git-checkout.sh - git - Git at Google

 #!/bin/sh

 USAGE='[-f] [-b <new_branch>] [-m] [<branch>] [<paths>...]'
 SUBDIRECTORY_OK=Sometimes
 . git-sh-setup
 require_work_tree

 old_name=HEAD
 old=$(git-rev-parse --verify $old_name 2>/dev/null)
 oldbranch=$(git-symbolic-ref $old_name 2>/dev/null)
 new=
 new_name=
 force=
 branch=
 newbranch=
 newbranch_log=
 merge=
 LF='
 '
 while [ "$#" != "0" ]; do
     arg="$1"
     shift
     case "$arg" in
 	"-b")
 		newbranch="$1"
 		shift
 		[ -z "$newbranch" ] &&
 			die "git checkout: -b needs a branch name"
 		git-show-ref --verify --quiet -- "refs/heads/$newbranch" &&
 			die "git checkout: branch $newbranch already exists"
 		git-check-ref-format "heads/$newbranch" ||
 			die "git checkout: we do not like '$newbranch' as a branch name."
 		;;
 	"-l")
 		newbranch_log=1
 		;;
 	"-f")
 		force=1
 		;;
 	-m)
 		merge=1
 		;;
 	--)
 		break
 		;;
 	-*)
 		usage
 		;;
 	*)
 		if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
 		then
 			if [ -z "$rev" ]; then
 				echo "unknown flag $arg"
 				exit 1
 			fi
 			new="$rev"
 			new_name="$arg"
 			if git-show-ref --verify --quiet -- "refs/heads/$arg"
 			then
 				branch="$arg"
 			fi
 		elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
 		then
 			# checking out selected paths from a tree-ish.
 			new="$rev"
 			new_name="$arg^{tree}"
 			branch=
 		else
 			new=
 			new_name=
 			branch=
 			set x "$arg" "$@"
 			shift
 		fi
 		case "$1" in
 		--)
 			shift ;;
 		esac
 		break
 		;;
     esac
 done

 case "$force$merge" in
 11)
 	die "git checkout: -f and -m are incompatible"
 esac

 # The behaviour of the command with and without explicit path
 # parameters is quite different.
 #
 # Without paths, we are checking out everything in the work tree,
 # possibly switching branches.  This is the traditional behaviour.
 #
 # With paths, we are _never_ switching branch, but checking out
 # the named paths from either index (when no rev is given),
 # or the named tree-ish (when rev is given).

 if test "$#" -ge 1
 then
 	hint=
 	if test "$#" -eq 1
 	then
 		hint="
 Did you intend to checkout '$@' which can not be resolved as commit?"
 	fi
 	if test '' != "$newbranch$force$merge"
 	then
 		die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
 	fi
 	if test '' != "$new"
 	then
 		# from a specific tree-ish; note that this is for
 		# rescuing paths and is never meant to remove what
 		# is not in the named tree-ish.
 		git-ls-tree --full-name -r "$new" "$@" |
 		git-update-index --index-info || exit $?
 	fi

 	# Make sure the request is about existing paths.
 	git-ls-files --error-unmatch -- "$@" >/dev/null || exit
 	git-ls-files -- "$@" |
 	git-checkout-index -f -u --stdin
 	exit $?
 else
 	# Make sure we did not fall back on $arg^{tree} codepath
 	# since we are not checking out from an arbitrary tree-ish,
 	# but switching branches.
 	if test '' != "$new"
 	then
 		git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
 		die "Cannot switch branch to a non-commit."
 	fi
 fi

 # We are switching branches and checking out trees, so
 # we *NEED* to be at the toplevel.
 cd_to_toplevel

 [ -z "$new" ] && new=$old && new_name="$old_name"

 # If we don't have an existing branch that we're switching to,
 # and we don't have a new branch name for the target we
 # are switching to, then we are detaching our HEAD from any
 # branch.  However, if "git checkout HEAD" detaches the HEAD
 # from the current branch, even though that may be logically
 # correct, it feels somewhat funny.  More importantly, we do not
 # want "git checkout" nor "git checkout -f" to detach HEAD.

