[PATCHv4 1/3] submodule: implement `list` as a builtin helper

[PATCHv4 1/3] submodule: implement `list` as a builtin helper

[Stefan Beller]

Most of the submodule operations work on a set of submodules.
Calculating and using this set is usually done via:

       module_list "$@" | {
           while read mode sha1 stage sm_path
           do
                # the actual operation
           done
       }

Currently the function `module_list` is implemented in the
git-submodule.sh as a shell script wrapping a perl script.
The rewrite is in C, such that it is faster and can later be
easily adapted when other functions are rewritten in C.

git-submodule.sh, similar to the builtin commands, will navigate
to the top-most directory of the repository and keep the
subdirectory as a variable. As the helper is called from
within the git-submodule.sh script, we are already navigated
to the root level, but the path arguments are still relative
to the subdirectory we were in when calling git-submodule.sh.
That's why there is a `--prefix` option pointing to an alternative
path which to anchor relative path arguments.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 .gitignore                  |   1 +
 Makefile                    |   1 +
 builtin.h                   |   1 +
 builtin/submodule--helper.c | 137 ++++++++++++++++++++++++++++++++++++++++++++
 git-submodule.sh            |  54 ++---------------
 git.c                       |   1 +
 6 files changed, 147 insertions(+), 48 deletions(-)
 create mode 100644 builtin/submodule--helper.c

diff --git a/.gitignore b/.gitignore
index 4fd81ba..1c2f832 100644
--- a/.gitignore
+++ b/.gitignore
@@ -155,6 +155,7 @@
 /git-status
 /git-stripspace
 /git-submodule
+/git-submodule--helper
 /git-svn
 /git-symbolic-ref
 /git-tag
diff --git a/Makefile b/Makefile
index 24b636d..d434e73 100644
--- a/Makefile
+++ b/Makefile
@@ -901,6 +901,7 @@ BUILTIN_OBJS += builtin/shortlog.o
 BUILTIN_OBJS += builtin/show-branch.o
 BUILTIN_OBJS += builtin/show-ref.o
 BUILTIN_OBJS += builtin/stripspace.o
+BUILTIN_OBJS += builtin/submodule--helper.o
 BUILTIN_OBJS += builtin/symbolic-ref.o
 BUILTIN_OBJS += builtin/tag.o
 BUILTIN_OBJS += builtin/unpack-file.o
diff --git a/builtin.h b/builtin.h
index 839483d..924e6c4 100644
--- a/builtin.h
+++ b/builtin.h
@@ -119,6 +119,7 @@ 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_status(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);
 extern int cmd_tag(int argc, const char **argv, const char *prefix);
 extern int cmd_tar_tree(int argc, const char **argv, const char *prefix);
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
new file mode 100644
index 0000000..16d9abe
--- /dev/null
+++ b/builtin/submodule--helper.c
@@ -0,0 +1,137 @@
+#include "builtin.h"
+#include "cache.h"
+#include "parse-options.h"
+#include "quote.h"
+#include "pathspec.h"
+#include "dir.h"
+#include "utf8.h"
+
+static const struct cache_entry **ce_entries;
+static int ce_alloc, ce_used;
+
+static int module_list_compute(int argc, const char **argv,
+				const char *prefix,
+				struct pathspec *pathspec)
+{
+	int i, result = 0;
+	char *max_prefix, *ps_matched = NULL;
+	int max_prefix_len;
+	parse_pathspec(pathspec, 0,
+		       PATHSPEC_PREFER_FULL |
+		       PATHSPEC_STRIP_SUBMODULE_SLASH_CHEAP,
+		       prefix, argv);
+
+	/* Find common prefix for all pathspec's */
+	max_prefix = common_prefix(pathspec);
+	max_prefix_len = max_prefix ? strlen(max_prefix) : 0;
+
+	if (pathspec->nr)
+		ps_matched = xcalloc(pathspec->nr, 1);
+
+	if (read_cache() < 0)
+		die(_("index file corrupt"));
+
+	for (i = 0; i < active_nr; i++) {
+		const struct cache_entry *ce = active_cache[i];
+
+		if (!match_pathspec(pathspec, ce->name, ce_namelen(ce),
+				    max_prefix_len, ps_matched,
+				    S_ISGITLINK(ce->ce_mode) | S_ISDIR(ce->ce_mode)))
+			continue;
+
+		if (S_ISGITLINK(ce->ce_mode)) {
+			ALLOC_GROW(ce_entries, ce_used + 1, ce_alloc);
+			ce_entries[ce_used++] = ce;
+		}
+
+		while (i + 1 < active_nr && !strcmp(ce->name, active_cache[i + 1]->name))
+			/*
+			 * Skip entries with the same name in different stages
+			 * to make sure an entry is returned only once.
+			 */
+			i++;
+	}
+	free(max_prefix);
+
+	if (ps_matched && report_path_error(ps_matched, pathspec, prefix))
+		result = -1;
+
+	free(ps_matched);
+
+	return result;
+}
+
+static int module_list(int argc, const char **argv, const char *prefix)
+{
+	int i;
+	struct pathspec pathspec;
+	const char *alternative_path;
+
+	struct option module_list_options[] = {
+		OPT_STRING(0, "prefix", &alternative_path,
+			   N_("path"),
+			   N_("alternative anchor for relative paths")),
+		OPT_END()
+	};
+
+	const char *const git_submodule_helper_usage[] = {
+		N_("git submodule--helper list [--prefix=<path>] [<path>...]"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, module_list_options,
+			     git_submodule_helper_usage, 0);
+
+	if (module_list_compute(argc, argv, alternative_path
+					    ? alternative_path
+					    : prefix, &pathspec) < 0) {
+		printf("#unmatched\n");
+		return 1;
+	}
+
+	for (i = 0; i < ce_used; i++) {
+		const struct cache_entry *ce = ce_entries[i];
+
+		if (ce_stage(ce))
+			printf("%06o %s U\t", ce->ce_mode, sha1_to_hex(null_sha1));
+		else
+			printf("%06o %s %d\t", ce->ce_mode, sha1_to_hex(ce->sha1), ce_stage(ce));
+
+		utf8_fprintf(stdout, "%s\n", ce->name);
+	}
+	return 0;
+}
+
+
+struct cmd_struct {
+	const char *cmd;
+	int (*fct)(int, const char **, const char *);
+};
+
+static struct cmd_struct commands[] = {
+	{"list", module_list},
+};
+
+int cmd_submodule__helper(int argc, const char **argv, const char *prefix)
+{
+	int i;
+	if (argc < 2)
+		goto out;
+
+	for (i = 0; i < ARRAY_SIZE(commands); i++)
+		if (!strcmp(argv[1], commands[i].cmd))
+			return commands[i].fct(argc - 1, argv + 1, prefix);
+
+out:
+	if (argc > 1)
+		fprintf(stderr, _("fatal: '%s' is not a valid submodule--helper "
+				  "subcommand, which are:\n"), argv[1]);
+	else
+		fprintf(stderr, _("fatal: submodule--helper subcommand must be "
+				  "called with a subcommand, which are:\n"));
+
+	for (i = 0; i < ARRAY_SIZE(commands); i++)
+		fprintf(stderr, "\t%s\n", commands[i].cmd);
+
+	exit(129);
+}
diff --git a/git-submodule.sh b/git-submodule.sh
index 36797c3..95c04fc 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -145,48 +145,6 @@ relative_path ()
 	echo "$result$target"
 }
 
