git-commit-vandalism/git-checkout.sh
Nicolas Pitre d117452a80 tone down the detached head warning
This is not meant to frighten people or even to suggest they might be
doing something wrong, but rather to notify them of a state change and
provide a likely option in the case this state was entered by mistake.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-01-31 13:09:57 -08:00

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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="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