 detached=
 detach_warn=

 if test -z "$branch$newbranch" && test "$new" != "$old"
 then
 	detached="$new"
 	if test -n "$oldbranch"
 	then
 		detach_warn="Note: you are not on ANY branch anymore.
 If you want to create a new branch from this checkout, you may do so
 (now or later) by using -b with the checkout command again. Example:
   git checkout -b <new_branch_name>"
 	fi
 elif test -z "$oldbranch" && test -n "$branch"
 then
 	# Coming back...
 	if test -z "$force"
 	then
 		git show-ref -d -s | grep "$old" >/dev/null || {
 			echo >&2 \
 "You are not on any branch and switching to branch '$new_name'
 may lose your changes.  At this point, you can do one of two things:
  (1) Decide it is Ok and say 'git checkout -f $new_name';
  (2) Start a new branch from the current commit, by saying
      'git checkout -b <branch-name>'.
 Leaving your HEAD detached; not switching to branch '$new_name'."
 			exit 1;
 		}
 	fi
 fi

 if [ "X$old" = X ]
 then
 	echo >&2 "warning: You appear to be on a branch yet to be born."
 	echo >&2 "warning: Forcing checkout of $new_name."
 	force=1
 fi

 if [ "$force" ]
 then
     git-read-tree --reset -u $new
 else
     git-update-index --refresh >/dev/null
     merge_error=$(git-read-tree -m -u --exclude-per-directory=.gitignore $old $new 2>&1) || (
 	case "$merge" in
 	'')
 		echo >&2 "$merge_error"
 		exit 1 ;;
 	esac

 	# Match the index to the working tree, and do a three-way.
     	git diff-files --name-only | git update-index --remove --stdin &&
 	work=`git write-tree` &&
 	git read-tree --reset -u $new || exit

 	eval GITHEAD_$new=${new_name:-${branch:-$new}} &&
 	eval GITHEAD_$work=local &&
 	export GITHEAD_$new GITHEAD_$work &&
 	git merge-recursive $old -- $new $work

 	# Do not register the cleanly merged paths in the index yet.
 	# this is not a real merge before committing, but just carrying
 	# the working tree changes along.
 	unmerged=`git ls-files -u`
 	git read-tree --reset $new
 	case "$unmerged" in
 	'')	;;
 	*)
 		(
 			z40=0000000000000000000000000000000000000000
 			echo "$unmerged" |
 			sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
 			echo "$unmerged"
 		) | git update-index --index-info
 		;;
 	esac
 	exit 0
     )
     saved_err=$?
     if test "$saved_err" = 0
     then
 	test "$new" = "$old" || git diff-index --name-status "$new"
     fi
     (exit $saved_err)
 fi

 #
 # Switch the HEAD pointer to the new branch if we
 # checked out a branch head, and remove any potential
 # old MERGE_HEAD's (subsequent commits will clearly not
 # be based on them, since we re-set the index)
 #
 if [ "$?" -eq 0 ]; then
 	if [ "$newbranch" ]; then
 		if [ "$newbranch_log" ]; then
 			mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$newbranch")
 			touch "$GIT_DIR/logs/refs/heads/$newbranch"
 		fi
 		git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new || exit
 		branch="$newbranch"
 	fi
 	if test -n "$branch"
 	then
 		GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
 	elif test -n "$detached"
 	then
 		# NEEDSWORK: we would want a command to detach the HEAD
 		# atomically, instead of this handcrafted command sequence.
 		# Perhaps:
 		#	git update-ref --detach HEAD $new
 		# or something like that...
 		#
 		echo "$detached" >"$GIT_DIR/HEAD.new" &&
 		mv "$GIT_DIR/HEAD.new" "$GIT_DIR/HEAD" ||
 			die "Cannot detach HEAD"
 		if test -n "$detach_warn"
 		then
 			echo >&2 "$detach_warn"
 		fi
 	fi
 	rm -f "$GIT_DIR/MERGE_HEAD"
 else
 	exit 1
 fi
	#!/bin/sh

