[PATCH 4/5] stash: introduce 'git stash store'

[Ramkumar Ramachandra <artagnon@gmail.com>]

save_stash() contains the logic for doing two potentially independent
operations; the first is preparing the stash merge commit, and the
second is updating the stash ref/ reflog accordingly.  While the first
operation is abstracted out into a create_stash() for callers to access
via 'git stash create', the second one is not.  Fix this by factoring
out the logic for storing the stash into a store_stash() that callers
can access via 'git stash store'.

Like create, store is not intended for end user interactive use, but for
callers in other scripts.  We can simplify the logic in the
rebase.autostash feature using this new subcommand.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 Documentation/git-stash.txt |  7 +++++++
 git-stash.sh                | 48 +++++++++++++++++++++++++++++++++++++++------
 t/t3903-stash.sh            | 19 ++++++++++++++++++
 3 files changed, 68 insertions(+), 6 deletions(-)

diff --git a/Documentation/git-stash.txt b/Documentation/git-stash.txt
index 08cdf2f..ec3a9a3 100644
--- a/Documentation/git-stash.txt
+++ b/Documentation/git-stash.txt
@@ -17,6 +17,7 @@ SYNOPSIS
 	     [-u|--include-untracked] [-a|--all] [<message>]]
 'git stash' clear
 'git stash' create [<message>]
+'git stash' store [-m|--message <message>] [-e|--error <message>] <commit>
 
 DESCRIPTION
 -----------
@@ -153,6 +154,12 @@ create::
 	object name, without storing it anywhere in the ref namespace.
 	This is probably not what you want to use; see "save" above.
 
+store::
+
+	Store a given stash created via 'git stash create' (which is a
+	dangling merge commit) in the stash ref, updating the stash
+	reflog.  This is probably not what you want to use; see
+	"save" above.
 
 DISCUSSION
 ----------
diff --git a/git-stash.sh b/git-stash.sh
index 64800b8..7985473 100755
--- a/git-stash.sh
+++ b/git-stash.sh
@@ -156,6 +156,43 @@ create_stash () {
 	die "$(gettext "Cannot record working tree state")"
 }
 
+store_stash () {
+	while test $# != 0
+	do
+		case "$1" in
+		-m|--message)
+			shift
+			stash_msg="$1"
+			;;
+		-e|--error)
+			shift
+			error_msg="$1"
+			;;
+		*)
+			break
+			;;
+		esac
+		shift
+	done
+	test $# == 1 ||
+	die "$(eval_gettext "\"$dashless store\" requires one <commit> argument")"
+
+	w_commit="$1"
+	if test -z "$stash_msg"
+	then
+		stash_msg="Created via \"git stash store\"."
+	fi
+	if test -z "$error_msg"
+	then
+		error_msg="Cannot update $ref_stash with $w_commit."
+	fi
+
+	# Make sure the reflog for stash is kept.
+	: >>"$GIT_DIR/logs/$ref_stash"
+	git update-ref -m "$stash_msg" $ref_stash $w_commit ||
+	die "$(eval_gettext "$error_msg")"
+}
+
 save_stash () {
 	keep_index=
 	patch_mode=
@@ -227,12 +264,7 @@ save_stash () {
 		clear_stash || die "$(gettext "Cannot initialize stash")"
 
 	create_stash "$stash_msg" $untracked
-
-	# Make sure the reflog for stash is kept.
-	: >>"$GIT_DIR/logs/$ref_stash"
-
-	git update-ref -m "$stash_msg" $ref_stash $w_commit ||
-		die "$(gettext "Cannot save the current status")"
+	store_stash -m "$stash_msg" -e "Cannot save the current status." $w_commit
 	say Saved working directory and index state "$stash_msg"
 
 	if test -z "$patch_mode"
@@ -549,6 +581,10 @@ create)
 	shift
 	create_stash "$*" && echo "$w_commit"
 	;;
+store)
+	shift
+	store_stash "$@"
+	;;
 drop)
 	shift
 	drop_stash "$@"
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 5dfbda7..75189ec 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -637,4 +637,23 @@ test_expect_success 'stash where working directory contains "HEAD" file' '
 	test_cmp output expect
 '
 
+test_expect_success 'store called with invalid commit' '
+	test_must_fail git stash store foo
+'
+
+test_expect_success 'store updates stash ref and reflog' '
+	git stash clear &&
+	git reset --hard &&
+	echo quux >bazzy &&
+	git add bazzy &&
+	STASH_ID=$(git stash create) &&
+	git reset --hard &&
+	! grep quux bazzy &&
+	git stash store -m quuxery $STASH_ID &&
+	test $(cat .git/refs/stash) = $STASH_ID &&
+	grep $STASH_ID .git/logs/refs/stash &&
+	git stash pop &&
+	grep quux bazzy
+'
+
 test_done
-- 
1.8.3.1.383.g0d5ad6b