Merge branch 'ps/stash-in-c'

"git stash" rewritten in C.

* ps/stash-in-c: (28 commits)
  tests: add a special setup where stash.useBuiltin is off
  stash: optionally use the scripted version again
  stash: add back the original, scripted `git stash`
  stash: convert `stash--helper.c` into `stash.c`
  stash: replace all `write-tree` child processes with API calls
  stash: optimize `get_untracked_files()` and `check_changes()`
  stash: convert save to builtin
  stash: make push -q quiet
  stash: convert push to builtin
  stash: convert create to builtin
  stash: convert store to builtin
  stash: convert show to builtin
  stash: convert list to builtin
  stash: convert pop to builtin
  stash: convert branch to builtin
  stash: convert drop and clear to builtin
  stash: convert apply to builtin
  stash: mention options in `show` synopsis
  stash: add tests for `git stash show` config
  stash: rename test cases to be more descriptive
  ...

16 files changed, 2017 insertions, 72 deletions

diff --git a/.gitignore b/.gitignore
index 5cb84f1d1a..44c74402c8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -82,6 +82,7 @@
 /git-init-db
 /git-interpret-trailers
 /git-instaweb
+/git-legacy-stash
 /git-log
 /git-ls-files
 /git-ls-remote
diff --git a/Documentation/git-stash.txt b/Documentation/git-stash.txt
index 7ef8c47911..e31ea7d303 100644
--- a/Documentation/git-stash.txt
+++ b/Documentation/git-stash.txt
@@ -9,7 +9,7 @@ SYNOPSIS
 --------
 [verse]
 'git stash' list [<options>]
-'git stash' show [<stash>]
+'git stash' show [<options>] [<stash>]
 'git stash' drop [-q|--quiet] [<stash>]
 'git stash' ( pop | apply ) [--index] [-q|--quiet] [<stash>]
 'git stash' branch <branchname> [<stash>]
@@ -106,7 +106,7 @@ stash@{1}: On master: 9cc0589... Add git-stash
 The command takes options applicable to the 'git log'
 command to control what is shown and how. See linkgit:git-log[1].
 
-show [<stash>]::
+show [<options>] [<stash>]::
 
 	Show the changes recorded in the stash entry as a diff between the
 	stashed contents and the commit back when the stash entry was first
diff --git a/Makefile b/Makefile
index 5e5489aa1a..c16e75ea80 100644
--- a/Makefile
+++ b/Makefile
@@ -613,9 +613,9 @@ SCRIPT_SH += git-merge-one-file.sh
 SCRIPT_SH += git-merge-resolve.sh
 SCRIPT_SH += git-mergetool.sh
 SCRIPT_SH += git-quiltimport.sh
+SCRIPT_SH += git-legacy-stash.sh
 SCRIPT_SH += git-remote-testgit.sh
 SCRIPT_SH += git-request-pull.sh
-SCRIPT_SH += git-stash.sh
 SCRIPT_SH += git-submodule.sh
 SCRIPT_SH += git-web--browse.sh
 
@@ -1130,6 +1130,7 @@ BUILTIN_OBJS += builtin/shortlog.o
 BUILTIN_OBJS += builtin/show-branch.o
 BUILTIN_OBJS += builtin/show-index.o
 BUILTIN_OBJS += builtin/show-ref.o
+BUILTIN_OBJS += builtin/stash.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 6538932e99..b78ab6e30b 100644
--- a/builtin.h
+++ b/builtin.h
@@ -225,6 +225,7 @@ 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_show_index(int argc, const char **argv, const char *prefix);
 extern int cmd_status(int argc, const char **argv, const char *prefix);
+extern int cmd_stash(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.c b/builtin/stash.c
new file mode 100644
index 0000000000..51df092633
--- /dev/null
+++ b/builtin/stash.c
@@ -0,0 +1,1635 @@
+#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#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"
+#include "rerere.h"
+#include "revision.h"
