[PATCH v4 2/5] stash: convert apply to builtin

[Joel Teichroeb <joel@teichroeb.net>]

Add a bulitin helper for performing stash commands. Converting
all at once proved hard to review, so starting with just apply
let conversion get started without the other command being
finished.

The helper is being implemented as a drop in replacement for
stash so that when it is complete it can simply be renamed and
the shell script deleted.

Delete the contents of the apply_stash shell function and replace
it with a call to stash--helper apply until pop is also
converted.

Signed-off-by: Joel Teichroeb <joel@teichroeb.net>
---
 .gitignore              |   1 +
 Makefile                |   1 +
 builtin.h               |   1 +
 builtin/stash--helper.c | 444 ++++++++++++++++++++++++++++++++++++++++++++++++
 git-stash.sh            |  75 +-------
 git.c                   |   1 +
 6 files changed, 453 insertions(+), 70 deletions(-)
 create mode 100644 builtin/stash--helper.c

diff --git a/.gitignore b/.gitignore
index 833ef3b0b..296d5f376 100644
--- a/.gitignore
+++ b/.gitignore
@@ -152,6 +152,7 @@
 /git-show-ref
 /git-stage
 /git-stash
+/git-stash--helper
 /git-status
 /git-stripspace
 /git-submodule
diff --git a/Makefile b/Makefile
index 96f6138f6..6cfdbe9a3 100644
--- a/Makefile
+++ b/Makefile
@@ -1028,6 +1028,7 @@ BUILTIN_OBJS += builtin/send-pack.o
 BUILTIN_OBJS += builtin/shortlog.o
 BUILTIN_OBJS += builtin/show-branch.o
 BUILTIN_OBJS += builtin/show-ref.o
+BUILTIN_OBJS += builtin/stash--helper.o
 BUILTIN_OBJS += builtin/stripspace.o
 BUILTIN_OBJS += builtin/submodule--helper.o
 BUILTIN_OBJS += builtin/symbolic-ref.o
diff --git a/builtin.h b/builtin.h
index 42378f3aa..a14fd85b0 100644
--- a/builtin.h
+++ b/builtin.h
@@ -219,6 +219,7 @@ extern int cmd_shortlog(int argc, const char **argv, const char *prefix);
 extern int cmd_show(int argc, const char **argv, const char *prefix);
 extern int cmd_show_branch(int argc, const char **argv, const char *prefix);
 extern int cmd_status(int argc, const char **argv, const char *prefix);
+extern int cmd_stash__helper(int argc, const char **argv, const char *prefix);
 extern int cmd_stripspace(int argc, const char **argv, const char *prefix);
 extern int cmd_submodule__helper(int argc, const char **argv, const char *prefix);
 extern int cmd_symbolic_ref(int argc, const char **argv, const char *prefix);
diff --git a/builtin/stash--helper.c b/builtin/stash--helper.c
new file mode 100644
index 000000000..00e854734
--- /dev/null
+++ b/builtin/stash--helper.c
@@ -0,0 +1,444 @@
+#include "builtin.h"
+#include "config.h"
+#include "parse-options.h"
+#include "refs.h"
+#include "lockfile.h"
+#include "cache-tree.h"
+#include "unpack-trees.h"
+#include "merge-recursive.h"
+#include "argv-array.h"
+#include "run-command.h"
+#include "dir.h"
+
+static const char * const git_stash_helper_usage[] = {
+	N_("git stash--helper apply [--index] [-q|--quiet] [<stash>]"),
+	NULL
+};
+
+static const char * const git_stash_helper_apply_usage[] = {
+	N_("git stash--helper apply [--index] [-q|--quiet] [<stash>]"),
+	NULL
+};
+
+static const char *ref_stash = "refs/stash";
+static int quiet;
+static char stash_index_path[PATH_MAX];
+
+struct stash_info {
+	struct object_id w_commit;
+	struct object_id b_commit;
+	struct object_id i_commit;
