i].dst].p->two->path);
 	}
 	return count;
 }
@@ -640,7 +1039,9 @@
 	rename_src_nr = new_num_src;
 }
 
-void diffcore_rename(struct diff_options *options)
+void diffcore_rename_extended(struct diff_options *options,
+			      struct strset *dirs_removed,
+			      struct strmap *dir_rename_count)
 {
 	int detect_rename = options->detect_rename;
 	int minimum_score = options->rename_score;
@@ -651,9 +1052,14 @@
 	int num_destinations, dst_cnt;
 	int num_sources, want_copies;
 	struct progress *progress = NULL;
+	struct dir_rename_info info;
 
 	trace2_region_enter("diff", "setup", options->repo);
+	info.setup = 0;
+	assert(!dir_rename_count || strmap_empty(dir_rename_count));
 	want_copies = (detect_rename == DIFF_DETECT_COPY);
+	if (dirs_removed && (break_idx || want_copies))
+		BUG("dirs_removed incompatible with break/copy detection");
 	if (!minimum_score)
 		minimum_score = DEFAULT_RENAME_SCORE;
 
@@ -745,10 +1151,17 @@
 		remove_unneeded_paths_from_src(want_copies);
 		trace2_region_leave("diff", "cull after exact", options->repo);
 
+		/* Preparation for basename-driven matching. */
+		trace2_region_enter("diff", "dir rename setup", options->repo);
+		initialize_dir_rename_info(&info,
+					   dirs_removed, dir_rename_count);
+		trace2_region_leave("diff", "dir rename setup", options->repo);
+
 		/* Utilize file basenames to quickly find renames. */
 		trace2_region_enter("diff", "basename matches", options->repo);
 		rename_count += find_basename_matches(options,
-						      min_basename_score);
+						      min_basename_score,
+						      &info, dirs_removed);
 		trace2_region_leave("diff", "basename matches", options->repo);
 
 		/*
@@ -787,8 +1200,7 @@
 				(uint64_t)num_destinations * (uint64_t)num_sources);
 	}
 
-	mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_destinations),
-		     sizeof(*mx));
+	CALLOC_ARRAY(mx, st_mult(NUM_CANDIDATE_PER_DST, num_destinations));
 	for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 		struct diff_filespec *two = rename_dst[i].p->two;
 		struct diff_score *m;
@@ -834,9 +1246,11 @@
 	/* cost matrix sorted by most to least similar pair */
 	STABLE_QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
 
-	rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
+	rename_count += find_renames(mx, dst_cnt, minimum_score, 0,
+				     &info, dirs_removed);
 	if (want_copies)
-		rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
+		rename_count += find_renames(mx, dst_cnt, minimum_score, 1,
+					     &info, dirs_removed);
 	free(mx);
 	trace2_region_leave("diff", "inexact renames", options->repo);
 
@@ -912,6 +1326,7 @@
 		if (rename_dst[i].filespec_to_free)
 			free_filespec(rename_dst[i].filespec_to_free);
 
+	cleanup_dir_rename_info(&info, dirs_removed, dir_rename_count != NULL);
 	FREE_AND_NULL(rename_dst);
 	rename_dst_nr = rename_dst_alloc = 0;
 	FREE_AND_NULL(rename_src);
@@ -923,3 +1338,8 @@
 	trace2_region_leave("diff", "write back to queue", options->repo);
 	return;
 }
+
+void diffcore_rename(struct diff_options *options)
+{
+	diffcore_rename_extended(options, NULL, NULL);
+}
diff --git a/diffcore.h b/diffcore.h
index c1592bc..b9a230a 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -8,6 +8,8 @@
 
 struct diff_options;
 struct repository;
+struct strmap;
+struct strset;
 struct userdiff_driver;
 
 /* This header file is internal between diff.c and its diff transformers
@@ -159,8 +161,13 @@
 				 struct diff_filespec *);
 void diff_q(struct diff_queue_struct *, struct diff_filepair *);
 
+void partial_clear_dir_rename_count(struct strmap *dir_rename_count);
+
 void diffcore_break(struct repository *, int);
 void diffcore_rename(struct diff_options *);
+void diffcore_rename_extended(struct diff_options *options,
+			      struct strset *dirs_removed,
+			      struct strmap *dir_rename_count);
 void diffcore_merge_broken(void);
 void diffcore_pickaxe(struct diff_options *);
 void diffcore_order(const char *orderfile);
diff --git a/dir.c b/dir.c
index fd8aa7c..3474e67 100644
--- a/dir.c
+++ b/dir.c
@@ -1035,6 +1035,9 @@
 				    const char *base, int baselen,
 				    struct pattern_list *pl);
 
+/* Flags for add_patterns() */
+#define PATTERN_NOFOLLOW (1<<0)
+
 /*
  * Given a file with name "fname", read it (either from disk, or from
  * an index if 'istate' is non-null), parse it and store the
@@ -1046,7 +1049,7 @@
  */
 static int add_patterns(const char *fname, const char *base, int baselen,
 			struct pattern_list *pl, struct index_state *istate,
-			struct oid_stat *oid_stat)
+			unsigned flags, struct oid_stat *oid_stat)
 {
 	struct stat st;
 	int r;
@@ -1054,7 +1057,11 @@
 	size_t size = 0;
 	char *buf;
 
-	fd = open(fname, O_RDONLY);
+	if (flags & PATTERN_NOFOLLOW)
+		fd = open_nofollow(fname, O_RDONLY);
+	else
+		fd = open(fname, O_RDONLY);
+
 	if (fd < 0 || fstat(fd, &st) < 0) {
 		if (fd < 0)
 			warn_on_fopen_errors(fname);
@@ -1143,9 +1150,10 @@
 
 int add_patterns_from_file_to_list(const char *fname, const char *base,
 				   int baselen, struct pattern_list *pl,
-				   struct index_state *istate)
+				   struct index_state *istate,
+				   unsigned flags)
 {
-	return add_patterns(fname, base, baselen, pl, istate, NULL);
+	return add_patterns(fname, base, baselen, pl, istate, flags, NULL);
 }
 
 int add_patterns_from_blob_to_list(
@@ -1194,7 +1202,7 @@
 	if (!dir->untracked)
 		dir->unmanaged_exclude_files++;
 	pl = add_pattern_list(dir, EXC_FILE, fname);
-	if (add_patterns(fname, "", 0, pl, NULL, oid_stat) < 0)
+	if (add_patterns(fname, "", 0, pl, NULL, 0, oid_stat) < 0)
 		die(_("cannot use %s as an exclude file"), fname);
 }
 
@@ -1488,7 +1496,7 @@
 		const char *cp;
 		struct oid_stat oid_stat;
 
-		stk = xcalloc(1, sizeof(*stk));
+		CALLOC_ARRAY(stk, 1);
 		if (current < 0) {
 			cp = base;
 			current = 0;
@@ -1558,6 +1566,7 @@
 			strbuf_addstr(&sb, dir->exclude_per_dir);
 			pl->src = strbuf_detach(&sb, NULL);
 			add_patterns(pl->src, pl->src, stk->baselen, pl, istate,
+				     PATTERN_NOFOLLOW,
 				     untracked ? &oid_stat : NULL);
 		}
 		/*
@@ -3006,7 +3015,7 @@
 	char *sparse_filename = get_sparse_checkout_filename();
 
 	pl->use_cone_patterns = core_sparse_checkout_cone;
-	res = add_patterns_from_file_to_list(sparse_filename, "", 0, pl, NULL);
+	res = add_patterns_from_file_to_list(sparse_filename, "", 0, pl, NULL, 0);
 
 	free(sparse_filename);
 	return res;
@@ -3162,7 +3171,7 @@
 	int varint_len;
 	const unsigned hashsz = the_hash_algo->rawsz;
 
-	ouc = xcalloc(1, sizeof(*ouc));
+	CALLOC_ARRAY(ouc, 1);
 	stat_data_to_disk(&ouc->info_exclude_stat, &untracked->ss_info_exclude.stat);
 	stat_data_to_disk(&ouc->excludes_file_stat, &untracked->ss_excludes_file.stat);
 	ouc->dir_flags = htonl(untracked->dir_flags);
@@ -3373,7 +3382,7 @@
 	if (next + exclude_per_dir_offset + 1 > end)
 		return NULL;
 
-	uc = xcalloc(1, sizeof(*uc));
+	CALLOC_ARRAY(uc, 1);
 	strbuf_init(&uc->ident, ident_len);
 	strbuf_add(&uc->ident, ident, ident_len);
 	load_oid_stat(&uc->ss_info_exclude,
diff --git a/dir.h b/dir.h
index facfae4..04d886c 100644
--- a/dir.h
+++ b/dir.h
@@ -420,7 +420,8 @@
 struct pattern_list *add_pattern_list(struct dir_struct *dir,
 				      int group_type, const char *src);
 int add_patterns_from_file_to_list(const char *fname, const char *base, int baselen,
-				   struct pattern_list *pl, struct  index_state *istate);
+				   struct pattern_list *pl, struct index_state *istate,
+				   unsigned flags);
 void add_patterns_from_file(struct dir_struct *, const char *fname);
 int add_patterns_from_blob_to_list(struct object_id *oid,
 				   const char *base, int baselen,
diff --git a/entry.c b/entry.c
index 7b9f437..2dc94ba 100644
--- a/entry.c
+++ b/entry.c
@@ -6,6 +6,7 @@
 #include "submodule.h"
 #include "progress.h"
 #include "fsmonitor.h"
+#include "entry.h"
 
 static void create_directories(const char *path, int path_len,
 			       const struct checkout *state)
@@ -83,7 +84,7 @@
 	return open(path, O_WRONLY | O_CREAT | O_EXCL, mode);
 }
 
-static void *read_blob_entry(const struct cache_entry *ce, unsigned long *size)
+void *read_blob_entry(const struct cache_entry *ce, unsigned long *size)
 {
 	enum object_type type;
 	void *blob_data = read_object_file(&ce->oid, &type, size);
@@ -108,7 +109,7 @@
 	}
 }
 
-static int fstat_output(int fd, const struct checkout *state, struct stat *st)
+int fstat_checkout_output(int fd, const struct checkout *state, struct stat *st)
 {
 	/* use fstat() only when path == ce->name */
 	if (fstat_is_reliable() &&
@@ -131,7 +132,7 @@
 		return -1;
 
 	result |= stream_blob_to_fd(fd, &ce->oid, filter, 1);
-	*fstat_done = fstat_output(fd, state, statbuf);
+	*fstat_done = fstat_checkout_output(fd, state, statbuf);
 	result |= close(fd);
 
 	if (result)
@@ -250,8 +251,21 @@
 	return errs;
 }
 
-static int write_entry(struct cache_entry *ce,
-		       char *path, const struct checkout *state, int to_tempfile)
+void update_ce_after_write(const struct checkout *state, struct cache_entry *ce,
+			   struct stat *st)
+{
+	if (state->refresh_cache) {
+		assert(state->istate);
+		fill_stat_cache_info(state->istate, ce, st);
+		ce->ce_flags |= CE_UPDATE_IN_BASE;
+		mark_fsmonitor_invalid(state->istate, ce);
+		state->istate->cache_changed |= CE_ENTRY_CHANGED;
+	}
+}
+
+/* Note: ca is used (and required) iff the entry refers to a regular file. */
+static int write_entry(struct cache_entry *ce, char *path, struct conv_attrs *ca,
+		       const struct checkout *state, int to_tempfile)
 {
 	unsigned int ce_mode_s_ifmt = ce->ce_mode & S_IFMT;
 	struct delayed_checkout *dco = state->delayed_checkout;
@@ -268,8 +282,7 @@
 	clone_checkout_metadata(&meta, &state->meta, &ce->oid);
 
 	if (ce_mode_s_ifmt == S_IFREG) {
-		struct stream_filter *filter = get_stream_filter(state->istate, ce->name,
-								 &ce->oid);
+		struct stream_filter *filter = get_stream_filter_ca(ca, &ce->oid);
 		if (filter &&
 		    !streaming_write_entry(ce, path, filter,
 					   state, to_tempfile,
@@ -316,14 +329,17 @@
 		 * Convert from git internal format to working tree format
 		 */
 		if (dco && dco->state != CE_NO_DELAY) {
-			ret = async_convert_to_working_tree(state->istate, ce->name, new_blob,
-							    size, &buf, &meta, dco);
+			ret = async_convert_to_working_tree_ca(ca, ce->name,
+							       new_blob, size,
+							       &buf, &meta, dco);
 			if (ret && string_list_has_string(&dco->paths, ce->name)) {
 				free(new_blob);
 				goto delayed;
 			}
-		} else
-			ret = convert_to_working_tree(state->istate, ce->name, new_blob, size, &buf, &meta);
+		} else {
+			ret = convert_to_working_tree_ca(ca, ce->name, new_blob,
+							 size, &buf, &meta);
+		}
 
 		if (ret) {
 			free(new_blob);
@@ -345,7 +361,7 @@
 
 		wrote = write_in_full(fd, new_blob, size);
 		if (!to_tempfile)
-			fstat_done = fstat_output(fd, state, &st);
+			fstat_done = fstat_checkout_output(fd, state, &st);
 		close(fd);
 		free(new_blob);
 		if (wrote < 0)
@@ -370,15 +386,10 @@
 
 finish:
 	if (state->refresh_cache) {
-		assert(state->istate);
-		if (!fstat_done)
-			if (lstat(ce->name, &st) < 0)
-				return error_errno("unable to stat just-written file %s",
-						   ce->name);
-		fill_stat_cache_info(state->istate, ce, &st);
-		ce->ce_flags |= CE_UPDATE_IN_BASE;
-		mark_fsmonitor_invalid(state->istate, ce);
-		state->istate->cache_changed |= CE_ENTRY_CHANGED;
+		if (!fstat_done && lstat(ce->name, &st) < 0)
+			return error_errno("unable to stat just-written file %s",
+					   ce->name);
+		update_ce_after_write(state, ce , &st);
 	}
 delayed:
 	return 0;
@@ -429,19 +440,13 @@
 	}
 }
 
-/*
- * Write the contents from ce out to the working tree.
- *
- * When topath[] is not NULL, instead of writing to the working tree
- * file named by ce, a temporary file is created by this function and
- * its name is returned in topath[], which must be able to hold at
- * least TEMPORARY_FILENAME_LENGTH bytes long.
- */
-int checkout_entry(struct cache_entry *ce, const struct checkout *state,
-		   char *topath, int *nr_checkouts)
+int checkout_entry_ca(struct cache_entry *ce, struct conv_attrs *ca,
+		      const struct checkout *state, char *topath,
+		      int *nr_checkouts)
 {
 	static struct strbuf path = STRBUF_INIT;
 	struct stat st;
+	struct conv_attrs ca_buf;
 
 	if (ce->ce_flags & CE_WT_REMOVE) {
 		if (topath)
@@ -454,8 +459,13 @@
 		return 0;
 	}
 
-	if (topath)
-		return write_entry(ce, topath, state, 1);
+	if (topath) {
+		if (S_ISREG(ce->ce_mode) && !ca) {
+			convert_attrs(state->istate, &ca_buf, ce->name);
+			ca = &ca_buf;
+		}
+		return write_entry(ce, topath, ca, state, 1);
+	}
 
 	strbuf_reset(&path);
 	strbuf_add(&path, state->base_dir, state->base_dir_len);
@@ -517,9 +527,16 @@
 		return 0;
 
 	create_directories(path.buf, path.len, state);
+
 	if (nr_checkouts)
 		(*nr_checkouts)++;
-	return write_entry(ce, path.buf, state, 0);
+
+	if (S_ISREG(ce->ce_mode) && !ca) {
+		convert_attrs(state->istate, &ca_buf, ce->name);
+		ca = &ca_buf;
+	}
+
+	return write_entry(ce, path.buf, ca, state, 0);
 }
 
 void unlink_entry(const struct cache_entry *ce)
@@ -530,7 +547,7 @@
 		submodule_move_head(ce->name, "HEAD", NULL,
 				    SUBMODULE_MOVE_HEAD_FORCE);
 	}
-	if (!check_leading_path(ce->name, ce_namelen(ce)))
+	if (check_leading_path(ce->name, ce_namelen(ce), 1) >= 0)
 		return;
 	if (remove_or_warn(ce->ce_mode, ce->name))
 		return;
diff --git a/entry.h b/entry.h
new file mode 100644
index 0000000..b8c0e17
--- /dev/null
+++ b/entry.h
@@ -0,0 +1,59 @@
+#ifndef ENTRY_H
+#define ENTRY_H
+
+#include "cache.h"
+#include "convert.h"
+
+struct checkout {
+	struct index_state *istate;
+	const char *base_dir;
+	int base_dir_len;
+	struct delayed_checkout *delayed_checkout;
+	struct checkout_metadata meta;
+	unsigned force:1,
+		 quiet:1,
+		 not_new:1,
+		 clone:1,
+		 refresh_cache:1;
+};
+#define CHECKOUT_INIT { NULL, "" }
+
+#define TEMPORARY_FILENAME_LENGTH 25
+/*
+ * Write the contents from ce out to the working tree.
+ *
+ * When topath[] is not NULL, instead of writing to the working tree
+ * file named by ce, a temporary file is created by this function and
+ * its name is returned in topath[], which must be able to hold at
+ * least TEMPORARY_FILENAME_LENGTH bytes long.
+ *
+ * With checkout_entry_ca(), callers can optionally pass a preloaded
+ * conv_attrs struct (to avoid reloading it), when ce refers to a
+ * regular file. If ca is NULL, the attributes will be loaded
+ * internally when (and if) needed.
+ */
+int checkout_entry_ca(struct cache_entry *ce, struct conv_attrs *ca,
+		      const struct checkout *state, char *topath,
+		      int *nr_checkouts);
+static inline int checkout_entry(struct cache_entry *ce,
+				 const struct checkout *state, char *topath,
+				 int *nr_checkouts)
+{
+	return checkout_entry_ca(ce, NULL, state, topath, nr_checkouts);
+}
+
+void enable_delayed_checkout(struct checkout *state);
+int finish_delayed_checkout(struct checkout *state, int *nr_checkouts);
+
+/*
+ * Unlink the last component and schedule the leading directories for
+ * removal, such that empty directories get removed.
+ */
+void unlink_entry(const struct cache_entry *ce);
+
+void *read_blob_entry(const struct cache_entry *ce, unsigned long *size);
+int fstat_checkout_output(int fd, const struct checkout *state, struct stat *st);
+void update_ce_after_write(const struct checkout *state, struct cache_entry *ce,
+			   struct stat *st);
+
+#endif /* ENTRY_H */
diff --git a/ewah/bitmap.c b/ewah/bitmap.c
index 0d31cdc..38a47c4 100644
--- a/ewah/bitmap.c
+++ b/ewah/bitmap.c
@@ -25,7 +25,7 @@
 struct bitmap *bitmap_word_alloc(size_t word_alloc)
 {
 	struct bitmap *bitmap = xmalloc(sizeof(struct bitmap));
-	bitmap->words = xcalloc(word_alloc, sizeof(eword_t));
+	CALLOC_ARRAY(bitmap->words, word_alloc);
 	bitmap->word_alloc = word_alloc;
 	return bitmap;
 }
diff --git a/fetch-pack.c b/fetch-pack.c
index 0392d36..c80eaee 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -1901,7 +1901,7 @@
 	 * remote is also shallow, check what ref is safe to update
 	 * without updating .git/shallow
 	 */
-	status = xcalloc(nr_sought, sizeof(*status));
+	CALLOC_ARRAY(status, nr_sought);
 	assign_shallow_commits_to_refs(si, NULL, status);
 	if (si->nr_ours || si->nr_theirs) {
 		for (i = 0; i < nr_sought; i++)
diff --git a/fmt-merge-msg.c b/fmt-merge-msg.c
index 1e51492..0f66818 100644
--- a/fmt-merge-msg.c
+++ b/fmt-merge-msg.c
@@ -130,7 +130,7 @@
 	if (!find_merge_parent(merge_parents, &oid, NULL))
 		return 0; /* subsumed by other parents */
 
-	origin_data = xcalloc(1, sizeof(struct origin_data));
+	CALLOC_ARRAY(origin_data, 1);
 	oidcpy(&origin_data->oid, &oid);
 
 	if (line[len - 1] == '\n')
diff --git a/fsmonitor.c b/fsmonitor.c
index 23f8a0c..ab9bfc6 100644
--- a/fsmonitor.c
+++ b/fsmonitor.c
@@ -185,10 +185,10 @@
 int fsmonitor_is_trivial_response(const struct strbuf *query_result)
 {
 	static char trivial_response[3] = { '\0', '/', '\0' };
-	int is_trivial = !memcmp(trivial_response,
-				 &query_result->buf[query_result->len - 3], 3);
 
-	return is_trivial;
+	return query_result->len >= 3 &&
+		!memcmp(trivial_response,
+			&query_result->buf[query_result->len - 3], 3);
 }
 
 static void fsmonitor_refresh_callback(struct index_state *istate, char *name)
diff --git a/fsmonitor.h b/fsmonitor.h
index 7f1794b..f20d726 100644
--- a/fsmonitor.h
+++ b/fsmonitor.h
@@ -50,6 +50,17 @@
 int fsmonitor_is_trivial_response(const struct strbuf *query_result);
 
 /*
+ * Check if refresh_fsmonitor has been called at least once.
+ * refresh_fsmonitor is idempotent. Returns true if fsmonitor is
+ * not enabled (since the state will be "fresh" w/ CE_FSMONITOR_VALID unset)
+ * This version is useful for assertions
+ */
+static inline int is_fsmonitor_refreshed(const struct index_state *istate)
+{
+	return !core_fsmonitor || istate->fsmonitor_has_run_once;
+}
+
+/*
  * Set the given cache entries CE_FSMONITOR_VALID bit. This should be
  * called any time the cache entry has been updated to reflect the
  * current state of the file on disk.
diff --git a/git-compat-util.h b/git-compat-util.h
index 3b2738c..9ddf9d7 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -898,7 +898,7 @@
 #define FREE_AND_NULL(p) do { free(p); (p) = NULL; } while (0)
 
 #define ALLOC_ARRAY(x, alloc) (x) = xmalloc(st_mult(sizeof(*(x)), (alloc)))
-#define CALLOC_ARRAY(x, alloc) (x) = xcalloc((alloc), sizeof(*(x)));
+#define CALLOC_ARRAY(x, alloc) (x) = xcalloc((alloc), sizeof(*(x)))
 #define REALLOC_ARRAY(x, alloc) (x) = xrealloc((x), st_mult(sizeof(*(x)), (alloc)))
 
 #define COPY_ARRAY(dst, src, n) copy_array((dst), (src), (n), sizeof(*(dst)) + \
@@ -1242,6 +1242,13 @@
 /* Warn on an inaccessible file if errno indicates this is an error */
 int warn_on_fopen_errors(const char *path);
 
+/*
+ * Open with O_NOFOLLOW, or equivalent. Note that the fallback equivalent
+ * may be racy. Do not use this as protection against an attacker who can
+ * simultaneously create paths.
+ */
+int open_nofollow(const char *path, int flags);
+
 #if !defined(USE_PARENS_AROUND_GETTEXT_N) && defined(__GNUC__)
 #define USE_PARENS_AROUND_GETTEXT_N 1
 #endif
diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index fea7964..cb89372 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -492,14 +492,12 @@
 		sha1=$(git rev-parse "$ref"^0)
 		test -f "$workdir"/../map/$sha1 && continue
 		ancestor=$(git rev-list --simplify-merges -1 "$ref" "$@")
-		test "$ancestor" && echo $(map $ancestor) >> "$workdir"/../map/$sha1
+		test "$ancestor" && echo $(map $ancestor) >"$workdir"/../map/$sha1
 	done < "$tempdir"/heads
 fi
 
 # Finally update the refs
 
-_x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
-_x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
 echo
 while read ref
 do
@@ -519,7 +517,7 @@
 		git update-ref -m "filter-branch: delete" -d "$ref" $sha1 ||
 			die "Could not delete $ref"
 	;;
-	$_x40)
+	*)
 		echo "Ref '$ref' was rewritten"
 		if ! git update-ref -m "filter-branch: rewrite" \
 					"$ref" $rewritten $sha1 2>/dev/null; then
@@ -533,16 +531,6 @@
 			fi
 		fi
 	;;
-	*)
-		# NEEDSWORK: possibly add -Werror, making this an error
-		warn "WARNING: '$ref' was rewritten into multiple commits:"
-		warn "$rewritten"
-		warn "WARNING: Ref '$ref' points to the first one now."
-		rewritten=$(echo "$rewritten" | head -n 1)
-		git update-ref -m "filter-branch: rewrite to first" \
-				"$ref" $rewritten $sha1 ||
-			die "Could not rewrite $ref"
-	;;
 	esac
 	git update-ref -m "filter-branch: backup" "$orig_namespace$ref" $sha1 ||
 		 exit
diff --git a/git-send-email.perl b/git-send-email.perl
index 1f425c0..f5bbf16 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -1942,7 +1942,7 @@
 	my ($fn, $xfer_encoding) = @_;
 
 	if ($repo) {
-		my $validate_hook = catfile(catdir($repo->repo_path(), 'hooks'),
+		my $validate_hook = catfile($repo->hooks_path(),
 					    'sendemail-validate');
 		my $hook_error;
 		if (-x $validate_hook) {
diff --git a/grep.c b/grep.c
index aabfaaa..c5c348b 100644
--- a/grep.c
+++ b/grep.c
@@ -40,20 +40,6 @@
 	.output = std_output,
 };
 
-#ifdef USE_LIBPCRE2
-static pcre2_general_context *pcre2_global_context;
-
-static void *pcre2_malloc(PCRE2_SIZE size, MAYBE_UNUSED void *memory_data)
-{
-	return malloc(size);
-}
-
-static void pcre2_free(void *pointer, MAYBE_UNUSED void *memory_data)
-{
-	free(pointer);
-}
-#endif
-
 static const char *color_grep_slots[] = {
 	[GREP_COLOR_CONTEXT]	    = "context",
 	[GREP_COLOR_FILENAME]	    = "filename",
@@ -152,20 +138,9 @@
  * Initialize one instance of grep_opt and copy the
  * default values from the template we read the configuration
  * information in an earlier call to git_config(grep_config).
- *
- * If using PCRE, make sure that the library is configured
- * to use the same allocator as Git (e.g. nedmalloc on Windows).
- *
- * Any allocated memory needs to be released in grep_destroy().
  */
 void grep_init(struct grep_opt *opt, struct repository *repo, const char *prefix)
 {
-#if defined(USE_LIBPCRE2)
-	if (!pcre2_global_context)
-		pcre2_global_context = pcre2_general_context_create(
-					pcre2_malloc, pcre2_free, NULL);
-#endif
-
 	*opt = grep_defaults;
 
 	opt->repo = repo;
@@ -175,13 +150,6 @@
 	opt->header_tail = &opt->header_list;
 }
 
-void grep_destroy(void)
-{
-#ifdef USE_LIBPCRE2
-	pcre2_general_context_free(pcre2_global_context);
-#endif
-}
-
 static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, struct grep_opt *opt)
 {
 	/*
@@ -363,6 +331,28 @@
 }
 
 #ifdef USE_LIBPCRE2
+#define GREP_PCRE2_DEBUG_MALLOC 0
+
+static void *pcre2_malloc(PCRE2_SIZE size, MAYBE_UNUSED void *memory_data)
+{
+	void *pointer = malloc(size);
+#if GREP_PCRE2_DEBUG_MALLOC
+	static int count = 1;
+	fprintf(stderr, "PCRE2:%p -> #%02d: alloc(%lu)\n", pointer, count++, size);
+#endif
+	return pointer;
+}
+
+static void pcre2_free(void *pointer, MAYBE_UNUSED void *memory_data)
+{
+#if GREP_PCRE2_DEBUG_MALLOC
+	static int count = 1;
+	if (pointer)
+		fprintf(stderr, "PCRE2:%p -> #%02d: free()\n", pointer, count++);
+#endif
+	free(pointer);
+}
+
 static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt)
 {
 	int error;
@@ -373,17 +363,20 @@
 	int patinforet;
 	size_t jitsizearg;
 
-	assert(opt->pcre2);
+	/*
+	 * Call pcre2_general_context_create() before calling any
+	 * other pcre2_*(). It sets up our malloc()/free() functions
+	 * with which everything else is allocated.
+	 */
+	p->pcre2_general_context = pcre2_general_context_create(
+		pcre2_malloc, pcre2_free, NULL);
+	if (!p->pcre2_general_context)
+		die("Couldn't allocate PCRE2 general context");
 
-	p->pcre2_compile_context = NULL;
-
-	/* pcre2_global_context is initialized in append_grep_pattern */
 	if (opt->ignore_case) {
 		if (!opt->ignore_locale && has_non_ascii(p->pattern)) {
-			if (!pcre2_global_context)
-				BUG("pcre2_global_context uninitialized");
-			p->pcre2_tables = pcre2_maketables(pcre2_global_context);
-			p->pcre2_compile_context = pcre2_compile_context_create(NULL);
+			p->pcre2_tables = pcre2_maketables(p->pcre2_general_context);
+			p->pcre2_compile_context = pcre2_compile_context_create(p->pcre2_general_context);
 			pcre2_set_character_tables(p->pcre2_compile_context,
 							p->pcre2_tables);
 		}
@@ -393,28 +386,18 @@
 	    !(!opt->ignore_case && (p->fixed || p->is_fixed)))
 		options |= (PCRE2_UTF | PCRE2_MATCH_INVALID_UTF);
 
+#ifdef GIT_PCRE2_VERSION_10_36_OR_HIGHER
 	/* Work around https://bugs.exim.org/show_bug.cgi?id=2642 fixed in 10.36 */
-	if (PCRE2_MATCH_INVALID_UTF && options & (PCRE2_UTF | PCRE2_CASELESS)) {
-		struct strbuf buf;
-		int len;
-		int err;
-
-		if ((len = pcre2_config(PCRE2_CONFIG_VERSION, NULL)) < 0)
-			BUG("pcre2_config(..., NULL) failed: %d", len);
-		strbuf_init(&buf, len + 1);
-		if ((err = pcre2_config(PCRE2_CONFIG_VERSION, buf.buf)) < 0)
-			BUG("pcre2_config(..., buf.buf) failed: %d", err);
-		if (versioncmp(buf.buf, "10.36") < 0)
-			options |= PCRE2_NO_START_OPTIMIZE;
-		strbuf_release(&buf);
-	}
+	if (PCRE2_MATCH_INVALID_UTF && options & (PCRE2_UTF | PCRE2_CASELESS))
+		options |= PCRE2_NO_START_OPTIMIZE;
+#endif
 
 	p->pcre2_pattern = pcre2_compile((PCRE2_SPTR)p->pattern,
 					 p->patternlen, options, &error, &erroffset,
 					 p->pcre2_compile_context);
 
 	if (p->pcre2_pattern) {
-		p->pcre2_match_data = pcre2_match_data_create_from_pattern(p->pcre2_pattern, NULL);
+		p->pcre2_match_data = pcre2_match_data_create_from_pattern(p->pcre2_pattern, p->pcre2_general_context);
 		if (!p->pcre2_match_data)
 			die("Couldn't allocate PCRE2 match data");
 	} else {
@@ -493,7 +476,12 @@
 	pcre2_compile_context_free(p->pcre2_compile_context);
 	pcre2_code_free(p->pcre2_pattern);
 	pcre2_match_data_free(p->pcre2_match_data);
+#ifdef GIT_PCRE2_VERSION_10_34_OR_HIGHER
+	pcre2_maketables_free(p->pcre2_general_context, p->pcre2_tables);
+#else
 	free((void *)p->pcre2_tables);
+#endif
+	pcre2_general_context_free(p->pcre2_general_context);
 }
 #else /* !USE_LIBPCRE2 */
 static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt)
@@ -555,7 +543,6 @@
 #endif
 	if (p->fixed || p->is_fixed) {
 #ifdef USE_LIBPCRE2
-		opt->pcre2 = 1;
 		if (p->is_fixed) {
 			compile_pcre2_pattern(p, opt);
 		} else {
@@ -621,7 +608,7 @@
 	case GREP_PATTERN: /* atom */
 	case GREP_PATTERN_HEAD:
 	case GREP_PATTERN_BODY:
-		x = xcalloc(1, sizeof (struct grep_expr));
+		CALLOC_ARRAY(x, 1);
 		x->node = GREP_NODE_ATOM;
 		x->u.atom = p;
 		*list = p->next;
@@ -651,7 +638,7 @@
 		if (!p->next)
 			die("--not not followed by pattern expression");
 		*list = p->next;
-		x = xcalloc(1, sizeof (struct grep_expr));
+		CALLOC_ARRAY(x, 1);
 		x->node = GREP_NODE_NOT;
 		x->u.unary = compile_pattern_not(list);
 		if (!x->u.unary)
@@ -676,7 +663,7 @@
 		y = compile_pattern_and(list);
 		if (!y)
 			die("--and not followed by pattern expression");
-		z = xcalloc(1, sizeof (struct grep_expr));
+		CALLOC_ARRAY(z, 1);
 		z->node = GREP_NODE_AND;
 		z->u.binary.left = x;
 		z->u.binary.right = y;
@@ -696,7 +683,7 @@
 		y = compile_pattern_or(list);
 		if (!y)
 			die("not a pattern expression %s", p->pattern);
-		z = xcalloc(1, sizeof (struct grep_expr));
+		CALLOC_ARRAY(z, 1);
 		z->node = GREP_NODE_OR;
 		z->u.binary.left = x;
 		z->u.binary.right = y;
diff --git a/grep.h b/grep.h
index ae89d62..72f82b1 100644
--- a/grep.h
+++ b/grep.h
@@ -4,10 +4,17 @@
 #ifdef USE_LIBPCRE2
 #define PCRE2_CODE_UNIT_WIDTH 8
 #include <pcre2.h>
+#if (PCRE2_MAJOR >= 10 && PCRE2_MINOR >= 36) || PCRE2_MAJOR >= 11
+#define GIT_PCRE2_VERSION_10_36_OR_HIGHER
+#endif
+#if (PCRE2_MAJOR >= 10 && PCRE2_MINOR >= 34) || PCRE2_MAJOR >= 11
+#define GIT_PCRE2_VERSION_10_34_OR_HIGHER
+#endif
 #else
 typedef int pcre2_code;
 typedef int pcre2_match_data;
 typedef int pcre2_compile_context;
+typedef int pcre2_general_context;
 #endif
 #ifndef PCRE2_MATCH_INVALID_UTF
 /* PCRE2_MATCH_* dummy also with !USE_LIBPCRE2, for test-pcre2-config.c */
@@ -69,6 +76,7 @@
 	pcre2_code *pcre2_pattern;
 	pcre2_match_data *pcre2_match_data;
 	pcre2_compile_context *pcre2_compile_context;
+	pcre2_general_context *pcre2_general_context;
 	const uint8_t *pcre2_tables;
 	uint32_t pcre2_jit_on;
 	unsigned fixed:1;
@@ -161,7 +169,6 @@
 
 int grep_config(const char *var, const char *value, void *);
 void grep_init(struct grep_opt *, struct repository *repo, const char *prefix);
-void grep_destroy(void);
 void grep_commit_pattern_type(enum grep_pattern_type, struct grep_opt *opt);
 
 void append_grep_pat(struct grep_opt *opt, const char *pat, size_t patlen, const char *origin, int no, enum grep_pat_token t);
diff --git a/hashmap.c b/hashmap.c
index 5009471..134d2ee 100644
--- a/hashmap.c
+++ b/hashmap.c
@@ -76,7 +76,7 @@
 static void alloc_table(struct hashmap *map, unsigned int size)
 {
 	map->tablesize = size;
-	map->table = xcalloc(size, sizeof(struct hashmap_entry *));
+	CALLOC_ARRAY(map->table, size);
 