+#include "log-tree.h"
+#include "diffcore.h"
+#include "exec-cmd.h"
+
+#define INCLUDE_ALL_FILES 2
+
+static const char * const git_stash_usage[] = {
+	N_("git stash list [<options>]"),
+	N_("git stash show [<options>] [<stash>]"),
+	N_("git stash drop [-q|--quiet] [<stash>]"),
+	N_("git stash ( pop | apply ) [--index] [-q|--quiet] [<stash>]"),
+	N_("git stash branch <branchname> [<stash>]"),
+	N_("git stash clear"),
+	N_("git stash [push [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]\n"
+	   "          [-u|--include-untracked] [-a|--all] [-m|--message <message>]\n"
+	   "          [--] [<pathspec>...]]"),
+	N_("git stash save [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]\n"
+	   "          [-u|--include-untracked] [-a|--all] [<message>]"),
+	NULL
+};
+
+static const char * const git_stash_list_usage[] = {
+	N_("git stash list [<options>]"),
+	NULL
+};
+
+static const char * const git_stash_show_usage[] = {
+	N_("git stash show [<options>] [<stash>]"),
+	NULL
+};
+
+static const char * const git_stash_drop_usage[] = {
+	N_("git stash drop [-q|--quiet] [<stash>]"),
+	NULL
+};
+
+static const char * const git_stash_pop_usage[] = {
+	N_("git stash pop [--index] [-q|--quiet] [<stash>]"),
+	NULL
+};
+
+static const char * const git_stash_apply_usage[] = {
+	N_("git stash apply [--index] [-q|--quiet] [<stash>]"),
+	NULL
+};
+
+static const char * const git_stash_branch_usage[] = {
+	N_("git stash branch <branchname> [<stash>]"),
+	NULL
+};
+
+static const char * const git_stash_clear_usage[] = {
+	N_("git stash clear"),
+	NULL
+};
+
+static const char * const git_stash_store_usage[] = {
+	N_("git stash store [-m|--message <message>] [-q|--quiet] <commit>"),
+	NULL
+};
+
+static const char * const git_stash_push_usage[] = {
+	N_("git stash [push [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]\n"
+	   "          [-u|--include-untracked] [-a|--all] [-m|--message <message>]\n"
+	   "          [--] [<pathspec>...]]"),
+	NULL
+};
+
+static const char * const git_stash_save_usage[] = {
+	N_("git stash save [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]\n"
+	   "          [-u|--include-untracked] [-a|--all] [<message>]"),
+	NULL
+};
+
+static const char *ref_stash = "refs/stash";
+static struct strbuf stash_index_path = STRBUF_INIT;
+
+/*
+ * w_commit is set to the commit containing the working tree
+ * b_commit is set to the base commit
+ * i_commit is set to the commit containing the index tree
+ * u_commit is set to the commit containing the untracked files tree
+ * w_tree is set to the working tree
+ * b_tree is set to the base tree
+ * i_tree is set to the index tree
+ * u_tree is set to the untracked files tree
+ */
+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 void free_stash_info(struct stash_info *info)
+{
+	strbuf_release(&info->revision);
+}
+
+static void assert_stash_like(struct stash_info *info, const char *revision)
+{
+	if (get_oidf(&info->b_commit, "%s^1", revision) ||
+	    get_oidf(&info->w_tree, "%s:", revision) ||
+	    get_oidf(&info->b_tree, "%s^1:", revision) ||
+	    get_oidf(&info->i_tree, "%s^2:", revision))
+		die(_("'%s' is not a stash-like commit"), revision);
+}
+
+static int get_stash_info(struct stash_info *info, int argc, const char **argv)
+{
+	int ret;
+	char *end_of_rev;
+	char *expanded_ref;
+	const char *revision;
+	const char *commit = NULL;
+	struct object_id dummy;
+	struct strbuf symbolic = STRBUF_INIT;
+