+	struct object_id u_commit;
+	struct object_id w_tree;
+	struct object_id b_tree;
+	struct object_id i_tree;
+	struct object_id u_tree;
+	struct strbuf revision;
+	int is_stash_ref;
+	int has_u;
+};
+
+static int get_symbolic_name(const char *symbolic, struct strbuf *out)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	cp.git_cmd = 1;
+	argv_array_pushl(&cp.args, "rev-parse", "--symbolic-full-name", NULL);
+	argv_array_push(&cp.args, symbolic);
+	return pipe_command(&cp, NULL, 0, out, 0, NULL, 0);
+}
+
+static int have_stash(void)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	cp.git_cmd = 1;
+	cp.no_stdout = 1;
+	argv_array_pushl(&cp.args, "rev-parse", "--verify", "--quiet", NULL);
+	argv_array_push(&cp.args, ref_stash);
+	return pipe_command(&cp, NULL, 0, NULL, 0, NULL, 0);
+}
+
+static void free_stash_info(struct stash_info *info)
+{
+	strbuf_release(&info->revision);
+}
+
+static int get_stash_info(struct stash_info *info, int argc, const char **argv)
+{
+	struct strbuf w_commit_rev = STRBUF_INIT;
+	struct strbuf b_commit_rev = STRBUF_INIT;
+	struct strbuf w_tree_rev = STRBUF_INIT;
+	struct strbuf b_tree_rev = STRBUF_INIT;
+	struct strbuf i_tree_rev = STRBUF_INIT;
+	struct strbuf u_tree_rev = STRBUF_INIT;
+	struct strbuf symbolic = STRBUF_INIT;
+	struct strbuf out = STRBUF_INIT;
+	int ret;
+	const char *revision;
+	const char *commit = NULL;
+	char *end_of_rev;
+	info->is_stash_ref = 0;
+
+	if (argc > 1) {
+		int i;
+		struct strbuf refs_msg = STRBUF_INIT;
+		for (i = 0; i < argc; ++i)
+			strbuf_addf(&refs_msg, " '%s'", argv[i]);
+
+		fprintf_ln(stderr, _("Too many revisions specified:%s"), refs_msg.buf);
+		strbuf_release(&refs_msg);
+
+		return -1;
+	}
+
+	if (argc == 1)
+		commit = argv[0];
+
+	strbuf_init(&info->revision, 0);
+	if (commit == NULL) {
+		if (have_stash()) {
+			free_stash_info(info);
+			return error(_("No stash entries found."));
+		}
+
+		strbuf_addf(&info->revision, "%s@{0}", ref_stash);
+	} else if (strspn(commit, "0123456789") == strlen(commit)) {
+		strbuf_addf(&info->revision, "%s@{%s}", ref_stash, commit);
+	} else {
+		strbuf_addstr(&info->revision, commit);
+	}
+
+	revision = info->revision.buf;
+
+	strbuf_addstr(&w_commit_rev, revision);
+
+	ret = !get_oid(w_commit_rev.buf, &info->w_commit);
+
+	strbuf_release(&w_commit_rev);
+
+	if (!ret) {
+		error(_("%s is not a valid reference"), revision);
+		free_stash_info(info);
+		return -1;
+	}
+
+	strbuf_addf(&b_commit_rev, "%s^1", revision);
+	strbuf_addf(&w_tree_rev, "%s:", revision);
+	strbuf_addf(&b_tree_rev, "%s^1:", revision);
+	strbuf_addf(&i_tree_rev, "%s^2:", revision);
+
+	ret = !get_oid(b_commit_rev.buf, &info->b_commit) &&
+		!get_oid(w_tree_rev.buf, &info->w_tree) &&
+		!get_oid(b_tree_rev.buf, &info->b_tree) &&
+		!get_oid(i_tree_rev.buf, &info->i_tree);
+
+	strbuf_release(&b_commit_rev);
+	strbuf_release(&w_tree_rev);
+	strbuf_release(&b_tree_rev);
+	strbuf_release(&i_tree_rev);
+
+	if (!ret) {
+		error(_("'%s' is not a stash-like commit"), revision);
+		free_stash_info(info);
+		return -1;
+	}
+
+	strbuf_addf(&u_tree_rev, "%s^3:", revision);
+
+	info->has_u = !get_oid(u_tree_rev.buf, &info->u_tree);
+
+	strbuf_release(&u_tree_rev);
+
+	end_of_rev = strchrnul(revision, '@');
+	strbuf_add(&symbolic, revision, end_of_rev - revision);
