http-push: ensure unforced pushes fail when data would be lost

When we push using the DAV-based protocol, the client is the one that
performs the ref updates and therefore makes the checks to see whether
an unforced push should be allowed.  We make this check by determining
if either (a) we lack the object file for the old value of the ref or
(b) the new value of the ref is not newer than the old value, and in
either case, reject the push.

However, the ref_newer function, which performs this latter check, has
an odd behavior due to the reuse of certain object flags.  Specifically,
it will incorrectly return false in its first invocation and then
correctly return true on a subsequent invocation.  This occurs because
the object flags used by http-push.c are the same as those used by
commit-reach.c, which implements ref_newer, and one piece of code
misinterprets the flags set by the other.

Note that this does not occur in all cases.  For example, if the example
used in the tests is changed to use one repository instead of two and
rewind the head to add a commit, the test passes and we correctly reject
the push.  However, the example provided does trigger this behavior, and
the code has been broken in this way since at least Git 2.0.0.

To solve this problem, let's move the two sets of object flags so that
they don't overlap, since we're clearly using them at the same time.
The new set should not conflict with other usage because other users are
either builtin code (which is not compiled into git http-push) or
upload-pack (which we similarly do not use here).

Reported-by: Michael Ward <mward@smartsoftwareinc.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
3 files changed
tree: 1a4882b433dc98cfb992e6bf60a645b5eadd3e03
  1. .github/
  2. block-sha1/
  3. builtin/
  4. ci/
  5. compat/
  6. contrib/
  7. Documentation/
  8. ewah/
  9. git-gui/
  10. gitk-git/
  11. gitweb/
  12. mergetools/
  13. negotiator/
  14. perl/
  15. po/
  16. ppc/
  17. refs/
  18. sha1dc/
  19. sha256/
  20. t/
  21. templates/
  22. trace2/
  23. vcs-svn/
  24. xdiff/
  25. .cirrus.yml
  26. .clang-format
  27. .editorconfig
  28. .gitattributes
  29. .gitignore
  30. .gitmodules
  31. .mailmap
  32. .travis.yml
  33. .tsan-suppressions
  34. abspath.c
  35. aclocal.m4
  36. add-interactive.c
  37. add-interactive.h
  38. add-patch.c
  39. advice.c
  40. advice.h
  41. alias.c
  42. alias.h
  43. alloc.c
  44. alloc.h
  45. apply.c
  46. apply.h
  47. archive-tar.c
  48. archive-zip.c
  49. archive.c
  50. archive.h
  51. argv-array.c
  52. argv-array.h
  53. attr.c
  54. attr.h
  55. azure-pipelines.yml
  56. banned.h
  57. base85.c
  58. bisect.c
  59. bisect.h
  60. blame.c
  61. blame.h
  62. blob.c
  63. blob.h
  64. branch.c
  65. branch.h
  66. builtin.h
  67. bulk-checkin.c
  68. bulk-checkin.h
  69. bundle.c
  70. bundle.h
  71. cache-tree.c
  72. cache-tree.h
  73. cache.h
  74. chdir-notify.c
  75. chdir-notify.h
  76. check-builtins.sh
  77. check_bindir
  78. checkout.c
  79. checkout.h
  80. CODE_OF_CONDUCT.md
  81. color.c
  82. color.h
  83. column.c
  84. column.h
  85. combine-diff.c
  86. command-list.txt
  87. commit-graph.c
  88. commit-graph.h
  89. commit-reach.c
  90. commit-reach.h
  91. commit-slab-decl.h
  92. commit-slab-impl.h
  93. commit-slab.h
  94. commit.c
  95. commit.h
  96. common-main.c
  97. config.c
  98. config.h
  99. config.mak.dev
  100. config.mak.in
  101. config.mak.uname
  102. configure.ac
  103. connect.c
  104. connect.h
  105. connected.c
  106. connected.h
  107. convert.c
  108. convert.h
  109. copy.c
  110. COPYING
  111. credential-cache--daemon.c
  112. credential-cache.c
  113. credential-store.c
  114. credential.c
  115. credential.h
  116. csum-file.c
  117. csum-file.h
  118. ctype.c
  119. daemon.c
  120. date.c
  121. decorate.c
  122. decorate.h
  123. delta-islands.c
  124. delta-islands.h
  125. delta.h
  126. detect-compiler
  127. diff-delta.c
  128. diff-lib.c
  129. diff-no-index.c
  130. diff.c
  131. diff.h
  132. diffcore-break.c