+	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) {
+		if (!ref_exists(ref_stash)) {
+			free_stash_info(info);
+			fprintf_ln(stderr, _("No stash entries found."));
+			return -1;
+		}
+
+		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;
+
+	if (get_oid(revision, &info->w_commit)) {
+		error(_("%s is not a valid reference"), revision);
+		free_stash_info(info);
+		return -1;
+	}
+
+	assert_stash_like(info, revision);
+
+	info->has_u = !get_oidf(&info->u_tree, "%s^3:", revision);
+
+	end_of_rev = strchrnul(revision, '@');
+	strbuf_add(&symbolic, revision, end_of_rev - revision);
+
+	ret = dwim_ref(symbolic.buf, symbolic.len, &dummy, &expanded_ref);
+	strbuf_release(&symbolic);
+	switch (ret) {
+	case 0: /* Not found, but valid ref */
+		info->is_stash_ref = 0;
+		break;
+	case 1:
+		info->is_stash_ref = !strcmp(expanded_ref, ref_stash);
+		break;
+	default: /* Invalid or ambiguous */
+		free_stash_info(info);
+	}
+
+	free(expanded_ref);
+	return !(ret == 0 || ret == 1);
+}
+
+static int do_clear_stash(void)
+{
+	struct object_id obj;
+	if (get_oid(ref_stash, &obj))
+		return 0;
+
+	return delete_ref(NULL, ref_stash, &obj, 0);
+}
+
+static int clear_stash(int argc, const char **argv, const char *prefix)
+{
+	struct option options[] = {
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, prefix, options,
+			     git_stash_clear_usage,
+			     PARSE_OPT_STOP_AT_NON_OPTION);
+
+	if (argc)
+		return error(_("git stash clear with parameters is "
+			       "unimplemented"));
+
+	return do_clear_stash();
+}
+
+static int reset_tree(struct object_id *i_tree, int update, int reset)
+{
+	int nr_trees = 1;
+	struct unpack_trees_options opts;
+	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);
+
+	/*
+	 * Diff-tree would not be very hard to replace with a native function,
+	 * however it should be done together with apply_cached.
+	 */
+	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;
+
+	/*
+	 * Apply currently only reads either from stdin or a file, thus
+	 * apply_all_patches would have to be updated to optionally take a
+	 * buffer.
+	 */
+	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(void)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	/*
+	 * Reset is overall quite simple, however there is no current public
+	 * API for resetting.
+	 */
+	cp.git_cmd = 1;
+	argv_array_push(&cp.args, "reset");
+
+	return run_command(&cp);
+}
+
+static void add_diff_to_buf(struct diff_queue_struct *q,
+			    struct diff_options *options,
+			    void *data)
+{
+	int i;
+
+	for (i = 0; i < q->nr; i++) {
+		strbuf_addstr(data, q->queue[i]->one->path);
+
+		/* NUL-terminate: will be fed to update-index -z */
+		strbuf_addch(data, '\0');
+	}
+}
+
+static int get_newly_staged(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);
+
+	/*
+	 * diff-index is very similar to diff-tree above, and should be
+	 * converted together with update_index.
+	 */
+	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;
+
+	/*
+	 * Update-index is very complicated and may need to have a public
+	 * function exposed in order to remove this forking.
+	 */
+	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)
+{
+	int res;
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	/*
+	 * We need to run restore files from a given index, but without
+	 * affecting the current index, so we use GIT_INDEX_FILE with
+	 * run_command to fork processes that will not interfere.