+
+	ret = get_symbolic_name(symbolic.buf, &out);
+	strbuf_release(&symbolic);
+	if (ret) {
+		free_stash_info(info);
+		strbuf_release(&out);
+		return -1;
+	}
+
+	if (out.len - 1 == strlen(ref_stash))
+		info->is_stash_ref = !strncmp(out.buf, ref_stash, out.len - 1);
+	strbuf_release(&out);
+
+	return 0;
+}
+
+static int reset_tree(struct object_id *i_tree, int update, int reset)
+{
+	struct unpack_trees_options opts;
+	int nr_trees = 1;
+	struct tree_desc t[MAX_UNPACK_TREES];
+	struct tree *tree;
+	struct lock_file lock_file = LOCK_INIT;
+
+	read_cache_preload(NULL);
+	if (refresh_cache(REFRESH_QUIET))
+		return -1;
+
+	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+
+	memset(&opts, 0, sizeof(opts));
+
+	tree = parse_tree_indirect(i_tree);
+	if (parse_tree(tree))
+		return -1;
+
+	init_tree_desc(t, tree->buffer, tree->size);
+
+	opts.head_idx = 1;
+	opts.src_index = &the_index;
+	opts.dst_index = &the_index;
+	opts.merge = 1;
+	opts.reset = reset;
+	opts.update = update;
+	opts.fn = oneway_merge;
+
+	if (unpack_trees(nr_trees, t, &opts))
+		return -1;
+
+	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
+		return error(_("unable to write new index file"));
+
+	return 0;
+}
+
+static int diff_tree_binary(struct strbuf *out, struct object_id *w_commit)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	const char *w_commit_hex = oid_to_hex(w_commit);
+
+	cp.git_cmd = 1;
+	argv_array_pushl(&cp.args, "diff-tree", "--binary", NULL);
+	argv_array_pushf(&cp.args, "%s^2^..%s^2", w_commit_hex, w_commit_hex);
+
+	return pipe_command(&cp, NULL, 0, out, 0, NULL, 0);
+}
+
+static int apply_cached(struct strbuf *out)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	cp.git_cmd = 1;
+	argv_array_pushl(&cp.args, "apply", "--cached", NULL);
+	return pipe_command(&cp, out->buf, out->len, NULL, 0, NULL, 0);
+}
+
+static int reset_head(const char *prefix)
+{
+	struct argv_array args = ARGV_ARRAY_INIT;
+
+	argv_array_push(&args, "reset");
+	return cmd_reset(args.argc, args.argv, prefix);
+}
+
+static int diff_cached_index(struct strbuf *out, struct object_id *c_tree)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	const char *c_tree_hex = oid_to_hex(c_tree);
+
+	cp.git_cmd = 1;
+	argv_array_pushl(&cp.args, "diff-index", "--cached", "--name-only", "--diff-filter=A", NULL);
+	argv_array_push(&cp.args, c_tree_hex);
+	return pipe_command(&cp, NULL, 0, out, 0, NULL, 0);
+}
+
+static int update_index(struct strbuf *out)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	cp.git_cmd = 1;
+	argv_array_pushl(&cp.args, "update-index", "--add", "--stdin", NULL);
+	return pipe_command(&cp, out->buf, out->len, NULL, 0, NULL, 0);
+}
+
+static int restore_untracked(struct object_id *u_tree)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	int res;
+
+	cp.git_cmd = 1;
+	argv_array_push(&cp.args, "read-tree");
+	argv_array_push(&cp.args, oid_to_hex(u_tree));
+	argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s", stash_index_path);
+	if (run_command(&cp)) {
+		remove_path(stash_index_path);
+		return -1;
+	}
+
+	child_process_init(&cp);
+	cp.git_cmd = 1;
+	argv_array_pushl(&cp.args, "checkout-index", "--all", NULL);
+	argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s", stash_index_path);
+
+	res = run_command(&cp);
