[GSoC][PATCH 4/5 v4] submodule: port submodule subcommand 'status' from shell to C

[Prathamesh Chavan <pc44800@gmail.com>]

This aims to make git-submodule 'status' a built-in. Hence, the function
cmd_status() is ported from shell to C. This is done by introducing
three functions: module_status(), submodule_status() and print_status().

The function module_status() acts as the front-end of the subcommand.
It parses subcommand's options and then calls the function
module_list_compute() for computing the list of submodules. Then
this functions calls for_each_submodule_list() looping through the
list obtained.

Then for_each_submodule_list() calls submodule_status() for each of the
submodule in its list. The function submodule_status() is responsible
for generating the status each submodule it is called for, and
then calls print_status().

Finally, the function print_status() handles the printing of submodule's
status.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Prathamesh Chavan <pc44800@gmail.com>
---
In this new version of patch:

Instead of using cmd_diff_files(), the process is optimized
by using ce_match_stat().

Also, the child_process running the command 'rev-parse --verify HEAD'
is removed for optimization reasons, and instead head_ref_submodule()
is used with callback function handle_submodule_head_ref().

The series differs from the complete weekly-update series as these patches
have been reviewed with mentors as well as on mailing list more no. of
times then the rest patches from the complete series, and hence
IMO, are ready for getting included. If not so, I would like to have
suggestions for improvising it.

The patches pass the complete test suite.

 builtin/submodule--helper.c | 146 ++++++++++++++++++++++++++++++++++++++++++++
 git-submodule.sh            |  49 +--------------
 2 files changed, 147 insertions(+), 48 deletions(-)

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 80f744407..9c1630495 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -560,6 +560,151 @@ static int module_init(int argc, const char **argv, const char *prefix)
 	return 0;
 }
 
+struct status_cb {
+	const char *prefix;
+	unsigned int quiet: 1;
+	unsigned int recursive: 1;
+	unsigned int cached: 1;
+};
+#define STATUS_CB_INIT { NULL, 0, 0, 0 }
+
+static void print_status(struct status_cb *info, char state, const char *path,
+			 char *sub_sha1, char *displaypath)
+{
+	if (info->quiet)
+		return;
+
+	printf("%c%s %s", state, sub_sha1, displaypath);
+
+	if (state == ' ' || state == '+') {
+		struct argv_array name_rev_args = ARGV_ARRAY_INIT;
+
+		argv_array_pushl(&name_rev_args, "print-name-rev",
+				 path, sub_sha1, NULL);
+		print_name_rev(name_rev_args.argc, name_rev_args.argv,
+			       info->prefix);
+	} else {
+		printf("\n");
+	}
+}
+
+static int handle_submodule_head_ref(const char *refname,
+				     const struct object_id *oid, int flags,
+				     void *cb_data)
+{
+	struct strbuf *output = cb_data;
+	if (oid)
+		strbuf_addstr(output, oid_to_hex(oid));
+	return 0;
+}
+
+static void status_submodule(const struct cache_entry *list_item, void *cb_data)
+{
+	struct status_cb *info = cb_data;
+	char *sub_sha1 = xstrdup(oid_to_hex(&list_item->oid));
+	char *displaypath;
+	struct stat st;
+
+	if (!submodule_from_path(null_sha1, list_item->name))
+		die(_("no submodule mapping found in .gitmodules for path '%s'"),
+		      list_item->name);
+
+	displaypath = get_submodule_displaypath(list_item->name, info->prefix);
+
+	if (list_item->ce_flags) {
+		print_status(info, 'U', list_item->name,
+			     sha1_to_hex(null_sha1), displaypath);
+		goto cleanup;
+	}
+
+	if (!is_submodule_active(the_repository, list_item->name)) {
+		print_status(info, '-', list_item->name, sub_sha1, displaypath);
+		goto cleanup;
+	}
+
+	if (!lstat(list_item->name, &st) && !ce_match_stat(list_item, &st, 0)) {
+		print_status(info, ' ', list_item->name, sub_sha1, displaypath);
+	} else {
+		if (!info->cached) {
+			struct strbuf sb = STRBUF_INIT;
+			if (head_ref_submodule(list_item->name,
+					       handle_submodule_head_ref, &sb))
+				die(_("could not resolve HEAD ref inside the"
+				      "submodule '%s'"), list_item->name);
+			print_status(info, '+', list_item->name, sb.buf,
+				     displaypath);
+			strbuf_release(&sb);
+		} else {
+			print_status(info, '+', list_item->name, sub_sha1,
+				     displaypath);
+		}
+	}
+
+	if (info->recursive) {
+		struct child_process cpr = CHILD_PROCESS_INIT;
+
+		cpr.git_cmd = 1;
+		cpr.dir = list_item->name;
+		prepare_submodule_repo_env(&cpr.env_array);
+
+		argv_array_pushl(&cpr.args, "--super-prefix", displaypath,
+				 "submodule--helper", "status", "--recursive",
+				 NULL);
+
+		if (info->cached)
+			argv_array_push(&cpr.args, "--cached");
+
+		if (info->quiet)
+			argv_array_push(&cpr.args, "--quiet");
+
+		if (run_command(&cpr))
+			die(_("failed to recurse into submodule '%s'"),
+			      list_item->name);
+	}
+
+cleanup:
+	free(displaypath);
+	free(sub_sha1);
+}
+
+static int module_status(int argc, const char **argv, const char *prefix)
+{
+	struct status_cb info = STATUS_CB_INIT;
+	struct pathspec pathspec;
+	struct module_list list = MODULE_LIST_INIT;
+	int quiet = 0;
+	int cached = 0;
+	int recursive = 0;
+
+	struct option module_status_options[] = {
+		OPT__QUIET(&quiet, N_("Suppress submodule status output")),
+		OPT_BOOL(0, "cached", &cached, N_("Use commit stored in the index instead of the one stored in the submodule HEAD")),
+		OPT_BOOL(0, "recursive", &recursive, N_("Recurse into nested submodules")),
+		OPT_END()
+	};
+
+	const char *const git_submodule_helper_usage[] = {
+		N_("git submodule status [--quiet] [--cached] [--recursive] [<path>]"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, module_status_options,
+			     git_submodule_helper_usage, 0);
+
+	if (module_list_compute(argc, argv, prefix, &pathspec, &list) < 0)
+		return 1;
+
+	info.prefix = prefix;
+	info.quiet = !!quiet;
+	info.recursive = !!recursive;
+	info.cached = !!cached;
+
+	gitmodules_config();
+	for_each_submodule_list(list, status_submodule, &info);
+
+	return 0;
+}
+
 static int module_name(int argc, const char **argv, const char *prefix)
 {
 	const struct submodule *sub;
@@ -1306,6 +1451,7 @@ static struct cmd_struct commands[] = {
 	{"resolve-relative-url-test", resolve_relative_url_test, 0},
 	{"print-name-rev", print_name_rev, 0},
 	{"init", module_init, SUPPORT_SUPER_PREFIX},
+	{"status", module_status, SUPPORT_SUPER_PREFIX},
 	{"remote-branch", resolve_remote_submodule_branch, 0},
 	{"push-check", push_check, 0},
 	{"absorb-git-dirs", absorb_git_dirs, SUPPORT_SUPER_PREFIX},
diff --git a/git-submodule.sh b/git-submodule.sh
index e988167e0..51b057d82 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -1005,54 +1005,7 @@ cmd_status()
 		shift
 	done
 