+	 */
+	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.buf);
+	if (run_command(&cp)) {
+		remove_path(stash_index_path.buf);
+		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.buf);
+
+	res = run_command(&cp);
+	remove_path(stash_index_path.buf);
+	return res;
+}
+
+static int do_apply_stash(const char *prefix, struct stash_info *info,
+			  int index, int quiet)
+{
+	int ret;
+	int has_index = index;
+	struct merge_options o;
+	struct object_id c_tree;
+	struct object_id index_tree;
+	struct commit *result;
+	const struct object_id *bases[1];
+
+	read_cache_preload(NULL);
+	if (refresh_cache(REFRESH_QUIET))
+		return -1;
+
+	if (write_cache_as_tree(&c_tree, 0, NULL))
+		return error(_("cannot apply a stash in the middle of a merge"));
+
+	if (index) {
+		if (oideq(&info->b_tree, &info->i_tree) ||
+		    oideq(&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 error(_("could not generate diff %s^!."),
+					     oid_to_hex(&info->w_commit));
+			}
+
+			ret = apply_cached(&out);
+			strbuf_release(&out);
+			if (ret)
+				return error(_("conflicts in index."
+					       "Try without --index."));
+
+			discard_cache();
+			read_cache();
+			if (write_cache_as_tree(&index_tree, 0, NULL))
+				return error(_("could not save index tree"));
+
+			reset_head();
+		}
+	}
+
+	if (info->has_u && restore_untracked(&info->u_tree))
+		return error(_("could not restore untracked files from stash"));
+
+	init_merge_options(&o, the_repository);
+
+	o.branch1 = "Updated upstream";
+	o.branch2 = "Stashed changes";
+
+	if (oideq(&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, 1, bases,
+				      &result);
+	if (ret) {
+		rerere(0);
+
+		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 (get_newly_staged(&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) {
+		if (refresh_cache(REFRESH_QUIET))
+			warning("could not refresh index");
+	} else {
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		/*
+		 * Status is quite simple and could be replaced with calls to
+		 * wt_status in the future, but it adds complexities which may
+		 * require more tests.
+		 */
+		cp.git_cmd = 1;
+		cp.dir = prefix;
+		argv_array_push(&cp.args, "status");
+		run_command(&cp);
+	}
+
+	return 0;
+}
+
+static int apply_stash(int argc, const char **argv, const char *prefix)
+{
+	int ret;
+	int quiet = 0;
+	int index = 0;
+	struct stash_info info;
+	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_apply_usage, 0);
+
+	if (get_stash_info(&info, argc, argv))
+		return -1;
+
+	ret = do_apply_stash(prefix, &info, index, quiet);
+	free_stash_info(&info);
+	return ret;
+}
+
+static int do_drop_stash(const char *prefix, struct stash_info *info, int quiet)
+{
+	int ret;
+	struct child_process cp_reflog = CHILD_PROCESS_INIT;
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	/*
+	 * reflog does not provide a simple function for deleting refs. One will
+	 * need to be added to avoid implementing too much reflog code here
+	 */
+
+	cp_reflog.git_cmd = 1;
+	argv_array_pushl(&cp_reflog.args, "reflog", "delete", "--updateref",
+			 "--rewrite", NULL);
+	argv_array_push(&cp_reflog.args, info->revision.buf);
+	ret = run_command(&cp_reflog);
+	if (!ret) {
+		if (!quiet)
+			printf_ln(_("Dropped %s (%s)"), info->revision.buf,
+				  oid_to_hex(&info->w_commit));
+	} else {
+		return error(_("%s: Could not drop stash entry"),
+			     info->revision.buf);
+	}
+
+	/*
+	 * This could easily be replaced by get_oid, but currently it will throw
+	 * a fatal error when a reflog is empty, which we can not recover from.