+	remove_path(stash_index_path);
+	return res;
+}
+
+static int do_apply_stash(const char *prefix, struct stash_info *info, int index)
+{
+	struct merge_options o;
+	struct object_id c_tree;
+	struct object_id index_tree;
+	const struct object_id *bases[1];
+	int bases_count = 1;
+	struct commit *result;
+	int ret;
+	int has_index = index;
+
+	read_cache_preload(NULL);
+	if (refresh_cache(REFRESH_QUIET))
+		return -1;
+
+	if (write_cache_as_tree(&c_tree, 0, NULL) || reset_tree(&c_tree, 0, 0))
+		return error(_("Cannot apply a stash in the middle of a merge"));
+
+	if (index) {
+		if (!oidcmp(&info->b_tree, &info->i_tree) || !oidcmp(&c_tree, &info->i_tree)) {
+			has_index = 0;
+		} else {
+			struct strbuf out = STRBUF_INIT;
+
+			if (diff_tree_binary(&out, &info->w_commit)) {
+				strbuf_release(&out);
+				return -1;
+			}
+
+			ret = apply_cached(&out);
+			strbuf_release(&out);
+			if (ret)
+				return -1;
+
+			discard_cache();
+			read_cache();
+			if (write_cache_as_tree(&index_tree, 0, NULL))
+				return -1;
+
+			reset_head(prefix);
+		}
+	}
+
+	if (info->has_u) {
+		if (restore_untracked(&info->u_tree))
+			return error(_("Could not restore untracked files from stash"));
+	}
+
+	init_merge_options(&o);
+
+	o.branch1 = "Updated upstream";
+	o.branch2 = "Stashed changes";
+
+	if (!oidcmp(&info->b_tree, &c_tree))
+		o.branch1 = "Version stash was based on";
+
+	if (quiet)
+		o.verbosity = 0;
+
+	if (o.verbosity >= 3)
+		printf_ln(_("Merging %s with %s"), o.branch1, o.branch2);
+
+	bases[0] = &info->b_tree;
+
+	ret = merge_recursive_generic(&o, &c_tree, &info->w_tree, bases_count, bases, &result);
+	if (ret != 0) {
+		struct argv_array args = ARGV_ARRAY_INIT;
+		argv_array_push(&args, "rerere");
+		cmd_rerere(args.argc, args.argv, prefix);
+
+		if (index)
+			fprintf_ln(stderr, _("Index was not unstashed."));
+
+		return ret;
+	}
+
+	if (has_index) {
+		if (reset_tree(&index_tree, 0, 0))
+			return -1;
+	} else {
+		struct strbuf out = STRBUF_INIT;
+
+		if (diff_cached_index(&out, &c_tree)) {
+			strbuf_release(&out);
+			return -1;
+		}
+
+		if (reset_tree(&c_tree, 0, 1)) {
+			strbuf_release(&out);
+			return -1;
+		}
+
+		ret = update_index(&out);
+		strbuf_release(&out);
+		if (ret)
+			return -1;
+
+		discard_cache();
+	}
+
+	if (!quiet) {
+		struct argv_array args = ARGV_ARRAY_INIT;
+		argv_array_push(&args, "status");
+		cmd_status(args.argc, args.argv, prefix);
+	}
+
+	return 0;
+}
+
+static int apply_stash(int argc, const char **argv, const char *prefix)
+{
+	int index = 0;
+	struct stash_info info;
+	int ret;
+	struct option options[] = {
+		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
+		OPT_BOOL(0, "index", &index,
+			N_("attempt to recreate the index")),
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, prefix, options,
+			git_stash_helper_apply_usage, 0);
+
+	if (get_stash_info(&info, argc, argv))
+		return -1;
+
+	ret = do_apply_stash(prefix, &info, index);
+	free_stash_info(&info);
+	return ret;
+}
+
+int cmd_stash__helper(int argc, const char **argv, const char *prefix)
+{
+	int result = 0;
+	pid_t pid = getpid();
+	const char *index_file;
+
+	struct option options[] = {
+		OPT_END()
+	};
+
+	git_config(git_default_config, NULL);
+
+	argc = parse_options(argc, argv, prefix, options, git_stash_helper_usage,