 	/* calculate resize thresholds for new size */
 	map->grow_at = (unsigned int) ((uint64_t) size * HASHMAP_LOAD_FACTOR / 100);
diff --git a/http-backend.c b/http-backend.c
index a03b4ba..b329bf6 100644
--- a/http-backend.c
+++ b/http-backend.c
@@ -39,7 +39,7 @@
 	if (!query_params) {
 		const char *query = getenv("QUERY_STRING");
 
-		query_params = xcalloc(1, sizeof(*query_params));
+		CALLOC_ARRAY(query_params, 1);
 		while (query && *query) {
 			char *name = url_decode_parameter_name(&query);
 			char *value = url_decode_parameter_value(&query);
diff --git a/http-push.c b/http-push.c
index 6a4a43e..b60d5fc 100644
--- a/http-push.c
+++ b/http-push.c
@@ -896,7 +896,7 @@
 	curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, dav_headers);
 	curl_easy_setopt(slot->curl, CURLOPT_FILE, &in_buffer);
 
-	lock = xcalloc(1, sizeof(*lock));
+	CALLOC_ARRAY(lock, 1);
 	lock->timeout = -1;
 
 	if (start_active_slot(slot)) {
@@ -1713,7 +1713,7 @@
 	int new_refs;
 	struct ref *ref, *local_refs;
 
-	repo = xcalloc(1, sizeof(*repo));
+	CALLOC_ARRAY(repo, 1);
 
 	argv++;
 	for (i = 1; i < argc; i++, argv++) {
diff --git a/http.c b/http.c
index f8ea28b..406410f 100644
--- a/http.c
+++ b/http.c
@@ -1635,23 +1635,33 @@
 
 	if (results->curl_result == CURLE_OK) {
 		credential_approve(&http_auth);
-		if (proxy_auth.password)
-			credential_approve(&proxy_auth);
+		credential_approve(&proxy_auth);
+		credential_approve(&cert_auth);
 		return HTTP_OK;
+	} else if (results->curl_result == CURLE_SSL_CERTPROBLEM) {
+		/*
+		 * We can't tell from here whether it's a bad path, bad
+		 * certificate, bad password, or something else wrong
+		 * with the certificate.  So we reject the credential to
+		 * avoid caching or saving a bad password.
+		 */
+		credential_reject(&cert_auth);
+		return HTTP_NOAUTH;
 	} else if (missing_target(results))
 		return HTTP_MISSING_TARGET;
 	else if (results->http_code == 401) {
+#ifdef LIBCURL_CAN_HANDLE_AUTH_ANY
+		http_auth_methods &= ~CURLAUTH_GSSNEGOTIATE;
+		if (results->auth_avail) {
+			http_auth_methods &= results->auth_avail;
+			http_auth_methods_restricted = 1;
+			return HTTP_REAUTH;
+		}
+#endif
 		if (http_auth.username && http_auth.password) {
 			credential_reject(&http_auth);
 			return HTTP_NOAUTH;
 		} else {
-#ifdef LIBCURL_CAN_HANDLE_AUTH_ANY
-			http_auth_methods &= ~CURLAUTH_GSSNEGOTIATE;
-			if (results->auth_avail) {
-				http_auth_methods &= results->auth_avail;
-				http_auth_methods_restricted = 1;
-			}
-#endif
 			return HTTP_REAUTH;
 		}
 	} else {
@@ -2324,7 +2334,7 @@
 	off_t prev_posn = 0;
 	struct http_pack_request *preq;
 
-	preq = xcalloc(1, sizeof(*preq));
+	CALLOC_ARRAY(preq, 1);
 	strbuf_init(&preq->tmpfile, 0);
 
 	preq->url = url;
@@ -2419,7 +2429,7 @@
 	off_t prev_posn = 0;
 	struct http_object_request *freq;
 
-	freq = xcalloc(1, sizeof(*freq));
+	CALLOC_ARRAY(freq, 1);
 	strbuf_init(&freq->tmpfile, 0);
 	oidcpy(&freq->oid, oid);
 	freq->localfile = -1;
diff --git a/imap-send.c b/imap-send.c
index d0b94f9..bb085d6 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -963,9 +963,9 @@
 	char *arg, *rsp;
 	int s = -1, preauth;
 
-	ctx = xcalloc(1, sizeof(*ctx));
+	CALLOC_ARRAY(ctx, 1);
 
-	ctx->imap = imap = xcalloc(1, sizeof(*imap));
+	ctx->imap = CALLOC_ARRAY(imap, 1);
 	imap->buf.sock.fd[0] = imap->buf.sock.fd[1] = -1;
 	imap->in_progress_append = &imap->in_progress;
 
diff --git a/line-log.c b/line-log.c
index 75c8b1a..51d9331 100644
--- a/line-log.c
+++ b/line-log.c
@@ -296,7 +296,7 @@
 		return;
 	}
 
-	p = xcalloc(1, sizeof(struct line_log_data));
+	CALLOC_ARRAY(p, 1);
 	p->path = path;
 	range_set_append(&p->ranges, begin, end);
 	if (ip) {
diff --git a/line-range.c b/line-range.c
index 9b50583..955a8a9 100644
--- a/line-range.c
+++ b/line-range.c
@@ -202,7 +202,7 @@
 	drv = userdiff_find_by_path(istate, path);
 	if (drv && drv->funcname.pattern) {
 		const struct userdiff_funcname *pe = &drv->funcname;
-		xecfg = xcalloc(1, sizeof(*xecfg));
+		CALLOC_ARRAY(xecfg, 1);
 		xdiff_set_find_func(xecfg, pe->pattern, pe->cflags);
 	}
 
diff --git a/list-objects-filter.c b/list-objects-filter.c
index 4ec0041..39e2f15 100644
--- a/list-objects-filter.c
+++ b/list-objects-filter.c
@@ -186,7 +186,7 @@
 		seen_info = oidmap_get(
 			&filter_data->seen_at_depth, &obj->oid);
 		if (!seen_info) {
-			seen_info = xcalloc(1, sizeof(*seen_info));
+			CALLOC_ARRAY(seen_info, 1);
 			oidcpy(&seen_info->base.oid, &obj->oid);
 			seen_info->depth = filter_data->current_depth;
 			oidmap_put(&filter_data->seen_at_depth, seen_info);
@@ -626,7 +626,7 @@
 	size_t sub;
 
 	d->nr = filter_options->sub_nr;
-	d->sub = xcalloc(d->nr, sizeof(*d->sub));
+	CALLOC_ARRAY(d->sub, d->nr);
 	for (sub = 0; sub < d->nr; sub++)
 		d->sub[sub].filter = list_objects_filter__init(
 			filter->omits ? &d->sub[sub].omits : NULL,
@@ -674,7 +674,7 @@
 	if (!init_fn)
 		return NULL;
 
-	filter = xcalloc(1, sizeof(*filter));
+	CALLOC_ARRAY(filter, 1);
 	filter->omits = omitted;
 	init_fn(filter_options, filter);
 	return filter;
diff --git a/ll-merge.c b/ll-merge.c
index 1ec0b95..9a8a2c3 100644
--- a/ll-merge.c
+++ b/ll-merge.c
@@ -268,7 +268,7 @@
 		if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 			break;
 	if (!fn) {
-		fn = xcalloc(1, sizeof(struct ll_merge_driver));
+		CALLOC_ARRAY(fn, 1);
 		fn->name = xmemdupz(name, namelen);
 		fn->fn = ll_ext_merge;
 		*ll_user_merge_tail = fn;
diff --git a/log-tree.c b/log-tree.c
index 4531ceb..f3178a6 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -369,8 +369,14 @@
 	int start_len = filename->len;
 	int max_len = start_len + info->patch_name_max - (strlen(suffix) + 1);
 
-	if (0 < info->reroll_count)
-		strbuf_addf(filename, "v%d-", info->reroll_count);
+	if (info->reroll_count) {
+		struct strbuf temp = STRBUF_INIT;
+
+		strbuf_addf(&temp, "v%s", info->reroll_count);
+		format_sanitized_subject(filename, temp.buf, temp.len);
+		strbuf_addstr(filename, "-");
+		strbuf_release(&temp);
+	}
 	strbuf_addf(filename, "%04d-%s", nr, subject);
 
 	if (max_len < filename->len)
diff --git a/mailmap.c b/mailmap.c
index 9bb9cf8..d1f7c0d 100644
--- a/mailmap.c
+++ b/mailmap.c
@@ -83,7 +83,7 @@
 	if (item->util) {
 		me = (struct mailmap_entry *)item->util;
 	} else {
-		me = xcalloc(1, sizeof(struct mailmap_entry));
+		CALLOC_ARRAY(me, 1);
 		me->namemap.strdup_strings = 1;
 		me->namemap.cmp = namemap_cmp;
 		item->util = me;
@@ -157,20 +157,30 @@
 		add_mapping(map, name1, email1, name2, email2);
 }
 
-static int read_mailmap_file(struct string_list *map, const char *filename)
+/* Flags for read_mailmap_file() */
+#define MAILMAP_NOFOLLOW (1<<0)
+
+static int read_mailmap_file(struct string_list *map, const char *filename,
+			     unsigned flags)
 {
 	char buffer[1024];
 	FILE *f;
+	int fd;
 
 	if (!filename)
 		return 0;
 
-	f = fopen(filename, "r");
-	if (!f) {
+	if (flags & MAILMAP_NOFOLLOW)
+		fd = open_nofollow(filename, O_RDONLY);
+	else
+		fd = open(filename, O_RDONLY);
+
+	if (fd < 0) {
 		if (errno == ENOENT)
 			return 0;
 		return error_errno("unable to open mailmap at %s", filename);
 	}
+	f = xfdopen(fd, "r");
 
 	while (fgets(buffer, sizeof(buffer), f) != NULL)
 		read_mailmap_line(map, buffer);
@@ -226,10 +236,12 @@
 		git_mailmap_blob = "HEAD:.mailmap";
 
 	if (!startup_info->have_repository || !is_bare_repository())
-		err |= read_mailmap_file(map, ".mailmap");
+		err |= read_mailmap_file(map, ".mailmap",
+					 startup_info->have_repository ?
+					 MAILMAP_NOFOLLOW : 0);
 	if (startup_info->have_repository)
 		err |= read_mailmap_blob(map, git_mailmap_blob);
-	err |= read_mailmap_file(map, git_mailmap_file);
+	err |= read_mailmap_file(map, git_mailmap_file, 0);
 	return err;
 }
 
diff --git a/mem-pool.c b/mem-pool.c
index 8401761..ccdcad2 100644
--- a/mem-pool.c
+++ b/mem-pool.c
@@ -5,7 +5,7 @@
 #include "cache.h"
 #include "mem-pool.h"
 
-#define BLOCK_GROWTH_SIZE 1024*1024 - sizeof(struct mp_block);
+#define BLOCK_GROWTH_SIZE (1024 * 1024 - sizeof(struct mp_block))
 
 /*
  * Allocate a new mp_block and insert it after the block specified in
diff --git a/merge-ort.c b/merge-ort.c
index 603d30c..ba35600 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -351,17 +351,11 @@
 
 	/* Free memory used by various renames maps */
 	for (i = MERGE_SIDE1; i <= MERGE_SIDE2; ++i) {
-		struct hashmap_iter iter;
-		struct strmap_entry *entry;
-
 		strset_func(&renames->dirs_removed[i]);
 
-		strmap_for_each_entry(&renames->dir_rename_count[i],
-				      &iter, entry) {
-			struct strintmap *counts = entry->value;
-			strintmap_clear(counts);
-		}
-		strmap_func(&renames->dir_rename_count[i], 1);
+		partial_clear_dir_rename_count(&renames->dir_rename_count[i]);
+		if (!reinitialize)
+			strmap_clear(&renames->dir_rename_count[i], 1);
 
 		strmap_func(&renames->dir_renames[i], 0);
 	}
@@ -1302,131 +1296,6 @@
 	return new_path;
 }
 
-static void dirname_munge(char *filename)
-{
-	char *slash = strrchr(filename, '/');
-	if (!slash)
-		slash = filename;
-	*slash = '\0';
-}
-
-static void increment_count(struct strmap *dir_rename_count,
-			    char *old_dir,
-			    char *new_dir)
-{
-	struct strintmap *counts;
-	struct strmap_entry *e;
-
-	/* Get the {new_dirs -> counts} mapping using old_dir */
-	e = strmap_get_entry(dir_rename_count, old_dir);
-	if (e) {
-		counts = e->value;
-	} else {
-		counts = xmalloc(sizeof(*counts));
-		strintmap_init_with_options(counts, 0, NULL, 1);
-		strmap_put(dir_rename_count, old_dir, counts);
-	}
-
-	/* Increment the count for new_dir */
-	strintmap_incr(counts, new_dir, 1);
-}
-
-static void update_dir_rename_counts(struct strmap *dir_rename_count,
-				     struct strset *dirs_removed,
-				     const char *oldname,
-				     const char *newname)
-{
-	char *old_dir = xstrdup(oldname);
-	char *new_dir = xstrdup(newname);
-	char new_dir_first_char = new_dir[0];
-	int first_time_in_loop = 1;
-
-	while (1) {
-		dirname_munge(old_dir);
-		dirname_munge(new_dir);
-
-		/*
-		 * When renaming
-		 *   "a/b/c/d/e/foo.c" -> "a/b/some/thing/else/e/foo.c"
-		 * then this suggests that both
-		 *   a/b/c/d/e/ => a/b/some/thing/else/e/
-		 *   a/b/c/d/   => a/b/some/thing/else/
-		 * so we want to increment counters for both.  We do NOT,
-		 * however, also want to suggest that there was the following
-		 * rename:
-		 *   a/b/c/ => a/b/some/thing/
-		 * so we need to quit at that point.
-		 *
-		 * Note the when first_time_in_loop, we only strip off the
-		 * basename, and we don't care if that's different.
-		 */
-		if (!first_time_in_loop) {
-			char *old_sub_dir = strchr(old_dir, '\0')+1;
-			char *new_sub_dir = strchr(new_dir, '\0')+1;
-			if (!*new_dir) {
-				/*
-				 * Special case when renaming to root directory,
-				 * i.e. when new_dir == "".  In this case, we had
-				 * something like
-				 *    a/b/subdir => subdir
-				 * and so dirname_munge() sets things up so that
-				 *    old_dir = "a/b\0subdir\0"
-				 *    new_dir = "\0ubdir\0"
-				 * We didn't have a '/' to overwrite a '\0' onto
-				 * in new_dir, so we have to compare differently.
-				 */
-				if (new_dir_first_char != old_sub_dir[0] ||
-				    strcmp(old_sub_dir+1, new_sub_dir))
-					break;
-			} else {
-				if (strcmp(old_sub_dir, new_sub_dir))
-					break;
-			}
-		}
-
-		if (strset_contains(dirs_removed, old_dir))
-			increment_count(dir_rename_count, old_dir, new_dir);
-		else
-			break;
-
-		/* If we hit toplevel directory ("") for old or new dir, quit */
-		if (!*old_dir || !*new_dir)
-			break;
-
-		first_time_in_loop = 0;
-	}
-
-	/* Free resources we don't need anymore */
-	free(old_dir);
-	free(new_dir);
-}
-
-static void compute_rename_counts(struct diff_queue_struct *pairs,
-				  struct strmap *dir_rename_count,
-				  struct strset *dirs_removed)
-{
-	int i;
-
-	for (i = 0; i < pairs->nr; ++i) {
-		struct diff_filepair *pair = pairs->queue[i];
-
-		/* File not part of directory rename if it wasn't renamed */
-		if (pair->status != 'R')
-			continue;
-
-		/*
-		 * Make dir_rename_count contain a map of a map:
-		 *   old_directory -> {new_directory -> count}
-		 * In other words, for every pair look at the directories for
-		 * the old filename and the new filename and count how many
-		 * times that pairing occurs.
-		 */
-		update_dir_rename_counts(dir_rename_count, dirs_removed,
-					 pair->one->path,
-					 pair->two->path);
-	}
-}
-
 static void get_provisional_directory_renames(struct merge_options *opt,
 					      unsigned side,
 					      int *clean)
@@ -1435,9 +1304,6 @@
 	struct strmap_entry *entry;
 	struct rename_info *renames = &opt->priv->renames;
 
-	compute_rename_counts(&renames->pairs[side],
-			      &renames->dir_rename_count[side],
-			      &renames->dirs_removed[side]);
 	/*
 	 * Collapse
 	 *    dir_rename_count: old_directory -> {new_directory -> count}
@@ -1576,8 +1442,7 @@
 		if (collision_info) {
 			free(new_path);
 		} else {
-			collision_info = xcalloc(1,
-						 sizeof(struct collision_info));
+			CALLOC_ARRAY(collision_info, 1);
 			string_list_init(&collision_info->source_files, 0);
 			strmap_put(collisions, new_path, collision_info);
 		}
@@ -1718,7 +1583,7 @@
 		struct conflict_info *dir_ci;
 		char *cur_dir = dirs_to_insert.items[i].string;
 
-		dir_ci = xcalloc(1, sizeof(*dir_ci));
+		CALLOC_ARRAY(dir_ci, 1);
 
 		dir_ci->merged.directory_name = parent_name;
 		len = strlen(parent_name);
@@ -2162,7 +2027,9 @@
 
 	diff_queued_diff = renames->pairs[side_index];
 	trace2_region_enter("diff", "diffcore_rename", opt->repo);
-	diffcore_rename(&diff_opts);
+	diffcore_rename_extended(&diff_opts,
+				 &renames->dirs_removed[side_index],
+				 &renames->dir_rename_count[side_index]);
 	trace2_region_leave("diff", "diffcore_rename", opt->repo);
 	resolve_diffpair_statuses(&diff_queued_diff);
 
@@ -2703,7 +2570,7 @@
 		 * the directory to remain here, so we need to move this
 		 * path to some new location.
 		 */
-		new_ci = xcalloc(1, sizeof(*new_ci));
+		CALLOC_ARRAY(new_ci, 1);
 		/* We don't really want new_ci->merged.result copied, but it'll
 		 * be overwritten below so it doesn't matter.  We also don't
 		 * want any directory mode/oid values copied, but we'll zero
@@ -3083,7 +2950,7 @@
 	unpack_opts.verbose_update = (opt->verbosity > 2);
 	unpack_opts.fn = twoway_merge;
 	if (1/* FIXME: opts->overwrite_ignore*/) {
-		unpack_opts.dir = xcalloc(1, sizeof(*unpack_opts.dir));
+		CALLOC_ARRAY(unpack_opts.dir, 1);
 		unpack_opts.dir->flags |= DIR_SHOW_IGNORED;
 		setup_standard_excludes(unpack_opts.dir);
 	}
diff --git a/merge-recursive.c b/merge-recursive.c
index b052974..ed31f94 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -303,7 +303,7 @@
 		return;
 	}
 
-	ci = xcalloc(1, sizeof(struct rename_conflict_info));
+	CALLOC_ARRAY(ci, 1);
 	ci->rename_type = rename_type;
 	ci->ren1 = ren1;
 	ci->ren2 = ren2;
@@ -453,7 +453,7 @@
 
 static int save_files_dirs(const struct object_id *oid,
 			   struct strbuf *base, const char *path,
-			   unsigned int mode, int stage, void *context)
+			   unsigned int mode, void *context)
 {
 	struct path_hashmap_entry *entry;
 	int baselen = base->len;
@@ -473,8 +473,8 @@
 {
 	struct pathspec match_all;
 	memset(&match_all, 0, sizeof(match_all));
-	read_tree_recursive(opt->repo, tree, "", 0, 0,
-			    &match_all, save_files_dirs, opt);
+	read_tree(opt->repo, tree,
+		  &match_all, save_files_dirs, opt);
 }
 
 static int get_tree_entry_if_blob(struct repository *r,
@@ -2389,8 +2389,7 @@
 			continue;
 		collision_ent = collision_find_entry(collisions, new_path);
 		if (!collision_ent) {
-			collision_ent = xcalloc(1,
-						sizeof(struct collision_entry));
+			CALLOC_ARRAY(collision_ent, 1);
 			hashmap_entry_init(&collision_ent->ent,
 						strhash(new_path));
 			hashmap_put(collisions, &collision_ent->ent);
@@ -2594,7 +2593,7 @@
 	struct string_list *renames;
 
 	compute_collisions(&collisions, dir_renames, pairs);
-	renames = xcalloc(1, sizeof(struct string_list));
+	CALLOC_ARRAY(renames, 1);
 
 	for (i = 0; i < pairs->nr; ++i) {
 		struct string_list_item *item;
@@ -3664,7 +3663,7 @@
 		return -1;
 	}
 
-	opt->priv = xcalloc(1, sizeof(*opt->priv));
+	CALLOC_ARRAY(opt->priv, 1);
 	string_list_init(&opt->priv->df_conflict_file_set, 1);
 	return 0;
 }
diff --git a/midx.c b/midx.c
index 971faa8..becfafe 100644
--- a/midx.c
+++ b/midx.c
@@ -145,8 +145,8 @@
 
 	m->num_objects = ntohl(m->chunk_oid_fanout[255]);
 
-	m->pack_names = xcalloc(m->num_packs, sizeof(*m->pack_names));
-	m->packs = xcalloc(m->num_packs, sizeof(*m->packs));
+	CALLOC_ARRAY(m->pack_names, m->num_packs);
+	CALLOC_ARRAY(m->packs, m->num_packs);
 
 	cur_pack_name = (const char *)m->chunk_pack_names;
 	for (i = 0; i < m->num_packs; i++) {
@@ -1144,7 +1144,7 @@
 	if (!m)
 		return 0;
 
-	count = xcalloc(m->num_packs, sizeof(uint32_t));
+	CALLOC_ARRAY(count, m->num_packs);
 
 	if (flags & MIDX_PROGRESS)
 		progress = start_delayed_progress(_("Counting referenced objects"),
@@ -1315,7 +1315,7 @@
 	if (!m)
 		return 0;
 
-	include_pack = xcalloc(m->num_packs, sizeof(unsigned char));
+	CALLOC_ARRAY(include_pack, m->num_packs);
 
 	if (batch_size) {
 		if (fill_included_packs_batch(r, m, include_pack, batch_size))
diff --git a/name-hash.c b/name-hash.c
index 4e03fac..ce28f3f 100644
--- a/name-hash.c
+++ b/name-hash.c
@@ -225,7 +225,7 @@
 {
 	int j;
 
-	lazy_dir_mutex_array = xcalloc(LAZY_MAX_MUTEX, sizeof(pthread_mutex_t));
+	CALLOC_ARRAY(lazy_dir_mutex_array, LAZY_MAX_MUTEX);
 
 	for (j = 0; j < LAZY_MAX_MUTEX; j++)
 		init_recursive_mutex(&lazy_dir_mutex_array[j]);
@@ -514,9 +514,9 @@
 	k_start = 0;
 	nr_each = DIV_ROUND_UP(istate->cache_nr, lazy_nr_dir_threads);
 
-	lazy_entries = xcalloc(istate->cache_nr, sizeof(struct lazy_entry));
-	td_dir = xcalloc(lazy_nr_dir_threads, sizeof(struct lazy_dir_thread_data));
-	td_name = xcalloc(1, sizeof(struct lazy_name_thread_data));
+	CALLOC_ARRAY(lazy_entries, istate->cache_nr);
+	CALLOC_ARRAY(td_dir, lazy_nr_dir_threads);
+	CALLOC_ARRAY(td_name, 1);
 
 	init_dir_mutex();
 
diff --git a/negotiator/default.c b/negotiator/default.c
index 4b78f6b..434189a 100644
--- a/negotiator/default.c
+++ b/negotiator/default.c
@@ -167,7 +167,7 @@
 	negotiator->next = next;
 	negotiator->ack = ack;
 	negotiator->release = release;
-	negotiator->data = ns = xcalloc(1, sizeof(*ns));
+	negotiator->data = CALLOC_ARRAY(ns, 1);
 	ns->rev_list.compare = compare_commits_by_commit_date;
 
 	if (marked)
diff --git a/negotiator/skipping.c b/negotiator/skipping.c
index dffbc76..1236e79 100644
--- a/negotiator/skipping.c
+++ b/negotiator/skipping.c
@@ -62,7 +62,7 @@
 	struct entry *entry;
 	commit->object.flags |= mark | SEEN;
 
-	entry = xcalloc(1, sizeof(*entry));
+	CALLOC_ARRAY(entry, 1);
 	entry->commit = commit;
 	prio_queue_put(&data->rev_list, entry);
 
@@ -241,7 +241,7 @@
 	negotiator->next = next;
 	negotiator->ack = ack;
 	negotiator->release = release;
-	negotiator->data = data = xcalloc(1, sizeof(*data));
+	negotiator->data = CALLOC_ARRAY(data, 1);
 	data->rev_list.compare = compare;
 
 	if (marked)
diff --git a/notes-merge.c b/notes-merge.c
index 2fe724f..d2771fa 100644
--- a/notes-merge.c
+++ b/notes-merge.c
@@ -136,7 +136,7 @@
 	diff_tree_oid(base, remote, "", &opt);
 	diffcore_std(&opt);
 
-	changes = xcalloc(diff_queued_diff.nr, sizeof(struct notes_merge_pair));
+	CALLOC_ARRAY(changes, diff_queued_diff.nr);
 
 	for (i = 0; i < diff_queued_diff.nr; i++) {
 		struct diff_filepair *p = diff_queued_diff.queue[i];
diff --git a/notes-utils.c b/notes-utils.c
index 4bf4888..d7d18e3 100644
--- a/notes-utils.c
+++ b/notes-utils.c
@@ -129,7 +129,7 @@
 	c->cmd = cmd;
 	c->enabled = 1;
 	c->combine = combine_notes_concatenate;
-	c->refs = xcalloc(1, sizeof(struct string_list));
+	CALLOC_ARRAY(c->refs, 1);
 	c->refs->strdup_strings = 1;
 	c->refs_from_env = 0;
 	c->mode_from_env = 0;
diff --git a/notes.c b/notes.c
index d5ac081..a19e4ad 100644
--- a/notes.c
+++ b/notes.c
@@ -452,7 +452,7 @@
 			goto handle_non_note;
 		}
 
-		l = xcalloc(1, sizeof(*l));
+		CALLOC_ARRAY(l, 1);
 		oidcpy(&l->key_oid, &object_oid);
 		oidcpy(&l->val_oid, &entry.oid);
 		if (note_tree_insert(t, node, n, l, type,
diff --git a/object-file.c b/object-file.c
index 5bcfde8..624af40 100644
--- a/object-file.c
+++ b/object-file.c
@@ -546,7 +546,7 @@
 		return -1;
 	}
 
-	ent = xcalloc(1, sizeof(*ent));
+	CALLOC_ARRAY(ent, 1);
 	ent->path = xstrdup(pathbuf.buf);
 
 	/* add the alternate entry */
diff --git a/object-store.h b/object-store.h
index 541dab0..ec32c23 100644
--- a/object-store.h
+++ b/object-store.h
@@ -153,6 +153,11 @@
 	/* A most-recently-used ordered version of the packed_git list. */
 	struct list_head packed_git_mru;
 
+	struct {
+		struct packed_git **packs;
+		unsigned flags;
+	} kept_pack_cache;
+
 	/*
 	 * A map of packfiles to packed_git structs for tracking which
 	 * packs have been loaded already.
diff --git a/object.c b/object.c
index 98017be..7834378 100644
--- a/object.c
+++ b/object.c
@@ -127,7 +127,7 @@
 	int new_hash_size = r->parsed_objects->obj_hash_size < 32 ? 32 : 2 * r->parsed_objects->obj_hash_size;
 	struct object **new_hash;
 
-	new_hash = xcalloc(new_hash_size, sizeof(struct object *));
+	CALLOC_ARRAY(new_hash, new_hash_size);
 	for (i = 0; i < r->parsed_objects->obj_hash_size; i++) {
 		struct object *obj = r->parsed_objects->obj_hash[i];
 
@@ -478,7 +478,7 @@
 	o->object_state = allocate_alloc_state();
 
 	o->is_shallow = -1;
-	o->shallow_stat = xcalloc(1, sizeof(*o->shallow_stat));
+	CALLOC_ARRAY(o->shallow_stat, 1);
 
 	o->buffer_slab = allocate_commit_buffer_slab();
 
diff --git a/pack-bitmap.c b/pack-bitmap.c
index 1f69b5f..b4513f8 100644
--- a/pack-bitmap.c
+++ b/pack-bitmap.c
@@ -978,7 +978,7 @@
 
 	/* try to open a bitmapped pack, but don't parse it yet
 	 * because we may not need to use it */
-	bitmap_git = xcalloc(1, sizeof(*bitmap_git));
+	CALLOC_ARRAY(bitmap_git, 1);
 	if (open_pack_bitmap(revs->repo, bitmap_git) < 0)
 		goto cleanup;
 
@@ -997,6 +997,7 @@
 				object_list_insert(object, &wants);
 
 			object = parse_object_or_die(get_tagged_oid(tag), NULL);
+			object->flags |= (tag->object.flags & UNINTERESTING);
 		}
 
 		if (object->flags & UNINTERESTING)
@@ -1388,7 +1389,7 @@
 	uint32_t *reposition;
 
 	num_objects = bitmap_git->pack->num_objects;
-	reposition = xcalloc(num_objects, sizeof(uint32_t));
+	CALLOC_ARRAY(reposition, num_objects);
 
 	for (i = 0; i < num_objects; ++i) {
 		struct object_id oid;
diff --git a/pack-objects.c b/pack-objects.c
index f2a4338..fe2a4ea 100644
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -49,7 +49,7 @@
 		pdata->index_size = 1024;
 
 	free(pdata->index);
-	pdata->index = xcalloc(pdata->index_size, sizeof(*pdata->index));
+	CALLOC_ARRAY(pdata->index, pdata->index_size);
 
 	entry = pdata->objects;
 
diff --git a/packfile.c b/packfile.c
index 1fec12a..6661f33 100644
--- a/packfile.c
+++ b/packfile.c
@@ -638,7 +638,7 @@
 			if (p->pack_fd == -1 && open_packed_git(p))
 				die("packfile %s cannot be accessed", p->pack_name);
 
-			win = xcalloc(1, sizeof(*win));
+			CALLOC_ARRAY(win, 1);
 			win->offset = (offset / window_align) * window_align;
 			len = p->pack_size - win->offset;
 			if (len > packed_git_window_size)
@@ -2066,12 +2066,79 @@
 	return 0;
 }
 
+static void maybe_invalidate_kept_pack_cache(struct repository *r,
+					     unsigned flags)
+{
+	if (!r->objects->kept_pack_cache.packs)
+		return;
+	if (r->objects->kept_pack_cache.flags == flags)
+		return;
+	FREE_AND_NULL(r->objects->kept_pack_cache.packs);
+	r->objects->kept_pack_cache.flags = 0;
+}
+
+static struct packed_git **kept_pack_cache(struct repository *r, unsigned flags)
+{
+	maybe_invalidate_kept_pack_cache(r, flags);
+
+	if (!r->objects->kept_pack_cache.packs) {
+		struct packed_git **packs = NULL;
+		size_t nr = 0, alloc = 0;
+		struct packed_git *p;
+
+		/*
+		 * We want "all" packs here, because we need to cover ones that
+		 * are used by a midx, as well. We need to look in every one of
+		 * them (instead of the midx itself) to cover duplicates. It's
+		 * possible that an object is found in two packs that the midx
+		 * covers, one kept and one not kept, but the midx returns only
+		 * the non-kept version.
+		 */
+		for (p = get_all_packs(r); p; p = p->next) {
+			if ((p->pack_keep && (flags & ON_DISK_KEEP_PACKS)) ||
+			    (p->pack_keep_in_core && (flags & IN_CORE_KEEP_PACKS))) {
+				ALLOC_GROW(packs, nr + 1, alloc);
+				packs[nr++] = p;
+			}
+		}
+		ALLOC_GROW(packs, nr + 1, alloc);
+		packs[nr] = NULL;
+
+		r->objects->kept_pack_cache.packs = packs;
+		r->objects->kept_pack_cache.flags = flags;
+	}
+
+	return r->objects->kept_pack_cache.packs;
+}
+
+int find_kept_pack_entry(struct repository *r,
+			 const struct object_id *oid,
+			 unsigned flags,
+			 struct pack_entry *e)
+{
+	struct packed_git **cache;
+
+	for (cache = kept_pack_cache(r, flags); *cache; cache++) {
+		struct packed_git *p = *cache;
+		if (fill_pack_entry(oid, e, p))
+			return 1;
+	}
+
+	return 0;
+}
+
 int has_object_pack(const struct object_id *oid)
 {
 	struct pack_entry e;
 	return find_pack_entry(the_repository, oid, &e);
 }
 
+int has_object_kept_pack(const struct object_id *oid, unsigned flags)
+{
+	struct pack_entry e;
+	return find_kept_pack_entry(the_repository, oid, flags, &e);
+}
+
 int has_pack_index(const unsigned char *sha1)
 {
 	struct stat st;
diff --git a/packfile.h b/packfile.h
index 4cfec9e..3ae117a 100644
--- a/packfile.h
+++ b/packfile.h
@@ -162,13 +162,18 @@
 void mark_bad_packed_object(struct packed_git *p, const unsigned char *sha1);
 const struct packed_git *has_packed_and_bad(struct repository *r, const unsigned char *sha1);
 
+#define ON_DISK_KEEP_PACKS 1
+#define IN_CORE_KEEP_PACKS 2
+
 /*
  * Iff a pack file in the given repository contains the object named by sha1,
  * return true and store its location to e.
  */
 int find_pack_entry(struct repository *r, const struct object_id *oid, struct pack_entry *e);
+int find_kept_pack_entry(struct repository *r, const struct object_id *oid, unsigned flags, struct pack_entry *e);
 
 int has_object_pack(const struct object_id *oid);
+int has_object_kept_pack(const struct object_id *oid, unsigned flags);
 
 int has_pack_index(const unsigned char *sha1);
 
diff --git a/parse-options.c b/parse-options.c
index fbea16e..e6f5676 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -625,6 +625,8 @@
  *
  * Right now this is only used to preprocess and substitute
  * OPTION_ALIAS.
+ *
+ * The returned options should be freed using free_preprocessed_options.
  */
 static struct option *preprocess_options(struct parse_opt_ctx_t *ctx,
 					 const struct option *options)
@@ -678,6 +680,7 @@
 			newopt[i].short_name = short_name;
 			newopt[i].long_name = long_name;
 			newopt[i].help = strbuf_detach(&help, NULL);
+			newopt[i].flags |= PARSE_OPT_FROM_ALIAS;
 			break;
 		}
 