  133. diffcore-delta.c
  134. diffcore-order.c
  135. diffcore-pickaxe.c
  136. diffcore-rename.c
  137. diffcore.h
  138. dir-iterator.c
  139. dir-iterator.h
  140. dir.c
  141. dir.h
  142. editor.c
  143. entry.c
  144. environment.c
  145. exec-cmd.c
  146. exec-cmd.h
  147. fast-import.c
  148. fetch-negotiator.c
  149. fetch-negotiator.h
  150. fetch-pack.c
  151. fetch-pack.h
  152. fmt-merge-msg.h
  153. fsck.c
  154. fsck.h
  155. fsmonitor.c
  156. fsmonitor.h
  157. fuzz-commit-graph.c
  158. fuzz-pack-headers.c
  159. fuzz-pack-idx.c
  160. generate-cmdlist.sh
  161. gettext.c
  162. gettext.h
  163. git-add--interactive.perl
  164. git-archimport.perl
  165. git-bisect.sh
  166. git-compat-util.h
  167. git-cvsexportcommit.perl
  168. git-cvsimport.perl
  169. git-cvsserver.perl
  170. git-difftool--helper.sh
  171. git-filter-branch.sh
  172. git-instaweb.sh
  173. git-legacy-stash.sh
  174. git-merge-octopus.sh
  175. git-merge-one-file.sh
  176. git-merge-resolve.sh
  177. git-mergetool--lib.sh
  178. git-mergetool.sh
  179. git-p4.py
  180. git-parse-remote.sh
  181. git-quiltimport.sh
  182. git-rebase--preserve-merges.sh
  183. git-request-pull.sh
  184. git-send-email.perl
  185. git-sh-i18n.sh
  186. git-sh-setup.sh
  187. git-submodule.sh
  188. git-svn.perl
  189. GIT-VERSION-GEN
  190. git-web--browse.sh
  191. git.c
  192. git.rc
  193. gpg-interface.c
  194. gpg-interface.h
  195. graph.c
  196. graph.h
  197. grep.c
  198. grep.h
  199. hash.h
  200. hashmap.c
  201. hashmap.h
  202. help.c
  203. help.h
  204. hex.c
  205. http-backend.c
  206. http-fetch.c
  207. http-push.c
  208. http-walker.c
  209. http.c
  210. http.h
  211. ident.c
  212. imap-send.c
  213. INSTALL
  214. interdiff.c
  215. interdiff.h
  216. iterator.h
  217. json-writer.c
  218. json-writer.h
  219. khash.h
  220. kwset.c
  221. kwset.h
  222. levenshtein.c
  223. levenshtein.h
  224. LGPL-2.1
  225. line-log.c
  226. line-log.h
  227. line-range.c
  228. line-range.h
  229. linear-assignment.c
  230. linear-assignment.h
  231. list-objects-filter-options.c
  232. list-objects-filter-options.h
  233. list-objects-filter.c
  234. list-objects-filter.h
  235. list-objects.c
  236. list-objects.h
  237. list.h
  238. ll-merge.c
  239. ll-merge.h
  240. lockfile.c
  241. lockfile.h
  242. log-tree.c
  243. log-tree.h
  244. ls-refs.c
  245. ls-refs.h
  246. mailinfo.c
  247. mailinfo.h
  248. mailmap.c
  249. mailmap.h
  250. Makefile
  251. match-trees.c
  252. mem-pool.c
  253. mem-pool.h
  254. merge-blobs.c
  255. merge-blobs.h
  256. merge-recursive.c
  257. merge-recursive.h
  258. merge.c
  259. mergesort.c
  260. mergesort.h
  261. midx.c
  262. midx.h
  263. name-hash.c
  264. notes-cache.c
  265. notes-cache.h
  266. notes-merge.c
  267. notes-merge.h
  268. notes-utils.c
  269. notes-utils.h
  270. notes.c
  271. notes.h
  272. object-store.h
  273. object.c
  274. object.h
  275. oidmap.c
  276. oidmap.h
  277. oidset.c
  278. oidset.h
  279. pack-bitmap-write.c
  280. pack-bitmap.c
  281. pack-bitmap.h
  282. pack-check.c
  283. pack-objects.c
  284. pack-objects.h
  285. pack-revindex.c
  286. pack-revindex.h
  287. pack-write.c
  288. pack.h
  289. packfile.c
  290. packfile.h
  291. pager.c
  292. parse-options-cb.c
  293. parse-options.c
  294. parse-options.h
  295. patch-delta.c
  296. patch-ids.c
  297. patch-ids.h
  298. path.c
  299. path.h
  300. pathspec.c
  301. pathspec.h
  302. pkt-line.c
  303. pkt-line.h
  304. preload-index.c
  305. pretty.c
  306. pretty.h
  307. prio-queue.c
  308. prio-queue.h
  309. progress.c
  310. progress.h
  311. promisor-remote.c
  312. promisor-remote.h
  313. prompt.c
  314. prompt.h
  315. protocol.c
  316. protocol.h
  317. quote.c
  318. quote.h
  319. range-diff.c
  320. range-diff.h
  321. reachable.c
  322. reachable.h
  323. read-cache.c
  324. README.md
  325. rebase-interactive.c
  326. rebase-interactive.h
  327. rebase.c
  328. rebase.h
  329. ref-filter.c
  330. ref-filter.h
  331. reflog-walk.c
  332. reflog-walk.h