	USAGE='[-f] [-b <new_branch>] [-m] [<branch>] [<paths>...]'
	SUBDIRECTORY_OK=Sometimes
	. git-sh-setup
	require_work_tree

	old_name=HEAD
	old=$(git-rev-parse --verify $old_name 2>/dev/null)
	oldbranch=$(git-symbolic-ref $old_name 2>/dev/null)
	new=
	new_name=
	force=
	branch=
	newbranch=
	newbranch_log=
	merge=
	LF='
	'
	while [ "$#" != "0" ]; do
	arg="$1"
	shift
	case "$arg" in
	"-b")
	newbranch="$1"
	shift
	[ -z "$newbranch" ] &&
	die "git checkout: -b needs a branch name"
	git-show-ref --verify --quiet -- "refs/heads/$newbranch" &&
	die "git checkout: branch $newbranch already exists"
	git-check-ref-format "heads/$newbranch" \|\|
	die "git checkout: we do not like '$newbranch' as a branch name."
	;;
	"-l")
	newbranch_log=1
	;;
	"-f")
	force=1
	;;
	-m)
	merge=1
	;;
	--)
	break
	;;
	-*)
	usage
	;;
	*)
	if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
	then
	if [ -z "$rev" ]; then
	echo "unknown flag $arg"
	exit 1
	fi
	new="$rev"
	new_name="$arg"
	if git-show-ref --verify --quiet -- "refs/heads/$arg"
	then
	branch="$arg"
	fi
	elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
	then
	# checking out selected paths from a tree-ish.
	new="$rev"
	new_name="$arg^{tree}"
	branch=
	else
	new=
	new_name=
	branch=
	set x "$arg" "$@"
	shift
	fi
	case "$1" in
	--)
	shift ;;
	esac
	break
	;;
	esac
	done

	case "$force$merge" in
	11)
	die "git checkout: -f and -m are incompatible"
	esac

	# The behaviour of the command with and without explicit path
	# parameters is quite different.
	#
	# Without paths, we are checking out everything in the work tree,
	# possibly switching branches. This is the traditional behaviour.
	#
	# With paths, we are _never_ switching branch, but checking out
	# the named paths from either index (when no rev is given),
	# or the named tree-ish (when rev is given).

	if test "$#" -ge 1
	then
	hint=
	if test "$#" -eq 1
	then
	hint="
	Did you intend to checkout '$@' which can not be resolved as commit?"
	fi
	if test '' != "$newbranch$force$merge"
	then
	die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
	fi
	if test '' != "$new"
	then
	# from a specific tree-ish; note that this is for
	# rescuing paths and is never meant to remove what
	# is not in the named tree-ish.
	git-ls-tree --full-name -r "$new" "$@" \|
	git-update-index --index-info \|\| exit $?
	fi

	# Make sure the request is about existing paths.
	git-ls-files --error-unmatch -- "$@" >/dev/null \|\| exit
	git-ls-files -- "$@" \|
	git-checkout-index -f -u --stdin
	exit $?
	else
	# Make sure we did not fall back on $arg^{tree} codepath
	# since we are not checking out from an arbitrary tree-ish,
	# but switching branches.
	if test '' != "$new"
	then
	git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 \|\|
	die "Cannot switch branch to a non-commit."
	fi
	fi

	# We are switching branches and checking out trees, so
	# we NEED to be at the toplevel.
	cd_to_toplevel

	[ -z "$new" ] && new=$old && new_name="$old_name"

	# If we don't have an existing branch that we're switching to,
	# and we don't have a new branch name for the target we
	# are switching to, then we are detaching our HEAD from any
	# branch. However, if "git checkout HEAD" detaches the HEAD
	# from the current branch, even though that may be logically
	# correct, it feels somewhat funny. More importantly, we do not
	# want "git checkout" nor "git checkout -f" to detach HEAD.