@@ -693,6 +696,20 @@
 	return newopt;
 }
 
+static void free_preprocessed_options(struct option *options)
+{
+	int i;
+
+	if (!options)
+		return;
+
+	for (i = 0; options[i].type != OPTION_END; i++) {
+		if (options[i].flags & PARSE_OPT_FROM_ALIAS)
+			free((void *)options[i].help);
+	}
+	free(options);
+}
+
 static int usage_with_options_internal(struct parse_opt_ctx_t *,
 				       const char * const *,
 				       const struct option *, int, int);
@@ -870,7 +887,7 @@
 	}
 
 	precompose_argv_prefix(argc, argv, NULL);
-	free(real_options);
+	free_preprocessed_options(real_options);
 	free(ctx.alias_groups);
 	return parse_options_end(&ctx);
 }
diff --git a/parse-options.h b/parse-options.h
index ff6506a..a845a9d 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -28,26 +28,27 @@
 };
 
 enum parse_opt_flags {
-	PARSE_OPT_KEEP_DASHDASH = 1,
-	PARSE_OPT_STOP_AT_NON_OPTION = 2,
-	PARSE_OPT_KEEP_ARGV0 = 4,
-	PARSE_OPT_KEEP_UNKNOWN = 8,
-	PARSE_OPT_NO_INTERNAL_HELP = 16,
-	PARSE_OPT_ONE_SHOT = 32
+	PARSE_OPT_KEEP_DASHDASH = 1 << 0,
+	PARSE_OPT_STOP_AT_NON_OPTION = 1 << 1,
+	PARSE_OPT_KEEP_ARGV0 = 1 << 2,
+	PARSE_OPT_KEEP_UNKNOWN = 1 << 3,
+	PARSE_OPT_NO_INTERNAL_HELP = 1 << 4,
+	PARSE_OPT_ONE_SHOT = 1 << 5,
 };
 
 enum parse_opt_option_flags {
-	PARSE_OPT_OPTARG  = 1,
-	PARSE_OPT_NOARG   = 2,
-	PARSE_OPT_NONEG   = 4,
-	PARSE_OPT_HIDDEN  = 8,
-	PARSE_OPT_LASTARG_DEFAULT = 16,
-	PARSE_OPT_NODASH = 32,
-	PARSE_OPT_LITERAL_ARGHELP = 64,
-	PARSE_OPT_SHELL_EVAL = 256,
-	PARSE_OPT_NOCOMPLETE = 512,
-	PARSE_OPT_COMP_ARG = 1024,
-	PARSE_OPT_CMDMODE = 2048
+	PARSE_OPT_OPTARG  = 1 << 0,
+	PARSE_OPT_NOARG   = 1 << 1,
+	PARSE_OPT_NONEG   = 1 << 2,
+	PARSE_OPT_HIDDEN  = 1 << 3,
+	PARSE_OPT_LASTARG_DEFAULT = 1 << 4,
+	PARSE_OPT_NODASH = 1 << 5,
+	PARSE_OPT_LITERAL_ARGHELP = 1 << 6,
+	PARSE_OPT_FROM_ALIAS = 1 << 7,
+	PARSE_OPT_SHELL_EVAL = 1 << 8,
+	PARSE_OPT_NOCOMPLETE = 1 << 9,
+	PARSE_OPT_COMP_ARG = 1 << 10,
+	PARSE_OPT_CMDMODE = 1 << 11,
 };
 
 enum parse_opt_result {
diff --git a/patch-ids.c b/patch-ids.c
index 3f404e4..8bf4255 100644
--- a/patch-ids.c
+++ b/patch-ids.c
@@ -124,7 +124,7 @@
 	if (!patch_id_defined(commit))
 		return NULL;
 
-	key = xcalloc(1, sizeof(*key));
+	CALLOC_ARRAY(key, 1);
 	if (init_patch_id_entry(key, commit, ids)) {
 		free(key);
 		return NULL;
diff --git a/pathspec.c b/pathspec.c
index 7a229d8..18b3be3 100644
--- a/pathspec.c
+++ b/pathspec.c
@@ -154,7 +154,7 @@
 	string_list_remove_empty_items(&list, 0);
 
 	item->attr_check = attr_check_alloc();
-	item->attr_match = xcalloc(list.nr, sizeof(struct attr_match));
+	CALLOC_ARRAY(item->attr_match, list.nr);
 
 	for_each_string_list_item(si, &list) {
 		size_t attr_len;
@@ -561,7 +561,7 @@
 		if (!(flags & PATHSPEC_PREFER_CWD))
 			BUG("PATHSPEC_PREFER_CWD requires arguments");
 
-		pathspec->items = item = xcalloc(1, sizeof(*item));
+		pathspec->items = CALLOC_ARRAY(item, 1);
 		item->match = xstrdup(prefix);
 		item->original = xstrdup(prefix);
 		item->nowildcard_len = item->len = strlen(prefix);
diff --git a/perl/Git.pm b/perl/Git.pm
index 02eacef..73ebbf8 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -619,6 +619,19 @@
 
 sub repo_path { $_[0]->{opts}->{Repository} }
 
+=item hooks_path ()
+
+Return path to the hooks directory. Must be called on a repository instance.
+
+=cut
+
+sub hooks_path {
+	my ($self) = @_;
+
+	my $dir = $self->command_oneline('rev-parse', '--git-path', 'hooks');
+	my $abs = abs_path($dir);
+	return $abs;
+}
 
 =item wc_path ()
 
diff --git a/pkt-line.c b/pkt-line.c
index d633005..0194137 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -196,17 +196,26 @@
 
 static int packet_write_gently(const int fd_out, const char *buf, size_t size)
 {
-	static char packet_write_buffer[LARGE_PACKET_MAX];
+	char header[4];
 	size_t packet_size;
 
-	if (size > sizeof(packet_write_buffer) - 4)
+	if (size > LARGE_PACKET_DATA_MAX)
 		return error(_("packet write failed - data exceeds max packet size"));
 
 	packet_trace(buf, size, 1);
 	packet_size = size + 4;
-	set_packet_header(packet_write_buffer, packet_size);
-	memcpy(packet_write_buffer + 4, buf, size);
-	if (write_in_full(fd_out, packet_write_buffer, packet_size) < 0)
+
+	set_packet_header(header, packet_size);
+
+	/*
+	 * Write the header and the buffer in 2 parts so that we do
+	 * not need to allocate a buffer or rely on a static buffer.
+	 * This also avoids putting a large buffer on the stack which
+	 * might have multi-threading issues.
+	 */
+
+	if (write_in_full(fd_out, header, 4) < 0 ||
+	    write_in_full(fd_out, buf, size) < 0)
 		return error(_("packet write failed"));
 	return 0;
 }
@@ -242,26 +251,27 @@
 	packet_trace(data, len, 1);
 }
 
-int write_packetized_from_fd(int fd_in, int fd_out)
+int write_packetized_from_fd_no_flush(int fd_in, int fd_out)
 {
-	static char buf[LARGE_PACKET_DATA_MAX];
+	char *buf = xmalloc(LARGE_PACKET_DATA_MAX);
 	int err = 0;
 	ssize_t bytes_to_write;
 
 	while (!err) {
-		bytes_to_write = xread(fd_in, buf, sizeof(buf));
-		if (bytes_to_write < 0)
+		bytes_to_write = xread(fd_in, buf, LARGE_PACKET_DATA_MAX);
+		if (bytes_to_write < 0) {
+			free(buf);
 			return COPY_READ_ERROR;
+		}
 		if (bytes_to_write == 0)
 			break;
 		err = packet_write_gently(fd_out, buf, bytes_to_write);
 	}
-	if (!err)
-		err = packet_flush_gently(fd_out);
+	free(buf);
 	return err;
 }
 
-int write_packetized_from_buf(const char *src_in, size_t len, int fd_out)
+int write_packetized_from_buf_no_flush(const char *src_in, size_t len, int fd_out)
 {
 	int err = 0;
 	size_t bytes_written = 0;
@@ -277,8 +287,6 @@
 		err = packet_write_gently(fd_out, src_in + bytes_written, bytes_to_write);
 		bytes_written += bytes_to_write;
 	}
-	if (!err)
-		err = packet_flush_gently(fd_out);
 	return err;
 }
 
@@ -298,8 +306,11 @@
 		*src_size -= ret;
 	} else {
 		ret = read_in_full(fd, dst, size);
-		if (ret < 0)
+		if (ret < 0) {
+			if (options & PACKET_READ_GENTLE_ON_READ_ERROR)
+				return error_errno(_("read error"));
 			die_errno(_("read error"));
+		}
 	}
 
 	/* And complain if we didn't get enough bytes to satisfy the read. */
@@ -307,6 +318,8 @@
 		if (options & PACKET_READ_GENTLE_ON_EOF)
 			return -1;
 
+		if (options & PACKET_READ_GENTLE_ON_READ_ERROR)
+			return error(_("the remote end hung up unexpectedly"));
 		die(_("the remote end hung up unexpectedly"));
 	}
 
@@ -335,6 +348,9 @@
 	len = packet_length(linelen);
 
 	if (len < 0) {
+		if (options & PACKET_READ_GENTLE_ON_READ_ERROR)
+			return error(_("protocol error: bad line length "
+				       "character: %.4s"), linelen);
 		die(_("protocol error: bad line length character: %.4s"), linelen);
 	} else if (!len) {
 		packet_trace("0000", 4, 0);
@@ -349,12 +365,19 @@
 		*pktlen = 0;
 		return PACKET_READ_RESPONSE_END;
 	} else if (len < 4) {
+		if (options & PACKET_READ_GENTLE_ON_READ_ERROR)
+			return error(_("protocol error: bad line length %d"),
+				     len);
 		die(_("protocol error: bad line length %d"), len);
 	}
 
 	len -= 4;
-	if ((unsigned)len >= size)
+	if ((unsigned)len >= size) {
+		if (options & PACKET_READ_GENTLE_ON_READ_ERROR)
+			return error(_("protocol error: bad line length %d"),
+				     len);
 		die(_("protocol error: bad line length %d"), len);
+	}
 
 	if (get_packet_data(fd, src_buffer, src_len, buffer, len, options) < 0) {
 		*pktlen = -1;
@@ -421,7 +444,7 @@
 	return packet_read_line_generic(-1, src, src_len, dst_len);
 }
 
-ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out)
+ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out, int options)
 {
 	int packet_len;
 
@@ -437,7 +460,7 @@
 			 * that there is already room for the extra byte.
 			 */
 			sb_out->buf + sb_out->len, LARGE_PACKET_DATA_MAX+1,
-			PACKET_READ_GENTLE_ON_EOF);
+			options);
 		if (packet_len <= 0)
 			break;
 		sb_out->len += packet_len;
diff --git a/pkt-line.h b/pkt-line.h
index 8c90daa..5af5f45 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -32,8 +32,8 @@
 void packet_buf_write_len(struct strbuf *buf, const char *data, size_t len);
 int packet_flush_gently(int fd);
 int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
-int write_packetized_from_fd(int fd_in, int fd_out);
-int write_packetized_from_buf(const char *src_in, size_t len, int fd_out);
+int write_packetized_from_fd_no_flush(int fd_in, int fd_out);
+int write_packetized_from_buf_no_flush(const char *src_in, size_t len, int fd_out);
 
 /*
  * Read a packetized line into the buffer, which must be at least size bytes
@@ -68,10 +68,15 @@
  *
  * If options contains PACKET_READ_DIE_ON_ERR_PACKET, it dies when it sees an
  * ERR packet.
+ *
+ * If options contains PACKET_READ_GENTLE_ON_READ_ERROR, we will not die
+ * on read errors, but instead return -1.  However, we may still die on an
+ * ERR packet (if requested).
  */
-#define PACKET_READ_GENTLE_ON_EOF     (1u<<0)
-#define PACKET_READ_CHOMP_NEWLINE     (1u<<1)
-#define PACKET_READ_DIE_ON_ERR_PACKET (1u<<2)
+#define PACKET_READ_GENTLE_ON_EOF        (1u<<0)
+#define PACKET_READ_CHOMP_NEWLINE        (1u<<1)
+#define PACKET_READ_DIE_ON_ERR_PACKET    (1u<<2)
+#define PACKET_READ_GENTLE_ON_READ_ERROR (1u<<3)
 int packet_read(int fd, char **src_buffer, size_t *src_len, char
 		*buffer, unsigned size, int options);
 
@@ -131,7 +136,7 @@
 /*
  * Reads a stream of variable sized packets until a flush packet is detected.
  */
-ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out);
+ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out, int options);
 
 /*
  * Receive multiplexed output stream over git native protocol.
diff --git a/pretty.c b/pretty.c
index c5f5ecc..e5b33ba 100644
--- a/pretty.c
+++ b/pretty.c
@@ -12,6 +12,7 @@
 #include "reflog-walk.h"
 #include "gpg-interface.h"
 #include "trailer.h"
+#include "run-command.h"
 
 static char *user_format;
 static struct cmt_fmt_map {
@@ -678,7 +679,7 @@
 {
 	static struct string_list *mail_map;
 	if (!mail_map) {
-		mail_map = xcalloc(1, sizeof(*mail_map));
+		CALLOC_ARRAY(mail_map, 1);
 		read_mailmap(mail_map);
 	}
 	return mail_map->nr && map_user(mail_map, email, email_len, name, name_len);
@@ -1206,6 +1207,34 @@
 	return 0;
 }
 
+static size_t parse_describe_args(const char *start, struct strvec *args)
+{
+	const char *options[] = { "match", "exclude" };
+	const char *arg = start;
+
+	for (;;) {
+		const char *matched = NULL;
+		const char *argval;
+		size_t arglen = 0;
+		int i;
+
+		for (i = 0; i < ARRAY_SIZE(options); i++) {
+			if (match_placeholder_arg_value(arg, options[i], &arg,
+							&argval, &arglen)) {
+				matched = options[i];
+				break;
+			}
+		}
+		if (!matched)
+			break;
+
+		if (!arglen)
+			return 0;
+		strvec_pushf(args, "--%s=%.*s", matched, (int)arglen, argval);
+	}
+	return arg - start;
+}
+
 static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 				const char *placeholder,
 				void *context)
@@ -1271,6 +1300,41 @@
 		return parse_padding_placeholder(placeholder, c);
 	}
 
+	if (skip_prefix(placeholder, "(describe", &arg)) {
+		struct child_process cmd = CHILD_PROCESS_INIT;
+		struct strbuf out = STRBUF_INIT;
+		struct strbuf err = STRBUF_INIT;
+		struct pretty_print_describe_status *describe_status;
+
+		describe_status = c->pretty_ctx->describe_status;
+		if (describe_status) {
+			if (!describe_status->max_invocations)
+				return 0;
+			describe_status->max_invocations--;
+		}
+
+		cmd.git_cmd = 1;
+		strvec_push(&cmd.args, "describe");
+
+		if (*arg == ':') {
+			arg++;
+			arg += parse_describe_args(arg, &cmd.args);
+		}
+
+		if (*arg != ')') {
+			child_process_clear(&cmd);
+			return 0;
+		}
+
+		strvec_push(&cmd.args, oid_to_hex(&commit->object.oid));
+		pipe_command(&cmd, NULL, 0, &out, 0, &err, 0);
+		strbuf_rtrim(&out);
+		strbuf_addbuf(sb, &out);
+		strbuf_release(&out);
+		strbuf_release(&err);
+		return arg - placeholder + 1;
+	}
+
 	/* these depend on the commit */
 	if (!commit->object.parsed)
 		parse_object(the_repository, &commit->object.oid);
diff --git a/pretty.h b/pretty.h
index d902cdd..f034609 100644
--- a/pretty.h
+++ b/pretty.h
@@ -24,6 +24,10 @@
 	CMIT_FMT_UNSPECIFIED
 };
 
+struct pretty_print_describe_status {
+	unsigned int max_invocations;
+};
+
 struct pretty_print_context {
 	/*
 	 * Callers should tweak these to change the behavior of pp_* functions.
@@ -45,6 +49,7 @@
 	int color;
 	struct ident_split *from_ident;
 	unsigned encode_email_headers:1;
+	struct pretty_print_describe_status *describe_status;
 
 	/*
 	 * Fields below here are manipulated internally by pp_* functions and
diff --git a/progress.c b/progress.c
index 31014e6..680c6a8 100644
--- a/progress.c
+++ b/progress.c
@@ -196,7 +196,7 @@
 	now_ns = progress_getnanotime(progress);
 
 	if (!tp) {
-		progress->throughput = tp = xcalloc(1, sizeof(*tp));
+		progress->throughput = CALLOC_ARRAY(tp, 1);
 		tp->prev_total = tp->curr_total = total;
 		tp->prev_ns = now_ns;
 		strbuf_init(&tp->display, 0);
diff --git a/promisor-remote.c b/promisor-remote.c
index 3c572b1..da3f2ca 100644
--- a/promisor-remote.c
+++ b/promisor-remote.c
@@ -208,7 +208,7 @@
 
 	if (remaining_nr) {
 		int j = 0;
-		new_oids = xcalloc(remaining_nr, sizeof(*new_oids));
+		CALLOC_ARRAY(new_oids, remaining_nr);
 		for (i = 0; i < oid_nr; i++)
 			if (remaining[i])
 				oidcpy(&new_oids[j++], &old_oids[i]);
diff --git a/range-diff.c b/range-diff.c
index a3cc7c9..116fb07 100644
--- a/range-diff.c
+++ b/range-diff.c
@@ -96,7 +96,7 @@
 				string_list_append(list, buf.buf)->util = util;
 				strbuf_reset(&buf);
 			}
-			util = xcalloc(sizeof(*util), 1);
+			CALLOC_ARRAY(util, 1);
 			if (get_oid(p, &util->oid)) {
 				error(_("could not parse commit '%s'"), p);
 				free(util);
diff --git a/read-cache.c b/read-cache.c
index 1e9a50c..5a907af 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -2097,7 +2097,7 @@
 	/* ensure we have no more threads than we have blocks to process */
 	if (nr_threads > ieot->nr)
 		nr_threads = ieot->nr;
-	data = xcalloc(nr_threads, sizeof(*data));
+	CALLOC_ARRAY(data, nr_threads);
 
 	offset = ieot_start = 0;
 	ieot_blocks = DIV_ROUND_UP(ieot->nr, nr_threads);
@@ -2199,7 +2199,7 @@
 	istate->version = ntohl(hdr->hdr_version);
 	istate->cache_nr = ntohl(hdr->hdr_entries);
 	istate->cache_alloc = alloc_nr(istate->cache_nr);
-	istate->cache = xcalloc(istate->cache_alloc, sizeof(*istate->cache));
+	CALLOC_ARRAY(istate->cache, istate->cache_alloc);
 	istate->initialized = 1;
 
 	p.istate = istate;
@@ -2326,7 +2326,7 @@
 	if (split_index->base)
 		discard_index(split_index->base);
 	else
-		split_index->base = xcalloc(1, sizeof(*split_index->base));
+		CALLOC_ARRAY(split_index->base, 1);
 
 	base_oid_hex = oid_to_hex(&split_index->base_oid);
 	base_path = xstrfmt("%s/sharedindex.%s", gitdir, base_oid_hex);
@@ -2373,6 +2373,7 @@
 	cache_tree_free(&(istate->cache_tree));
 	istate->initialized = 0;
 	istate->fsmonitor_has_run_once = 0;
+	FREE_AND_NULL(istate->fsmonitor_last_update);
 	FREE_AND_NULL(istate->cache);
 	istate->cache_alloc = 0;
 	discard_split_index(istate);
@@ -3427,7 +3428,7 @@
 		stat_validity_clear(sv);
 	else {
 		if (!sv->sd)
-			sv->sd = xcalloc(1, sizeof(struct stat_data));
+			CALLOC_ARRAY(sv->sd, 1);
 		fill_stat_data(sv->sd, &st);
 	}
 }
diff --git a/rebase-interactive.c b/rebase-interactive.c
index 762853b..b6cbd16 100644
--- a/rebase-interactive.c
+++ b/rebase-interactive.c
@@ -44,7 +44,10 @@
 "r, reword <commit> = use commit, but edit the commit message\n"
 "e, edit <commit> = use commit, but stop for amending\n"
 "s, squash <commit> = use commit, but meld into previous commit\n"
-"f, fixup <commit> = like \"squash\", but discard this commit's log message\n"
+"f, fixup [-C | -c] <commit> = like \"squash\" but keep only the previous\n"
+"                   commit's log message, unless -C is used, in which case\n"
+"                   keep only this commit's message; -c is same as -C but\n"
+"                   opens the editor\n"
 "x, exec <command> = run command (the rest of the line) using shell\n"
 "b, break = stop here (continue rebase later with 'git rebase --continue')\n"
 "d, drop <commit> = remove commit\n"
@@ -53,7 +56,7 @@
 "m, merge [-C <commit> | -c <commit>] <label> [# <oneline>]\n"
 ".       create a merge commit using the original merge commit's\n"
 ".       message (or the oneline, if no original merge commit was\n"
-".       specified). Use -c <commit> to reword the commit message.\n"
+".       specified); use -c <commit> to reword the commit message\n"
 "\n"
 "These lines can be re-ordered; they are executed from top to bottom.\n");
 	unsigned edit_todo = !(shortrevisions && shortonto);
diff --git a/ref-filter.c b/ref-filter.c
index e84efb5..f0bd32f 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -772,7 +772,8 @@
 			   struct strbuf *unused_err)
 {
 	struct ref_formatting_stack *new_stack;
-	struct if_then_else *if_then_else = xcalloc(sizeof(struct if_then_else), 1);
+	struct if_then_else *if_then_else = xcalloc(1,
+						    sizeof(struct if_then_else));
 
 	if_then_else->str = atomv->atom->u.if_then_else.str;
 	if_then_else->cmp_status = atomv->atom->u.if_then_else.cmp_status;
@@ -1676,7 +1677,7 @@
 	int i;
 	struct object_info empty = OBJECT_INFO_INIT;
 
-	ref->value = xcalloc(used_atom_cnt, sizeof(struct atom_value));
+	CALLOC_ARRAY(ref->value, used_atom_cnt);
 
 	if (need_symref && (ref->flag & REF_ISSYMREF) && !ref->symref) {
 		ref->symref = resolve_refdup(ref->refname, RESOLVE_REF_READING,
@@ -2185,7 +2186,7 @@
 	if (!check_reachable)
 		return;
 
-	to_clear = xcalloc(sizeof(struct commit *), array->nr);
+	CALLOC_ARRAY(to_clear, array->nr);
 
 	repo_init_revisions(the_repository, &revs, NULL);
 
@@ -2490,7 +2491,7 @@
 {
 	struct ref_sorting *s;
 
-	s = xcalloc(1, sizeof(*s));
+	CALLOC_ARRAY(s, 1);
 	s->next = *sorting_tail;
 	*sorting_tail = s;
 
diff --git a/reflog-walk.c b/reflog-walk.c
index 3a25b27..e9cd328 100644
--- a/reflog-walk.c
+++ b/reflog-walk.c
@@ -112,7 +112,7 @@
 
 void init_reflog_walk(struct reflog_walk_info **info)
 {
-	*info = xcalloc(1, sizeof(struct reflog_walk_info));
+	CALLOC_ARRAY(*info, 1);
 	(*info)->complete_reflogs.strdup_strings = 1;
 }
 
@@ -181,7 +181,7 @@
 	}
 	free(branch);
 
-	commit_reflog = xcalloc(1, sizeof(struct commit_reflog));
+	CALLOC_ARRAY(commit_reflog, 1);
 	if (recno < 0) {
 		commit_reflog->recno = get_reflog_recno_by_time(reflogs, timestamp);
 		if (commit_reflog->recno < 0) {
diff --git a/refs.c b/refs.c
index a665ed5..261fd82 100644
--- a/refs.c
+++ b/refs.c
@@ -1007,7 +1007,7 @@
 	struct ref_transaction *tr;
 	assert(err);
 
-	tr = xcalloc(1, sizeof(struct ref_transaction));
+	CALLOC_ARRAY(tr, 1);
 	tr->ref_store = refs;
 	return tr;
 }
@@ -1306,7 +1306,7 @@
 		while (len && ref[len - 1] == '/')
 			ref[--len] = '\0';
 		if (!hide_refs) {
-			hide_refs = xcalloc(1, sizeof(*hide_refs));
+			CALLOC_ARRAY(hide_refs, 1);
 			hide_refs->strdup_strings = 1;
 		}
 		string_list_append(hide_refs, ref);
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 4fdc688..119972e 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -549,7 +549,7 @@
 
 	/* First lock the file so it can't change out from under us. */
 
-	*lock_p = lock = xcalloc(1, sizeof(*lock));
+	*lock_p = CALLOC_ARRAY(lock, 1);
 
 	lock->ref_name = xstrdup(refname);
 	files_ref_path(refs, &ref_file, refname);
@@ -843,7 +843,7 @@
 
 	overlay_iter = overlay_ref_iterator_begin(loose_iter, packed_iter);
 
-	iter = xcalloc(1, sizeof(*iter));
+	CALLOC_ARRAY(iter, 1);
 	ref_iterator = &iter->base;
 	base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable,
 			       overlay_iter->ordered);
@@ -930,7 +930,7 @@
 	files_assert_main_repository(refs, "lock_ref_oid_basic");
 	assert(err);
 
-	lock = xcalloc(1, sizeof(struct ref_lock));
+	CALLOC_ARRAY(lock, 1);
 
 	if (mustexist)
 		resolve_flags |= RESOLVE_REF_READING;
@@ -2152,7 +2152,7 @@
 		return empty_ref_iterator_begin();
 	}
 
-	iter = xcalloc(1, sizeof(*iter));
+	CALLOC_ARRAY(iter, 1);
 	ref_iterator = &iter->base;
 
 	base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable, 0);
@@ -2597,7 +2597,7 @@
 	if (!transaction->nr)
 		goto cleanup;
 
-	backend_data = xcalloc(1, sizeof(*backend_data));
+	CALLOC_ARRAY(backend_data, 1);
 	transaction->backend_data = backend_data;
 
 	/*
diff --git a/refs/iterator.c b/refs/iterator.c
index 629e00a..a89d132 100644
--- a/refs/iterator.c
+++ b/refs/iterator.c
@@ -393,7 +393,7 @@
 	if (!*prefix && !trim)
 		return iter0; /* optimization: no need to wrap iterator */
 
-	iter = xcalloc(1, sizeof(*iter));
+	CALLOC_ARRAY(iter, 1);
 	ref_iterator = &iter->base;
 
 	base_ref_iterator_init(ref_iterator, &prefix_ref_iterator_vtable, iter0->ordered);
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index b912f25..dfecdbc 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -941,7 +941,7 @@
 	if (start == snapshot->eof)
 		return empty_ref_iterator_begin();
 
-	iter = xcalloc(1, sizeof(*iter));
+	CALLOC_ARRAY(iter, 1);
 	ref_iterator = &iter->base;
 	base_ref_iterator_init(ref_iterator, &packed_ref_iterator_vtable, 1);
 
@@ -1424,7 +1424,7 @@
 	 * do so itself.
 	 */
 
-	data = xcalloc(1, sizeof(*data));
+	CALLOC_ARRAY(data, 1);
 	string_list_init(&data->updates, 0);
 
 	transaction->backend_data = data;
diff --git a/refs/ref-cache.c b/refs/ref-cache.c
index b7052f7..46f1e54 100644
--- a/refs/ref-cache.c
+++ b/refs/ref-cache.c
@@ -530,7 +530,7 @@
 	if (prime_dir)
 		prime_ref_dir(dir, prefix);
 
-	iter = xcalloc(1, sizeof(*iter));
+	CALLOC_ARRAY(iter, 1);
 	ref_iterator = &iter->base;
 	base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable, 1);
 	ALLOC_GROW(iter->levels, 10, iter->levels_alloc);
diff --git a/remote.c b/remote.c
index c3f85c1..6d1e8d0 100644
--- a/remote.c
+++ b/remote.c
@@ -151,7 +151,7 @@
 	if (e)
 		return container_of(e, struct remote, ent);
 
-	ret = xcalloc(1, sizeof(struct remote));
+	CALLOC_ARRAY(ret, 1);
 	ret->prune = -1;  /* unspecified */
 	ret->prune_tags = -1;  /* unspecified */
 	ret->name = xstrndup(name, len);
@@ -186,7 +186,7 @@
 	}
 
 	ALLOC_GROW(branches, branches_nr + 1, branches_alloc);
-	ret = xcalloc(1, sizeof(struct branch));
+	CALLOC_ARRAY(ret, 1);
 	branches[branches_nr++] = ret;
 	ret->name = xstrndup(name, len);
 	ret->refname = xstrfmt("refs/heads/%s", ret->name);
@@ -207,7 +207,7 @@
 	}
 
 	ALLOC_GROW(r->rewrite, r->rewrite_nr + 1, r->rewrite_alloc);
-	ret = xcalloc(1, sizeof(struct rewrite));
+	CALLOC_ARRAY(ret, 1);
 	r->rewrite[r->rewrite_nr++] = ret;
 	ret->base = xstrndup(base, len);
 	ret->baselen = len;
@@ -1664,7 +1664,7 @@
 
 	remote = remote_get(ret->remote_name);
 
-	ret->merge = xcalloc(ret->merge_nr, sizeof(*ret->merge));
+	CALLOC_ARRAY(ret->merge, ret->merge_nr);
 	for (i = 0; i < ret->merge_nr; i++) {
 		ret->merge[i] = xcalloc(1, sizeof(**ret->merge));
 		ret->merge[i]->src = xstrdup(ret->merge_name[i]);
diff --git a/repository.c b/repository.c
index c98298a..87b355e 100644
--- a/repository.c
+++ b/repository.c
@@ -72,7 +72,7 @@
 	repo_set_commondir(repo, o->commondir);
 
 	if (!repo->objects->odb) {
-		repo->objects->odb = xcalloc(1, sizeof(*repo->objects->odb));
+		CALLOC_ARRAY(repo->objects->odb, 1);
 		repo->objects->odb_tail = &repo->objects->odb->next;
 	}
 	expand_base_dir(&repo->objects->odb->path, o->object_dir,
@@ -262,7 +262,7 @@
 int repo_read_index(struct repository *repo)
 {
 	if (!repo->index)
-		repo->index = xcalloc(1, sizeof(*repo->index));
+		CALLOC_ARRAY(repo->index, 1);
 
 	/* Complete the double-reference */
 	if (!repo->index->repo)
diff --git a/resolve-undo.c b/resolve-undo.c
index 236320f..bbd2e57 100644
--- a/resolve-undo.c
+++ b/resolve-undo.c
@@ -15,7 +15,7 @@
 		return;
 
 	if (!istate->resolve_undo) {
-		resolve_undo = xcalloc(1, sizeof(*resolve_undo));
+		CALLOC_ARRAY(resolve_undo, 1);
 		resolve_undo->strdup_strings = 1;
 		istate->resolve_undo = resolve_undo;
 	}
@@ -57,7 +57,7 @@
 	int i;
 	const unsigned rawsz = the_hash_algo->rawsz;
 
-	resolve_undo = xcalloc(1, sizeof(*resolve_undo));
+	CALLOC_ARRAY(resolve_undo, 1);
 	resolve_undo->strdup_strings = 1;
 
 	while (size) {
diff --git a/revision.c b/revision.c
index b78733f..553c0fa 100644
--- a/revision.c
+++ b/revision.c
@@ -154,7 +154,7 @@
 
 	entry = hashmap_get_entry(map, &key, ent, NULL);
 	if (!entry) {
-		entry = xcalloc(1, sizeof(struct path_and_oids_entry));
+		CALLOC_ARRAY(entry, 1);
 		hashmap_entry_init(&entry->ent, hash);
 		entry->path = xstrdup(key.path);
 		oidset_init(&entry->trees, 16);
@@ -1555,7 +1555,7 @@
 void add_ref_exclusion(struct string_list **ref_excludes_p, const char *exclude)
 {
 	if (!*ref_excludes_p) {
-		*ref_excludes_p = xcalloc(1, sizeof(**ref_excludes_p));
+		CALLOC_ARRAY(*ref_excludes_p, 1);
 		(*ref_excludes_p)->strdup_strings = 1;
 	}
 	string_list_append(*ref_excludes_p, exclude);
@@ -2336,6 +2336,16 @@
 		revs->unpacked = 1;
 	} else if (starts_with(arg, "--unpacked=")) {
 		die(_("--unpacked=<packfile> no longer supported"));
+	} else if (!strcmp(arg, "--no-kept-objects")) {
+		revs->no_kept_objects = 1;
+		revs->keep_pack_cache_flags |= IN_CORE_KEEP_PACKS;
+		revs->keep_pack_cache_flags |= ON_DISK_KEEP_PACKS;
+	} else if (skip_prefix(arg, "--no-kept-objects=", &optarg)) {
+		revs->no_kept_objects = 1;
+		if (!strcmp(optarg, "in-core"))
+			revs->keep_pack_cache_flags |= IN_CORE_KEEP_PACKS;
+		if (!strcmp(optarg, "on-disk"))
+			revs->keep_pack_cache_flags |= ON_DISK_KEEP_PACKS;
 	} else if (!strcmp(arg, "-r")) {
 		revs->diff = 1;
 		revs->diffopt.flags.recursive = 1;
@@ -2929,7 +2939,7 @@
 
 	st = lookup_decoration(&revs->merge_simplification, &commit->object);
 	if (!st) {
-		st = xcalloc(1, sizeof(*st));
+		CALLOC_ARRAY(st, 1);
 		add_decoration(&revs->merge_simplification, &commit->object, st);
 	}
 	return st;
@@ -3795,6 +3805,11 @@
 		return commit_ignore;
 	if (revs->unpacked && has_object_pack(&commit->object.oid))
 		return commit_ignore;
+	if (revs->no_kept_objects) {
+		if (has_object_kept_pack(&commit->object.oid,
+					 revs->keep_pack_cache_flags))
+			return commit_ignore;
+	}
 	if (commit->object.flags & UNINTERESTING)
 		return commit_ignore;
 	if (revs->line_level_traverse && !want_ancestry(revs)) {
diff --git a/revision.h b/revision.h
index e6be3c8..a24f72d 100644
--- a/revision.h
+++ b/revision.h
@@ -148,6 +148,7 @@
 			edge_hint_aggressive:1,
 			limited:1,
 			unpacked:1,
+			no_kept_objects:1,
 			boundary:2,
 			count:1,
 			left_right:1,
@@ -235,7 +236,7 @@
 	const char	*mime_boundary;
 	const char	*patch_suffix;
 	int		numbered_files;
-	int		reroll_count;
+	const char	*reroll_count;
 	char		*message_id;
 	struct ident_split from_ident;
 	struct string_list *ref_message_ids;
@@ -317,6 +318,9 @@
 	 * This is loaded from the commit-graph being used.
 	 */
 	struct bloom_filter_settings *bloom_filter_settings;
+
+	/* misc. flags related to '--no-kept-objects' */
+	unsigned keep_pack_cache_flags;
 };
 
 int ref_excluded(struct string_list *, const char *path);
diff --git a/run-command.c b/run-command.c
index 4e34623..be6bc12 100644
--- a/run-command.c
+++ b/run-command.c
@@ -1638,8 +1638,8 @@
 	pp->nr_processes = 0;
 	pp->output_owner = 0;
 	pp->shutdown = 0;
-	pp->children = xcalloc(n, sizeof(*pp->children));
-	pp->pfd = xcalloc(n, sizeof(*pp->pfd));
+	CALLOC_ARRAY(pp->children, n);
+	CALLOC_ARRAY(pp->pfd, n);
 	strbuf_init(&pp->buffered_output, 0);
 
 	for (i = 0; i < n; i++) {
diff --git a/send-pack.c b/send-pack.c
index 9045f8a..5f215b1 100644
--- a/send-pack.c
+++ b/send-pack.c
@@ -188,13 +188,13 @@
 			}
 			if (new_report) {
 				if (!hint->report) {
-					hint->report = xcalloc(1, sizeof(struct ref_push_report));
+					CALLOC_ARRAY(hint->report, 1);
 					report = hint->report;
 				} else {
 					report = hint->report;
 					while (report->next)
 						report = report->next;
-					report->next = xcalloc(1, sizeof(struct ref_push_report));
+					CALLOC_ARRAY(report->next, 1);
 					report = report->next;
 				}
 				new_report = 0;
diff --git a/sequencer.c b/sequencer.c
index d2332d3..b4c63ae 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -1726,13 +1726,183 @@
 	}
 }
 