+	 */
+	cp.git_cmd = 1;
+	/* Even though --quiet is specified, rev-parse still outputs the hash */
+	cp.no_stdout = 1;
+	argv_array_pushl(&cp.args, "rev-parse", "--verify", "--quiet", NULL);
+	argv_array_pushf(&cp.args, "%s@{0}", ref_stash);
+	ret = run_command(&cp);
+
+	/* do_clear_stash if we just dropped the last stash entry */
+	if (ret)
+		do_clear_stash();
+
+	return 0;
+}
+
+static void assert_stash_ref(struct stash_info *info)
+{
+	if (!info->is_stash_ref) {
+		error(_("'%s' is not a stash reference"), info->revision.buf);
+		free_stash_info(info);
+		exit(1);
+	}
+}
+
+static int drop_stash(int argc, const char **argv, const char *prefix)
+{
+	int ret;
+	int quiet = 0;
+	struct stash_info info;
+	struct option options[] = {
+		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, prefix, options,
+			     git_stash_drop_usage, 0);
+
+	if (get_stash_info(&info, argc, argv))
+		return -1;
+
+	assert_stash_ref(&info);
+
+	ret = do_drop_stash(prefix, &info, quiet);
+	free_stash_info(&info);
+	return ret;
+}
+
+static int pop_stash(int argc, const char **argv, const char *prefix)
+{
+	int ret;
+	int index = 0;
+	int quiet = 0;
+	struct stash_info info;
+	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_pop_usage, 0);
+
+	if (get_stash_info(&info, argc, argv))
+		return -1;
+
+	assert_stash_ref(&info);
+	if ((ret = do_apply_stash(prefix, &info, index, quiet)))
+		printf_ln(_("The stash entry is kept in case "
+			    "you need it again."));
+	else
+		ret = do_drop_stash(prefix, &info, quiet);
+
+	free_stash_info(&info);
+	return ret;
+}
+
+static int branch_stash(int argc, const char **argv, const char *prefix)
+{
+	int ret;
+	const char *branch = NULL;
+	struct stash_info info;
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct option options[] = {
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, prefix, options,
+			     git_stash_branch_usage, 0);
+
+	if (!argc) {
+		fprintf_ln(stderr, _("No branch name specified"));
+		return -1;
+	}
+
+	branch = argv[0];
+
+	if (get_stash_info(&info, argc - 1, argv + 1))
+		return -1;
+
+	cp.git_cmd = 1;
+	argv_array_pushl(&cp.args, "checkout", "-b", NULL);
+	argv_array_push(&cp.args, branch);
+	argv_array_push(&cp.args, oid_to_hex(&info.b_commit));
+	ret = run_command(&cp);
+	if (!ret)
+		ret = do_apply_stash(prefix, &info, 1, 0);
+	if (!ret && info.is_stash_ref)
+		ret = do_drop_stash(prefix, &info, 0);
+
+	free_stash_info(&info);
+
+	return ret;
+}
+
+static int list_stash(int argc, const char **argv, const char *prefix)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct option options[] = {
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, prefix, options,
+			     git_stash_list_usage,
+			     PARSE_OPT_KEEP_UNKNOWN);
+
+	if (!ref_exists(ref_stash))
+		return 0;
+
+	cp.git_cmd = 1;
+	argv_array_pushl(&cp.args, "log", "--format=%gd: %gs", "-g",
+			 "--first-parent", "-m", NULL);
+	argv_array_pushv(&cp.args, argv);
+	argv_array_push(&cp.args, ref_stash);
+	argv_array_push(&cp.args, "--");
+	return run_command(&cp);
+}
+
+static int show_stat = 1;
+static int show_patch;
+
+static int git_stash_config(const char *var, const char *value, void *cb)
+{
+	if (!strcmp(var, "stash.showstat")) {
+		show_stat = git_config_bool(var, value);
+		return 0;
+	}
+	if (!strcmp(var, "stash.showpatch")) {
+		show_patch = git_config_bool(var, value);
+		return 0;
+	}
+	return git_default_config(var, value, cb);
+}
+
+static int show_stash(int argc, const char **argv, const char *prefix)
+{
+	int i;
+	int opts = 0;
+	int ret = 0;
+	struct stash_info info;
+	struct rev_info rev;
+	struct argv_array stash_args = ARGV_ARRAY_INIT;
+	struct option options[] = {
+		OPT_END()
+	};
+
+	init_diff_ui_defaults();
+	git_config(git_diff_ui_config, NULL);
+	init_revisions(&rev, prefix);
+
+	for (i = 1; i < argc; i++) {
+		if (argv[i][0] != '-')
+			argv_array_push(&stash_args, argv[i]);
+		else
+			opts++;
+	}
+
+	ret = get_stash_info(&info, stash_args.argc, stash_args.argv);
+	argv_array_clear(&stash_args);
+	if (ret)
+		return -1;
+
+	/*
+	 * The config settings are applied only if there are not passed
+	 * any options.