-	{
-		git submodule--helper list --prefix "$wt_prefix" "$@" ||
-		echo "#unmatched" $?
-	} |
-	while read -r mode sha1 stage sm_path
-	do
-		die_if_unmatched "$mode" "$sha1"
-		name=$(git submodule--helper name "$sm_path") || exit
-		displaypath=$(git submodule--helper relative-path "$prefix$sm_path" "$wt_prefix")
-		if test "$stage" = U
-		then
-			say "U$sha1 $displaypath"
-			continue
-		fi
-		if ! git submodule--helper is-active "$sm_path" ||
-		{
-			! test -d "$sm_path"/.git &&
-			! test -f "$sm_path"/.git
-		}
-		then
-			say "-$sha1 $displaypath"
-			continue;
-		fi
-		if git diff-files --ignore-submodules=dirty --quiet -- "$sm_path"
-		then
-			revname=$(git submodule--helper print-name-rev "$sm_path" "$sha1")
-			say " $sha1 $displaypath$revname"
-		else
-			if test -z "$cached"
-			then
-				sha1=$(sanitize_submodule_env; cd "$sm_path" && git rev-parse --verify HEAD)
-			fi
-			revname=$(git submodule--helper print-name-rev "$sm_path" "$sha1")
-			say "+$sha1 $displaypath$revname"
-		fi
-
-		if test -n "$recursive"
-		then
-			(
-				prefix="$displaypath/"
-				sanitize_submodule_env
-				wt_prefix=
-				cd "$sm_path" &&
-				eval cmd_status
-			) ||
-			die "$(eval_gettext "Failed to recurse into submodule path '\$sm_path'")"
-		fi
-	done
+	git ${wt_prefix:+-C "$wt_prefix"} ${prefix:+--super-prefix "$prefix"} submodule--helper status ${GIT_QUIET:+--quiet} ${cached:+--cached} ${recursive:+--recursive} "$@"
 }
 #
 # Sync remote urls for submodules
-- 
2.13.0