+enum todo_item_flags {
+	TODO_EDIT_MERGE_MSG    = (1 << 0),
+	TODO_REPLACE_FIXUP_MSG = (1 << 1),
+	TODO_EDIT_FIXUP_MSG    = (1 << 2),
+};
+
+static const char first_commit_msg_str[] = N_("This is the 1st commit message:");
+static const char nth_commit_msg_fmt[] = N_("This is the commit message #%d:");
+static const char skip_first_commit_msg_str[] = N_("The 1st commit message will be skipped:");
+static const char skip_nth_commit_msg_fmt[] = N_("The commit message #%d will be skipped:");
+static const char combined_commit_msg_fmt[] = N_("This is a combination of %d commits.");
+
+static int is_fixup_flag(enum todo_command command, unsigned flag)
+{
+	return command == TODO_FIXUP && ((flag & TODO_REPLACE_FIXUP_MSG) ||
+					 (flag & TODO_EDIT_FIXUP_MSG));
+}
+
+/*
+ * Wrapper around strbuf_add_commented_lines() which avoids double
+ * commenting commit subjects.
+ */
+static void add_commented_lines(struct strbuf *buf, const void *str, size_t len)
+{
+	const char *s = str;
+	while (len > 0 && s[0] == comment_line_char) {
+		size_t count;
+		const char *n = memchr(s, '\n', len);
+		if (!n)
+			count = len;
+		else
+			count = n - s + 1;
+		strbuf_add(buf, s, count);
+		s += count;
+		len -= count;
+	}
+	strbuf_add_commented_lines(buf, s, len);
+}
+
+/* Does the current fixup chain contain a squash command? */
+static int seen_squash(struct replay_opts *opts)
+{
+	return starts_with(opts->current_fixups.buf, "squash") ||
+		strstr(opts->current_fixups.buf, "\nsquash");
+}
+
+static void update_comment_bufs(struct strbuf *buf1, struct strbuf *buf2, int n)
+{
+	strbuf_setlen(buf1, 2);
+	strbuf_addf(buf1, _(nth_commit_msg_fmt), n);
+	strbuf_addch(buf1, '\n');
+	strbuf_setlen(buf2, 2);
+	strbuf_addf(buf2, _(skip_nth_commit_msg_fmt), n);
+	strbuf_addch(buf2, '\n');
+}
+
+/*
+ * Comment out any un-commented commit messages, updating the message comments
+ * to say they will be skipped but do not comment out the empty lines that
+ * surround commit messages and their comments.
+ */
+static void update_squash_message_for_fixup(struct strbuf *msg)
+{
+	void (*copy_lines)(struct strbuf *, const void *, size_t) = strbuf_add;
+	struct strbuf buf1 = STRBUF_INIT, buf2 = STRBUF_INIT;
+	const char *s, *start;
+	char *orig_msg;
+	size_t orig_msg_len;
+	int i = 1;
+
+	strbuf_addf(&buf1, "# %s\n", _(first_commit_msg_str));
+	strbuf_addf(&buf2, "# %s\n", _(skip_first_commit_msg_str));
+	s = start = orig_msg = strbuf_detach(msg, &orig_msg_len);
+	while (s) {
+		const char *next;
+		size_t off;
+		if (skip_prefix(s, buf1.buf, &next)) {
+			/*
+			 * Copy the last message, preserving the blank line
+			 * preceding the current line
+			 */
+			off = (s > start + 1 && s[-2] == '\n') ? 1 : 0;
+			copy_lines(msg, start, s - start - off);
+			if (off)
+				strbuf_addch(msg, '\n');
+			/*
+			 * The next message needs to be commented out but the
+			 * message header is already commented out so just copy
+			 * it and the blank line that follows it.
+			 */
+			strbuf_addbuf(msg, &buf2);
+			if (*next == '\n')
+				strbuf_addch(msg, *next++);
+			start = s = next;
+			copy_lines = add_commented_lines;
+			update_comment_bufs(&buf1, &buf2, ++i);
+		} else if (skip_prefix(s, buf2.buf, &next)) {
+			off = (s > start + 1 && s[-2] == '\n') ? 1 : 0;
+			copy_lines(msg, start, s - start - off);
+			start = s - off;
+			s = next;
+			copy_lines = strbuf_add;
+			update_comment_bufs(&buf1, &buf2, ++i);
+		} else {
+			s = strchr(s, '\n');
+			if (s)
+				s++;
+		}
+	}
+	copy_lines(msg, start, orig_msg_len - (start - orig_msg));
+	free(orig_msg);
+	strbuf_release(&buf1);
+	strbuf_release(&buf2);
+}
+
+static int append_squash_message(struct strbuf *buf, const char *body,
+			 enum todo_command command, struct replay_opts *opts,
+			 unsigned flag)
+{
+	const char *fixup_msg;
+	size_t commented_len = 0, fixup_off;
+	/*
+	 * amend is non-interactive and not normally used with fixup!
+	 * or squash! commits, so only comment out those subjects when
+	 * squashing commit messages.
+	 */
+	if (starts_with(body, "amend!") ||
+	    ((command == TODO_SQUASH || seen_squash(opts)) &&
+	     (starts_with(body, "squash!") || starts_with(body, "fixup!"))))
+		commented_len = commit_subject_length(body);
+
+	strbuf_addf(buf, "\n%c ", comment_line_char);
+	strbuf_addf(buf, _(nth_commit_msg_fmt),
+		    ++opts->current_fixup_count + 1);
+	strbuf_addstr(buf, "\n\n");
+	strbuf_add_commented_lines(buf, body, commented_len);
+	/* buf->buf may be reallocated so store an offset into the buffer */
+	fixup_off = buf->len;
+	strbuf_addstr(buf, body + commented_len);
+
+	/* fixup -C after squash behaves like squash */
+	if (is_fixup_flag(command, flag) && !seen_squash(opts)) {
+		/*
+		 * We're replacing the commit message so we need to
+		 * append the Signed-off-by: trailer if the user
+		 * requested '--signoff'.
+		 */
+		if (opts->signoff)
+			append_signoff(buf, 0, 0);
+
+		if ((command == TODO_FIXUP) &&
+		    (flag & TODO_REPLACE_FIXUP_MSG) &&
+		    (file_exists(rebase_path_fixup_msg()) ||
+		     !file_exists(rebase_path_squash_msg()))) {
+			fixup_msg = skip_blank_lines(buf->buf + fixup_off);
+			if (write_message(fixup_msg, strlen(fixup_msg),
+					rebase_path_fixup_msg(), 0) < 0)
+				return error(_("cannot write '%s'"),
+					rebase_path_fixup_msg());
+		} else {
+			unlink(rebase_path_fixup_msg());
+		}
+	} else  {
+		unlink(rebase_path_fixup_msg());
+	}
+
+	return 0;
+}
+
 static int update_squash_messages(struct repository *r,
 				  enum todo_command command,
 				  struct commit *commit,
-				  struct replay_opts *opts)
+				  struct replay_opts *opts,
+				  unsigned flag)
 {
 	struct strbuf buf = STRBUF_INIT;
-	int res;
+	int res = 0;
 	const char *message, *body;
 	const char *encoding = get_commit_output_encoding();
 
@@ -1748,10 +1918,12 @@
 			buf.buf : strchrnul(buf.buf, '\n');
 
 		strbuf_addf(&header, "%c ", comment_line_char);
-		strbuf_addf(&header, _("This is a combination of %d commits."),
+		strbuf_addf(&header, _(combined_commit_msg_fmt),
 			    opts->current_fixup_count + 2);
 		strbuf_splice(&buf, 0, eol - buf.buf, header.buf, header.len);
 		strbuf_release(&header);
+		if (is_fixup_flag(command, flag) && !seen_squash(opts))
+			update_squash_message_for_fixup(&buf);
 	} else {
 		struct object_id head;
 		struct commit *head_commit;
@@ -1765,19 +1937,22 @@
 			return error(_("could not read HEAD's commit message"));
 
 		find_commit_subject(head_message, &body);
-		if (write_message(body, strlen(body),
-				  rebase_path_fixup_msg(), 0)) {
+		if (command == TODO_FIXUP && !flag && write_message(body, strlen(body),
+							rebase_path_fixup_msg(), 0) < 0) {
 			unuse_commit_buffer(head_commit, head_message);
-			return error(_("cannot write '%s'"),
-				     rebase_path_fixup_msg());
+			return error(_("cannot write '%s'"), rebase_path_fixup_msg());
 		}
-
 		strbuf_addf(&buf, "%c ", comment_line_char);
-		strbuf_addf(&buf, _("This is a combination of %d commits."), 2);
+		strbuf_addf(&buf, _(combined_commit_msg_fmt), 2);
 		strbuf_addf(&buf, "\n%c ", comment_line_char);
-		strbuf_addstr(&buf, _("This is the 1st commit message:"));
+		strbuf_addstr(&buf, is_fixup_flag(command, flag) ?
+			      _(skip_first_commit_msg_str) :
+			      _(first_commit_msg_str));
 		strbuf_addstr(&buf, "\n\n");
-		strbuf_addstr(&buf, body);
+		if (is_fixup_flag(command, flag))
+			strbuf_add_commented_lines(&buf, body, strlen(body));
+		else
+			strbuf_addstr(&buf, body);
 
 		unuse_commit_buffer(head_commit, head_message);
 	}
@@ -1787,16 +1962,11 @@
 			     oid_to_hex(&commit->object.oid));
 	find_commit_subject(message, &body);
 
-	if (command == TODO_SQUASH) {
-		unlink(rebase_path_fixup_msg());
-		strbuf_addf(&buf, "\n%c ", comment_line_char);
-		strbuf_addf(&buf, _("This is the commit message #%d:"),
-			    ++opts->current_fixup_count + 1);
-		strbuf_addstr(&buf, "\n\n");
-		strbuf_addstr(&buf, body);
+	if (command == TODO_SQUASH || is_fixup_flag(command, flag)) {
+		res = append_squash_message(&buf, body, command, opts, flag);
 	} else if (command == TODO_FIXUP) {
 		strbuf_addf(&buf, "\n%c ", comment_line_char);
-		strbuf_addf(&buf, _("The commit message #%d will be skipped:"),
+		strbuf_addf(&buf, _(skip_nth_commit_msg_fmt),
 			    ++opts->current_fixup_count + 1);
 		strbuf_addstr(&buf, "\n\n");
 		strbuf_add_commented_lines(&buf, body, strlen(body));
@@ -1804,7 +1974,9 @@
 		return error(_("unknown command: %d"), command);
 	unuse_commit_buffer(commit, message);
 
-	res = write_message(buf.buf, buf.len, rebase_path_squash_msg(), 0);
+	if (!res)
+		res = write_message(buf.buf, buf.len, rebase_path_squash_msg(),
+				    0);
 	strbuf_release(&buf);
 
 	if (!res) {
@@ -1861,8 +2033,7 @@
 }
 
 static int do_pick_commit(struct repository *r,
-			  enum todo_command command,
-			  struct commit *commit,
+			  struct todo_item *item,
 			  struct replay_opts *opts,
 			  int final_fixup, int *check_todo)
 {
@@ -1875,6 +2046,8 @@
 	struct commit_message msg = { NULL, NULL, NULL, NULL };
 	struct strbuf msgbuf = STRBUF_INIT;
 	int res, unborn = 0, reword = 0, allow, drop_commit;
+	enum todo_command command = item->command;
+	struct commit *commit = item->commit;
 
 	if (opts->no_commit) {
 		/*
@@ -2004,7 +2177,8 @@
 	if (command == TODO_REWORD)
 		reword = 1;
 	else if (is_fixup(command)) {
-		if (update_squash_messages(r, command, commit, opts))
+		if (update_squash_messages(r, command, commit,
+					   opts, item->flags))
 			return -1;
 		flags |= AMEND_MSG;
 		if (!final_fixup)
@@ -2169,10 +2343,6 @@
 	return 0;
 }
 
-enum todo_item_flags {
-	TODO_EDIT_MERGE_MSG = 1
-};
-
 void todo_list_release(struct todo_list *todo_list)
 {
 	strbuf_release(&todo_list->buf);
@@ -2259,6 +2429,18 @@
 		return 0;
 	}
 
+	if (item->command == TODO_FIXUP) {
+		if (skip_prefix(bol, "-C", &bol) &&
+		   (*bol == ' ' || *bol == '\t')) {
+			bol += strspn(bol, " \t");
+			item->flags |= TODO_REPLACE_FIXUP_MSG;
+		} else if (skip_prefix(bol, "-c", &bol) &&
+				  (*bol == ' ' || *bol == '\t')) {
+			bol += strspn(bol, " \t");
+			item->flags |= TODO_EDIT_FIXUP_MSG;
+		}
+	}
+
 	if (item->command == TODO_MERGE) {
 		if (skip_prefix(bol, "-C", &bol))
 			bol += strspn(bol, " \t");
@@ -4124,8 +4306,8 @@
 				setenv(GIT_REFLOG_ACTION, reflog_message(opts,
 					command_to_string(item->command), NULL),
 					1);
-			res = do_pick_commit(r, item->command, item->commit,
-					     opts, is_final_fixup(todo_list),
+			res = do_pick_commit(r, item, opts,
+					     is_final_fixup(todo_list),
 					     &check_todo);
 			if (is_rebase_i(opts))
 				setenv(GIT_REFLOG_ACTION, prev_reflog_action, 1);
@@ -4587,11 +4769,14 @@
 		       struct replay_opts *opts)
 {
 	int check_todo;
+	struct todo_item item;
+
+	item.command = opts->action == REPLAY_PICK ?
+			TODO_PICK : TODO_REVERT;
+	item.commit = cmit;
 
 	setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
-	return do_pick_commit(r, opts->action == REPLAY_PICK ?
-			      TODO_PICK : TODO_REVERT, cmit, opts, 0,
-			      &check_todo);
+	return do_pick_commit(r, &item, opts, 0, &check_todo);
 }
 
 int sequencer_pick_revisions(struct repository *r,
@@ -5171,7 +5356,7 @@
 	int i, insert, nr = 0, alloc = 0;
 	struct todo_item *items = NULL, *base_items = NULL;
 
-	base_items = xcalloc(commands->nr, sizeof(struct todo_item));
+	CALLOC_ARRAY(base_items, commands->nr);
 	for (i = 0; i < commands->nr; i++) {
 		size_t command_len = strlen(commands->items[i].string);
 
@@ -5262,6 +5447,14 @@
 					  short_commit_name(item->commit) :
 					  oid_to_hex(&item->commit->object.oid);
 
+			if (item->command == TODO_FIXUP) {
+				if (item->flags & TODO_EDIT_FIXUP_MSG)
+					strbuf_addstr(buf, " -c");
+				else if (item->flags & TODO_REPLACE_FIXUP_MSG) {
+					strbuf_addstr(buf, " -C");
+				}
+			}
+
 			if (item->command == TODO_MERGE) {
 				if (item->flags & TODO_EDIT_MERGE_MSG)
 					strbuf_addstr(buf, " -c");
@@ -5462,6 +5655,12 @@
 
 define_commit_slab(commit_todo_item, struct todo_item *);
 
+static int skip_fixupish(const char *subject, const char **p) {
+	return skip_prefix(subject, "fixup! ", p) ||
+	       skip_prefix(subject, "amend! ", p) ||
+	       skip_prefix(subject, "squash! ", p);
+}
+
 /*
  * Rearrange the todo list that has both "pick commit-id msg" and "pick
  * commit-id fixup!/squash! msg" in it so that the latter is put immediately
@@ -5520,15 +5719,13 @@
 		format_subject(&buf, subject, " ");
 		subject = subjects[i] = strbuf_detach(&buf, &subject_len);
 		unuse_commit_buffer(item->commit, commit_buffer);
-		if ((skip_prefix(subject, "fixup! ", &p) ||
-		     skip_prefix(subject, "squash! ", &p))) {
+		if (skip_fixupish(subject, &p)) {
 			struct commit *commit2;
 
 			for (;;) {
 				while (isspace(*p))
 					p++;
-				if (!skip_prefix(p, "fixup! ", &p) &&
-				    !skip_prefix(p, "squash! ", &p))
+				if (!skip_fixupish(p, &p))
 					break;
 			}
 
@@ -5558,9 +5755,14 @@
 		}
 		if (i2 >= 0) {
 			rearranged = 1;
-			todo_list->items[i].command =
-				starts_with(subject, "fixup!") ?
-				TODO_FIXUP : TODO_SQUASH;
+			if (starts_with(subject, "fixup!")) {
+				todo_list->items[i].command = TODO_FIXUP;
+			} else if (starts_with(subject, "amend!")) {
+				todo_list->items[i].command = TODO_FIXUP;
+				todo_list->items[i].flags = TODO_REPLACE_FIXUP_MSG;
+			} else {
+				todo_list->items[i].command = TODO_SQUASH;
+			}
 			if (tail[i2] < 0) {
 				next[i] = next[i2];
 				next[i2] = i;
diff --git a/server-info.c b/server-info.c
index bae2cdf..de0aa44 100644
--- a/server-info.c
+++ b/server-info.c
@@ -296,7 +296,7 @@
 
 		i = num_pack++;
 		ALLOC_GROW(info, num_pack, alloc);
-		info[i] = xcalloc(1, sizeof(struct pack_info));
+		CALLOC_ARRAY(info[i], 1);
 		info[i]->p = p;
 		info[i]->old_num = -1;
 	}
diff --git a/simple-ipc.h b/simple-ipc.h
new file mode 100644
index 0000000..dc3606e
--- /dev/null
+++ b/simple-ipc.h
@@ -0,0 +1,239 @@
+#ifndef GIT_SIMPLE_IPC_H
+#define GIT_SIMPLE_IPC_H
+
+/*
+ * See Documentation/technical/api-simple-ipc.txt
+ */
+
+#if defined(GIT_WINDOWS_NATIVE) || !defined(NO_UNIX_SOCKETS)
+#define SUPPORTS_SIMPLE_IPC
+#endif
+
+#ifdef SUPPORTS_SIMPLE_IPC
+#include "pkt-line.h"
+
+/*
+ * Simple IPC Client Side API.
+ */
+
+enum ipc_active_state {
+	/*
+	 * The pipe/socket exists and the daemon is waiting for connections.
+	 */
+	IPC_STATE__LISTENING = 0,
+
+	/*
+	 * The pipe/socket exists, but the daemon is not listening.
+	 * Perhaps it is very busy.
+	 * Perhaps the daemon died without deleting the path.
+	 * Perhaps it is shutting down and draining existing clients.
+	 * Perhaps it is dead, but other clients are lingering and
+	 * still holding a reference to the pathname.
+	 */
+	IPC_STATE__NOT_LISTENING,
+
+	/*
+	 * The requested pathname is bogus and no amount of retries
+	 * will fix that.
+	 */
+	IPC_STATE__INVALID_PATH,
+
+	/*
+	 * The requested pathname is not found.  This usually means
+	 * that there is no daemon present.
+	 */
+	IPC_STATE__PATH_NOT_FOUND,
+
+	IPC_STATE__OTHER_ERROR,
+};
+
+struct ipc_client_connect_options {
+	/*
+	 * Spin under timeout if the server is running but can't
+	 * accept our connection yet.  This should always be set
+	 * unless you just want to poke the server and see if it
+	 * is alive.
+	 */
+	unsigned int wait_if_busy:1;
+
+	/*
+	 * Spin under timeout if the pipe/socket is not yet present
+	 * on the file system.  This is useful if we just started
+	 * the service and need to wait for it to become ready.
+	 */
+	unsigned int wait_if_not_found:1;
+
+	/*
+	 * Disallow chdir() when creating a Unix domain socket.
+	 */
+	unsigned int uds_disallow_chdir:1;
+};
+
+#define IPC_CLIENT_CONNECT_OPTIONS_INIT { \
+	.wait_if_busy = 0, \
+	.wait_if_not_found = 0, \
+	.uds_disallow_chdir = 0, \
+}
+
+/*
+ * Determine if a server is listening on this named pipe or socket using
+ * platform-specific logic.  This might just probe the filesystem or it
+ * might make a trivial connection to the server using this pathname.
+ */
+enum ipc_active_state ipc_get_active_state(const char *path);
+
+struct ipc_client_connection {
+	int fd;
+};
+
+/*
+ * Try to connect to the daemon on the named pipe or socket.
+ *
+ * Returns IPC_STATE__LISTENING and a connection handle.
+ *
+ * Otherwise, returns info to help decide whether to retry or to
+ * spawn/respawn the server.
+ */
+enum ipc_active_state ipc_client_try_connect(
+	const char *path,
+	const struct ipc_client_connect_options *options,
+	struct ipc_client_connection **p_connection);
+
+void ipc_client_close_connection(struct ipc_client_connection *connection);
+
+/*
+ * Used by the client to synchronously send and receive a message with
+ * the server on the provided client connection.
+ *
+ * Returns 0 when successful.
+ *
+ * Calls error() and returns non-zero otherwise.
+ */
+int ipc_client_send_command_to_connection(
+	struct ipc_client_connection *connection,
+	const char *message, struct strbuf *answer);
+
+/*
+ * Used by the client to synchronously connect and send and receive a
+ * message to the server listening at the given path.
+ *
+ * Returns 0 when successful.
+ *
+ * Calls error() and returns non-zero otherwise.
+ */
+int ipc_client_send_command(const char *path,
+			    const struct ipc_client_connect_options *options,
+			    const char *message, struct strbuf *answer);
+
+/*
+ * Simple IPC Server Side API.
+ */
+
+struct ipc_server_reply_data;
+
+typedef int (ipc_server_reply_cb)(struct ipc_server_reply_data *,
+				  const char *response,
+				  size_t response_len);
+
+/*
+ * Prototype for an application-supplied callback to process incoming
+ * client IPC messages and compose a reply.  The `application_cb` should
+ * use the provided `reply_cb` and `reply_data` to send an IPC response
+ * back to the client.  The `reply_cb` callback can be called multiple
+ * times for chunking purposes.  A reply message is optional and may be
+ * omitted if not necessary for the application.
+ *
+ * The return value from the application callback is ignored.
+ * The value `SIMPLE_IPC_QUIT` can be used to shutdown the server.
+ */
+typedef int (ipc_server_application_cb)(void *application_data,
+					const char *request,
+					ipc_server_reply_cb *reply_cb,
+					struct ipc_server_reply_data *reply_data);
+
+#define SIMPLE_IPC_QUIT -2
+
+/*
+ * Opaque instance data to represent an IPC server instance.
+ */
+struct ipc_server_data;
+
+/*
+ * Control parameters for the IPC server instance.
+ * Use this to hide platform-specific settings.
+ */
+struct ipc_server_opts
+{
+	int nr_threads;
+
+	/*
+	 * Disallow chdir() when creating a Unix domain socket.
+	 */
+	unsigned int uds_disallow_chdir:1;
+};
+
+/*
+ * Start an IPC server instance in one or more background threads
+ * and return a handle to the pool.
+ *
+ * Returns 0 if the asynchronous server pool was started successfully.
+ * Returns -1 if not.
+ * Returns -2 if we could not startup because another server is using
+ * the socket or named pipe.
+ *
+ * When a client IPC message is received, the `application_cb` will be
+ * called (possibly on a random thread) to handle the message and
+ * optionally compose a reply message.
+ */
+int ipc_server_run_async(struct ipc_server_data **returned_server_data,
+			 const char *path, const struct ipc_server_opts *opts,
+			 ipc_server_application_cb *application_cb,
+			 void *application_data);
+
+/*
+ * Gently signal the IPC server pool to shutdown.  No new client
+ * connections will be accepted, but existing connections will be
+ * allowed to complete.
+ */
+int ipc_server_stop_async(struct ipc_server_data *server_data);
+
+/*
+ * Block the calling thread until all threads in the IPC server pool
+ * have completed and been joined.
+ */
+int ipc_server_await(struct ipc_server_data *server_data);
+
+/*
+ * Close and free all resource handles associated with the IPC server
+ * pool.
+ */
+void ipc_server_free(struct ipc_server_data *server_data);
+
+/*
+ * Run an IPC server instance and block the calling thread of the
+ * current process.  It does not return until the IPC server has
+ * either shutdown or had an unrecoverable error.
+ *
+ * The IPC server handles incoming IPC messages from client processes
+ * and may use one or more background threads as necessary.
+ *
+ * Returns 0 after the server has completed successfully.
+ * Returns -1 if the server cannot be started.
+ * Returns -2 if we could not startup because another server is using
+ * the socket or named pipe.
+ *
+ * When a client IPC message is received, the `application_cb` will be
+ * called (possibly on a random thread) to handle the message and
+ * optionally compose a reply message.
+ *
+ * Note that `ipc_server_run()` is a synchronous wrapper around the
+ * above asynchronous routines.  It effectively hides all of the
+ * server state and thread details from the caller and presents a
+ * simple synchronous interface.
+ */
+int ipc_server_run(const char *path, const struct ipc_server_opts *opts,
+		   ipc_server_application_cb *application_cb,
+		   void *application_data);
+
+#endif /* SUPPORTS_SIMPLE_IPC */
+#endif /* GIT_SIMPLE_IPC_H */
diff --git a/split-index.c b/split-index.c
index c0e8ad6..94937d2 100644
--- a/split-index.c
+++ b/split-index.c
@@ -5,7 +5,7 @@
 struct split_index *init_split_index(struct index_state *istate)
 {
 	if (!istate->split_index) {
-		istate->split_index = xcalloc(1, sizeof(*istate->split_index));
+		CALLOC_ARRAY(istate->split_index, 1);
 		istate->split_index->refcount = 1;
 	}
 	return istate->split_index;
@@ -87,7 +87,7 @@
 		mem_pool_combine(istate->ce_mem_pool, istate->split_index->base->ce_mem_pool);
 	}
 
-	si->base = xcalloc(1, sizeof(*si->base));
+	CALLOC_ARRAY(si->base, 1);
 	si->base->version = istate->version;
 	/* zero timestamp disables racy test in ce_write_index() */
 	si->base->timestamp = istate->timestamp;
diff --git a/symlinks.c b/symlinks.c
index 7dbb6b2..5232d02 100644
--- a/symlinks.c
+++ b/symlinks.c
@@ -1,6 +1,7 @@
 #include "cache.h"
 
-static int threaded_check_leading_path(struct cache_def *cache, const char *name, int len);
+static int threaded_check_leading_path(struct cache_def *cache, const char *name,
+				       int len, int warn_on_lstat_err);
 static int threaded_has_dirs_only_path(struct cache_def *cache, const char *name, int len, int prefix_len);
 
 /*
@@ -72,7 +73,7 @@
 				int prefix_len_stat_func)
 {
 	int match_len, last_slash, last_slash_dir, previous_slash;
-	int save_flags, ret;
+	int save_flags, ret, saved_errno = 0;
 	struct stat st;
 
 	if (cache->track_flags != track_flags ||
@@ -139,6 +140,7 @@
 
 		if (ret) {
 			*ret_flags = FL_LSTATERR;
+			saved_errno = errno;
 			if (errno == ENOENT)
 				*ret_flags |= FL_NOENT;
 		} else if (S_ISDIR(st.st_mode)) {
@@ -180,6 +182,8 @@
 	} else {
 		reset_lstat_cache(cache);
 	}
+	if (saved_errno)
+		errno = saved_errno;
 	return match_len;
 }
 
@@ -202,57 +206,47 @@
 	return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK;
 }
 
-/*
- * Return non-zero if path 'name' has a leading symlink component
- */
 int has_symlink_leading_path(const char *name, int len)
 {
 	return threaded_has_symlink_leading_path(&default_cache, name, len);
 }
 
-/*
- * Return zero if path 'name' has a leading symlink component or
- * if some leading path component does not exists.
- *
- * Return -1 if leading path exists and is a directory.
- *
- * Return path length if leading path exists and is neither a
- * directory nor a symlink.
- */
-int check_leading_path(const char *name, int len)
+int check_leading_path(const char *name, int len, int warn_on_lstat_err)
 {
-	return threaded_check_leading_path(&default_cache, name, len);
+	return threaded_check_leading_path(&default_cache, name, len,
+					   warn_on_lstat_err);
 }
 
 /*
- * Return zero if path 'name' has a leading symlink component or
- * if some leading path component does not exists.
+ * Return zero if some leading path component of 'name' does not exist.
  *
  * Return -1 if leading path exists and is a directory.
  *
- * Return path length if leading path exists and is neither a
- * directory nor a symlink.
+ * Return the length of a leading component if it either exists but it's not a
+ * directory, or if we were unable to lstat() it. If warn_on_lstat_err is true,
+ * also emit a warning for this error.
  */
-static int threaded_check_leading_path(struct cache_def *cache, const char *name, int len)
+static int threaded_check_leading_path(struct cache_def *cache, const char *name,
+				       int len, int warn_on_lstat_err)
 {
 	int flags;
 	int match_len = lstat_cache_matchlen(cache, name, len, &flags,
 			   FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT);
+	int saved_errno = errno;
+
 	if (flags & FL_NOENT)
 		return 0;
 	else if (flags & FL_DIR)
 		return -1;
-	else
-		return match_len;
+	if (warn_on_lstat_err && (flags & FL_LSTATERR)) {
+		char *path = xmemdupz(name, match_len);
+		errno = saved_errno;
+		warning_errno(_("failed to lstat '%s'"), path);
+		free(path);
+	}
+	return match_len;
 }
 
-/*
- * Return non-zero if all path components of 'name' exists as a
- * directory.  If prefix_len > 0, we will test with the stat()
- * function instead of the lstat() function for a prefix length of
- * 'prefix_len', thus we then allow for symlinks in the prefix part as
- * long as those points to real existing directories.
- */
 int has_dirs_only_path(const char *name, int len, int prefix_len)
 {
 	return threaded_has_dirs_only_path(&default_cache, name, len, prefix_len);
diff --git a/t/README b/t/README
index 593d4a4..fd9375b 100644
--- a/t/README
+++ b/t/README
@@ -387,9 +387,6 @@
 be written after every 'git commit' command, and overrides the
 'core.commitGraph' setting to true.
 
