stash: optionally use the scripted version again

We recently converted the `git stash` command from Unix shell scripts
to builtins.

Let's end users a way out when they discover a bug in the
builtin command: `stash.useBuiltin`.

As the file name `git-stash` is already in use, let's rename the
scripted backend to `git-legacy-stash`.

To make the test suite pass with `stash.useBuiltin=false`, this commit
also backports rudimentary support for `-q` (but only *just* enough
to appease the test suite), and adds a super-ugly hack to force exit
code 129 for `git stash -h`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

.gitignore

@@ -82,6 +82,7 @@
 /git-interpret-trailers
 /git-instaweb
 /git-legacy-rebase
+/git-legacy-stash
 /git-log
 /git-ls-files
 /git-ls-remote

Makefile

@@ -617,6 +617,7 @@ SCRIPT_SH += git-merge-resolve.sh
 SCRIPT_SH += git-mergetool.sh
 SCRIPT_SH += git-quiltimport.sh
 SCRIPT_SH += git-legacy-rebase.sh
+SCRIPT_SH += git-legacy-stash.sh
 SCRIPT_SH += git-remote-testgit.sh
 SCRIPT_SH += git-request-pull.sh
 SCRIPT_SH += git-submodule.sh

builtin/stash.c

@@ -13,6 +13,7 @@
 #include "revision.h"
 #include "log-tree.h"
 #include "diffcore.h"
+#include "exec-cmd.h"
 
 #define INCLUDE_ALL_FILES 2
 
@@ -1510,6 +1511,26 @@ static int save_stash(int argc, const char **argv, const char *prefix)
 	return ret;
 }
 
+static int use_builtin_stash(void)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct strbuf out = STRBUF_INIT;
+	int ret;
+
+	argv_array_pushl(&cp.args,
+			 "config", "--bool", "stash.usebuiltin", NULL);
+	cp.git_cmd = 1;
+	if (capture_command(&cp, &out, 6)) {
+		strbuf_release(&out);
+		return 1;
+	}
+
+	strbuf_trim(&out);
+	ret = !strcmp("true", out.buf);
+	strbuf_release(&out);
+	return ret;
+}
+
 int cmd_stash(int argc, const char **argv, const char *prefix)
 {
 	int i = -1;
@@ -1521,6 +1542,20 @@ int cmd_stash(int argc, const char **argv, const char *prefix)
 		OPT_END()
 	};
 
+	if (!use_builtin_stash()) {
+		const char *path = mkpath("%s/git-legacy-stash",
+					  git_exec_path());
+
+		if (sane_execvp(path, (char **)argv) < 0)
+			die_errno(_("could not exec %s"), path);
+		else
+			BUG("sane_execvp() returned???");
+	}
+
+	prefix = setup_git_directory();
+	trace_repo_setup(prefix);
+	setup_work_tree();
+
 	git_config(git_diff_basic_config, NULL);
 
 	argc = parse_options(argc, argv, prefix, options, git_stash_usage,

git-legacy-stash.sh

@@ -80,6 +80,28 @@ clear_stash () {
 	fi
 }
 
+maybe_quiet () {
+	case "$1" in
+	--keep-stdout)
+		shift
+		if test -n "$GIT_QUIET"
+		then
+			eval "$@" 2>/dev/null
+		else
+			eval "$@"
+		fi
+		;;
+	*)
+		if test -n "$GIT_QUIET"
+		then
+			eval "$@" >/dev/null 2>&1
+		else
+			eval "$@"
+		fi
+		;;
+	esac
+}
+
 create_stash () {
 
 	prepare_fallback_ident
@@ -112,15 +134,18 @@ create_stash () {
 	done
 
 	git update-index -q --refresh
-	if no_changes "$@"
+	if maybe_quiet no_changes "$@"
 	then
 		exit 0
 	fi
 
 	# state of the base commit
-	if b_commit=$(git rev-parse --verify HEAD)
+	if b_commit=$(maybe_quiet --keep-stdout git rev-parse --verify HEAD)
 	then
 		head=$(git rev-list --oneline -n 1 HEAD --)
+	elif test -n "$GIT_QUIET"
+	then
+		exit 1
 	else
 		die "$(gettext "You do not have the initial commit yet")"
 	fi
@@ -315,7 +340,7 @@ push_stash () {
 	test -n "$untracked" || git ls-files --error-unmatch -- "$@" >/dev/null || exit 1
 
 	git update-index -q --refresh
-	if no_changes "$@"
+	if maybe_quiet no_changes "$@"
 	then
 		say "$(gettext "No local changes to save")"
 		exit 0
@@ -370,6 +395,9 @@ save_stash () {
 	while test $# != 0
 	do
 		case "$1" in
+		-q|--quiet)
+			GIT_QUIET=t
+			;;
 		--)
 			shift
 			break

git-sh-setup.sh

@@ -101,6 +101,7 @@ $LONG_USAGE")"
 	case "$1" in
 		-h)
 		echo "$LONG_USAGE"
+		case "$0" in *git-legacy-stash) exit 129;; esac
 		exit
 	esac
 fi

git.c

@@ -554,7 +554,12 @@ static struct cmd_struct commands[] = {
 	{ "show-index", cmd_show_index },
 	{ "show-ref", cmd_show_ref, RUN_SETUP },
 	{ "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
-	{ "stash", cmd_stash, RUN_SETUP | NEED_WORK_TREE },
+	/*
+	 * NEEDSWORK: Until the builtin stash is thoroughly robust and no
+	 * longer needs redirection to the stash shell script this is kept as
+	 * is, then should be changed to RUN_SETUP | NEED_WORK_TREE
+	 */
+	{ "stash", cmd_stash },
 	{ "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 	{ "stripspace", cmd_stripspace },
 	{ "submodule--helper", cmd_submodule__helper, RUN_SETUP | SUPPORT_SUPER_PREFIX | NO_PARSEOPT },