+	 */
+	if (!opts) {
+		git_config(git_stash_config, NULL);
+		if (show_stat)
+			rev.diffopt.output_format = DIFF_FORMAT_DIFFSTAT;
+
+		if (show_patch)
+			rev.diffopt.output_format |= DIFF_FORMAT_PATCH;
+
+		if (!show_stat && !show_patch) {
+			free_stash_info(&info);
+			return 0;
+		}
+	}
+
+	argc = setup_revisions(argc, argv, &rev, NULL);
+	if (argc > 1) {
+		free_stash_info(&info);
+		usage_with_options(git_stash_show_usage, options);
+	}
+
+	rev.diffopt.flags.recursive = 1;
+	setup_diff_pager(&rev.diffopt);
+	diff_tree_oid(&info.b_commit, &info.w_commit, "", &rev.diffopt);
+	log_tree_diff_flush(&rev);
+
+	free_stash_info(&info);
+	return diff_result_code(&rev.diffopt, 0);
+}
+
+static int do_store_stash(const struct object_id *w_commit, const char *stash_msg,
+			  int quiet)
+{
+	if (!stash_msg)
+		stash_msg = "Created via \"git stash store\".";
+
+	if (update_ref(stash_msg, ref_stash, w_commit, NULL,
+		       REF_FORCE_CREATE_REFLOG,
+		       quiet ? UPDATE_REFS_QUIET_ON_ERR :
+		       UPDATE_REFS_MSG_ON_ERR)) {
+		if (!quiet) {
+			fprintf_ln(stderr, _("Cannot update %s with %s"),
+				   ref_stash, oid_to_hex(w_commit));
+		}
+		return -1;
+	}
+
+	return 0;
+}
+
+static int store_stash(int argc, const char **argv, const char *prefix)
+{
+	int quiet = 0;
+	const char *stash_msg = NULL;
+	struct object_id obj;
+	struct object_context dummy;
+	struct option options[] = {
+		OPT__QUIET(&quiet, N_("be quiet")),
+		OPT_STRING('m', "message", &stash_msg, "message",
+			   N_("stash message")),
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, prefix, options,
+			     git_stash_store_usage,
+			     PARSE_OPT_KEEP_UNKNOWN);
+
+	if (argc != 1) {
+		if (!quiet)
+			fprintf_ln(stderr, _("\"git stash store\" requires one "
+					     "<commit> argument"));
+		return -1;
+	}
+
+	if (get_oid_with_context(the_repository,
+				 argv[0], quiet ? GET_OID_QUIETLY : 0, &obj,
+				 &dummy)) {
+		if (!quiet)
+			fprintf_ln(stderr, _("Cannot update %s with %s"),
+					     ref_stash, argv[0]);
+		return -1;
+	}
+
+	return do_store_stash(&obj, stash_msg, quiet);
+}
+
+static void add_pathspecs(struct argv_array *args,
+			  struct pathspec ps) {
+	int i;
+
+	for (i = 0; i < ps.nr; i++)
+		argv_array_push(args, ps.items[i].match);
+}
+
+/*
+ * `untracked_files` will be filled with the names of untracked files.