-GIT_TEST_COMMIT_GRAPH_NO_GDAT=<boolean>, when true, forces the
-commit-graph to be written without generation data chunk.
-
 GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS=<boolean>, when true, forces
 commit-graph write to compute and write changed path Bloom filters for
 every 'git commit-graph write', as if the `--changed-paths` option was
diff --git a/t/helper/test-bloom.c b/t/helper/test-bloom.c
index 46e97b0..2a1ae3d 100644
--- a/t/helper/test-bloom.c
+++ b/t/helper/test-bloom.c
@@ -69,7 +69,7 @@
 		struct bloom_filter filter;
 		int i = 2;
 		filter.len =  (settings.bits_per_entry + BITS_PER_WORD - 1) / BITS_PER_WORD;
-		filter.data = xcalloc(filter.len, sizeof(unsigned char));
+		CALLOC_ARRAY(filter.data, filter.len);
 
 		if (argc - 1 < i)
 			usage(bloom_usage);
diff --git a/t/helper/test-chmtime.c b/t/helper/test-chmtime.c
index aa22af4..524b55c 100644
--- a/t/helper/test-chmtime.c
+++ b/t/helper/test-chmtime.c
@@ -109,9 +109,9 @@
 		uintmax_t mtime;
 
 		if (stat(argv[i], &sb) < 0) {
-			fprintf(stderr, "Failed to stat %s: %s\n",
+			fprintf(stderr, "Failed to stat %s: %s. Skipping\n",
 			        argv[i], strerror(errno));
-			return 1;
+			continue;
 		}
 
 #ifdef GIT_WINDOWS_NATIVE
diff --git a/t/helper/test-simple-ipc.c b/t/helper/test-simple-ipc.c
new file mode 100644
index 0000000..42040ef
--- /dev/null
+++ b/t/helper/test-simple-ipc.c
@@ -0,0 +1,787 @@
+/*
+ * test-simple-ipc.c: verify that the Inter-Process Communication works.
+ */
+
+#include "test-tool.h"
+#include "cache.h"
+#include "strbuf.h"
+#include "simple-ipc.h"
+#include "parse-options.h"
+#include "thread-utils.h"
+#include "strvec.h"
+
+#ifndef SUPPORTS_SIMPLE_IPC
+int cmd__simple_ipc(int argc, const char **argv)
+{
+	die("simple IPC not available on this platform");
+}
+#else
+
+/*
+ * The test daemon defines an "application callback" that supports a
+ * series of commands (see `test_app_cb()`).
+ *
+ * Unknown commands are caught here and we send an error message back
+ * to the client process.
+ */
+static int app__unhandled_command(const char *command,
+				  ipc_server_reply_cb *reply_cb,
+				  struct ipc_server_reply_data *reply_data)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int ret;
+
+	strbuf_addf(&buf, "unhandled command: %s", command);
+	ret = reply_cb(reply_data, buf.buf, buf.len);
+	strbuf_release(&buf);
+
+	return ret;
+}
+
+/*
+ * Reply with a single very large buffer.  This is to ensure that
+ * long response are properly handled -- whether the chunking occurs
+ * in the kernel or in the (probably pkt-line) layer.
+ */
+#define BIG_ROWS (10000)
+static int app__big_command(ipc_server_reply_cb *reply_cb,
+			    struct ipc_server_reply_data *reply_data)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int row;
+	int ret;
+
+	for (row = 0; row < BIG_ROWS; row++)
+		strbuf_addf(&buf, "big: %.75d\n", row);
+
+	ret = reply_cb(reply_data, buf.buf, buf.len);
+	strbuf_release(&buf);
+
+	return ret;
+}
+
+/*
+ * Reply with a series of lines.  This is to ensure that we can incrementally
+ * compute the response and chunk it to the client.
+ */
+#define CHUNK_ROWS (10000)
+static int app__chunk_command(ipc_server_reply_cb *reply_cb,
+			      struct ipc_server_reply_data *reply_data)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int row;
+	int ret;
+
+	for (row = 0; row < CHUNK_ROWS; row++) {
+		strbuf_setlen(&buf, 0);
+		strbuf_addf(&buf, "big: %.75d\n", row);
+		ret = reply_cb(reply_data, buf.buf, buf.len);
+	}
+
+	strbuf_release(&buf);
+
+	return ret;
+}
+
+/*
+ * Slowly reply with a series of lines.  This is to model an expensive to
+ * compute chunked response (which might happen if this callback is running
+ * in a thread and is fighting for a lock with other threads).
+ */
+#define SLOW_ROWS     (1000)
+#define SLOW_DELAY_MS (10)
+static int app__slow_command(ipc_server_reply_cb *reply_cb,
+			     struct ipc_server_reply_data *reply_data)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int row;
+	int ret;
+
+	for (row = 0; row < SLOW_ROWS; row++) {
+		strbuf_setlen(&buf, 0);
+		strbuf_addf(&buf, "big: %.75d\n", row);
+		ret = reply_cb(reply_data, buf.buf, buf.len);
+		sleep_millisec(SLOW_DELAY_MS);
+	}
+
+	strbuf_release(&buf);
+
+	return ret;
+}
+
+/*
+ * The client sent a command followed by a (possibly very) large buffer.
+ */
+static int app__sendbytes_command(const char *received,
+				  ipc_server_reply_cb *reply_cb,
+				  struct ipc_server_reply_data *reply_data)
+{
+	struct strbuf buf_resp = STRBUF_INIT;
+	const char *p = "?";
+	int len_ballast = 0;
+	int k;
+	int errs = 0;
+	int ret;
+
+	if (skip_prefix(received, "sendbytes ", &p))
+		len_ballast = strlen(p);
+
+	/*
+	 * Verify that the ballast is n copies of a single letter.
+	 * And that the multi-threaded IO layer didn't cross the streams.
+	 */
+	for (k = 1; k < len_ballast; k++)
+		if (p[k] != p[0])
+			errs++;
+
+	if (errs)
+		strbuf_addf(&buf_resp, "errs:%d\n", errs);
+	else
+		strbuf_addf(&buf_resp, "rcvd:%c%08d\n", p[0], len_ballast);
+
+	ret = reply_cb(reply_data, buf_resp.buf, buf_resp.len);
+
+	strbuf_release(&buf_resp);
+
+	return ret;
+}
+
+/*
+ * An arbitrary fixed address to verify that the application instance
+ * data is handled properly.
+ */
+static int my_app_data = 42;
+
+static ipc_server_application_cb test_app_cb;
+
+/*
+ * This is the "application callback" that sits on top of the
+ * "ipc-server".  It completely defines the set of commands supported
+ * by this application.
+ */
+static int test_app_cb(void *application_data,
+		       const char *command,
+		       ipc_server_reply_cb *reply_cb,
+		       struct ipc_server_reply_data *reply_data)
+{
+	/*
+	 * Verify that we received the application-data that we passed
+	 * when we started the ipc-server.  (We have several layers of
+	 * callbacks calling callbacks and it's easy to get things mixed
+	 * up (especially when some are "void*").)
+	 */
+	if (application_data != (void*)&my_app_data)
+		BUG("application_cb: application_data pointer wrong");
+
+	if (!strcmp(command, "quit")) {
+		/*
+		 * The client sent a "quit" command.  This is an async
+		 * request for the server to shutdown.
+		 *
+		 * We DO NOT send the client a response message
+		 * (because we have nothing to say and the other
+		 * server threads have not yet stopped).
+		 *
+		 * Tell the ipc-server layer to start shutting down.
+		 * This includes: stop listening for new connections
+		 * on the socket/pipe and telling all worker threads
+		 * to finish/drain their outgoing responses to other
+		 * clients.
+		 *
+		 * This DOES NOT force an immediate sync shutdown.
+		 */
+		return SIMPLE_IPC_QUIT;
+	}
+
+	if (!strcmp(command, "ping")) {
+		const char *answer = "pong";
+		return reply_cb(reply_data, answer, strlen(answer));
+	}
+
+	if (!strcmp(command, "big"))
+		return app__big_command(reply_cb, reply_data);
+
+	if (!strcmp(command, "chunk"))
+		return app__chunk_command(reply_cb, reply_data);
+
+	if (!strcmp(command, "slow"))
+		return app__slow_command(reply_cb, reply_data);
+
+	if (starts_with(command, "sendbytes "))
+		return app__sendbytes_command(command, reply_cb, reply_data);
+
+	return app__unhandled_command(command, reply_cb, reply_data);
+}
+
+struct cl_args
+{
+	const char *subcommand;
+	const char *path;
+	const char *token;
+
+	int nr_threads;
+	int max_wait_sec;
+	int bytecount;
+	int batchsize;
+
+	char bytevalue;
+};
+
+static struct cl_args cl_args = {
+	.subcommand = NULL,
+	.path = "ipc-test",
+	.token = NULL,
+
+	.nr_threads = 5,
+	.max_wait_sec = 60,
+	.bytecount = 1024,
+	.batchsize = 10,
+
+	.bytevalue = 'x',
+};
+
+/*
+ * This process will run as a simple-ipc server and listen for IPC commands
+ * from client processes.
+ */
+static int daemon__run_server(void)
+{
+	int ret;
+
+	struct ipc_server_opts opts = {
+		.nr_threads = cl_args.nr_threads,
+	};
+
+	/*
+	 * Synchronously run the ipc-server.  We don't need any application
+	 * instance data, so pass an arbitrary pointer (that we'll later
+	 * verify made the round trip).
+	 */
+	ret = ipc_server_run(cl_args.path, &opts, test_app_cb, (void*)&my_app_data);
+	if (ret == -2)
+		error(_("socket/pipe already in use: '%s'"), cl_args.path);
+	else if (ret == -1)
+		error_errno(_("could not start server on: '%s'"), cl_args.path);
+
+	return ret;
+}
+
+#ifndef GIT_WINDOWS_NATIVE
+/*
+ * This is adapted from `daemonize()`.  Use `fork()` to directly create and
+ * run the daemon in a child process.
+ */
+static int spawn_server(pid_t *pid)
+{
+	struct ipc_server_opts opts = {
+		.nr_threads = cl_args.nr_threads,
+	};
+
+	*pid = fork();
+
+	switch (*pid) {
+	case 0:
+		if (setsid() == -1)
+			error_errno(_("setsid failed"));
+		close(0);
+		close(1);
+		close(2);
+		sanitize_stdfds();
+
+		return ipc_server_run(cl_args.path, &opts, test_app_cb,
+				      (void*)&my_app_data);
+
+	case -1:
+		return error_errno(_("could not spawn daemon in the background"));
+
+	default:
+		return 0;
+	}
+}
+#else
+/*
+ * Conceptually like `daemonize()` but different because Windows does not
+ * have `fork(2)`.  Spawn a normal Windows child process but without the
+ * limitations of `start_command()` and `finish_command()`.
+ */
+static int spawn_server(pid_t *pid)
+{
+	char test_tool_exe[MAX_PATH];
+	struct strvec args = STRVEC_INIT;
+	int in, out;
+
+	GetModuleFileNameA(NULL, test_tool_exe, MAX_PATH);
+
+	in = open("/dev/null", O_RDONLY);
+	out = open("/dev/null", O_WRONLY);
+
+	strvec_push(&args, test_tool_exe);
+	strvec_push(&args, "simple-ipc");
+	strvec_push(&args, "run-daemon");
+	strvec_pushf(&args, "--name=%s", cl_args.path);
+	strvec_pushf(&args, "--threads=%d", cl_args.nr_threads);
+
+	*pid = mingw_spawnvpe(args.v[0], args.v, NULL, NULL, in, out, out);
+	close(in);
+	close(out);
+
+	strvec_clear(&args);
+
+	if (*pid < 0)
+		return error(_("could not spawn daemon in the background"));
+
+	return 0;
+}
+#endif
+
+/*
+ * This is adapted from `wait_or_whine()`.  Watch the child process and
+ * let it get started and begin listening for requests on the socket
+ * before reporting our success.
+ */
+static int wait_for_server_startup(pid_t pid_child)
+{
+	int status;
+	pid_t pid_seen;
+	enum ipc_active_state s;
+	time_t time_limit, now;
+
+	time(&time_limit);
+	time_limit += cl_args.max_wait_sec;
+
+	for (;;) {
+		pid_seen = waitpid(pid_child, &status, WNOHANG);
+
+		if (pid_seen == -1)
+			return error_errno(_("waitpid failed"));
+
+		else if (pid_seen == 0) {
+			/*
+			 * The child is still running (this should be
+			 * the normal case).  Try to connect to it on
+			 * the socket and see if it is ready for
+			 * business.
+			 *
+			 * If there is another daemon already running,
+			 * our child will fail to start (possibly
+			 * after a timeout on the lock), but we don't
+			 * care (who responds) if the socket is live.
+			 */
+			s = ipc_get_active_state(cl_args.path);
+			if (s == IPC_STATE__LISTENING)
+				return 0;
+
+			time(&now);
+			if (now > time_limit)
+				return error(_("daemon not online yet"));
+
+			continue;
+		}
+
+		else if (pid_seen == pid_child) {
+			/*
+			 * The new child daemon process shutdown while
+			 * it was starting up, so it is not listening
+			 * on the socket.
+			 *
+			 * Try to ping the socket in the odd chance
+			 * that another daemon started (or was already
+			 * running) while our child was starting.
+			 *
+			 * Again, we don't care who services the socket.
+			 */
+			s = ipc_get_active_state(cl_args.path);
+			if (s == IPC_STATE__LISTENING)
+				return 0;
+
+			/*
+			 * We don't care about the WEXITSTATUS() nor
+			 * any of the WIF*(status) values because
+			 * `cmd__simple_ipc()` does the `!!result`
+			 * trick on all function return values.
+			 *
+			 * So it is sufficient to just report the
+			 * early shutdown as an error.
+			 */
+			return error(_("daemon failed to start"));
+		}
+
+		else
+			return error(_("waitpid is confused"));
+	}
+}
+
+/*
+ * This process will start a simple-ipc server in a background process and
+ * wait for it to become ready.  This is like `daemonize()` but gives us
+ * more control and better error reporting (and makes it easier to write
+ * unit tests).
+ */
+static int daemon__start_server(void)
+{
+	pid_t pid_child;
+	int ret;
+
+	/*
+	 * Run the actual daemon in a background process.
+	 */
+	ret = spawn_server(&pid_child);
+	if (pid_child <= 0)
+		return ret;
+
+	/*
+	 * Let the parent wait for the child process to get started
+	 * and begin listening for requests on the socket.
+	 */
+	ret = wait_for_server_startup(pid_child);
+
+	return ret;
+}
+
+/*
+ * This process will run a quick probe to see if a simple-ipc server
+ * is active on this path.
+ *
+ * Returns 0 if the server is alive.
+ */
+static int client__probe_server(void)
+{
+	enum ipc_active_state s;
+
+	s = ipc_get_active_state(cl_args.path);
+	switch (s) {
+	case IPC_STATE__LISTENING:
+		return 0;
+
+	case IPC_STATE__NOT_LISTENING:
+		return error("no server listening at '%s'", cl_args.path);
+
+	case IPC_STATE__PATH_NOT_FOUND:
+		return error("path not found '%s'", cl_args.path);
+
+	case IPC_STATE__INVALID_PATH:
+		return error("invalid pipe/socket name '%s'", cl_args.path);
+
+	case IPC_STATE__OTHER_ERROR:
+	default:
+		return error("other error for '%s'", cl_args.path);
+	}
+}
+
+/*
+ * Send an IPC command token to an already-running server daemon and
+ * print the response.
+ *
+ * This is a simple 1 word command/token that `test_app_cb()` (in the
+ * daemon process) will understand.
+ */
+static int client__send_ipc(void)
+{
+	const char *command = "(no-command)";
+	struct strbuf buf = STRBUF_INIT;
+	struct ipc_client_connect_options options
+		= IPC_CLIENT_CONNECT_OPTIONS_INIT;
+
+	if (cl_args.token && *cl_args.token)
+		command = cl_args.token;
+
+	options.wait_if_busy = 1;
+	options.wait_if_not_found = 0;
+
+	if (!ipc_client_send_command(cl_args.path, &options, command, &buf)) {
+		if (buf.len) {
+			printf("%s\n", buf.buf);
+			fflush(stdout);
+		}
+		strbuf_release(&buf);
+
+		return 0;
+	}
+
+	return error("failed to send '%s' to '%s'", command, cl_args.path);
+}
+
+/*
+ * Send an IPC command to an already-running server and ask it to
+ * shutdown.  "send quit" is an async request and queues a shutdown
+ * event in the server, so we spin and wait here for it to actually
+ * shutdown to make the unit tests a little easier to write.
+ */
+static int client__stop_server(void)
+{
+	int ret;
+	time_t time_limit, now;
+	enum ipc_active_state s;
+
+	time(&time_limit);
+	time_limit += cl_args.max_wait_sec;
+
+	cl_args.token = "quit";
+
+	ret = client__send_ipc();
+	if (ret)
+		return ret;
+
+	for (;;) {
+		sleep_millisec(100);
+
+		s = ipc_get_active_state(cl_args.path);
+
+		if (s != IPC_STATE__LISTENING) {
+			/*
+			 * The socket/pipe is gone and/or has stopped
+			 * responding.  Lets assume that the daemon
+			 * process has exited too.
+			 */
+			return 0;
+		}
+
+		time(&now);
+		if (now > time_limit)
+			return error(_("daemon has not shutdown yet"));
+	}
+}
+
+/*
+ * Send an IPC command followed by ballast to confirm that a large
+ * message can be sent and that the kernel or pkt-line layers will
+ * properly chunk it and that the daemon receives the entire message.
+ */
+static int do_sendbytes(int bytecount, char byte, const char *path,
+			const struct ipc_client_connect_options *options)
+{
+	struct strbuf buf_send = STRBUF_INIT;
+	struct strbuf buf_resp = STRBUF_INIT;
+
+	strbuf_addstr(&buf_send, "sendbytes ");
+	strbuf_addchars(&buf_send, byte, bytecount);
+
+	if (!ipc_client_send_command(path, options, buf_send.buf, &buf_resp)) {
+		strbuf_rtrim(&buf_resp);
+		printf("sent:%c%08d %s\n", byte, bytecount, buf_resp.buf);
+		fflush(stdout);
+		strbuf_release(&buf_send);
+		strbuf_release(&buf_resp);
+
+		return 0;
+	}
+
+	return error("client failed to sendbytes(%d, '%c') to '%s'",
+		     bytecount, byte, path);
+}
+
+/*
+ * Send an IPC command with ballast to an already-running server daemon.
+ */
+static int client__sendbytes(void)
+{
+	struct ipc_client_connect_options options
+		= IPC_CLIENT_CONNECT_OPTIONS_INIT;
+
+	options.wait_if_busy = 1;
+	options.wait_if_not_found = 0;
+	options.uds_disallow_chdir = 0;
+
+	return do_sendbytes(cl_args.bytecount, cl_args.bytevalue, cl_args.path,
+			    &options);
+}
+
+struct multiple_thread_data {
+	pthread_t pthread_id;
+	struct multiple_thread_data *next;
+	const char *path;
+	int bytecount;
+	int batchsize;
+	int sum_errors;
+	int sum_good;
+	char letter;
+};
+
+static void *multiple_thread_proc(void *_multiple_thread_data)
+{
+	struct multiple_thread_data *d = _multiple_thread_data;
+	int k;
+	struct ipc_client_connect_options options
+		= IPC_CLIENT_CONNECT_OPTIONS_INIT;
+
+	options.wait_if_busy = 1;
+	options.wait_if_not_found = 0;
+	/*
+	 * A multi-threaded client should not be randomly calling chdir().
+	 * The test will pass without this restriction because the test is
+	 * not otherwise accessing the filesystem, but it makes us honest.
+	 */
+	options.uds_disallow_chdir = 1;
+
+	trace2_thread_start("multiple");
+
+	for (k = 0; k < d->batchsize; k++) {
+		if (do_sendbytes(d->bytecount + k, d->letter, d->path, &options))
+			d->sum_errors++;
+		else
+			d->sum_good++;
+	}
+
+	trace2_thread_exit();
+	return NULL;
+}
+
+/*
+ * Start a client-side thread pool.  Each thread sends a series of
+ * IPC requests.  Each request is on a new connection to the server.
+ */
+static int client__multiple(void)
+{
+	struct multiple_thread_data *list = NULL;
+	int k;
+	int sum_join_errors = 0;
+	int sum_thread_errors = 0;
+	int sum_good = 0;
+
+	for (k = 0; k < cl_args.nr_threads; k++) {
+		struct multiple_thread_data *d = xcalloc(1, sizeof(*d));
+		d->next = list;
+		d->path = cl_args.path;
+		d->bytecount = cl_args.bytecount + cl_args.batchsize*(k/26);
+		d->batchsize = cl_args.batchsize;
+		d->sum_errors = 0;
+		d->sum_good = 0;
+		d->letter = 'A' + (k % 26);
+
+		if (pthread_create(&d->pthread_id, NULL, multiple_thread_proc, d)) {
+			warning("failed to create thread[%d] skipping remainder", k);
+			free(d);
+			break;
+		}
+
+		list = d;
+	}
+
+	while (list) {
+		struct multiple_thread_data *d = list;
+
+		if (pthread_join(d->pthread_id, NULL))
+			sum_join_errors++;
+
+		sum_thread_errors += d->sum_errors;
+		sum_good += d->sum_good;
+
+		list = d->next;
+		free(d);
+	}
+
+	printf("client (good %d) (join %d), (errors %d)\n",
+	       sum_good, sum_join_errors, sum_thread_errors);
+
+	return (sum_join_errors + sum_thread_errors) ? 1 : 0;
+}
+
+int cmd__simple_ipc(int argc, const char **argv)
+{
+	const char * const simple_ipc_usage[] = {
+		N_("test-helper simple-ipc is-active    [<name>] [<options>]"),
+		N_("test-helper simple-ipc run-daemon   [<name>] [<threads>]"),
+		N_("test-helper simple-ipc start-daemon [<name>] [<threads>] [<max-wait>]"),
+		N_("test-helper simple-ipc stop-daemon  [<name>] [<max-wait>]"),
+		N_("test-helper simple-ipc send         [<name>] [<token>]"),
+		N_("test-helper simple-ipc sendbytes    [<name>] [<bytecount>] [<byte>]"),
+		N_("test-helper simple-ipc multiple     [<name>] [<threads>] [<bytecount>] [<batchsize>]"),
+		NULL
+	};
+
+	const char *bytevalue = NULL;
+
+	struct option options[] = {
+#ifndef GIT_WINDOWS_NATIVE
+		OPT_STRING(0, "name", &cl_args.path, N_("name"), N_("name or pathname of unix domain socket")),
+#else
+		OPT_STRING(0, "name", &cl_args.path, N_("name"), N_("named-pipe name")),
+#endif
+		OPT_INTEGER(0, "threads", &cl_args.nr_threads, N_("number of threads in server thread pool")),
+		OPT_INTEGER(0, "max-wait", &cl_args.max_wait_sec, N_("seconds to wait for daemon to start or stop")),
+
+		OPT_INTEGER(0, "bytecount", &cl_args.bytecount, N_("number of bytes")),
+		OPT_INTEGER(0, "batchsize", &cl_args.batchsize, N_("number of requests per thread")),
+
+		OPT_STRING(0, "byte", &bytevalue, N_("byte"), N_("ballast character")),
+		OPT_STRING(0, "token", &cl_args.token, N_("token"), N_("command token to send to the server")),
+
+		OPT_END()
+	};
+
+	if (argc < 2)
+		usage_with_options(simple_ipc_usage, options);
+
+	if (argc == 2 && !strcmp(argv[1], "-h"))
+		usage_with_options(simple_ipc_usage, options);
+
+	if (argc == 2 && !strcmp(argv[1], "SUPPORTS_SIMPLE_IPC"))
+		return 0;
+
+	cl_args.subcommand = argv[1];
+
+	argc--;
+	argv++;
+
+	argc = parse_options(argc, argv, NULL, options, simple_ipc_usage, 0);
+
+	if (cl_args.nr_threads < 1)
+		cl_args.nr_threads = 1;
+	if (cl_args.max_wait_sec < 0)
+		cl_args.max_wait_sec = 0;
+	if (cl_args.bytecount < 1)
+		cl_args.bytecount = 1;
+	if (cl_args.batchsize < 1)
+		cl_args.batchsize = 1;
+
+	if (bytevalue && *bytevalue)
+		cl_args.bytevalue = bytevalue[0];
+
+	/*
+	 * Use '!!' on all dispatch functions to map from `error()` style
+	 * (returns -1) style to `test_must_fail` style (expects 1).  This
+	 * makes shell error messages less confusing.
+	 */
+
+	if (!strcmp(cl_args.subcommand, "is-active"))
+		return !!client__probe_server();
+
+	if (!strcmp(cl_args.subcommand, "run-daemon"))
+		return !!daemon__run_server();
+
+	if (!strcmp(cl_args.subcommand, "start-daemon"))
+		return !!daemon__start_server();
+
+	/*
+	 * Client commands follow.  Ensure a server is running before
+	 * sending any data.  This might be overkill, but then again
+	 * this is a test harness.
+	 */
+
+	if (!strcmp(cl_args.subcommand, "stop-daemon")) {
+		if (client__probe_server())
+			return 1;
+		return !!client__stop_server();
+	}
+
+	if (!strcmp(cl_args.subcommand, "send")) {
+		if (client__probe_server())
+			return 1;
+		return !!client__send_ipc();
+	}
+
+	if (!strcmp(cl_args.subcommand, "sendbytes")) {
+		if (client__probe_server())
+			return 1;
+		return !!client__sendbytes();
+	}
+
+	if (!strcmp(cl_args.subcommand, "multiple")) {
+		if (client__probe_server())
+			return 1;
+		return !!client__multiple();
+	}
+
+	die("Unhandled subcommand: '%s'", cl_args.subcommand);
+}
+#endif
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index f97cd9f..287aa60 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -65,6 +65,7 @@
 	{ "sha1", cmd__sha1 },
 	{ "sha256", cmd__sha256 },
 	{ "sigchain", cmd__sigchain },
+	{ "simple-ipc", cmd__simple_ipc },
 	{ "strcmp-offset", cmd__strcmp_offset },
 	{ "string-list", cmd__string_list },
 	{ "submodule-config", cmd__submodule_config },
diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index 28072c0..9ea4b31 100644
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -55,6 +55,7 @@
 int cmd__oid_array(int argc, const char **argv);
 int cmd__sha256(int argc, const char **argv);
 int cmd__sigchain(int argc, const char **argv);
+int cmd__simple_ipc(int argc, const char **argv);
 int cmd__strcmp_offset(int argc, const char **argv);
 int cmd__string_list(int argc, const char **argv);
 int cmd__submodule_config(int argc, const char **argv);
diff --git a/t/lib-rebase.sh b/t/lib-rebase.sh
index 172d745..dc75b83 100644
--- a/t/lib-rebase.sh
+++ b/t/lib-rebase.sh
@@ -4,6 +4,7 @@
 #
 # - override the commit message with $FAKE_COMMIT_MESSAGE
 # - amend the commit message with $FAKE_COMMIT_AMEND
+# - copy the original commit message to a file with $FAKE_MESSAGE_COPY
 # - check that non-commit messages have a certain line count with $EXPECT_COUNT
 # - check the commit count in the commit message header with $EXPECT_HEADER_COUNT
 # - rewrite a rebase -i script as directed by $FAKE_LINES.
@@ -14,10 +15,11 @@
 #       specified line.
 #
 #   "<cmd> <lineno>" -- add a line with the specified command
-#       ("pick", "squash", "fixup", "edit", "reword" or "drop") and the
-#       SHA1 taken from the specified line.
+#       ("pick", "squash", "fixup"|"fixup_-C"|"fixup_-c", "edit", "reword" or "drop")
+#       and the SHA1 taken from the specified line.
 #
-#   "exec_cmd_with_args" -- add an "exec cmd with args" line.
+#   "_" -- add a space, like "fixup_-C" implies "fixup -C" and
+#       "exec_cmd_with_args" add an "exec cmd with args" line.
 #
 #   "#" -- Add a comment line.
 #
@@ -32,6 +34,7 @@
 			exit
 		test -z "$FAKE_COMMIT_MESSAGE" || echo "$FAKE_COMMIT_MESSAGE" > "$1"
 		test -z "$FAKE_COMMIT_AMEND" || echo "$FAKE_COMMIT_AMEND" >> "$1"
+		test -z "$FAKE_MESSAGE_COPY" || cat "$1" >"$FAKE_MESSAGE_COPY"
 		exit
 		;;
 	esac
@@ -50,6 +53,8 @@
 			action="$line";;
 		exec_*|x_*|break|b)
 			echo "$line" | sed 's/_/ /g' >> "$1";;
+		merge_*|fixup_*)
+			action=$(echo "$line" | sed 's/_/ /g');;
 		"#")
 			echo '# comment' >> "$1";;
 		">")
diff --git a/t/perf/p5303-many-packs.sh b/t/perf/p5303-many-packs.sh
index ce0c42c..35c0cbd 100755
--- a/t/perf/p5303-many-packs.sh
+++ b/t/perf/p5303-many-packs.sh
@@ -28,11 +28,18 @@
 			push @commits, $_ if $. % 5 == 1;
 		}
 		print reverse @commits;
-	' "$1" >pushes
+	' "$1" >pushes &&
 
 	# create base packfile
-	head -n 1 pushes |
-	git pack-objects --delta-base-offset --revs staging/pack
+	base_pack=$(
+		head -n 1 pushes |
+		git pack-objects --delta-base-offset --revs staging/pack
+	) &&
+	test_export base_pack &&
+
+	# create an empty packfile
+	empty_pack=$(git pack-objects staging/pack </dev/null) &&
+	test_export empty_pack &&
 
 	# and then incrementals between each pair of commits
 	last= &&
@@ -49,6 +56,12 @@
 		last=$rev
 	done <pushes &&
 
+	(
+		find staging -type f -name 'pack-*.pack' |
+			xargs -n 1 basename | grep -v "$base_pack" &&
+		printf "^pack-%s.pack\n" $base_pack
+	) >stdin.packs
+
 	# and install the whole thing
 	rm -f .git/objects/pack/* &&
 	mv staging/* .git/objects/pack/
@@ -91,6 +104,23 @@
 		  --reflog --indexed-objects --delta-base-offset \
 		  --stdout </dev/null >/dev/null
 	'
+
+	test_perf "repack with kept ($nr_packs)" '
+		git pack-objects --keep-true-parents \
+		  --keep-pack=pack-$empty_pack.pack \
+		  --honor-pack-keep --non-empty --all \
+		  --reflog --indexed-objects --delta-base-offset \
+		  --stdout </dev/null >/dev/null
+	'
+
+	test_perf "repack with --stdin-packs ($nr_packs)" '
+		git pack-objects \
+		  --keep-true-parents \
+		  --stdin-packs \
+		  --non-empty \
+		  --delta-base-offset \
+		  --stdout <stdin.packs >/dev/null
+	'
 done
 
 # Measure pack loading with 10,000 packs.
diff --git a/t/perf/p5310-pack-bitmaps.sh b/t/perf/p5310-pack-bitmaps.sh
index b3e725f..452be01 100755
--- a/t/perf/p5310-pack-bitmaps.sh
+++ b/t/perf/p5310-pack-bitmaps.sh
@@ -15,6 +15,12 @@
 	git config pack.writebitmaps true
 '
 
+# we need to create the tag up front such that it is covered by the repack and
+# thus by generated bitmaps.
+test_expect_success 'create tags' '
+	git tag --message="tag pointing to HEAD" perf-tag HEAD
+'
+
 test_perf 'repack to disk' '
 	git repack -ad
 '
@@ -43,6 +49,14 @@
 	git rev-list --all --use-bitmap-index --objects >/dev/null
 '
 
+test_perf 'rev-list with tag negated via --not --all (objects)' '
+	git rev-list perf-tag --not --all --use-bitmap-index --objects >/dev/null
+'
+
+test_perf 'rev-list with negative tag (objects)' '
+	git rev-list HEAD --not perf-tag --use-bitmap-index --objects >/dev/null
+'
+
 test_perf 'rev-list count with blob:none' '
 	git rev-list --use-bitmap-index --count --objects --all \
 		--filter=blob:none >/dev/null
diff --git a/t/perf/p7519-fsmonitor.sh b/t/perf/p7519-fsmonitor.sh
index b657564..5eb5044 100755
--- a/t/perf/p7519-fsmonitor.sh
+++ b/t/perf/p7519-fsmonitor.sh
@@ -216,6 +216,10 @@
 		git diff
 	'
 
+	test_perf_w_drop_caches "diff HEAD ($DESC)" '
+		git diff HEAD
+	'
+
 	test_perf_w_drop_caches "diff -- 0_files ($DESC)" '
 		git diff -- 1_file
 	'
diff --git a/t/perf/perf-lib.sh b/t/perf/perf-lib.sh
index e385c68..601d9f6 100644
--- a/t/perf/perf-lib.sh
+++ b/t/perf/perf-lib.sh
@@ -70,6 +70,19 @@
 	test_have_prereq SYMLINKS || git config core.symlinks false
 }
 
+test_perf_copy_repo_contents () {
+	for stuff in "$1"/*
+	do
+		case "$stuff" in
+		*/objects|*/hooks|*/config|*/commondir|*/gitdir|*/worktrees)
+			;;
+		*)
+			cp -R "$stuff" "$repo/.git/" || exit 1
+			;;
+		esac
+	done
+}
+
 test_perf_create_repo_from () {
 	test "$#" = 2 ||
 	BUG "not 2 parameters to test-create-repo"
@@ -77,20 +90,20 @@
 	source="$2"
 	source_git="$("$MODERN_GIT" -C "$source" rev-parse --git-dir)"
 	objects_dir="$("$MODERN_GIT" -C "$source" rev-parse --git-path objects)"
+	common_dir="$("$MODERN_GIT" -C "$source" rev-parse --git-common-dir)"
 	mkdir -p "$repo/.git"
 	(
 		cd "$source" &&
 		{ cp -Rl "$objects_dir" "$repo/.git/" 2>/dev/null ||
 			cp -R "$objects_dir" "$repo/.git/"; } &&
-		for stuff in "$source_git"/*; do
-			case "$stuff" in
-				*/objects|*/hooks|*/config|*/commondir)
-					;;
-				*)
-					cp -R "$stuff" "$repo/.git/" || exit 1
-					;;
-			esac
-		done
+
+		# common_dir must come first here, since we want source_git to
+		# take precedence and overwrite any overlapping files
+		test_perf_copy_repo_contents "$common_dir"
+		if test "$source_git" != "$common_dir"
+		then
+			test_perf_copy_repo_contents "$source_git"
+		fi
 	) &&
 	(
 		cd "$repo" &&
diff --git a/t/t0003-attributes.sh b/t/t0003-attributes.sh
index b660593..1e4c672 100755
--- a/t/t0003-attributes.sh
+++ b/t/t0003-attributes.sh
@@ -4,12 +4,16 @@
 
 . ./test-lib.sh
 
-attr_check () {
+attr_check_basic () {
 	path="$1" expect="$2" git_opts="$3" &&
 
 	git $git_opts check-attr test -- "$path" >actual 2>err &&
 	echo "$path: test: $expect" >expect &&
-	test_cmp expect actual &&
+	test_cmp expect actual
+}
+
+attr_check () {
+	attr_check_basic "$@" &&
 	test_must_be_empty err
 }
 
@@ -331,7 +335,6 @@
 	test_cmp expect actual
 '
 
-
 test_expect_success 'query binary macro directly' '
 	echo "file binary" >.gitattributes &&
 	echo file: binary: set >expect &&
@@ -339,4 +342,31 @@
 	test_cmp expect actual
 '
 
+test_expect_success SYMLINKS 'set up symlink tests' '
+	echo "* test" >attr &&
+	rm -f .gitattributes
+'
+
+test_expect_success SYMLINKS 'symlinks respected in core.attributesFile' '
+	test_when_finished "rm symlink" &&
+	ln -s attr symlink &&
+	test_config core.attributesFile "$(pwd)/symlink" &&
+	attr_check file set
+'
+
+test_expect_success SYMLINKS 'symlinks respected in info/attributes' '
+	test_when_finished "rm .git/info/attributes" &&
+	ln -s ../../attr .git/info/attributes &&
+	attr_check file set
+'
+
+test_expect_success SYMLINKS 'symlinks not respected in-tree' '
+	test_when_finished "rm -rf .gitattributes subdir" &&
+	ln -s attr .gitattributes &&
+	mkdir subdir &&
+	ln -s ../attr subdir/.gitattributes &&
+	attr_check_basic subdir/file unspecified &&
+	test_i18ngrep "unable to access.*gitattributes" err
+'
+
 test_done
diff --git a/t/t0008-ignores.sh b/t/t0008-ignores.sh
index f7abde6..a594b4a 100755
--- a/t/t0008-ignores.sh
+++ b/t/t0008-ignores.sh
@@ -865,4 +865,38 @@
 	test_cmp expect actual
 '
 
+test_expect_success SYMLINKS 'set up ignore file for symlink tests' '
+	echo "*" >ignore &&
+	rm -f .gitignore .git/info/exclude
+'
+
+test_expect_success SYMLINKS 'symlinks respected in core.excludesFile' '
+	test_when_finished "rm symlink" &&
+	ln -s ignore symlink &&
+	test_config core.excludesFile "$(pwd)/symlink" &&
+	echo file >expect &&
+	git check-ignore file >actual 2>err &&
+	test_cmp expect actual &&
+	test_must_be_empty err
+'
+
+test_expect_success SYMLINKS 'symlinks respected in info/exclude' '
+	test_when_finished "rm .git/info/exclude" &&
+	ln -s ../../ignore .git/info/exclude &&
+	echo file >expect &&
+	git check-ignore file >actual 2>err &&
+	test_cmp expect actual &&
+	test_must_be_empty err
+'
+
+test_expect_success SYMLINKS 'symlinks not respected in-tree' '
+	test_when_finished "rm .gitignore" &&
+	ln -s ignore .gitignore &&
+	mkdir subdir &&
+	ln -s ignore subdir/.gitignore &&
+	test_must_fail git check-ignore subdir/file >actual 2>err &&
+	test_must_be_empty actual &&
+	test_i18ngrep "unable to access.*gitignore" err
+'
+
 test_done
diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index a9e10a0..b5749f3 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -257,6 +257,30 @@
 	test_must_fail git add test.fc
 '
 