+		PARSE_OPT_KEEP_UNKNOWN|PARSE_OPT_KEEP_DASHDASH);
+
+	index_file = get_index_file();
+	xsnprintf(stash_index_path, PATH_MAX, "%s.stash.%"PRIuMAX, index_file, (uintmax_t)pid);
+
+	if (argc < 1)
+		usage_with_options(git_stash_helper_usage, options);
+	else if (!strcmp(argv[0], "apply"))
+		result = apply_stash(argc, argv, prefix);
+	else {
+		error(_("unknown subcommand: %s"), argv[0]);
+		usage_with_options(git_stash_helper_usage, options);
+		result = 1;
+	}
+
+	return result;
+}
diff --git a/git-stash.sh b/git-stash.sh
index 94793c1a9..0b5d1f374 100755
--- a/git-stash.sh
+++ b/git-stash.sh
@@ -566,76 +566,11 @@ assert_stash_ref() {
 }
 
 apply_stash () {
-
-	assert_stash_like "$@"
-
-	git update-index -q --refresh || die "$(gettext "unable to refresh index")"
-
-	# current index state
-	c_tree=$(git write-tree) ||
-		die "$(gettext "Cannot apply a stash in the middle of a merge")"
-
-	unstashed_index_tree=
-	if test -n "$INDEX_OPTION" && test "$b_tree" != "$i_tree" &&
-			test "$c_tree" != "$i_tree"
-	then
-		git diff-tree --binary $s^2^..$s^2 | git apply --cached
-		test $? -ne 0 &&
-			die "$(gettext "Conflicts in index. Try without --index.")"
-		unstashed_index_tree=$(git write-tree) ||
-			die "$(gettext "Could not save index tree")"
-		git reset
-	fi
-
-	if test -n "$u_tree"
-	then
-		GIT_INDEX_FILE="$TMPindex" git read-tree "$u_tree" &&
-		GIT_INDEX_FILE="$TMPindex" git checkout-index --all &&
-		rm -f "$TMPindex" ||
-		die "$(gettext "Could not restore untracked files from stash entry")"
-	fi
-
-	eval "
-		GITHEAD_$w_tree='Stashed changes' &&
-		GITHEAD_$c_tree='Updated upstream' &&
-		GITHEAD_$b_tree='Version stash was based on' &&
-		export GITHEAD_$w_tree GITHEAD_$c_tree GITHEAD_$b_tree
-	"
-
-	if test -n "$GIT_QUIET"
-	then
-		GIT_MERGE_VERBOSITY=0 && export GIT_MERGE_VERBOSITY
-	fi
-	if git merge-recursive $b_tree -- $c_tree $w_tree
-	then
-		# No conflict
-		if test -n "$unstashed_index_tree"
-		then
-			git read-tree "$unstashed_index_tree"
-		else
-			a="$TMP-added" &&
-			git diff-index --cached --name-only --diff-filter=A $c_tree >"$a" &&
-			git read-tree --reset $c_tree &&
-			git update-index --add --stdin <"$a" ||
-				die "$(gettext "Cannot unstage modified files")"
-			rm -f "$a"
-		fi
-		squelch=
-		if test -n "$GIT_QUIET"
-		then
-			squelch='>/dev/null 2>&1'
-		fi
-		(cd "$START_DIR" && eval "git status $squelch") || :
-	else
-		# Merge conflict; keep the exit status from merge-recursive
-		status=$?
-		git rerere
-		if test -n "$INDEX_OPTION"
-		then
-			gettextln "Index was not unstashed." >&2
-		fi
-		exit $status
-	fi
+	cd "$START_DIR"
+	git stash--helper apply "$@"
+	res=$?
+	cd_to_toplevel
+	return $res
 }
 
 pop_stash() {
diff --git a/git.c b/git.c
index ceaa58ef4..6ffe6364a 100644
--- a/git.c
+++ b/git.c
@@ -466,6 +466,7 @@ static struct cmd_struct commands[] = {
 	{ "show-branch", cmd_show_branch, RUN_SETUP },
 	{ "show-ref", cmd_show_ref, RUN_SETUP },
 	{ "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
+	{ "stash--helper", cmd_stash__helper, RUN_SETUP | NEED_WORK_TREE },
 	{ "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 	{ "stripspace", cmd_stripspace },
 	{ "submodule--helper", cmd_submodule__helper, RUN_SETUP | SUPPORT_SUPER_PREFIX},
-- 
2.16.2