git/git-checkout.sh

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#!/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="warning: you are not on ANY branch anymore.
If you meant to create a new branch from the commit, you need -b to
associate a new branch with the wanted checkout. Example:
git checkout -b <new_branch_name> $arg"
fi
elif test -z "$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 &&
git read-tree -m -u --aggressive --exclude-per-directory=.gitignore $old $new $work ||
exit
if result=`git write-tree 2>/dev/null`
then
echo >&2 "Trivially automerged."
else
git merge-index -o git-merge-one-file -a
fi
# 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