+test_expect_success 'required filter with absent clean field' '
+	test_config filter.absentclean.smudge cat &&
+	test_config filter.absentclean.required true &&
+
+	echo "*.ac filter=absentclean" >.gitattributes &&
+
+	echo test >test.ac &&
+	test_must_fail git add test.ac 2>stderr &&
+	test_i18ngrep "fatal: test.ac: clean filter .absentclean. failed" stderr
+'
+
+test_expect_success 'required filter with absent smudge field' '
+	test_config filter.absentsmudge.clean cat &&
+	test_config filter.absentsmudge.required true &&
+
+	echo "*.as filter=absentsmudge" >.gitattributes &&
+
+	echo test >test.as &&
+	git add test.as &&
+	rm -f test.as &&
+	test_must_fail git checkout -- test.as 2>stderr &&
+	test_i18ngrep "fatal: test.as: smudge filter absentsmudge failed" stderr
+'
+
 test_expect_success 'filtering large input to small output should use little memory' '
 	test_config filter.devnull.clean "cat >/dev/null" &&
 	test_config filter.devnull.required true &&
diff --git a/t/t0052-simple-ipc.sh b/t/t0052-simple-ipc.sh
new file mode 100755
index 0000000..ff98be3
--- /dev/null
+++ b/t/t0052-simple-ipc.sh
@@ -0,0 +1,122 @@
+#!/bin/sh
+
+test_description='simple command server'
+
+. ./test-lib.sh
+
+test-tool simple-ipc SUPPORTS_SIMPLE_IPC || {
+	skip_all='simple IPC not supported on this platform'
+	test_done
+}
+
+stop_simple_IPC_server () {
+	test-tool simple-ipc stop-daemon
+}
+
+test_expect_success 'start simple command server' '
+	test_atexit stop_simple_IPC_server &&
+	test-tool simple-ipc start-daemon --threads=8 &&
+	test-tool simple-ipc is-active
+'
+
+test_expect_success 'simple command server' '
+	test-tool simple-ipc send --token=ping >actual &&
+	echo pong >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'servers cannot share the same path' '
+	test_must_fail test-tool simple-ipc run-daemon &&
+	test-tool simple-ipc is-active
+'
+
+test_expect_success 'big response' '
+	test-tool simple-ipc send --token=big >actual &&
+	test_line_count -ge 10000 actual &&
+	grep -q "big: [0]*9999\$" actual
+'
+
+test_expect_success 'chunk response' '
+	test-tool simple-ipc send --token=chunk >actual &&
+	test_line_count -ge 10000 actual &&
+	grep -q "big: [0]*9999\$" actual
+'
+
+test_expect_success 'slow response' '
+	test-tool simple-ipc send --token=slow >actual &&
+	test_line_count -ge 100 actual &&
+	grep -q "big: [0]*99\$" actual
+'
+
+# Send an IPC with n=100,000 bytes of ballast.  This should be large enough
+# to force both the kernel and the pkt-line layer to chunk the message to the
+# daemon and for the daemon to receive it in chunks.
+#
+test_expect_success 'sendbytes' '
+	test-tool simple-ipc sendbytes --bytecount=100000 --byte=A >actual &&
+	grep "sent:A00100000 rcvd:A00100000" actual
+'
+
+# Start a series of <threads> client threads that each make <batchsize>
+# IPC requests to the server.  Each (<threads> * <batchsize>) request
+# will open a new connection to the server and randomly bind to a server
+# thread.  Each client thread exits after completing its batch.  So the
+# total number of live client threads will be smaller than the total.
+# Each request will send a message containing at least <bytecount> bytes
+# of ballast.  (Responses are small.)
+#
+# The purpose here is to test threading in the server and responding to
+# many concurrent client requests (regardless of whether they come from
+# 1 client process or many).  And to test that the server side of the
+# named pipe/socket is stable.  (On Windows this means that the server
+# pipe is properly recycled.)
+#
+# On Windows it also lets us adjust the connection timeout in the
+# `ipc_client_send_command()`.
+#
+# Note it is easy to drive the system into failure by requesting an
+# insane number of threads on client or server and/or increasing the
+# per-thread batchsize or the per-request bytecount (ballast).
+# On Windows these failures look like "pipe is busy" errors.
+# So I've chosen fairly conservative values for now.
+#
+# We expect output of the form "sent:<letter><length> ..."
+# With terms (7, 19, 13) we expect:
+#   <letter> in [A-G]
+#   <length> in [19+0 .. 19+(13-1)]
+# and (7 * 13) successful responses.
+#
+test_expect_success 'stress test threads' '
+	test-tool simple-ipc multiple \
+		--threads=7 \
+		--bytecount=19 \
+		--batchsize=13 \
+		>actual &&
+	test_line_count = 92 actual &&
+	grep "good 91" actual &&
+	grep "sent:A" <actual >actual_a &&
+	cat >expect_a <<-EOF &&
+		sent:A00000019 rcvd:A00000019
+		sent:A00000020 rcvd:A00000020
+		sent:A00000021 rcvd:A00000021
+		sent:A00000022 rcvd:A00000022
+		sent:A00000023 rcvd:A00000023
+		sent:A00000024 rcvd:A00000024
+		sent:A00000025 rcvd:A00000025
+		sent:A00000026 rcvd:A00000026
+		sent:A00000027 rcvd:A00000027
+		sent:A00000028 rcvd:A00000028
+		sent:A00000029 rcvd:A00000029
+		sent:A00000030 rcvd:A00000030
+		sent:A00000031 rcvd:A00000031
+	EOF
+	test_cmp expect_a actual_a
+'
+
+test_expect_success 'stop-daemon works' '
+	test-tool simple-ipc stop-daemon &&
+	test_must_fail test-tool simple-ipc is-active &&
+	test_must_fail test-tool simple-ipc send --token=ping
+'
+
+test_done
diff --git a/t/t2021-checkout-overwrite.sh b/t/t2021-checkout-overwrite.sh
index c2ada7d..70d6926 100755
--- a/t/t2021-checkout-overwrite.sh
+++ b/t/t2021-checkout-overwrite.sh
@@ -51,4 +51,16 @@
 	test -h a/b
 '
 
+test_expect_success SYMLINKS 'checkout -f must not follow symlinks when removing entries' '
+	git checkout -f start &&
+	mkdir dir &&
+	>dir/f &&
+	git add dir/f &&
+	git commit -m "add dir/f" &&
+	mv dir untracked &&
+	ln -s untracked dir &&
+	git checkout -f HEAD~ &&
+	test_path_is_file untracked/f
+'
+
 test_done
diff --git a/t/t3060-ls-files-with-tree.sh b/t/t3060-ls-files-with-tree.sh
index 52ed665..b257c79 100755
--- a/t/t3060-ls-files-with-tree.sh
+++ b/t/t3060-ls-files-with-tree.sh
@@ -47,6 +47,12 @@
 	git add .
 '
 
+test_expect_success 'usage' '
+	test_expect_code 128 git ls-files --with-tree=HEAD -u &&
+	test_expect_code 128 git ls-files --with-tree=HEAD -s &&
+	test_expect_code 128 git ls-files --recurse-submodules --with-tree=HEAD
+'
+
 test_expect_success 'git ls-files --with-tree should succeed from subdir' '
 	# We have to run from a sub-directory to trigger prune_path
 	# Then we finally get to run our --with-tree test
@@ -60,4 +66,39 @@
     'git ls-files --with-tree should add entries from named tree.' \
     'test_cmp expected output'
 
+test_expect_success 'no duplicates in --with-tree output' '
+	git ls-files --with-tree=HEAD >actual &&
+	sort -u actual >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'setup: output in a conflict' '
+	test_create_repo conflict &&
+	test_commit -C conflict BASE file &&
+	test_commit -C conflict A file foo &&
+	git -C conflict reset --hard BASE &&
+	test_commit -C conflict B file bar
+'
+
+test_expect_success 'output in a conflict' '
+	test_must_fail git -C conflict merge A B &&
+	cat >expected <<-\EOF &&
+	file
+	file
+	file
+	file
+	EOF
+	git -C conflict ls-files --with-tree=HEAD >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'output with removed .git/index' '
+	cat >expected <<-\EOF &&
+	file
+	EOF
+	rm conflict/.git/index &&
+	git -C conflict ls-files --with-tree=HEAD >actual &&
+	test_cmp expected actual
+'
+
 test_done
diff --git a/t/t3206-range-diff.sh b/t/t3206-range-diff.sh
index 1b26c4c..e30bc48 100755
--- a/t/t3206-range-diff.sh
+++ b/t/t3206-range-diff.sh
@@ -521,6 +521,30 @@
 	grep "> 1: .* new message" 0001-*
 '
 
+test_expect_success 'format-patch --range-diff reroll-count with a non-integer' '
+	git format-patch --range-diff=HEAD~1 -v2.9 HEAD~1 >actual &&
+	test_when_finished "rm v2.9-0001-*" &&
+	test_line_count = 1 actual &&
+	test_i18ngrep "^Range-diff:$" v2.9-0001-* &&
+	grep "> 1: .* new message" v2.9-0001-*
+'
+
+test_expect_success 'format-patch --range-diff reroll-count with a integer' '
+	git format-patch --range-diff=HEAD~1 -v2 HEAD~1 >actual &&
+	test_when_finished "rm v2-0001-*" &&
+	test_line_count = 1 actual &&
+	test_i18ngrep "^Range-diff ..* v1:$" v2-0001-* &&
+	grep "> 1: .* new message" v2-0001-*
+'
+
+test_expect_success 'format-patch --range-diff with v0' '
+	git format-patch --range-diff=HEAD~1 -v0 HEAD~1 >actual &&
+	test_when_finished "rm v0-0001-*" &&
+	test_line_count = 1 actual &&
+	test_i18ngrep "^Range-diff:$" v0-0001-* &&
+	grep "> 1: .* new message" v0-0001-*
+'
+
 test_expect_success 'range-diff overrides diff.noprefix internally' '
 	git -c diff.noprefix=true range-diff HEAD^...
 '
diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
index 587b408..0bb88aa 100755
--- a/t/t3400-rebase.sh
+++ b/t/t3400-rebase.sh
@@ -388,22 +388,6 @@
 	)
 '
 
-test_expect_success 'rebase -c rebase.useBuiltin=false warning' '
-	expected="rebase.useBuiltin support has been removed" &&
-
-	# Only warn when the legacy rebase is requested...
-	test_must_fail git -c rebase.useBuiltin=false rebase 2>err &&
-	test_i18ngrep "$expected" err &&
-	test_must_fail env GIT_TEST_REBASE_USE_BUILTIN=false git rebase 2>err &&
-	test_i18ngrep "$expected" err &&
-
-	# ...not when we would have used the built-in anyway
-	test_must_fail git -c rebase.useBuiltin=true rebase 2>err &&
-	test_must_be_empty err &&
-	test_must_fail env GIT_TEST_REBASE_USE_BUILTIN=true git rebase 2>err &&
-	test_must_be_empty err
-'
-
 test_expect_success 'switch to branch checked out here' '
 	git checkout main &&
 	git rebase main main
diff --git a/t/t3415-rebase-autosquash.sh b/t/t3415-rebase-autosquash.sh
index 908016c..78c2749 100755
--- a/t/t3415-rebase-autosquash.sh
+++ b/t/t3415-rebase-autosquash.sh
@@ -84,8 +84,7 @@
 	echo 1 >file1 &&
 	git add -u &&
 	test_tick &&
-	git commit -m "squash! first" &&
-
+	git commit -m "squash! first" -m "extra para for first" &&
 	git tag $1 &&
 	test_tick &&
 	git rebase $2 -i HEAD^^^ &&
@@ -142,7 +141,7 @@
 	echo 1 >file1 &&
 	git add -u &&
 	test_tick &&
-	git commit -m "squash! first" &&
+	git commit -m "squash! first" -m "extra para for first" &&
 	git tag final-multisquash &&
 	test_tick &&
 	git rebase --autosquash -i HEAD~4 &&
@@ -195,7 +194,7 @@
 	git add -u &&
 	test_tick &&
 	oid=$(git rev-parse --short HEAD^) &&
-	git commit -m "squash! $oid" &&
+	git commit -m "squash! $oid" -m "extra para" &&
 	git tag final-shasquash &&
 	test_tick &&
 	git rebase --autosquash -i HEAD^^^ &&
@@ -206,7 +205,8 @@
 	git cat-file blob HEAD^:file1 >actual &&
 	test_cmp expect actual &&
 	git cat-file commit HEAD^ >commit &&
-	grep squash commit >actual &&
+	! grep "squash" commit &&
+	grep "^extra para" commit >actual &&
 	test_line_count = 1 actual
 '
 
@@ -216,7 +216,7 @@
 	git add -u &&
 	test_tick &&
 	oid=$(git rev-parse --short=11 HEAD^) &&
-	git commit -m "squash! $oid" &&
+	git commit -m "squash! $oid" -m "extra para" &&
 	git tag final-longshasquash &&
 	test_tick &&
 	git rebase --autosquash -i HEAD^^^ &&
@@ -227,7 +227,8 @@
 	git cat-file blob HEAD^:file1 >actual &&
 	test_cmp expect actual &&
 	git cat-file commit HEAD^ >commit &&
-	grep squash commit >actual &&
+	! grep "squash" commit &&
+	grep "^extra para" commit >actual &&
 	test_line_count = 1 actual
 '
 
@@ -236,7 +237,7 @@
 	echo 1 >file1 &&
 	git add -u &&
 	test_tick &&
-	git commit --$1 first-commit &&
+	git commit --$1 first-commit -m "extra para for first" &&
 	git tag final-commit-$1 &&
 	test_tick &&
 	git rebase --autosquash -i HEAD^^^ &&
@@ -264,11 +265,11 @@
 	echo 1 >file1 &&
 	git add -u &&
 	test_tick &&
-	git commit -m "$1! first" &&
+	git commit -m "$1! first" -m "extra para for first" &&
 	echo 2 >file1 &&
 	git add -u &&
 	test_tick &&
-	git commit -m "$1! $2! first" &&
+	git commit -m "$1! $2! first" -m "second extra para for first" &&
 	git tag "final-$1-$2" &&
 	test_tick &&
 	(
@@ -329,12 +330,12 @@
 	git add -u &&
 	test_tick &&
 	oid=$(git rev-parse --short HEAD^) &&
-	git commit -m "squash! $oid" &&
+	git commit -m "squash! $oid" -m "extra para for first" &&
 	echo 1 >file1 &&
 	git add -u &&
 	test_tick &&
 	subject=$(git log -n 1 --format=%s HEAD~2) &&
-	git commit -m "squash! $subject" &&
+	git commit -m "squash! $subject" -m "second extra para for first" &&
 	git tag final-squash-instFmt &&
 	test_tick &&
 	git rebase --autosquash -i HEAD~4 &&
@@ -345,8 +346,9 @@
 	git cat-file blob HEAD^:file1 >actual &&
 	test_cmp expect actual &&
 	git cat-file commit HEAD^ >commit &&
-	grep squash commit >actual &&
-	test_line_count = 2 actual
+	! grep "squash" commit &&
+	grep first commit >actual &&
+	test_line_count = 3 actual
 '
 
 test_expect_success 'autosquash with empty custom instructionFormat' '
diff --git a/t/t3437-rebase-fixup-options.sh b/t/t3437-rebase-fixup-options.sh
new file mode 100755
index 0000000..d0bdc7e
--- /dev/null
+++ b/t/t3437-rebase-fixup-options.sh
@@ -0,0 +1,211 @@
+#!/bin/sh
+#
+# Copyright (c) 2018 Phillip Wood
+#
+
+test_description='git rebase interactive fixup options
+
+This test checks the "fixup [-C|-c]" command of rebase interactive.
+In addition to amending the contents of the commit, "fixup -C"
+replaces the original commit message with the message of the fixup
+commit. "fixup -c" also replaces the original message, but opens the
+editor to allow the user to edit the message before committing. Similar
+to the "fixup" command that works with "fixup!", "fixup -C" works with
+"amend!" upon --autosquash.
+'
+
+. ./test-lib.sh
+
+. "$TEST_DIRECTORY"/lib-rebase.sh
+
+EMPTY=""
+
+# test_commit_message <rev> -m <msg>
+# test_commit_message <rev> <path>
+# Verify that the commit message of <rev> matches
+# <msg> or the content of <path>.
+test_commit_message () {
+	git show --no-patch --pretty=format:%B "$1" >actual &&
+	case "$2" in
+	-m)
+		echo "$3" >expect &&
+		test_cmp expect actual ;;
+	*)
+		test_cmp "$2" actual ;;
+	esac
+}
+
+get_author () {
+	rev="$1" &&
+	git log -1 --pretty=format:"%an %ae %at" "$rev"
+}
+
+test_expect_success 'setup' '
+	cat >message <<-EOF &&
+	amend! B
+	$EMPTY
+	new subject
+	$EMPTY
+	new
+	body
+	EOF
+
+	test_commit A A &&
+	test_commit B B &&
+	get_author HEAD >expected-author &&
+	ORIG_AUTHOR_NAME="$GIT_AUTHOR_NAME" &&
+	ORIG_AUTHOR_EMAIL="$GIT_AUTHOR_EMAIL" &&
+	GIT_AUTHOR_NAME="Amend Author" &&
+	GIT_AUTHOR_EMAIL="amend@example.com" &&
+	test_commit "$(cat message)" A A1 A1 &&
+	test_commit A2 A &&
+	test_commit A3 A &&
+	GIT_AUTHOR_NAME="$ORIG_AUTHOR_NAME" &&
+	GIT_AUTHOR_EMAIL="$ORIG_AUTHOR_EMAIL" &&
+	git checkout -b conflicts-branch A &&
+	test_commit conflicts A &&
+
+	set_fake_editor &&
+	git checkout -b branch B &&
+	echo B1 >B &&
+	test_tick &&
+	git commit --fixup=HEAD -a &&
+	git tag B1 &&
+	test_tick &&
+	FAKE_COMMIT_AMEND="edited 1" git commit --fixup=reword:B &&
+	test_tick &&
+	FAKE_COMMIT_AMEND="edited 2" git commit --fixup=reword:HEAD &&
+	echo B2 >B &&
+	test_tick &&
+	FAKE_COMMIT_AMEND="edited squash" git commit --squash=HEAD -a &&
+	git tag B2 &&
+	echo B3 >B &&
+	test_tick &&
+	FAKE_COMMIT_AMEND="edited 3" git commit -a --fixup=amend:HEAD^ &&
+	git tag B3 &&
+
+	GIT_AUTHOR_NAME="Rebase Author" &&
+	GIT_AUTHOR_EMAIL="rebase.author@example.com" &&
+	GIT_COMMITTER_NAME="Rebase Committer" &&
+	GIT_COMMITTER_EMAIL="rebase.committer@example.com"
+'
+
+test_expect_success 'simple fixup -C works' '
+	test_when_finished "test_might_fail git rebase --abort" &&
+	git checkout --detach A2 &&
+	FAKE_LINES="1 fixup_-C 2" git rebase -i B &&
+	test_cmp_rev HEAD^ B &&
+	test_cmp_rev HEAD^{tree} A2^{tree} &&
+	test_commit_message HEAD -m "A2"
+'
+
+test_expect_success 'simple fixup -c works' '
+	test_when_finished "test_might_fail git rebase --abort" &&
+	git checkout --detach A2 &&
+	git log -1 --pretty=format:%B >expected-fixup-message &&
+	test_write_lines "" "Modified A2" >>expected-fixup-message &&
+	FAKE_LINES="1 fixup_-c 2" \
+		FAKE_COMMIT_AMEND="Modified A2" \
+		git rebase -i B &&
+	test_cmp_rev HEAD^ B &&
+	test_cmp_rev HEAD^{tree} A2^{tree} &&
+	test_commit_message HEAD expected-fixup-message
+'
+
+test_expect_success 'fixup -C removes amend! from message' '
+	test_when_finished "test_might_fail git rebase --abort" &&
+	git checkout --detach A1 &&
+	git log -1 --pretty=format:%b >expected-message &&
+	FAKE_LINES="1 fixup_-C 2" git rebase -i A &&
+	test_cmp_rev HEAD^ A &&
+	test_cmp_rev HEAD^{tree} A1^{tree} &&
+	test_commit_message HEAD expected-message &&
+	get_author HEAD >actual-author &&
+	test_cmp expected-author actual-author
+'
+
+test_expect_success 'fixup -C with conflicts gives correct message' '
+	test_when_finished "test_might_fail git rebase --abort" &&
+	git checkout --detach A1 &&
+	git log -1 --pretty=format:%b >expected-message &&
+	test_write_lines "" "edited" >>expected-message &&
+	test_must_fail env FAKE_LINES="1 fixup_-C 2" git rebase -i conflicts &&
+	git checkout --theirs -- A &&
+	git add A &&
+	FAKE_COMMIT_AMEND=edited git rebase --continue &&
+	test_cmp_rev HEAD^ conflicts &&
+	test_cmp_rev HEAD^{tree} A1^{tree} &&
+	test_commit_message HEAD expected-message &&
+	get_author HEAD >actual-author &&
+	test_cmp expected-author actual-author
+'
+
+test_expect_success 'skipping fixup -C after fixup gives correct message' '
+	test_when_finished "test_might_fail git rebase --abort" &&
+	git checkout --detach A3 &&
+	test_must_fail env FAKE_LINES="1 fixup 2 fixup_-C 4" git rebase -i A &&
+	git reset --hard &&
+	FAKE_COMMIT_AMEND=edited git rebase --continue &&
+	test_commit_message HEAD -m "B"
+'
+
+test_expect_success 'sequence of fixup, fixup -C & squash --signoff works' '
+	git checkout --detach B3 &&
+	FAKE_LINES="1 fixup 2 fixup_-C 3 fixup_-C 4 squash 5 fixup_-C 6" \
+		FAKE_COMMIT_AMEND=squashed \
+		FAKE_MESSAGE_COPY=actual-squash-message \
+		git -c commit.status=false rebase -ik --signoff A &&
+	git diff-tree --exit-code --patch HEAD B3 -- &&
+	test_cmp_rev HEAD^ A &&
+	test_i18ncmp "$TEST_DIRECTORY/t3437/expected-squash-message" \
+		actual-squash-message
+'
+
+test_expect_success 'first fixup -C commented out in sequence fixup fixup -C fixup -C' '
+	test_when_finished "test_might_fail git rebase --abort" &&
+	git checkout --detach B2~ &&
+	git log -1 --pretty=format:%b >expected-message &&
+	FAKE_LINES="1 fixup 2 fixup_-C 3 fixup_-C 4" git rebase -i A &&
+	test_cmp_rev HEAD^ A &&
+	test_commit_message HEAD expected-message
+'
+
+test_expect_success 'multiple fixup -c opens editor once' '
+	test_when_finished "test_might_fail git rebase --abort" &&
+	git checkout --detach A3 &&
+	git log -1 --pretty=format:%B >expected-message &&
+	test_write_lines "" "Modified-A3" >>expected-message &&
+	FAKE_COMMIT_AMEND="Modified-A3" \
+		FAKE_LINES="1 fixup_-C 2 fixup_-c 3 fixup_-c 4" \
+		EXPECT_HEADER_COUNT=4 \
+		git rebase -i A &&
+	test_cmp_rev HEAD^ A &&
+	get_author HEAD >actual-author &&
+	test_cmp expected-author actual-author &&
+	test_commit_message HEAD expected-message
+'
+
+test_expect_success 'sequence squash, fixup & fixup -c gives combined message' '
+	test_when_finished "test_might_fail git rebase --abort" &&
+	git checkout --detach A3 &&
+	FAKE_LINES="1 squash 2 fixup 3 fixup_-c 4" \
+		FAKE_MESSAGE_COPY=actual-combined-message \
+		git -c commit.status=false rebase -i A &&
+	test_i18ncmp "$TEST_DIRECTORY/t3437/expected-combined-message" \
+		actual-combined-message &&
+	test_cmp_rev HEAD^ A
+'
+
+test_expect_success 'fixup -C works upon --autosquash with amend!' '
+	git checkout --detach B3 &&
+	FAKE_COMMIT_AMEND=squashed \
+		FAKE_MESSAGE_COPY=actual-squash-message \
+		git -c commit.status=false rebase -ik --autosquash \
+						--signoff A &&
+	git diff-tree --exit-code --patch HEAD B3 -- &&
+	test_cmp_rev HEAD^ A &&
+	test_i18ncmp "$TEST_DIRECTORY/t3437/expected-squash-message" \
+		actual-squash-message
+'
+
+test_done
diff --git a/t/t3437/expected-combined-message b/t/t3437/expected-combined-message
new file mode 100644
index 0000000..a26cfb2
--- /dev/null
+++ b/t/t3437/expected-combined-message
@@ -0,0 +1,21 @@
+# This is a combination of 4 commits.
+# This is the 1st commit message:
+
+B
+
+# This is the commit message #2:
+
+# amend! B
+
+new subject
+
+new
+body
+
+# The commit message #3 will be skipped:
+
+# A2
+
+# This is the commit message #4:
+
+A3
diff --git a/t/t3437/expected-squash-message b/t/t3437/expected-squash-message
new file mode 100644
index 0000000..ab2434f
--- /dev/null
+++ b/t/t3437/expected-squash-message
@@ -0,0 +1,51 @@
+# This is a combination of 6 commits.
+# The 1st commit message will be skipped:
+
+# B
+#
+# Signed-off-by: Rebase Committer <rebase.committer@example.com>
+
+# The commit message #2 will be skipped:
+
+# fixup! B
+
+# The commit message #3 will be skipped:
+
+# amend! B
+#
+# B
+#
+# edited 1
+#
+# Signed-off-by: Rebase Committer <rebase.committer@example.com>
+
+# This is the commit message #4:
+
+# amend! amend! B
+
+B
+
+edited 1
+
+edited 2
+
+Signed-off-by: Rebase Committer <rebase.committer@example.com>
+
+# This is the commit message #5:
+
+# squash! amend! amend! B
+
+edited squash
+
+# This is the commit message #6:
+
+# amend! amend! amend! B
+
+B
+
+edited 1
+
+edited 2
+
+edited 3
+squashed
diff --git a/t/t3800-mktag.sh b/t/t3800-mktag.sh
index 60a666d..6275c98 100755
--- a/t/t3800-mktag.sh
+++ b/t/t3800-mktag.sh
@@ -17,7 +17,7 @@
 		grep '$2' message &&
 		if test '$3' != '--no-strict'
 		then
-			test_must_fail git mktag --no-strict <tag.sig 2>message.no-strict &&xb
+			test_must_fail git mktag --no-strict <tag.sig 2>message.no-strict &&
 			grep '$2' message.no-strict
 		fi
 	"
diff --git a/t/t3900-i18n-commit.sh b/t/t3900-i18n-commit.sh
index d277a9f..bfab245 100755
--- a/t/t3900-i18n-commit.sh
+++ b/t/t3900-i18n-commit.sh
@@ -226,10 +226,6 @@
 		git rev-list HEAD >actual &&
 		test_line_count = 3 actual &&
 		iconv -f $old -t UTF-8 "$TEST_DIRECTORY"/t3900/$msg >expect &&
-		if test $flag = squash; then
-			subject="$(head -1 expect)" &&
-			printf "\nsquash! %s\n" "$subject" >>expect
-		fi &&
 		git cat-file commit HEAD^ >raw &&
 		(sed "1,/^$/d" raw | iconv -f $new -t utf-8) >actual &&
 		test_cmp expect actual
diff --git a/t/t3905-stash-include-untracked.sh b/t/t3905-stash-include-untracked.sh
index 598b17f..8314ab2 100755
--- a/t/t3905-stash-include-untracked.sh
+++ b/t/t3905-stash-include-untracked.sh
@@ -297,4 +297,112 @@
 	test_path_is_missing untracked.txt
 '
 
+test_expect_success 'stash show --include-untracked shows untracked files' '
+	git reset --hard &&
+	git clean -xf &&
+	>untracked &&
+	>tracked &&
+	git add tracked &&
+	empty_blob_oid=$(git rev-parse --short :tracked) &&
+	git stash -u &&
+
+	cat >expect <<-EOF &&
+	 tracked   | 0
+	 untracked | 0
+	 2 files changed, 0 insertions(+), 0 deletions(-)
+	EOF
+	git stash show --include-untracked >actual &&
+	test_cmp expect actual &&
+	git stash show -u >actual &&
+	test_cmp expect actual &&
+	git stash show --no-include-untracked --include-untracked >actual &&
+	test_cmp expect actual &&
+	git stash show --only-untracked --include-untracked >actual &&
+	test_cmp expect actual &&
+	git -c stash.showIncludeUntracked=true stash show >actual &&
+	test_cmp expect actual &&
+
+	cat >expect <<-EOF &&
+	diff --git a/tracked b/tracked
+	new file mode 100644
+	index 0000000..$empty_blob_oid
+	diff --git a/untracked b/untracked
+	new file mode 100644
+	index 0000000..$empty_blob_oid
+	EOF
+	git stash show -p --include-untracked >actual &&
+	test_cmp expect actual &&
+	git stash show --include-untracked -p >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'stash show --only-untracked only shows untracked files' '
+	git reset --hard &&
+	git clean -xf &&
+	>untracked &&
+	>tracked &&
+	git add tracked &&
+	empty_blob_oid=$(git rev-parse --short :tracked) &&
+	git stash -u &&
+
+	cat >expect <<-EOF &&
+	 untracked | 0
+	 1 file changed, 0 insertions(+), 0 deletions(-)
+	EOF
+	git stash show --only-untracked >actual &&
+	test_cmp expect actual &&
+	git stash show --no-include-untracked --only-untracked >actual &&
+	test_cmp expect actual &&
+	git stash show --include-untracked --only-untracked >actual &&
+	test_cmp expect actual &&
+
+	cat >expect <<-EOF &&
+	diff --git a/untracked b/untracked
+	new file mode 100644
+	index 0000000..$empty_blob_oid
+	EOF
+	git stash show -p --only-untracked >actual &&
+	test_cmp expect actual &&
+	git stash show --only-untracked -p >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'stash show --no-include-untracked cancels --{include,show}-untracked' '
+	git reset --hard &&
+	git clean -xf &&
+	>untracked &&
+	>tracked &&
+	git add tracked &&
+	git stash -u &&
+
+	cat >expect <<-EOF &&
+	 tracked | 0
+	 1 file changed, 0 insertions(+), 0 deletions(-)
+	EOF
+	git stash show --only-untracked --no-include-untracked >actual &&
+	test_cmp expect actual &&
+	git stash show --include-untracked --no-include-untracked >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'stash show --include-untracked errors on duplicate files' '
+	git reset --hard &&
+	git clean -xf &&
+	>tracked &&
+	git add tracked &&
+	tree=$(git write-tree) &&
+	i_commit=$(git commit-tree -p HEAD -m "index on any-branch" "$tree") &&
+	test_when_finished "rm -f untracked_index" &&
+	u_commit=$(
+		GIT_INDEX_FILE="untracked_index" &&
+		export GIT_INDEX_FILE &&
+		git update-index --add tracked &&
+		u_tree=$(git write-tree) &&
+		git commit-tree -m "untracked files on any-branch" "$u_tree"
+	) &&
+	w_commit=$(git commit-tree -p HEAD -p "$i_commit" -p "$u_commit" -m "WIP on any-branch" "$tree") &&
+	test_must_fail git stash show --include-untracked "$w_commit" 2>err &&
+	test_i18ngrep "worktree and untracked commit have duplicate entries: tracked" err
+'
+
 test_done
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index cdd3154..712d4b5 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -386,6 +386,30 @@
 	! grep -v "^Subject: \[PATCH v4 [0-3]/3\] " subjects
 '
 
+test_expect_success 'reroll count (-v) with a fractional number' '
+	rm -fr patches &&
+	git format-patch -o patches --cover-letter -v4.4 main..side >list &&
+	! grep -v "^patches/v4.4-000[0-3]-" list &&
+	sed -n -e "/^Subject: /p" $(cat list) >subjects &&
+	! grep -v "^Subject: \[PATCH v4.4 [0-3]/3\] " subjects
+'
+
+test_expect_success 'reroll (-v) count with a non number' '
+	rm -fr patches &&
+	git format-patch -o patches --cover-letter -v4rev2 main..side >list &&
+	! grep -v "^patches/v4rev2-000[0-3]-" list &&
+	sed -n -e "/^Subject: /p" $(cat list) >subjects &&
+	! grep -v "^Subject: \[PATCH v4rev2 [0-3]/3\] " subjects
+'
+
+test_expect_success 'reroll (-v) count with a non-pathname character' '
+	rm -fr patches &&
+	git format-patch -o patches --cover-letter -v4---..././../--1/.2//  main..side >list &&
+	! grep -v "patches/v4-\.-\.-\.-1-\.2-000[0-3]-" list &&
+	sed -n -e "/^Subject: /p" $(cat list) >subjects &&
+	! grep -v "^Subject: \[PATCH v4---\.\.\./\./\.\./--1/\.2// [0-3]/3\] " subjects
+'
+
 check_threading () {
 	expect="$1" &&
 	shift &&
@@ -2255,6 +2279,16 @@
 	test_i18ngrep "^Interdiff ..* v1:$" v2-0000-cover-letter.patch
 '
 
+test_expect_success 'interdiff: reroll-count with a non-integer' '
+	git format-patch --cover-letter --interdiff=boop~2 -v2.2 -1 boop &&
+	test_i18ngrep "^Interdiff:$" v2.2-0000-cover-letter.patch
+'
+
+test_expect_success 'interdiff: reroll-count with a integer' '
+	git format-patch --cover-letter --interdiff=boop~2 -v2 -1 boop &&
+	test_i18ngrep "^Interdiff ..* v1:$" v2-0000-cover-letter.patch
+'
+
 test_expect_success 'interdiff: solo-patch' '
 	cat >expect <<-\EOF &&
 	  +fleep
diff --git a/t/t4053-diff-no-index.sh b/t/t4053-diff-no-index.sh
index 0168946..3feadf0 100755
--- a/t/t4053-diff-no-index.sh
+++ b/t/t4053-diff-no-index.sh
@@ -16,6 +16,11 @@
 	echo 1 >non/git/b
 '
 
+test_expect_success 'git diff --no-index --exit-code' '
+	git diff --no-index --exit-code a/1 non/git/a &&
+	test_expect_code 1 git diff --no-index --exit-code a/1 a/2
+'
+
 test_expect_success 'git diff --no-index directories' '
 	test_expect_code 1 git diff --no-index a b >cnt &&
 	test_line_count = 14 cnt
@@ -144,4 +149,59 @@
 	test_cmp expect actual
 '
 
+test_expect_success 'diff --no-index normalizes mode: no changes' '
+	echo foo >x &&
+	cp x y &&
+	git diff --no-index x y >out &&
+	test_must_be_empty out
+'
+
+test_expect_success POSIXPERM 'diff --no-index normalizes mode: chmod +x' '
+	chmod +x y &&
+	cat >expected <<-\EOF &&
+	diff --git a/x b/y
+	old mode 100644
+	new mode 100755
+	EOF
+	test_expect_code 1 git diff --no-index x y >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success POSIXPERM 'diff --no-index normalizes: mode not like git mode' '
+	chmod 666 x &&
+	chmod 777 y &&
+	cat >expected <<-\EOF &&
+	diff --git a/x b/y
+	old mode 100644
+	new mode 100755
+	EOF
+	test_expect_code 1 git diff --no-index x y >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success POSIXPERM,SYMLINKS 'diff --no-index normalizes: mode not like git mode (symlink)' '
+	ln -s y z &&
+	X_OID=$(git hash-object --stdin <x) &&
+	Z_OID=$(printf y | git hash-object --stdin) &&
+	cat >expected <<-EOF &&
+	diff --git a/x b/x
+	deleted file mode 100644
+	index $X_OID..$ZERO_OID
+	--- a/x
+	+++ /dev/null
+	@@ -1 +0,0 @@
+	-foo
+	diff --git a/z b/z
+	new file mode 120000
+	index $ZERO_OID..$Z_OID
+	--- /dev/null
+	+++ b/z
+	@@ -0,0 +1 @@
+	+y
+	\ No newline at end of file
+	EOF
+	test_expect_code 1 git -c core.abbrev=no diff --no-index x z >actual &&
+	test_cmp expected actual
+'
+
 test_done
diff --git a/t/t4203-mailmap.sh b/t/t4203-mailmap.sh
index 93caf9a..d8e7374 100755
--- a/t/t4203-mailmap.sh
+++ b/t/t4203-mailmap.sh
@@ -932,4 +932,35 @@
 	test_cmp expect actual
 '
 