  333. refs.c
  334. refs.h
  335. refspec.c
  336. refspec.h
  337. remote-curl.c
  338. remote-testsvn.c
  339. remote.c
  340. remote.h
  341. replace-object.c
  342. replace-object.h
  343. repo-settings.c
  344. repository.c
  345. repository.h
  346. rerere.c
  347. rerere.h
  348. resolve-undo.c
  349. resolve-undo.h
  350. revision.c
  351. revision.h
  352. run-command.c
  353. run-command.h
  354. send-pack.c
  355. send-pack.h
  356. sequencer.c
  357. sequencer.h
  358. serve.c
  359. serve.h
  360. server-info.c
  361. setup.c
  362. sh-i18n--envsubst.c
  363. sha1-array.c
  364. sha1-array.h
  365. sha1-file.c
  366. sha1-lookup.c
  367. sha1-lookup.h
  368. sha1-name.c
  369. sha1dc_git.c
  370. sha1dc_git.h
  371. shallow.c
  372. shell.c
  373. shortlog.h
  374. sideband.c
  375. sideband.h
  376. sigchain.c
  377. sigchain.h
  378. split-index.c
  379. split-index.h
  380. stable-qsort.c
  381. strbuf.c
  382. strbuf.h
  383. streaming.c
  384. streaming.h
  385. string-list.c
  386. string-list.h
  387. sub-process.c
  388. sub-process.h
  389. submodule-config.c
  390. submodule-config.h
  391. submodule.c
  392. submodule.h
  393. symlinks.c
  394. tag.c
  395. tag.h
  396. tar.h
  397. tempfile.c
  398. tempfile.h
  399. thread-utils.c
  400. thread-utils.h
  401. tmp-objdir.c
  402. tmp-objdir.h
  403. trace.c
  404. trace.h
  405. trace2.c
  406. trace2.h
  407. trailer.c
  408. trailer.h
  409. transport-helper.c
  410. transport-internal.h
  411. transport.c
  412. transport.h
  413. tree-diff.c
  414. tree-walk.c
  415. tree-walk.h
  416. tree.c
  417. tree.h
  418. unicode-width.h
  419. unimplemented.sh
  420. unix-socket.c
  421. unix-socket.h
  422. unpack-trees.c
  423. unpack-trees.h
  424. upload-pack.c
  425. upload-pack.h
  426. url.c
  427. url.h
  428. urlmatch.c
  429. urlmatch.h
  430. usage.c
  431. userdiff.c
  432. userdiff.h
  433. utf8.c
  434. utf8.h
  435. varint.c
  436. varint.h
  437. version.c
  438. version.h
  439. versioncmp.c
  440. walker.c
  441. walker.h
  442. wildmatch.c
  443. wildmatch.h
  444. worktree.c
  445. worktree.h
  446. wrap-for-bin.sh
  447. wrapper.c
  448. write-or-die.c
  449. ws.c
  450. wt-status.c
  451. wt-status.h
  452. xdiff-interface.c
  453. xdiff-interface.h
  454. zlib.c
README.md

Build Status

Git - fast, scalable, distributed revision control system

Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.

Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.

Please read the file INSTALL for installation instructions.

Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.

See Documentation/gittutorial.txt to get started, then see Documentation/giteveryday.txt for a useful minimum set of commands, and Documentation/git-<commandname>.txt for documentation of each command. If git has been correctly installed, then the tutorial can also be read with man gittutorial or git help tutorial, and the documentation of each command with man git-<commandname> or git help <commandname>.

CVS users may also want to read Documentation/gitcvs-migration.txt (man gitcvs-migration or git help cvs-migration if git is installed).

The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission). To subscribe to the list, send an email with just “subscribe git” in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://lore.kernel.org/git/, http://marc.info/?l=git and other archival sites.

Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.

The maintainer frequently sends the “What's cooking” reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.

The name “git” was given by Linus Torvalds when he wrote the very first version. He described the tool as “the stupid content tracker” and the name as (depending on your mood):

  • random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of “get” may or may not be relevant.
  • stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
  • “global information tracker”: you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
  • “goddamn idiotic truckload of sh*t”: when it breaks