[GSoC][PATCH v2 04/13] 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, the following changes have been made:
* parameters passed to the function print_status() have been changed.
  Instead of passing char *sub_sha1, instead the object_id is being passed.

* Also, since the passed parameter displaypath's value isn't changed
  by the function, it is passed to the funcition as const char *displaypath
  instead of char *displaypath.

* the output type of the function handle_submodule_head_ref() is changed
  from strbuf to object_id, as we will use the object_id instead of the
  hex of sha1 being stored in a struct strbuf.

* diff_files_Args is cleared after using it by passing it as args in the
  function cmd_diff_files.

* In the function status_submodule(), for checking if a submodule has merge
  conflicts, the patch currently checks if the value of any of the ce_flags
  is non-zero. Currently, I think the we aren't interested in a partiular flag,
  but I'm not sure on this.

* The confusion with displaypath being passed as te super-prefix in many
  of the ported subcommands may be a result of the fact that the
  function generating the displaypath: get_submodule_displaypath()
  uses the super-prefix as simply a path concatenated with the current
  submodule name to denote our current location.
  Also, for generating any submodule's displaypath, it would be important to
  have ".." passed to the submodule, and currently it is possible only via the
  super-prefix.

 builtin/submodule--helper.c | 157 ++++++++++++++++++++++++++++++++++++++++++++
 git-submodule.sh            |  49 +-------------
 2 files changed, 158 insertions(+), 48 deletions(-)

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 2cb72d68e..0bd969b7c 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -561,6 +561,162 @@ 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,
+			 const struct object_id *oid, const char *displaypath)
+{
+	if (info->quiet)
+		return;
+
+	printf("%c%s %s", state, oid_to_hex(oid), displaypath);
+
+
+	if (state == ' ' || state == '+') {
+		struct argv_array name_rev_args = ARGV_ARRAY_INIT;
+
+		argv_array_pushl(&name_rev_args, "print-name-rev",
+				 path, oid_to_hex(oid), 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 object_id *output = cb_data;
+	if (oid)
+		oidcpy(output, oid);
+
+	return 0;
+}
+
+static void status_submodule(const struct cache_entry *list_item, void *cb_data)
+{
+	struct status_cb *info = cb_data;
+	char *displaypath;
+	struct argv_array diff_files_args = ARGV_ARRAY_INIT;
+
+	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);
+
+	trace_printf("the value of flag is %d\n", list_item->ce_flags);
+	if (list_item->ce_flags) {
+		trace_printf("for U the value of flag is %d\n", list_item->ce_flags);
+		print_status(info, 'U', list_item->name,
+			     &null_oid, displaypath);
+		goto cleanup;
+	}
+
+	if (!is_submodule_active(the_repository, list_item->name)) {
+		print_status(info, '-', list_item->name, &list_item->oid,
+			     displaypath);
+		goto cleanup;
+	}
+
+	argv_array_pushl(&diff_files_args, "diff-files",
+			 "--ignore-submodules=dirty", "--quiet", "--",
+			 list_item->name, NULL);
+
+	if (!cmd_diff_files(diff_files_args.argc, diff_files_args.argv,
+			    info->prefix)) {
+		print_status(info, ' ', list_item->name, &list_item->oid,
+			     displaypath);
+	} else {
+		if (!info->cached) {
+			struct object_id oid;
+
+			if (head_ref_submodule(list_item->name,
+					       handle_submodule_head_ref, &oid))
+				die(_("could not resolve HEAD ref inside the"
+				      "submodule '%s'"), list_item->name);
+
+			print_status(info, '+', list_item->name, &oid,
+				     displaypath);
+		} else {
+			print_status(info, '+', list_item->name,
+				     &list_item->oid, 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:
+	argv_array_clear(&diff_files_args);
+	free(displaypath);
+}
+
+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;
@@ -1307,6 +1463,7 @@ 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