+test_expect_success SYMLINKS 'set up symlink tests' '
+	git commit --allow-empty -m foo --author="Orig <orig@example.com>" &&
+	echo "New <new@example.com> <orig@example.com>" >map &&
+	rm -f .mailmap
+'
+
+test_expect_success SYMLINKS 'symlinks respected in mailmap.file' '
+	test_when_finished "rm symlink" &&
+	ln -s map symlink &&
+	git -c mailmap.file="$(pwd)/symlink" log -1 --format=%aE >actual &&
+	echo "new@example.com" >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success SYMLINKS 'symlinks respected in non-repo shortlog' '
+	git log -1 >input &&
+	test_when_finished "nongit rm .mailmap" &&
+	nongit ln -sf "$TRASH_DIRECTORY/map" .mailmap &&
+	nongit git shortlog -s <input >actual &&
+	echo "     1	New" >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success SYMLINKS 'symlinks not respected in-tree' '
+	test_when_finished "rm .mailmap" &&
+	ln -s map .mailmap &&
+	git log -1 --format=%aE >actual &&
+	echo "orig@example.com" >expect&&
+	test_cmp expect actual
+'
+
 test_done
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 85432b8..cabdf7d 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -962,4 +962,39 @@
 	test_cmp expect actual
 '
 
+test_expect_success '%(describe) vs git describe' '
+	git log --format="%H" | while read hash
+	do
+		if desc=$(git describe $hash)
+		then
+			: >expect-contains-good
+		else
+			: >expect-contains-bad
+		fi &&
+		echo "$hash $desc"
+	done >expect &&
+	test_path_exists expect-contains-good &&
+	test_path_exists expect-contains-bad &&
+
+	git log --format="%H %(describe)" >actual 2>err &&
+	test_cmp expect actual &&
+	test_must_be_empty err
+'
+
+test_expect_success '%(describe:match=...) vs git describe --match ...' '
+	test_when_finished "git tag -d tag-match" &&
+	git tag -a -m tagged tag-match&&
+	git describe --match "*-match" >expect &&
+	git log -1 --format="%(describe:match=*-match)" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '%(describe:exclude=...) vs git describe --exclude ...' '
+	test_when_finished "git tag -d tag-exclude" &&
+	git tag -a -m tagged tag-exclude &&
+	git describe --exclude "*-exclude" >expect &&
+	git log -1 --format="%(describe:exclude=*-exclude)" >actual &&
+	test_cmp expect actual
+'
+
 test_done
diff --git a/t/t5001-archive-attr.sh b/t/t5001-archive-attr.sh
index e9aa971..712ae52 100755
--- a/t/t5001-archive-attr.sh
+++ b/t/t5001-archive-attr.sh
@@ -128,4 +128,18 @@
 	test_cmp substfile2 archive/substfile2
 '
 
+test_expect_success 'export-subst expands %(describe) once' '
+	echo "\$Format:%(describe)\$" >substfile3 &&
+	echo "\$Format:%(describe)\$" >>substfile3 &&
+	echo "\$Format:%(describe)${LF}%(describe)\$" >substfile4 &&
+	git add substfile[34] &&
+	git commit -m export-subst-describe &&
+	git tag -m export-subst-describe export-subst-describe &&
+	git archive HEAD >archive-describe.tar &&
+	extract_tar_to_dir archive-describe &&
+	desc=$(git describe) &&
+	grep -F "$desc" archive-describe/substfile[34] >substituted &&
+	test_line_count = 1 substituted
+'
+
 test_done
diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index d586fdc..2fc5e68 100755
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -427,7 +427,8 @@
 	test_path_is_file foo.idx
 '
 
-test_expect_success !PTHREADS 'index-pack --threads=N or pack.threads=N warns when no pthreads' '
+test_expect_success !PTHREADS,!FAIL_PREREQS \
+	'index-pack --threads=N or pack.threads=N warns when no pthreads' '
 	test_must_fail git index-pack --threads=2 2>err &&
 	grep ^warning: err >warnings &&
 	test_line_count = 1 warnings &&
@@ -445,7 +446,8 @@
 	grep -F "no threads support, ignoring pack.threads" err
 '
 
-test_expect_success !PTHREADS 'pack-objects --threads=N or pack.threads=N warns when no pthreads' '
+test_expect_success !PTHREADS,!FAIL_PREREQS \
+	'pack-objects --threads=N or pack.threads=N warns when no pthreads' '
 	git pack-objects --threads=2 --stdout --all </dev/null >/dev/null 2>err &&
 	grep ^warning: err >warnings &&
 	test_line_count = 1 warnings &&
@@ -532,4 +534,139 @@
 	test_line_count = 1 donelines
 '
 
+test_expect_success 'setup for --stdin-packs tests' '
+	git init stdin-packs &&
+	(
+		cd stdin-packs &&
+
+		test_commit A &&
+		test_commit B &&
+		test_commit C &&
+
+		for id in A B C
+		do
+			git pack-objects .git/objects/pack/pack-$id \
+				--incremental --revs <<-EOF
+			refs/tags/$id
+			EOF
+		done &&
+
+		ls -la .git/objects/pack
+	)
+'
+
+test_expect_success '--stdin-packs with excluded packs' '
+	(
+		cd stdin-packs &&
+
+		PACK_A="$(basename .git/objects/pack/pack-A-*.pack)" &&
+		PACK_B="$(basename .git/objects/pack/pack-B-*.pack)" &&
+		PACK_C="$(basename .git/objects/pack/pack-C-*.pack)" &&
+
+		git pack-objects test --stdin-packs <<-EOF &&
+		$PACK_A
+		^$PACK_B
+		$PACK_C
+		EOF
+
+		(
+			git show-index <$(ls .git/objects/pack/pack-A-*.idx) &&
+			git show-index <$(ls .git/objects/pack/pack-C-*.idx)
+		) >expect.raw &&
+		git show-index <$(ls test-*.idx) >actual.raw &&
+
+		cut -d" " -f2 <expect.raw | sort >expect &&
+		cut -d" " -f2 <actual.raw | sort >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success '--stdin-packs is incompatible with --filter' '
+	(
+		cd stdin-packs &&
+		test_must_fail git pack-objects --stdin-packs --stdout \
+			--filter=blob:none </dev/null 2>err &&
+		test_i18ngrep "cannot use --filter with --stdin-packs" err
+	)
+'
+
+test_expect_success '--stdin-packs is incompatible with --revs' '
+	(
+		cd stdin-packs &&
+		test_must_fail git pack-objects --stdin-packs --revs out \
+			</dev/null 2>err &&
+		test_i18ngrep "cannot use internal rev list with --stdin-packs" err
+	)
+'
+
+test_expect_success '--stdin-packs with loose objects' '
+	(
+		cd stdin-packs &&
+
+		PACK_A="$(basename .git/objects/pack/pack-A-*.pack)" &&
+		PACK_B="$(basename .git/objects/pack/pack-B-*.pack)" &&
+		PACK_C="$(basename .git/objects/pack/pack-C-*.pack)" &&
+
+		test_commit D && # loose
+
+		git pack-objects test2 --stdin-packs --unpacked <<-EOF &&
+		$PACK_A
+		^$PACK_B
+		$PACK_C
+		EOF
+
+		(
+			git show-index <$(ls .git/objects/pack/pack-A-*.idx) &&
+			git show-index <$(ls .git/objects/pack/pack-C-*.idx) &&
+			git rev-list --objects --no-object-names \
+				refs/tags/C..refs/tags/D
+
+		) >expect.raw &&
+		ls -la . &&
+		git show-index <$(ls test2-*.idx) >actual.raw &&
+
+		cut -d" " -f2 <expect.raw | sort >expect &&
+		cut -d" " -f2 <actual.raw | sort >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success '--stdin-packs with broken links' '
+	(
+		cd stdin-packs &&
+
+		# make an unreachable object with a bogus parent
+		git cat-file -p HEAD >commit &&
+		sed "s/$(git rev-parse HEAD^)/$(test_oid zero)/" <commit |
+		git hash-object -w -t commit --stdin >in &&
+
+		git pack-objects .git/objects/pack/pack-D <in &&
+
+		PACK_A="$(basename .git/objects/pack/pack-A-*.pack)" &&
+		PACK_B="$(basename .git/objects/pack/pack-B-*.pack)" &&
+		PACK_C="$(basename .git/objects/pack/pack-C-*.pack)" &&
+		PACK_D="$(basename .git/objects/pack/pack-D-*.pack)" &&
+
+		git pack-objects test3 --stdin-packs --unpacked <<-EOF &&
+		$PACK_A
+		^$PACK_B
+		$PACK_C
+		$PACK_D
+		EOF
+
+		(
+			git show-index <$(ls .git/objects/pack/pack-A-*.idx) &&
+			git show-index <$(ls .git/objects/pack/pack-C-*.idx) &&
+			git show-index <$(ls .git/objects/pack/pack-D-*.idx) &&
+			git rev-list --objects --no-object-names \
+				refs/tags/C..refs/tags/D
+		) >expect.raw &&
+		git show-index <$(ls test3-*.idx) >actual.raw &&
+
+		cut -d" " -f2 <expect.raw | sort >expect &&
+		cut -d" " -f2 <actual.raw | sort >actual &&
+		test_cmp expect actual
+	)
+'
+
 test_done
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index edeb6d6..af88f80 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -475,7 +475,7 @@
 
 test_expect_success 'git commit-graph verify' '
 	cd "$TRASH_DIRECTORY/full" &&
-	git rev-parse commits/8 | GIT_TEST_COMMIT_GRAPH_NO_GDAT=1 git commit-graph write --stdin-commits &&
+	git rev-parse commits/8 | git -c commitGraph.generationVersion=1 commit-graph write --stdin-commits &&
 	git commit-graph verify >output &&
 	graph_read_expect 9 extra_edges
 '
diff --git a/t/t5324-split-commit-graph.sh b/t/t5324-split-commit-graph.sh
index 8e90f34..587226e 100755
--- a/t/t5324-split-commit-graph.sh
+++ b/t/t5324-split-commit-graph.sh
@@ -489,7 +489,7 @@
 			test_commit $i &&
 			git branch commits/$i || return 1
 		done &&
-		git commit-graph write --reachable --split &&
+		git -c commitGraph.generationVersion=2 commit-graph write --reachable --split &&
 		graph_read_expect $NUM_FIRST_LAYER_COMMITS &&
 		test_line_count = 1 $graphdir/commit-graph-chain &&
 		for i in $(test_seq $SECOND_LAYER_SEQUENCE_START $SECOND_LAYER_SEQUENCE_END)
@@ -497,7 +497,7 @@
 			test_commit $i &&
 			git branch commits/$i || return 1
 		done &&
-		GIT_TEST_COMMIT_GRAPH_NO_GDAT=1 git commit-graph write --reachable --split=no-merge &&
+		git -c commitGraph.generationVersion=1 commit-graph write --reachable --split=no-merge &&
 		test_line_count = 2 $graphdir/commit-graph-chain &&
 		test-tool read-graph >output &&
 		cat >expect <<-EOF &&
diff --git a/t/t5505-remote.sh b/t/t5505-remote.sh
index 8c462f2..c7b3927 100755
--- a/t/t5505-remote.sh
+++ b/t/t5505-remote.sh
@@ -594,6 +594,7 @@
 		cd add-no-tags &&
 		git init &&
 		git remote add -f --no-tags origin ../one &&
+		grep tagOpt .git/config &&
 		git tag -l some-tag >../test/output &&
 		git tag -l foobar-tag >../test/output &&
 		git config remote.origin.tagopt >>../test/output
@@ -756,6 +757,7 @@
 		cd four &&
 		git config branch.main.pushRemote origin &&
 		git remote rename origin upstream &&
+		grep "pushRemote" .git/config &&
 		test -z "$(git for-each-ref refs/remotes/origin)" &&
 		test "$(git symbolic-ref refs/remotes/upstream/HEAD)" = "refs/remotes/upstream/main" &&
 		test "$(git rev-parse upstream/main)" = "$(git rev-parse main)" &&
@@ -772,6 +774,7 @@
 		cd four.1 &&
 		git config remote.pushDefault origin &&
 		git remote rename origin upstream &&
+		grep pushDefault .git/config &&
 		test "$(git config --local remote.pushDefault)" = "upstream"
 	)
 '
diff --git a/t/t5606-clone-options.sh b/t/t5606-clone-options.sh
index 52e5789..428b0aa 100755
--- a/t/t5606-clone-options.sh
+++ b/t/t5606-clone-options.sh
@@ -104,12 +104,20 @@
 
 '
 
+test_expect_success 'clone does not segfault with --bare and core.bare=false' '
+	test_config_global core.bare false &&
+	git clone --bare parent clone-bare &&
+	echo true >expect &&
+	git -C clone-bare rev-parse --is-bare-repository >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'chooses correct default initial branch name' '
 	GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME= \
 	git -c init.defaultBranch=foo init --bare empty &&
 	test_config -C empty lsrefs.unborn advertise &&
 	GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME= \
-	git -c init.defaultBranch=up clone empty whats-up &&
+	git -c init.defaultBranch=up -c protocol.version=2 clone empty whats-up &&
 	test refs/heads/foo = $(git -C whats-up symbolic-ref HEAD) &&
 	test refs/heads/foo = $(git -C whats-up config branch.foo.merge)
 '
diff --git a/t/t5612-clone-refspec.sh b/t/t5612-clone-refspec.sh
index 6a6af74..3126cfd 100755
--- a/t/t5612-clone-refspec.sh
+++ b/t/t5612-clone-refspec.sh
@@ -97,6 +97,7 @@
 test_expect_success 'clone with --no-tags' '
 	(
 		cd dir_all_no_tags &&
+		grep tagOpt .git/config &&
 		git fetch &&
 		git for-each-ref refs/tags >../actual
 	) &&
diff --git a/t/t6030-bisect-porcelain.sh b/t/t6030-bisect-porcelain.sh
index 0ba5a91..32bb66e 100755
--- a/t/t6030-bisect-porcelain.sh
+++ b/t/t6030-bisect-porcelain.sh
@@ -939,4 +939,16 @@
 	test_path_is_missing ".git/BISECT_START"
 '
 
+test_expect_success 'bisect handles annotated tags' '
+	test_commit commit-one &&
+	git tag -m foo tag-one &&
+	test_commit commit-two &&
+	git tag -m foo tag-two &&
+	git bisect start &&
+	git bisect good tag-one &&
+	git bisect bad tag-two >output &&
+	bad=$(git rev-parse --verify tag-two^{commit}) &&
+	grep "$bad is the first bad commit" output
+'
+
 test_done
diff --git a/t/t6114-keep-packs.sh b/t/t6114-keep-packs.sh
new file mode 100755
index 0000000..9239d8a
--- /dev/null
+++ b/t/t6114-keep-packs.sh
@@ -0,0 +1,69 @@
+#!/bin/sh
+
+test_description='rev-list with .keep packs'
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_commit loose &&
+	test_commit packed &&
+	test_commit kept &&
+
+	KEPT_PACK=$(git pack-objects --revs .git/objects/pack/pack <<-EOF
+	refs/tags/kept
+	^refs/tags/packed
+	EOF
+	) &&
+	MISC_PACK=$(git pack-objects --revs .git/objects/pack/pack <<-EOF
+	refs/tags/packed
+	^refs/tags/loose
+	EOF
+	) &&
+
+	touch .git/objects/pack/pack-$KEPT_PACK.keep
+'
+
+rev_list_objects () {
+	git rev-list "$@" >out &&
+	sort out
+}
+
+idx_objects () {
+	git show-index <$1 >expect-idx &&
+	cut -d" " -f2 <expect-idx | sort
+}
+
+test_expect_success '--no-kept-objects excludes trees and blobs in .keep packs' '
+	rev_list_objects --objects --all --no-object-names >kept &&
+	rev_list_objects --objects --all --no-object-names --no-kept-objects >no-kept &&
+
+	idx_objects .git/objects/pack/pack-$KEPT_PACK.idx >expect &&
+	comm -3 kept no-kept >actual &&
+
+	test_cmp expect actual
+'
+
+test_expect_success '--no-kept-objects excludes kept non-MIDX object' '
+	test_config core.multiPackIndex true &&
+
+	# Create a pack with just the commit object in pack, and do not mark it
+	# as kept (even though it appears in $KEPT_PACK, which does have a .keep
+	# file).
+	MIDX_PACK=$(git pack-objects .git/objects/pack/pack <<-EOF
+	$(git rev-parse kept)
+	EOF
+	) &&
+
+	# Write a MIDX containing all packs, but use the version of the commit
+	# at "kept" in a non-kept pack by touching $MIDX_PACK.
+	touch .git/objects/pack/pack-$MIDX_PACK.pack &&
+	git multi-pack-index write &&
+
+	rev_list_objects --objects --no-object-names --no-kept-objects HEAD >actual &&
+	(
+		idx_objects .git/objects/pack/pack-$MISC_PACK.idx &&
+		git rev-list --objects --no-object-names refs/tags/loose
+	) | sort >expect &&
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/t6600-test-reach.sh b/t/t6600-test-reach.sh
index e2d33a8..3d7a62d 100755
--- a/t/t6600-test-reach.sh
+++ b/t/t6600-test-reach.sh
@@ -55,7 +55,7 @@
 	git show-ref -s commit-5-5 | git commit-graph write --stdin-commits &&
 	mv .git/objects/info/commit-graph commit-graph-half &&
 	chmod u+w commit-graph-half &&
-	GIT_TEST_COMMIT_GRAPH_NO_GDAT=1 git commit-graph write --reachable &&
+	git -c commitGraph.generationVersion=1 commit-graph write --reachable &&
 	mv .git/objects/info/commit-graph commit-graph-no-gdat &&
 	chmod u+w commit-graph-no-gdat &&
 	git config core.commitGraph true
diff --git a/t/t7003-filter-branch.sh b/t/t7003-filter-branch.sh
index 1c55695..1349e5b 100755
--- a/t/t7003-filter-branch.sh
+++ b/t/t7003-filter-branch.sh
@@ -506,4 +506,35 @@
 	! fgrep fatal filter-output
 '
 
+test_expect_success 'filter-branch handles ref deletion' '
+	git switch --orphan empty-commit &&
+	git commit --allow-empty -m "empty commit" &&
+	git tag empty &&
+	git branch to-delete &&
+	git filter-branch -f --prune-empty to-delete >out 2>&1 &&
+	grep "to-delete.*was deleted" out &&
+	test_must_fail git rev-parse --verify to-delete
+'
+
+test_expect_success 'filter-branch handles ref rewrite' '
+	git checkout empty &&
+	test_commit to-drop &&
+	git branch rewrite &&
+	git filter-branch -f \
+		--index-filter "git rm --ignore-unmatch --cached to-drop.t" \
+		 rewrite >out 2>&1 &&
+	grep "rewrite.*was rewritten" out &&
+	! grep -i warning out &&
+	git diff-tree empty rewrite
+'
+
+test_expect_success 'filter-branch handles ancestor rewrite' '
+	test_commit to-exclude &&
+	git branch ancestor &&
+	git filter-branch -f ancestor -- :^to-exclude.t >out 2>&1 &&
+	grep "ancestor.*was rewritten" out &&
+	! grep -i warning out &&
+	git diff-tree HEAD^ ancestor
+'
+
 test_done
diff --git a/t/t7007-show.sh b/t/t7007-show.sh
index 42d3db6..d6cc69e 100755
--- a/t/t7007-show.sh
+++ b/t/t7007-show.sh
@@ -38,6 +38,45 @@
 	test_cmp expect actual.filtered
 '
 
+test_expect_success 'showing a tree' '
+	cat >expected <<-EOF &&
+	tree main1:
+
+	main1.t
+	EOF
+	git show main1: >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'showing two trees' '
+	cat >expected <<-EOF &&
+	tree main1^{tree}
+
+	main1.t
+
+	tree main2^{tree}
+
+	main1.t
+	main2.t
+	EOF
+	git show main1^{tree} main2^{tree} >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'showing a trees is not recursive' '
+	git worktree add not-recursive main1 &&
+	mkdir not-recursive/a &&
+	test_commit -C not-recursive a/file &&
+	cat >expected <<-EOF &&
+	tree HEAD^{tree}
+
+	a/
+	main1.t
+	EOF
+	git -C not-recursive show HEAD^{tree} >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'showing a range walks (linear)' '
 	cat >expect <<-EOF &&
 	commit $(git rev-parse main3)
diff --git a/t/t7500-commit-template-squash-signoff.sh b/t/t7500-commit-template-squash-signoff.sh
index e41ac18..9092db5 100755
--- a/t/t7500-commit-template-squash-signoff.sh
+++ b/t/t7500-commit-template-squash-signoff.sh
@@ -9,6 +9,8 @@
 
 . ./test-lib.sh
 
+. "$TEST_DIRECTORY"/lib-rebase.sh
+
 commit_msg_is () {
 	expect=commit_msg_is.expect
 	actual=commit_msg_is.actual
@@ -279,6 +281,163 @@
 
 extra"
 '
+get_commit_msg () {
+	rev="$1" &&
+	git log -1 --pretty=format:"%B" "$rev"
+}
+
+test_expect_success 'commit --fixup=amend: creates amend! commit' '
+	commit_for_rebase_autosquash_setup &&
+	cat >expected <<-EOF &&
+	amend! $(git log -1 --format=%s HEAD~)
+
+	$(get_commit_msg HEAD~)
+
+	edited
+	EOF
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_AMEND="edited" \
+			git commit --fixup=amend:HEAD~
+	) &&
+	get_commit_msg HEAD >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success '--fixup=amend: --only ignores staged changes' '
+	commit_for_rebase_autosquash_setup &&
+	cat >expected <<-EOF &&
+	amend! $(git log -1 --format=%s HEAD~)
+
+	$(get_commit_msg HEAD~)
+
+	edited
+	EOF
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_AMEND="edited" \
+			git commit --fixup=amend:HEAD~ --only
+	) &&
+	get_commit_msg HEAD >actual &&
+	test_cmp expected actual &&
+	test_cmp_rev HEAD@{1}^{tree} HEAD^{tree} &&
+	test_cmp_rev HEAD@{1} HEAD^ &&
+	test_expect_code 1 git diff --cached --exit-code &&
+	git cat-file blob :foo >actual &&
+	test_cmp foo actual
+'
+
+test_expect_success '--fixup=reword: ignores staged changes' '
+	commit_for_rebase_autosquash_setup &&
+	cat >expected <<-EOF &&
+	amend! $(git log -1 --format=%s HEAD~)
+
+	$(get_commit_msg HEAD~)
+
+	edited
+	EOF
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_AMEND="edited" \
+			git commit --fixup=reword:HEAD~
+	) &&
+	get_commit_msg HEAD >actual &&
+	test_cmp expected actual &&
+	test_cmp_rev HEAD@{1}^{tree} HEAD^{tree} &&
+	test_cmp_rev HEAD@{1} HEAD^ &&
+	test_expect_code 1 git diff --cached --exit-code &&
+	git cat-file blob :foo >actual &&
+	test_cmp foo actual
+'
+
+test_expect_success '--fixup=reword: error out with -m option' '
+	commit_for_rebase_autosquash_setup &&
+	echo "fatal: cannot combine -m with --fixup:reword" >expect &&
+	test_must_fail git commit --fixup=reword:HEAD~ -m "reword commit message" 2>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--fixup=amend: error out with -m option' '
+	commit_for_rebase_autosquash_setup &&
+	echo "fatal: cannot combine -m with --fixup:amend" >expect &&
+	test_must_fail git commit --fixup=amend:HEAD~ -m "amend commit message" 2>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'consecutive amend! commits remove amend! line from commit msg body' '
+	commit_for_rebase_autosquash_setup &&
+	cat >expected <<-EOF &&
+	amend! amend! $(git log -1 --format=%s HEAD~)
+
+	$(get_commit_msg HEAD~)
+
+	edited 1
+
+	edited 2
+	EOF
+	echo "reword new commit message" >actual &&
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_AMEND="edited 1" \
+			git commit --fixup=reword:HEAD~ &&
+		FAKE_COMMIT_AMEND="edited 2" \
+			git commit --fixup=reword:HEAD
+	) &&
+	get_commit_msg HEAD >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'deny to create amend! commit if its commit msg body is empty' '
+	commit_for_rebase_autosquash_setup &&
+	echo "Aborting commit due to empty commit message body." >expected &&
+	(
+		set_fake_editor &&
+		test_must_fail env FAKE_COMMIT_MESSAGE="amend! target message subject line" \
+			git commit --fixup=amend:HEAD~ 2>actual
+	) &&
+	test_cmp expected actual
+'
+
+test_expect_success 'amend! commit allows empty commit msg body with --allow-empty-message' '
+	commit_for_rebase_autosquash_setup &&
+	cat >expected <<-EOF &&
+	amend! $(git log -1 --format=%s HEAD~)
+	EOF
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_MESSAGE="amend! target message subject line" \
+			git commit --fixup=amend:HEAD~ --allow-empty-message &&
+		get_commit_msg HEAD >actual
+	) &&
+	test_cmp expected actual
+'
+
+test_fixup_reword_opt () {
+	test_expect_success C_LOCALE_OUTPUT "--fixup=reword: incompatible with $1" "
+		echo 'fatal: reword option of --fixup is mutually exclusive with'\
+			'--patch/--interactive/--all/--include/--only' >expect &&
+		test_must_fail git commit --fixup=reword:HEAD~ $1 2>actual &&
+		test_cmp expect actual
+	"
+}
+
+for opt in --all --include --only --interactive --patch
+do
+	test_fixup_reword_opt $opt
+done
+
+test_expect_success '--fixup=reword: give error with pathsec' '
+	commit_for_rebase_autosquash_setup &&
+	echo "fatal: cannot combine reword option of --fixup with path '\''foo'\''" >expect &&
+	test_must_fail git commit --fixup=reword:HEAD~ -- foo 2>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--fixup=reword: -F give error message' '
+	echo "fatal: Only one of -c/-C/-F/--fixup can be used." >expect &&
+	test_must_fail git commit --fixup=reword:HEAD~ -F msg  2>actual &&
+	test_cmp expect actual
+'
 
 test_expect_success 'commit --squash works with -F' '
 	commit_for_rebase_autosquash_setup &&
diff --git a/t/t7502-commit-porcelain.sh b/t/t7502-commit-porcelain.sh
index 6396897..38a532d 100755
--- a/t/t7502-commit-porcelain.sh
+++ b/t/t7502-commit-porcelain.sh
@@ -38,6 +38,16 @@
 	test_cmp exp act
 }
 
+trailer_commit_base () {
+	echo "fun" >>file &&
+	git add file &&
+	git commit -s --trailer "Signed-off-by=C1 E1 " \
+		--trailer "Helped-by:C2 E2 " \
+		--trailer "Reported-by=C3 E3" \
+		--trailer "Mentored-by:C4 E4" \
+		-m "hello"
+}
+
 test_expect_success 'output summary format' '
 
 	echo new >file1 &&
@@ -154,6 +164,308 @@
 
 '
 
+test_expect_success 'commit --trailer with "="' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	EOF
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d" commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and "replace" as ifexists' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	Helped-by: C3 E3
+	EOF
+	git -c trailer.ifexists="replace" \
+		commit --trailer "Mentored-by: C4 E4" \
+		 --trailer "Helped-by: C3 E3" \
+		--amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d"  commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and "add" as ifexists' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	EOF
+	git -c trailer.ifexists="add" \
+		commit --trailer "Reported-by: C3 E3" \
+		--trailer "Mentored-by: C4 E4" \
+		--amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d"  commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and "donothing" as ifexists' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	Reviewed-by: C6 E6
+	EOF
+	git -c trailer.ifexists="donothing" \
+		commit --trailer "Mentored-by: C5 E5" \
+		--trailer "Reviewed-by: C6 E6" \
+		--amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d"  commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and "addIfDifferent" as ifexists' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	Mentored-by: C5 E5
+	EOF
+	git -c trailer.ifexists="addIfDifferent" \
+		commit --trailer "Reported-by: C3 E3" \
+		--trailer "Mentored-by: C5 E5" \
+		--amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d"  commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and "addIfDifferentNeighbor" as ifexists' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	Reported-by: C3 E3
+	EOF
+	git -c trailer.ifexists="addIfDifferentNeighbor" \
+		commit --trailer "Mentored-by: C4 E4" \
+		--trailer "Reported-by: C3 E3" \
+		--amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d"  commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and "end" as where' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	EOF
+	git -c trailer.where="end" \
+		commit --trailer "Reported-by: C3 E3" \
+		--trailer "Mentored-by: C4 E4" \
+		--amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d" commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and "start" as where' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C1 E1
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	EOF
+	git -c trailer.where="start" \
+		commit --trailer "Signed-off-by: C O Mitter <committer@example.com>" \
+		--trailer "Signed-off-by: C1 E1" \
+		--amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d" commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and "after" as where' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	Mentored-by: C5 E5
+	EOF
+	git -c trailer.where="after" \
+		commit --trailer "Mentored-by: C4 E4" \
+		--trailer "Mentored-by: C5 E5" \
+		--amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d" commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and "before" as where' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Reported-by: C3 E3
+	Mentored-by: C2 E2
+	Mentored-by: C3 E3
+	Mentored-by: C4 E4
+	EOF
+	git -c trailer.where="before" \
+		commit --trailer "Mentored-by: C3 E3" \
+		--trailer "Mentored-by: C2 E2" \
+		--amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d" commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and "donothing" as ifmissing' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	Helped-by: C5 E5
+	EOF
+	git -c trailer.ifmissing="donothing" \
+		commit --trailer "Helped-by: C5 E5" \
+		--trailer "Based-by: C6 E6" \
+		--amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d" commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and "add" as ifmissing' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Reported-by: C3 E3
+	Mentored-by: C4 E4
+	Helped-by: C5 E5
+	Based-by: C6 E6
+	EOF
+	git -c trailer.ifmissing="add" \
+		commit --trailer "Helped-by: C5 E5" \
+		--trailer "Based-by: C6 E6" \
+		--amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d" commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c ack.key ' '
+	echo "fun" >>file1 &&
+	git add file1 &&
+	cat >expected <<-\EOF &&
+		hello
+
+		Acked-by: Peff
+	EOF
+	git -c trailer.ack.key="Acked-by" \
+		commit --trailer "ack = Peff" -m "hello" &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d" commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and ":=#" as separators' '
+	echo "fun" >>file1 &&
+	git add file1 &&
+	cat >expected <<-\EOF &&
+		I hate bug
+
+		Bug #42
+	EOF
+	git -c trailer.separators=":=#" \
+		-c trailer.bug.key="Bug #" \
+		commit --trailer "bug = 42" -m "I hate bug" &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d" commit.msg >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit --trailer with -c and command' '
+	trailer_commit_base &&
+	cat >expected <<-\EOF &&
+	hello
+
+	Signed-off-by: C O Mitter <committer@example.com>
+	Signed-off-by: C1 E1
+	Helped-by: C2 E2
+	Mentored-by: C4 E4
+	Reported-by: A U Thor <author@example.com>
+	EOF
+	git -c trailer.report.key="Reported-by: " \
+		-c trailer.report.ifexists="replace" \
+		-c trailer.report.command="NAME=\"\$ARG\"; test -n \"\$NAME\" && \
+		git log --author=\"\$NAME\" -1 --format=\"format:%aN <%aE>\" || true" \
+		commit --trailer "report = author" --amend &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -e "1,/^\$/d" commit.msg >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'multiple -m' '
 
 	>negative &&
diff --git a/t/t7703-repack-geometric.sh b/t/t7703-repack-geometric.sh
new file mode 100755
index 0000000..5ccaa44
--- /dev/null
+++ b/t/t7703-repack-geometric.sh
@@ -0,0 +1,183 @@
+#!/bin/sh
+
+test_description='git repack --geometric works correctly'
+
+. ./test-lib.sh
+
+GIT_TEST_MULTI_PACK_INDEX=0
+
+objdir=.git/objects
+midx=$objdir/pack/multi-pack-index
+
+test_expect_success '--geometric with no packs' '
+	git init geometric &&
+	test_when_finished "rm -fr geometric" &&
+	(
+		cd geometric &&
+
+		git repack --geometric 2 >out &&
+		test_i18ngrep "Nothing new to pack" out
+	)
+'
+
+test_expect_success '--geometric with one pack' '
+	git init geometric &&
+	test_when_finished "rm -fr geometric" &&
+	(
+		cd geometric &&
+
+		test_commit "base" &&
+		git repack -d &&
+
+		git repack --geometric 2 >out &&
+
+		test_i18ngrep "Nothing new to pack" out
+	)
+'
+
+test_expect_success '--geometric with an intact progression' '
+	git init geometric &&
+	test_when_finished "rm -fr geometric" &&
+	(
+		cd geometric &&
+
+		# These packs already form a geometric progression.
+		test_commit_bulk --start=1 1 && # 3 objects
+		test_commit_bulk --start=2 2 && # 6 objects
+		test_commit_bulk --start=4 4 && # 12 objects
+
+		find $objdir/pack -name "*.pack" | sort >expect &&
+		git repack --geometric 2 -d &&
+		find $objdir/pack -name "*.pack" | sort >actual &&
+
+		test_cmp expect actual
+	)
+'
+
+test_expect_success '--geometric with loose objects' '
+	git init geometric &&
+	test_when_finished "rm -fr geometric" &&
+	(
+		cd geometric &&
+
+		# These packs already form a geometric progression.
+		test_commit_bulk --start=1 1 && # 3 objects
+		test_commit_bulk --start=2 2 && # 6 objects
+		# The loose objects are packed together, breaking the
+		# progression.
+		test_commit loose && # 3 objects
+
+		find $objdir/pack -name "*.pack" | sort >before &&
+		git repack --geometric 2 -d &&
+		find $objdir/pack -name "*.pack" | sort >after &&
+
+		comm -13 before after >new &&
+		comm -23 before after >removed &&
+
+		test_line_count = 1 new &&
+		test_must_be_empty removed &&
+
+		git repack --geometric 2 -d &&
+		find $objdir/pack -name "*.pack" | sort >after &&
+
+		# The progression (3, 3, 6) is combined into one new pack.
+		test_line_count = 1 after
+	)
+'
+
+test_expect_success '--geometric with small-pack rollup' '
+	git init geometric &&
+	test_when_finished "rm -fr geometric" &&
+	(
+		cd geometric &&
+
+		test_commit_bulk --start=1 1 && # 3 objects
+		test_commit_bulk --start=2 1 && # 3 objects
+		find $objdir/pack -name "*.pack" | sort >small &&
+		test_commit_bulk --start=3 4 && # 12 objects
+		test_commit_bulk --start=7 8 && # 24 objects
+		find $objdir/pack -name "*.pack" | sort >before &&
+
+		git repack --geometric 2 -d &&
+
+		# Three packs in total; two of the existing large ones, and one
+		# new one.
+		find $objdir/pack -name "*.pack" | sort >after &&
+		test_line_count = 3 after &&
+		comm -3 small before | tr -d "\t" >large &&
+		grep -qFf large after
+	)
+'
+
+test_expect_success '--geometric with small- and large-pack rollup' '
+	git init geometric &&
+	test_when_finished "rm -fr geometric" &&
+	(
+		cd geometric &&
+
+		# size(small1) + size(small2) > size(medium) / 2
+		test_commit_bulk --start=1 1 && # 3 objects
+		test_commit_bulk --start=2 1 && # 3 objects
+		test_commit_bulk --start=2 3 && # 7 objects
+		test_commit_bulk --start=6 9 && # 27 objects &&
+
+		find $objdir/pack -name "*.pack" | sort >before &&
+
+		git repack --geometric 2 -d &&
+
+		find $objdir/pack -name "*.pack" | sort >after &&
+		comm -12 before after >untouched &&
+
+		# Two packs in total; the largest pack from before running "git
+		# repack", and one new one.
+		test_line_count = 1 untouched &&
+		test_line_count = 2 after
+	)
+'
+
+test_expect_success '--geometric ignores kept packs' '
+	git init geometric &&
+	test_when_finished "rm -fr geometric" &&
+	(
+		cd geometric &&
+
+		test_commit kept && # 3 objects
+		test_commit pack && # 3 objects
+
+		KEPT=$(git pack-objects --revs $objdir/pack/pack <<-EOF
+		refs/tags/kept
+		EOF
+		) &&
+		PACK=$(git pack-objects --revs $objdir/pack/pack <<-EOF
+		refs/tags/pack
+		^refs/tags/kept
+		EOF
+		) &&
+
+		# neither pack contains more than twice the number of objects in
+		# the other, so they should be combined. but, marking one as
+		# .kept on disk will "freeze" it, so the pack structure should
+		# remain unchanged.
+		touch $objdir/pack/pack-$KEPT.keep &&
+
+		find $objdir/pack -name "*.pack" | sort >before &&
+		git repack --geometric 2 -d &&
+		find $objdir/pack -name "*.pack" | sort >after &&
+
+		# both packs should still exist
+		test_path_is_file $objdir/pack/pack-$KEPT.pack &&
+		test_path_is_file $objdir/pack/pack-$PACK.pack &&
+
+		# and no new packs should be created
+		test_cmp before after &&
+
+		# Passing --pack-kept-objects causes packs with a .keep file to
+		# be repacked, too.
+		git repack --geometric 2 -d --pack-kept-objects &&
+
+		find $objdir/pack -name "*.pack" >after &&
+		test_line_count = 1 after
+	)
+'
+
+test_done
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index edfaa9a..5830733 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -969,7 +969,8 @@
 	"
 done
 