	detached=
	detach_warn=

	if test -z "$branch$newbranch" && test "$new" != "$old"
	then
	detached="$new"
	if test -n "$oldbranch"
	then
	detach_warn="Note: you are not on ANY branch anymore.
	If you want to create a new branch from this checkout, you may do so
	(now or later) by using -b with the checkout command again. Example:
	git checkout -b <new_branch_name>"
	fi
	elif test -z "$oldbranch" && test -n "$branch"
	then
	# Coming back...
	if test -z "$force"
	then
	git show-ref -d -s \| grep "$old" >/dev/null \|\| {
	echo >&2 \
	"You are not on any branch and switching to branch '$new_name'
	may lose your changes. At this point, you can do one of two things:
	(1) Decide it is Ok and say 'git checkout -f $new_name';
	(2) Start a new branch from the current commit, by saying
	'git checkout -b <branch-name>'.
	Leaving your HEAD detached; not switching to branch '$new_name'."
	exit 1;
	}
	fi
	fi

	if [ "X$old" = X ]
	then
	echo >&2 "warning: You appear to be on a branch yet to be born."
	echo >&2 "warning: Forcing checkout of $new_name."
	force=1
	fi

	if [ "$force" ]
	then
	git-read-tree --reset -u $new
	else
	git-update-index --refresh >/dev/null
	merge_error=$(git-read-tree -m -u --exclude-per-directory=.gitignore $old $new 2>&1) \|\| (
	case "$merge" in
	'')
	echo >&2 "$merge_error"
	exit 1 ;;
	esac

	# Match the index to the working tree, and do a three-way.
	git diff-files --name-only \| git update-index --remove --stdin &&
	work=`git write-tree` &&
	git read-tree --reset -u $new \|\| exit

	eval GITHEAD_$new=${new_name:-${branch:-$new}} &&
	eval GITHEAD_$work=local &&
	export GITHEAD_$new GITHEAD_$work &&
	git merge-recursive $old -- $new $work

	# Do not register the cleanly merged paths in the index yet.
	# this is not a real merge before committing, but just carrying
	# the working tree changes along.
	unmerged=`git ls-files -u`
	git read-tree --reset $new
	case "$unmerged" in
	'') ;;
	*)
	(
	z40=0000000000000000000000000000000000000000
	echo "$unmerged" \|
	sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
	echo "$unmerged"
	) \| git update-index --index-info
	;;
	esac
	exit 0
	)
	saved_err=$?
	if test "$saved_err" = 0
	then
	test "$new" = "$old" \|\| git diff-index --name-status "$new"
	fi
	(exit $saved_err)
	fi

	#
	# Switch the HEAD pointer to the new branch if we
	# checked out a branch head, and remove any potential
	# old MERGE_HEAD's (subsequent commits will clearly not
	# be based on them, since we re-set the index)
	#
	if [ "$?" -eq 0 ]; then
	if [ "$newbranch" ]; then
	if [ "$newbranch_log" ]; then
	mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$newbranch")
	touch "$GIT_DIR/logs/refs/heads/$newbranch"
	fi
	git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new \|\| exit
	branch="$newbranch"
	fi
	if test -n "$branch"
	then
	GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
	elif test -n "$detached"
	then
	# NEEDSWORK: we would want a command to detach the HEAD
	# atomically, instead of this handcrafted command sequence.
	# Perhaps:
	# git update-ref --detach HEAD $new
	# or something like that...
	#
	echo "$detached" >"$GIT_DIR/HEAD.new" &&
	mv "$GIT_DIR/HEAD.new" "$GIT_DIR/HEAD" \|\|
	die "Cannot detach HEAD"
	if test -n "$detach_warn"
	then
	echo >&2 "$detach_warn"
	fi
	fi
	rm -f "$GIT_DIR/MERGE_HEAD"
	else
	exit 1
	fi