+ * The return value is:
+ *
+ * = 0 if there are not any untracked files
+ * > 0 if there are untracked files
+ */
+static int get_untracked_files(struct pathspec ps, int include_untracked,
+			       struct strbuf *untracked_files)
+{
+	int i;
+	int max_len;
+	int found = 0;
+	char *seen;
+	struct dir_struct dir;
+
+	memset(&dir, 0, sizeof(dir));
+	if (include_untracked != INCLUDE_ALL_FILES)
+		setup_standard_excludes(&dir);
+
+	seen = xcalloc(ps.nr, 1);
+
+	max_len = fill_directory(&dir, the_repository->index, &ps);
+	for (i = 0; i < dir.nr; i++) {
+		struct dir_entry *ent = dir.entries[i];
+		if (dir_path_match(&the_index, ent, &ps, max_len, seen)) {
+			found++;
+			strbuf_addstr(untracked_files, ent->name);
+			/* NUL-terminate: will be fed to update-index -z */
+			strbuf_addch(untracked_files, '\0');
+		}
+		free(ent);
+	}
+
+	free(seen);
+	free(dir.entries);
+	free(dir.ignored);
+	clear_directory(&dir);
+	return found;
+}
+
+/*
+ * The return value of `check_changes_tracked_files()` can be:
+ *
+ * < 0 if there was an error
+ * = 0 if there are no changes.
+ * > 0 if there are changes.
+ */
+static int check_changes_tracked_files(struct pathspec ps)
+{
+	int result;
+	struct rev_info rev;
+	struct object_id dummy;
+
+	/* No initial commit. */
+	if (get_oid("HEAD", &dummy))
+		return -1;
+
+	if (read_cache() < 0)
+		return -1;
+
+	init_revisions(&rev, NULL);
+	rev.prune_data = ps;
+
+	rev.diffopt.flags.quick = 1;
+	rev.diffopt.flags.ignore_submodules = 1;
+	rev.abbrev = 0;
+
+	add_head_to_pending(&rev);
+	diff_setup_done(&rev.diffopt);
+
+	result = run_diff_index(&rev, 1);
+	if (diff_result_code(&rev.diffopt, result))
+		return 1;
+
+	object_array_clear(&rev.pending);
+	result = run_diff_files(&rev, 0);
+	if (diff_result_code(&rev.diffopt, result))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * The function will fill `untracked_files` with the names of untracked files
+ * It will return 1 if there were any changes and 0 if there were not.
+ */
+static int check_changes(struct pathspec ps, int include_untracked,
+			 struct strbuf *untracked_files)
+{
+	int ret = 0;
+	if (check_changes_tracked_files(ps))
+		ret = 1;
+
+	if (include_untracked && get_untracked_files(ps, include_untracked,
+						     untracked_files))
+		ret = 1;
+
+	return ret;
+}
+
+static int save_untracked_files(struct stash_info *info, struct strbuf *msg,
+				struct strbuf files)
+{
+	int ret = 0;
+	struct strbuf untracked_msg = STRBUF_INIT;
+	struct child_process cp_upd_index = CHILD_PROCESS_INIT;
+	struct index_state istate = { NULL };
+
+	cp_upd_index.git_cmd = 1;
+	argv_array_pushl(&cp_upd_index.args, "update-index", "-z", "--add",
+			 "--remove", "--stdin", NULL);
+	argv_array_pushf(&cp_upd_index.env_array, "GIT_INDEX_FILE=%s",
+			 stash_index_path.buf);
+
+	strbuf_addf(&untracked_msg, "untracked files on %s\n", msg->buf);
+	if (pipe_command(&cp_upd_index, files.buf, files.len, NULL, 0,
+			 NULL, 0)) {
+		ret = -1;
+		goto done;
+	}
+
+	if (write_index_as_tree(&info->u_tree, &istate, stash_index_path.buf, 0,
+				NULL)) {
+		ret = -1;
+		goto done;
+	}
+
+	if (commit_tree(untracked_msg.buf, untracked_msg.len,
+			&info->u_tree, NULL, &info->u_commit, NULL, NULL)) {
+		ret = -1;
+		goto done;
+	}
+
+done:
+	discard_index(&istate);
+	strbuf_release(&untracked_msg);