-test_expect_success !PTHREADS 'grep --threads=N or pack.threads=N warns when no pthreads' '
+test_expect_success !PTHREADS,!FAIL_PREREQS \
+	'grep --threads=N or pack.threads=N warns when no pthreads' '
 	git grep --threads=2 Hello hello_world 2>err &&
 	grep ^warning: err >warnings &&
 	test_line_count = 1 warnings &&
diff --git a/t/t9001-send-email.sh b/t/t9001-send-email.sh
index 4eee9c3..1a1caf8 100755
--- a/t/t9001-send-email.sh
+++ b/t/t9001-send-email.sh
@@ -513,6 +513,38 @@
 
 done
 
+test_expect_success $PREREQ "--validate respects relative core.hooksPath path" '
+	clean_fake_sendmail &&
+	mkdir my-hooks &&
+	test_when_finished "rm my-hooks.ran" &&
+	write_script my-hooks/sendemail-validate <<-\EOF &&
+	>my-hooks.ran
+	exit 1
+	EOF
+	test_config core.hooksPath "my-hooks" &&
+	test_must_fail git send-email \
+		--from="Example <nobody@example.com>" \
+		--to=nobody@example.com \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		--validate \
+		longline.patch 2>err &&
+	test_path_is_file my-hooks.ran &&
+	grep "rejected by sendemail-validate" err
+'
+
+test_expect_success $PREREQ "--validate respects absolute core.hooksPath path" '
+	test_config core.hooksPath "$(pwd)/my-hooks" &&
+	test_when_finished "rm my-hooks.ran" &&
+	test_must_fail git send-email \
+		--from="Example <nobody@example.com>" \
+		--to=nobody@example.com \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		--validate \
+		longline.patch 2>err &&
+	test_path_is_file my-hooks.ran &&
+	grep "rejected by sendemail-validate" err
+'
+
 for enc in 7bit 8bit quoted-printable base64
 do
 	test_expect_success $PREREQ "--transfer-encoding=$enc produces correct header" '
diff --git a/t/t9801-git-p4-branch.sh b/t/t9801-git-p4-branch.sh
index 56e6469..ff94c3f 100755
--- a/t/t9801-git-p4-branch.sh
+++ b/t/t9801-git-p4-branch.sh
@@ -203,19 +203,19 @@
 		git p4 clone --dest=. --detect-branches //depot@all &&
 		git log --all --graph --decorate --stat &&
 		git reset --hard p4/depot/branch1 &&
-		test -f file1 &&
-		test -f file2 &&
-		test -f file3 &&
+		test_path_is_file file1 &&
+		test_path_is_file file2 &&
+		test_path_is_file file3 &&
 		grep update file2 &&
 		git reset --hard p4/depot/branch2 &&
-		test -f file1 &&
-		test -f file2 &&
+		test_path_is_file file1 &&
+		test_path_is_file file2 &&
 		test ! -f file3 &&
 		! grep update file2 &&
 		git reset --hard p4/depot/branch3 &&
-		test -f file1 &&
-		test -f file2 &&
-		test -f file3 &&
+		test_path_is_file file1 &&
+		test_path_is_file file2 &&
+		test_path_is_file file3 &&
 		grep update file2 &&
 		cd "$cli" &&
 		cd branch1 &&
@@ -606,22 +606,22 @@
 		git p4 clone --dest=. --use-client-spec  --detect-branches //depot@all &&
 		git log --all --graph --decorate --stat &&
 		git reset --hard p4/depot/branch1 &&
-		test -f file1 &&
-		test -f file2 &&
-		test -f file3 &&
-		test -f sub_file1 &&
+		test_path_is_file file1 &&
+		test_path_is_file file2 &&
+		test_path_is_file file3 &&
+		test_path_is_file sub_file1 &&
 		grep update file2 &&
 		git reset --hard p4/depot/branch2 &&
-		test -f file1 &&
-		test -f file2 &&
+		test_path_is_file file1 &&
+		test_path_is_file file2 &&
 		test ! -f file3 &&
-		test -f sub_file1 &&
+		test_path_is_file sub_file1 &&
 		! grep update file2 &&
 		git reset --hard p4/depot/branch3 &&
-		test -f file1 &&
-		test -f file2 &&
-		test -f file3 &&
-		test -f sub_file1 &&
+		test_path_is_file file1 &&
+		test_path_is_file file2 &&
+		test_path_is_file file3 &&
+		test_path_is_file sub_file1 &&
 		grep update file2 &&
 		cd "$cli" &&
 		cd branch1 &&
diff --git a/trailer.c b/trailer.c
index 249ed61..be4e972 100644
--- a/trailer.c
+++ b/trailer.c
@@ -174,7 +174,7 @@
 
 static struct trailer_item *trailer_from_arg(struct arg_item *arg_tok)
 {
-	struct trailer_item *new_item = xcalloc(sizeof(*new_item), 1);
+	struct trailer_item *new_item = xcalloc(1, sizeof(*new_item));
 	new_item->token = arg_tok->token;
 	new_item->value = arg_tok->value;
 	arg_tok->token = arg_tok->value = NULL;
@@ -445,7 +445,7 @@
 	}
 
 	/* Item does not already exists, create it */
-	item = xcalloc(sizeof(*item), 1);
+	CALLOC_ARRAY(item, 1);
 	duplicate_conf(&item->conf, &default_conf_info);
 	item->conf.name = xstrdup(name);
 
@@ -664,7 +664,7 @@
 static struct trailer_item *add_trailer_item(struct list_head *head, char *tok,
 					     char *val)
 {
-	struct trailer_item *new_item = xcalloc(sizeof(*new_item), 1);
+	struct trailer_item *new_item = xcalloc(1, sizeof(*new_item));
 	new_item->token = tok;
 	new_item->value = val;
 	list_add_tail(&new_item->list, head);
@@ -675,7 +675,7 @@
 			 const struct conf_info *conf,
 			 const struct new_trailer_item *new_trailer_item)
 {
-	struct arg_item *new_item = xcalloc(sizeof(*new_item), 1);
+	struct arg_item *new_item = xcalloc(1, sizeof(*new_item));
 	new_item->token = tok;
 	new_item->value = val;
 	duplicate_conf(&new_item->conf, conf);
diff --git a/transport-helper.c b/transport-helper.c
index 49b7fb4..4cd7636 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -745,13 +745,13 @@
 			die(_("'option' without a matching 'ok/error' directive"));
 		if (state->new_report) {
 			if (!state->hint->report) {
-				state->hint->report = xcalloc(1, sizeof(struct ref_push_report));
+				CALLOC_ARRAY(state->hint->report, 1);
 				state->report = state->hint->report;
 			} else {
 				state->report = state->hint->report;
 				while (state->report->next)
 					state->report = state->report->next;
-				state->report->next = xcalloc(1, sizeof(struct ref_push_report));
+				CALLOC_ARRAY(state->report->next, 1);
 				state->report = state->report->next;
 			}
 			state->new_report = 0;
diff --git a/transport.c b/transport.c
index b13fab5..eb4b2d4 100644
--- a/transport.c
+++ b/transport.c
@@ -871,7 +871,7 @@
 		BUG("taking over transport requires non-NULL "
 		    "smart_options field.");
 
-	data = xcalloc(1, sizeof(*data));
+	CALLOC_ARRAY(data, 1);
 	data->options = *transport->smart_options;
 	data->conn = child;
 	data->fd[0] = data->conn->out;
@@ -1452,6 +1452,8 @@
 	int ret = 0;
 	if (transport->vtable->disconnect)
 		ret = transport->vtable->disconnect(transport);
+	if (transport->got_remote_refs)
+		free_refs((void *)transport->remote_refs);
 	free(transport);
 	return ret;
 }
diff --git a/tree.c b/tree.c
index a524798..410e3b4 100644
--- a/tree.c
+++ b/tree.c
@@ -11,58 +11,10 @@
 
 const char *tree_type = "tree";
 
-static int read_one_entry_opt(struct index_state *istate,
-			      const struct object_id *oid,
-			      const char *base, int baselen,
-			      const char *pathname,
-			      unsigned mode, int stage, int opt)
-{
-	int len;
-	struct cache_entry *ce;
-
-	if (S_ISDIR(mode))
-		return READ_TREE_RECURSIVE;
-
-	len = strlen(pathname);
-	ce = make_empty_cache_entry(istate, baselen + len);
-
-	ce->ce_mode = create_ce_mode(mode);
-	ce->ce_flags = create_ce_flags(stage);
-	ce->ce_namelen = baselen + len;
-	memcpy(ce->name, base, baselen);
-	memcpy(ce->name + baselen, pathname, len+1);
-	oidcpy(&ce->oid, oid);
-	return add_index_entry(istate, ce, opt);
-}
-
-static int read_one_entry(const struct object_id *oid, struct strbuf *base,
-			  const char *pathname, unsigned mode, int stage,
-			  void *context)
-{
-	struct index_state *istate = context;
-	return read_one_entry_opt(istate, oid, base->buf, base->len, pathname,
-				  mode, stage,
-				  ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
-}
-
-/*
- * This is used when the caller knows there is no existing entries at
- * the stage that will conflict with the entry being added.
- */
-static int read_one_entry_quick(const struct object_id *oid, struct strbuf *base,
-				const char *pathname, unsigned mode, int stage,
-				void *context)
-{
-	struct index_state *istate = context;
-	return read_one_entry_opt(istate, oid, base->buf, base->len, pathname,
-				  mode, stage,
-				  ADD_CACHE_JUST_APPEND);
-}
-
-static int read_tree_1(struct repository *r,
-		       struct tree *tree, struct strbuf *base,
-		       int stage, const struct pathspec *pathspec,
-		       read_tree_fn_t fn, void *context)
+int read_tree_at(struct repository *r,
+		 struct tree *tree, struct strbuf *base,
+		 const struct pathspec *pathspec,
+		 read_tree_fn_t fn, void *context)
 {
 	struct tree_desc desc;
 	struct name_entry entry;
@@ -86,7 +38,7 @@
 		}
 
 		switch (fn(&entry.oid, base,
-			   entry.path, entry.mode, stage, context)) {
+			   entry.path, entry.mode, context)) {
 		case 0:
 			continue;
 		case READ_TREE_RECURSIVE:
@@ -119,9 +71,9 @@
 		len = tree_entry_len(&entry);
 		strbuf_add(base, entry.path, len);
 		strbuf_addch(base, '/');
-		retval = read_tree_1(r, lookup_tree(r, &oid),
-				     base, stage, pathspec,
-				     fn, context);
+		retval = read_tree_at(r, lookup_tree(r, &oid),
+				      base, pathspec,
+				      fn, context);
 		strbuf_setlen(base, oldlen);
 		if (retval)
 			return -1;
@@ -129,17 +81,13 @@
 	return 0;
 }
 
-int read_tree_recursive(struct repository *r,
-			struct tree *tree,
-			const char *base, int baselen,
-			int stage, const struct pathspec *pathspec,
-			read_tree_fn_t fn, void *context)
+int read_tree(struct repository *r,
+	      struct tree *tree,
+	      const struct pathspec *pathspec,
+	      read_tree_fn_t fn, void *context)
 {
 	struct strbuf sb = STRBUF_INIT;
-	int ret;
-
-	strbuf_add(&sb, base, baselen);
-	ret = read_tree_1(r, tree, &sb, stage, pathspec, fn, context);
+	int ret = read_tree_at(r, tree, &sb, pathspec, fn, context);
 	strbuf_release(&sb);
 	return ret;
 }
@@ -154,47 +102,6 @@
 				  ce2->name, ce2->ce_namelen, ce_stage(ce2));
 }
 
-int read_tree(struct repository *r, struct tree *tree, int stage,
-	      struct pathspec *match, struct index_state *istate)
-{
-	read_tree_fn_t fn = NULL;
-	int i, err;
-
-	/*
-	 * Currently the only existing callers of this function all
-	 * call it with stage=1 and after making sure there is nothing
-	 * at that stage; we could always use read_one_entry_quick().
-	 *
-	 * But when we decide to straighten out git-read-tree not to
-	 * use unpack_trees() in some cases, this will probably start
-	 * to matter.
-	 */
-
-	/*
-	 * See if we have cache entry at the stage.  If so,
-	 * do it the original slow way, otherwise, append and then
-	 * sort at the end.
-	 */
-	for (i = 0; !fn && i < istate->cache_nr; i++) {
-		const struct cache_entry *ce = istate->cache[i];
-		if (ce_stage(ce) == stage)
-			fn = read_one_entry;
-	}
-
-	if (!fn)
-		fn = read_one_entry_quick;
-	err = read_tree_recursive(r, tree, "", 0, stage, match, fn, istate);
-	if (fn == read_one_entry || err)
-		return err;
-
-	/*
-	 * Sort the cache entry -- we need to nuke the cache tree, though.
-	 */
-	cache_tree_free(&istate->cache_tree);
-	QSORT(istate->cache, istate->cache_nr, cmp_cache_name_compare);
-	return 0;
-}
-
 struct tree *lookup_tree(struct repository *r, const struct object_id *oid)
 {
 	struct object *obj = lookup_object(r, oid);
diff --git a/tree.h b/tree.h
index 3eb0484..6efff00 100644
--- a/tree.h
+++ b/tree.h
@@ -31,16 +31,16 @@
 int cmp_cache_name_compare(const void *a_, const void *b_);
 
 #define READ_TREE_RECURSIVE 1
-typedef int (*read_tree_fn_t)(const struct object_id *, struct strbuf *, const char *, unsigned int, int, void *);
+typedef int (*read_tree_fn_t)(const struct object_id *, struct strbuf *, const char *, unsigned int, void *);
 
-int read_tree_recursive(struct repository *r,
-			struct tree *tree,
-			const char *base, int baselen,
-			int stage, const struct pathspec *pathspec,
-			read_tree_fn_t fn, void *context);
+int read_tree_at(struct repository *r,
+		 struct tree *tree, struct strbuf *base,
+		 const struct pathspec *pathspec,
+		 read_tree_fn_t fn, void *context);
 
-int read_tree(struct repository *r, struct tree *tree,
-	      int stage, struct pathspec *pathspec,
-	      struct index_state *istate);
+int read_tree(struct repository *r,
+	      struct tree *tree,
+	      const struct pathspec *pathspec,
+	      read_tree_fn_t fn, void *context);
 
 #endif /* TREE_H */
diff --git a/unix-socket.c b/unix-socket.c
index 19ed48b..e0be1ba 100644
--- a/unix-socket.c
+++ b/unix-socket.c
@@ -1,13 +1,7 @@
 #include "cache.h"
 #include "unix-socket.h"
 
-static int unix_stream_socket(void)
-{
-	int fd = socket(AF_UNIX, SOCK_STREAM, 0);
-	if (fd < 0)
-		die_errno("unable to create socket");
-	return fd;
-}
+#define DEFAULT_UNIX_STREAM_LISTEN_BACKLOG (5)
 
 static int chdir_len(const char *orig, int len)
 {
@@ -36,16 +30,23 @@
 }
 
 static int unix_sockaddr_init(struct sockaddr_un *sa, const char *path,
-			      struct unix_sockaddr_context *ctx)
+			      struct unix_sockaddr_context *ctx,
+			      int disallow_chdir)
 {
 	int size = strlen(path) + 1;
 
 	ctx->orig_dir = NULL;
 	if (size > sizeof(sa->sun_path)) {
-		const char *slash = find_last_dir_sep(path);
+		const char *slash;
 		const char *dir;
 		struct strbuf cwd = STRBUF_INIT;
 
+		if (disallow_chdir) {
+			errno = ENAMETOOLONG;
+			return -1;
+		}
+
+		slash = find_last_dir_sep(path);
 		if (!slash) {
 			errno = ENAMETOOLONG;
 			return -1;
@@ -71,15 +72,18 @@
 	return 0;
 }
 
-int unix_stream_connect(const char *path)
+int unix_stream_connect(const char *path, int disallow_chdir)
 {
-	int fd, saved_errno;
+	int fd = -1, saved_errno;
 	struct sockaddr_un sa;
 	struct unix_sockaddr_context ctx;
 
-	if (unix_sockaddr_init(&sa, path, &ctx) < 0)
+	if (unix_sockaddr_init(&sa, path, &ctx, disallow_chdir) < 0)
 		return -1;
-	fd = unix_stream_socket();
+	fd = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (fd < 0)
+		goto fail;
+
 	if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
 		goto fail;
 	unix_sockaddr_cleanup(&ctx);
@@ -87,28 +91,36 @@
 
 fail:
 	saved_errno = errno;
+	if (fd != -1)
+		close(fd);
 	unix_sockaddr_cleanup(&ctx);
-	close(fd);
 	errno = saved_errno;
 	return -1;
 }
 
-int unix_stream_listen(const char *path)
+int unix_stream_listen(const char *path,
+		       const struct unix_stream_listen_opts *opts)
 {
-	int fd, saved_errno;
+	int fd = -1, saved_errno;
+	int backlog;
 	struct sockaddr_un sa;
 	struct unix_sockaddr_context ctx;
 
 	unlink(path);
 
-	if (unix_sockaddr_init(&sa, path, &ctx) < 0)
+	if (unix_sockaddr_init(&sa, path, &ctx, opts->disallow_chdir) < 0)
 		return -1;
-	fd = unix_stream_socket();
+	fd = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (fd < 0)
+		goto fail;
 
 	if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
 		goto fail;
 
-	if (listen(fd, 5) < 0)
+	backlog = opts->listen_backlog_size;
+	if (backlog <= 0)
+		backlog = DEFAULT_UNIX_STREAM_LISTEN_BACKLOG;
+	if (listen(fd, backlog) < 0)
 		goto fail;
 
 	unix_sockaddr_cleanup(&ctx);
@@ -116,8 +128,9 @@
 
 fail:
 	saved_errno = errno;
+	if (fd != -1)
+		close(fd);
 	unix_sockaddr_cleanup(&ctx);
-	close(fd);
 	errno = saved_errno;
 	return -1;
 }
diff --git a/unix-socket.h b/unix-socket.h
index e271aee..8542cdd 100644
--- a/unix-socket.h
+++ b/unix-socket.h
@@ -1,7 +1,15 @@
 #ifndef UNIX_SOCKET_H
 #define UNIX_SOCKET_H
 
-int unix_stream_connect(const char *path);
-int unix_stream_listen(const char *path);
+struct unix_stream_listen_opts {
+	int listen_backlog_size;
+	unsigned int disallow_chdir:1;
+};
+
+#define UNIX_STREAM_LISTEN_OPTS_INIT { 0 }
+
+int unix_stream_connect(const char *path, int disallow_chdir);
+int unix_stream_listen(const char *path,
+		       const struct unix_stream_listen_opts *opts);
 
 #endif /* UNIX_SOCKET_H */
diff --git a/unix-stream-server.c b/unix-stream-server.c
new file mode 100644
index 0000000..efa2a20
--- /dev/null
+++ b/unix-stream-server.c
@@ -0,0 +1,125 @@
+#include "cache.h"
+#include "lockfile.h"
+#include "unix-socket.h"
+#include "unix-stream-server.h"
+
+#define DEFAULT_LOCK_TIMEOUT (100)
+
+/*
+ * Try to connect to a unix domain socket at `path` (if it exists) and
+ * see if there is a server listening.
+ *
+ * We don't know if the socket exists, whether a server died and
+ * failed to cleanup, or whether we have a live server listening, so
+ * we "poke" it.
+ *
+ * We immediately hangup without sending/receiving any data because we
+ * don't know anything about the protocol spoken and don't want to
+ * block while writing/reading data.  It is sufficient to just know
+ * that someone is listening.
+ */
+static int is_another_server_alive(const char *path,
+				   const struct unix_stream_listen_opts *opts)
+{
+	int fd = unix_stream_connect(path, opts->disallow_chdir);
+	if (fd >= 0) {
+		close(fd);
+		return 1;
+	}
+
+	return 0;
+}
+
+int unix_ss_create(const char *path,
+		   const struct unix_stream_listen_opts *opts,
+		   long timeout_ms,
+		   struct unix_ss_socket **new_server_socket)
+{
+	struct lock_file lock = LOCK_INIT;
+	int fd_socket;
+	struct unix_ss_socket *server_socket;
+
+	*new_server_socket = NULL;
+
+	if (timeout_ms < 0)
+		timeout_ms = DEFAULT_LOCK_TIMEOUT;
+
+	/*
+	 * Create a lock at "<path>.lock" if we can.
+	 */
+	if (hold_lock_file_for_update_timeout(&lock, path, 0, timeout_ms) < 0)
+		return -1;
+
+	/*
+	 * If another server is listening on "<path>" give up.  We do not
+	 * want to create a socket and steal future connections from them.
+	 */
+	if (is_another_server_alive(path, opts)) {
+		rollback_lock_file(&lock);
+		errno = EADDRINUSE;
+		return -2;
+	}
+
+	/*
+	 * Create and bind to a Unix domain socket at "<path>".
+	 */
+	fd_socket = unix_stream_listen(path, opts);
+	if (fd_socket < 0) {
+		int saved_errno = errno;
+		rollback_lock_file(&lock);
+		errno = saved_errno;
+		return -1;
+	}
+
+	server_socket = xcalloc(1, sizeof(*server_socket));
+	server_socket->path_socket = strdup(path);
+	server_socket->fd_socket = fd_socket;
+	lstat(path, &server_socket->st_socket);
+
+	*new_server_socket = server_socket;
+
+	/*
+	 * Always rollback (just delete) "<path>.lock" because we already created
+	 * "<path>" as a socket and do not want to commit_lock to do the atomic
+	 * rename trick.
+	 */
+	rollback_lock_file(&lock);
+
+	return 0;
+}
+
+void unix_ss_free(struct unix_ss_socket *server_socket)
+{
+	if (!server_socket)
+		return;
+
+	if (server_socket->fd_socket >= 0) {
+		if (!unix_ss_was_stolen(server_socket))
+			unlink(server_socket->path_socket);
+		close(server_socket->fd_socket);
+	}
+
+	free(server_socket->path_socket);
+	free(server_socket);
+}
+
+int unix_ss_was_stolen(struct unix_ss_socket *server_socket)
+{
+	struct stat st_now;
+
+	if (!server_socket)
+		return 0;
+
+	if (lstat(server_socket->path_socket, &st_now) == -1)
+		return 1;
+
+	if (st_now.st_ino != server_socket->st_socket.st_ino)
+		return 1;
+	if (st_now.st_dev != server_socket->st_socket.st_dev)
+		return 1;
+
+	if (!S_ISSOCK(st_now.st_mode))
+		return 1;
+
+	return 0;
+}
diff --git a/unix-stream-server.h b/unix-stream-server.h
new file mode 100644
index 0000000..ae2712b
--- /dev/null
+++ b/unix-stream-server.h
@@ -0,0 +1,33 @@
+#ifndef UNIX_STREAM_SERVER_H
+#define UNIX_STREAM_SERVER_H
+
+#include "unix-socket.h"
+
+struct unix_ss_socket {
+	char *path_socket;
+	struct stat st_socket;
+	int fd_socket;
+};
+
+/*
+ * Create a Unix Domain Socket at the given path under the protection
+ * of a '.lock' lockfile.
+ *
+ * Returns 0 on success, -1 on error, -2 if socket is in use.
+ */
+int unix_ss_create(const char *path,
+		   const struct unix_stream_listen_opts *opts,
+		   long timeout_ms,
+		   struct unix_ss_socket **server_socket);
+
+/*
+ * Close and delete the socket.
+ */
+void unix_ss_free(struct unix_ss_socket *server_socket);
+
+/*
+ * Return 1 if the inode of the pathname to our socket changes.
+ */
+int unix_ss_was_stolen(struct unix_ss_socket *server_socket);
+
+#endif /* UNIX_STREAM_SERVER_H */
diff --git a/unpack-trees.c b/unpack-trees.c
index eb8fcda..8a1afbc 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -16,6 +16,7 @@
 #include "fsmonitor.h"
 #include "object-store.h"
 #include "promisor-remote.h"
+#include "entry.h"
 
 /*
  * Error messages expected by scripts out of plumbing commands such as
@@ -1612,8 +1613,8 @@
 	o->merge_size = len;
 	mark_all_ce_unused(o->src_index);
 
-	if (o->src_index->fsmonitor_last_update)
-		o->result.fsmonitor_last_update = o->src_index->fsmonitor_last_update;
+	o->result.fsmonitor_last_update =
+		xstrdup_or_null(o->src_index->fsmonitor_last_update);
 
 	/*
 	 * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
@@ -2097,7 +2098,7 @@
 	if (o->index_only || o->reset || !o->update)
 		return 0;
 
-	len = check_leading_path(ce->name, ce_namelen(ce));
+	len = check_leading_path(ce->name, ce_namelen(ce), 0);
 	if (!len)
 		return 0;
 	else if (len > 0) {
@@ -2563,3 +2564,25 @@
 	}
 	return merged_entry(a, old, o);
 }
+
+/*
+ * Merge worktree and untracked entries in a stash entry.
+ *
+ * Ignore all index entries. Collapse remaining trees but make sure that they
+ * don't have any conflicting files.
+ */
+int stash_worktree_untracked_merge(const struct cache_entry * const *src,
+				   struct unpack_trees_options *o)
+{
+	const struct cache_entry *worktree = src[1];
+	const struct cache_entry *untracked = src[2];
+
+	if (o->merge_size != 2)
+		BUG("invalid merge_size: %d", o->merge_size);
+
+	if (worktree && untracked)
+		return error(_("worktree and untracked commit have duplicate entries: %s"),
+			     super_prefixed(worktree->name));
+
+	return merged_entry(worktree ? worktree : untracked, NULL, o);
+}
diff --git a/unpack-trees.h b/unpack-trees.h
index 2e87875..2d88b19 100644
--- a/unpack-trees.h
+++ b/unpack-trees.h
@@ -114,5 +114,7 @@
 	       struct unpack_trees_options *o);
 int oneway_merge(const struct cache_entry * const *src,
 		 struct unpack_trees_options *o);
+int stash_worktree_untracked_merge(const struct cache_entry * const *src,
+				   struct unpack_trees_options *o);
 
 #endif
diff --git a/vcs-svn/fast_export.h b/vcs-svn/fast_export.h
deleted file mode 100644
index 9dcf933..0000000
--- a/vcs-svn/fast_export.h
+++ /dev/null
@@ -1,34 +0,0 @@
-#ifndef FAST_EXPORT_H
-#define FAST_EXPORT_H
-
-struct strbuf;
-struct line_buffer;
-
-void fast_export_init(int fd);
-void fast_export_deinit(void);
-
-void fast_export_delete(const char *path);
-void fast_export_modify(const char *path, uint32_t mode, const char *dataref);
-void fast_export_note(const char *committish, const char *dataref);
-void fast_export_begin_note(uint32_t revision, const char *author,
-		const char *log, timestamp_t timestamp, const char *note_ref);
-void fast_export_begin_commit(uint32_t revision, const char *author,
-			const struct strbuf *log, const char *uuid,const char *url,
-			timestamp_t timestamp, const char *local_ref);
-void fast_export_end_commit(uint32_t revision);
-void fast_export_data(uint32_t mode, off_t len, struct line_buffer *input);
-void fast_export_buf_to_data(const struct strbuf *data);
-void fast_export_blob_delta(uint32_t mode,
-			uint32_t old_mode, const char *old_data,
-			off_t len, struct line_buffer *input);
-
-/* If there is no such file at that rev, returns -1, errno == ENOENT. */
-int fast_export_ls_rev(uint32_t rev, const char *path,
-			uint32_t *mode_out, struct strbuf *dataref_out);
-int fast_export_ls(const char *path,
-			uint32_t *mode_out, struct strbuf *dataref_out);
-
-void fast_export_copy(uint32_t revision, const char *src, const char *dst);
-const char *fast_export_read_path(const char *path, uint32_t *mode_out);
-
-#endif
diff --git a/vcs-svn/line_buffer.h b/vcs-svn/line_buffer.h
deleted file mode 100644
index e192aed..0000000
--- a/vcs-svn/line_buffer.h
+++ /dev/null
@@ -1,30 +0,0 @@
-#ifndef LINE_BUFFER_H
-#define LINE_BUFFER_H
-
-#include "strbuf.h"
-
-#define LINE_BUFFER_LEN 10000
-
-struct line_buffer {
-	char line_buffer[LINE_BUFFER_LEN];
-	FILE *infile;
-};
-#define LINE_BUFFER_INIT { "", NULL }
-
-int buffer_init(struct line_buffer *buf, const char *filename);
-int buffer_fdinit(struct line_buffer *buf, int fd);
-int buffer_deinit(struct line_buffer *buf);
-
-int buffer_tmpfile_init(struct line_buffer *buf);
-FILE *buffer_tmpfile_rewind(struct line_buffer *buf);	/* prepare to write. */
-long buffer_tmpfile_prepare_to_read(struct line_buffer *buf);
-
-int buffer_ferror(struct line_buffer *buf);
-char *buffer_read_line(struct line_buffer *buf);
-int buffer_read_char(struct line_buffer *buf);
-size_t buffer_read_binary(struct line_buffer *buf, struct strbuf *sb, size_t len);
-/* Returns number of bytes read (not necessarily written). */
-off_t buffer_copy_bytes(struct line_buffer *buf, off_t len);
-off_t buffer_skip_bytes(struct line_buffer *buf, off_t len);
-
-#endif
diff --git a/vcs-svn/sliding_window.h b/vcs-svn/sliding_window.h
deleted file mode 100644
index a7fc099..0000000
--- a/vcs-svn/sliding_window.h
+++ /dev/null
@@ -1,18 +0,0 @@
-#ifndef SLIDING_WINDOW_H
-#define SLIDING_WINDOW_H
-
-#include "strbuf.h"
-
-struct sliding_view {
-	struct line_buffer *file;
-	off_t off;
-	size_t width;
-	off_t max_off;	/* -1 means unlimited */
-	struct strbuf buf;
-};
-
-#define SLIDING_VIEW_INIT(input, len)	{ (input), 0, 0, (len), STRBUF_INIT }
-
-int move_window(struct sliding_view *view, off_t off, size_t width);
-
-#endif
diff --git a/vcs-svn/svndiff.h b/vcs-svn/svndiff.h
deleted file mode 100644
index 625d950..0000000
--- a/vcs-svn/svndiff.h
+++ /dev/null
@@ -1,10 +0,0 @@
-#ifndef SVNDIFF_H
-#define SVNDIFF_H
-
-struct line_buffer;
-struct sliding_view;
-
-int svndiff0_apply(struct line_buffer *delta, off_t delta_len,
-		   struct sliding_view *preimage, FILE *postimage);
-
-#endif
diff --git a/vcs-svn/svndump.h b/vcs-svn/svndump.h
deleted file mode 100644
index 26faed5..0000000
--- a/vcs-svn/svndump.h
+++ /dev/null
@@ -1,10 +0,0 @@
-#ifndef SVNDUMP_H
-#define SVNDUMP_H
-
-int svndump_init(const char *filename);
-int svndump_init_fd(int in_fd, int back_fd);
-void svndump_read(const char *url, const char *local_ref, const char *notes_ref);
-void svndump_deinit(void);
-void svndump_reset(void);
-
-#endif
diff --git a/worktree.c b/worktree.c
index e008585..f35ac40 100644
--- a/worktree.c
+++ b/worktree.c
@@ -53,7 +53,7 @@
 	strbuf_add_real_path(&worktree_path, get_git_common_dir());
 	strbuf_strip_suffix(&worktree_path, "/.git");
 
-	worktree = xcalloc(1, sizeof(*worktree));
+	CALLOC_ARRAY(worktree, 1);
 	worktree->path = strbuf_detach(&worktree_path, NULL);
 	/*
 	 * NEEDSWORK: If this function is called from a secondary worktree and
@@ -84,7 +84,7 @@
 	strbuf_rtrim(&worktree_path);
 	strbuf_strip_suffix(&worktree_path, "/.git");
 
-	worktree = xcalloc(1, sizeof(*worktree));
+	CALLOC_ARRAY(worktree, 1);
 	worktree->path = strbuf_detach(&worktree_path, NULL);
 	worktree->id = xstrdup(id);
 	add_head_info(worktree);
diff --git a/wrapper.c b/wrapper.c
index bcda41e..563ad59 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -678,3 +678,19 @@
 
 	return !st.st_size;
 }
+
+int open_nofollow(const char *path, int flags)
+{
+#ifdef O_NOFOLLOW
+	return open(path, flags | O_NOFOLLOW);
+#else
+	struct stat st;
+	if (lstat(path, &st) < 0)
+		return -1;
+	if (S_ISLNK(st.st_mode)) {
+		errno = ELOOP;
+		return -1;
+	}
+	return open(path, flags);
+#endif
+}
diff --git a/wt-status.c b/wt-status.c
index 0c8287a..1aed68c 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -456,7 +456,7 @@
 		it = string_list_insert(&s->change, p->two->path);
 		d = it->util;
 		if (!d) {
-			d = xcalloc(1, sizeof(*d));
+			CALLOC_ARRAY(d, 1);
 			it->util = d;
 		}
 		if (!d->worktree_status)
@@ -540,7 +540,7 @@
 		it = string_list_insert(&s->change, p->two->path);
 		d = it->util;
 		if (!d) {
-			d = xcalloc(1, sizeof(*d));
+			CALLOC_ARRAY(d, 1);
 			it->util = d;
 		}
 		if (!d->index_status)
@@ -671,7 +671,7 @@
 		it = string_list_insert(&s->change, ce->name);
 		d = it->util;
 		if (!d) {
-			d = xcalloc(1, sizeof(*d));
+			CALLOC_ARRAY(d, 1);
 			it->util = d;
 		}
 		if (ce_stage(ce)) {