git/git-checkout.sh

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#!/bin/sh
USAGE='[-f] [-b <new_branch>] [-m] [<branch>] [<paths>...]'
SUBDIRECTORY_OK=Sometimes
. git-sh-setup
old=$(git-rev-parse HEAD)
new=
force=
branch=
newbranch=
merge=
while [ "$#" != "0" ]; do
arg="$1"
shift
case "$arg" in
"-b")
newbranch="$1"
shift
[ -z "$newbranch" ] &&
die "git checkout: -b needs a branch name"
[ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
die "git checkout: branch $newbranch already exists"
git-check-ref-format "heads/$newbranch" ||
die "git checkout: we do not like '$newbranch' as a branch name."
;;
"-f")
force=1
;;
-m)
merge=1
;;
--)
break
;;
-*)
usage
;;
*)
if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
then
if [ -z "$rev" ]; then
echo "unknown flag $arg"
exit 1
fi
new="$rev"
if [ -f "$GIT_DIR/refs/heads/$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"
branch=
else
new=
branch=
set x "$arg" "$@"
shift
fi
break
;;
esac
done
# 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 $?
fi
git-checkout-index -f -u -- "$@"
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 "$new^{commit}" >/dev/null 2>&1 ||
die "Cannot switch branch to a non-commit."
fi
fi
# We are switching branches and checking out trees, so
# we *NEED* to be at the toplevel.
cdup=$(git-rev-parse --show-cdup)
if test ! -z "$cdup"
then
cd "$cdup"
fi
[ -z "$new" ] && new=$old
# If we don't have an old branch that we're switching to,
# and we don't have a new branch name for the target we
# are switching to, then we'd better just be checking out
# what we already had
[ -z "$branch$newbranch" ] &&
[ "$new" != "$old" ] &&
die "git checkout: to checkout the requested commit you need to specify
a name for a new branch which is created and switched to"
if [ "$force" ]
then
git-read-tree --reset $new &&
git-checkout-index -q -f -u -a
else
git-update-index --refresh >/dev/null
merge_error=$(git-read-tree -m -u $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 $new &&
git checkout-index -f -u -q -a &&
git read-tree -m -u $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 [ "$newbranch" ]; then
leading=`expr "refs/heads/$newbranch" : '\(.*\)/'` &&
mkdir -p "$GIT_DIR/$leading" &&
echo $new >"$GIT_DIR/refs/heads/$newbranch" || exit
branch="$newbranch"
fi
[ "$branch" ] &&
GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
rm -f "$GIT_DIR/MERGE_HEAD"
else
exit 1
fi