#!/bin/sh
-: ${GIT_DIR=.git}
-old=$(git-rev-parse HEAD)
-new=$(git-rev-parse --revs-only "$@")
-new=${new:-$old}
-args=($(git-rev-parse --no-revs "$@"))
+. git-sh-setup-script || die "Not a git archive"
-i=0
-force=0
-while [ $i -lt ${#args} ]; do
- case "${args[$i]}" in
+old=$(git-rev-parse HEAD)
+new=
+force=
+branch=
+newbranch=
+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"
+ ;;
"-f")
- force=1;;
- "")
+ force=1
;;
*)
- echo "unknown flag ${args[$i]}"
- exit 1;;
+ rev=$(git-rev-parse --verify --revs-only "$arg^0") || exit
+ if [ -z "$rev" ]; then
+ echo "unknown flag $arg"
+ exit 1
+ fi
+ if [ "$new" ]; then
+ echo "Multiple revisions?"
+ exit 1
+ fi
+ new="$rev"
+ if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
+ branch="$arg"
+ fi
+ ;;
esac
i=$(($i+1))
done
+[ -z "$new" ] && new=$old
-if $force
+#
+# If we don't have an old branch that we're switching to,
+# and we don't have a new branch name for the target we
+# are switching to, then we'd better just be checking out
+# what we already had
+#
+[ -z "$branch$newbranch" ] &&
+ [ "$new" != "$old" ] &&
+ die "git checkout: you need to specify a new branch name"
+
+if [ "$force" ]
then
git-read-tree --reset $new &&
- git-checkout-cache -q -f -u -a &&
- echo $new > "$GIT_DIR/HEAD"
+ git-checkout-cache -q -f -u -a
else
- git-read-tree -m -u $old $new && echo $new > "$GIT_DIR/HEAD"
+ git-read-tree -m -u $old $new
+fi
+
+#
+# Switch the HEAD pointer to the new branch if it we
+# checked out a branch head, and remove any potential
+# old MERGE_HEAD's (subsequent commits will clearly not
+# be based on them, since we re-set the index)
+#
+if [ "$?" -eq 0 ]; then
+ if [ "$newbranch" ]; then
+ echo $new > "$GIT_DIR/refs/heads/$newbranch"
+ branch="$newbranch"
+ fi
+ [ "$branch" ] && ln -sf "refs/heads/$branch" "$GIT_DIR/HEAD"
+ rm -f "$GIT_DIR/MERGE_HEAD"
fi