-#
-# Get submodule info for registered submodules
-# $@ = path to limit submodule list
-#
-module_list()
-{
-	eval "set $(git rev-parse --sq --prefix "$wt_prefix" -- "$@")"
-	(
-		git ls-files -z --error-unmatch --stage -- "$@" ||
-		echo "unmatched pathspec exists"
-	) |
-	@@PERL@@ -e '
-	my %unmerged = ();
-	my ($null_sha1) = ("0" x 40);
-	my @out = ();
-	my $unmatched = 0;
-	$/ = "\0";
-	while (<STDIN>) {
-		if (/^unmatched pathspec/) {
-			$unmatched = 1;
-			next;
-		}
-		chomp;
-		my ($mode, $sha1, $stage, $path) =
-			/^([0-7]+) ([0-9a-f]{40}) ([0-3])\t(.*)$/;
-		next unless $mode eq "160000";
-		if ($stage ne "0") {
-			if (!$unmerged{$path}++) {
-				push @out, "$mode $null_sha1 U\t$path\n";
-			}
-			next;
-		}
-		push @out, "$_\n";
-	}
-	if ($unmatched) {
-		print "#unmatched\n";
-	} else {
-		print for (@out);
-	}
-	'
-}
-
 die_if_unmatched ()
 {
 	if test "$1" = "#unmatched"
@@ -532,7 +490,7 @@ cmd_foreach()
 	# command in the subshell (and a recursive call to this function)
 	exec 3<&0
 
-	module_list |
+	git submodule--helper list --prefix "$wt_prefix"|
 	while read mode sha1 stage sm_path
 	do
 		die_if_unmatched "$mode"
@@ -592,7 +550,7 @@ cmd_init()
 		shift
 	done
 
-	module_list "$@" |
+	git submodule--helper list --prefix "$wt_prefix" "$@" |
 	while read mode sha1 stage sm_path
 	do
 		die_if_unmatched "$mode"
@@ -674,7 +632,7 @@ cmd_deinit()
 		die "$(eval_gettext "Use '.' if you really want to deinitialize all submodules")"
 	fi
 
-	module_list "$@" |
+	git submodule--helper list --prefix "$wt_prefix" "$@" |
 	while read mode sha1 stage sm_path
 	do
 		die_if_unmatched "$mode"
@@ -790,7 +748,7 @@ cmd_update()
 	fi
 
 	cloned_modules=
-	module_list "$@" | {
+	git submodule--helper list --prefix "$wt_prefix" "$@" | {
 	err=
 	while read mode sha1 stage sm_path
 	do
@@ -1222,7 +1180,7 @@ cmd_status()
 		shift
 	done
 
-	module_list "$@" |
+	git submodule--helper list --prefix "$wt_prefix" "$@" |
 	while read mode sha1 stage sm_path
 	do
 		die_if_unmatched "$mode"
@@ -1299,7 +1257,7 @@ cmd_sync()
 		esac
 	done
 	cd_to_toplevel
-	module_list "$@" |
+	git submodule--helper list --prefix "$wt_prefix" "$@" |
 	while read mode sha1 stage sm_path
 	do
 		die_if_unmatched "$mode"
diff --git a/git.c b/git.c
index 55c327c..deecba0 100644
--- a/git.c
+++ b/git.c
@@ -469,6 +469,7 @@ static struct cmd_struct commands[] = {
 	{ "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 	{ "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 	{ "stripspace", cmd_stripspace },
+	{ "submodule--helper", cmd_submodule__helper, RUN_SETUP },
 	{ "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 	{ "tag", cmd_tag, RUN_SETUP },
 	{ "unpack-file", cmd_unpack_file, RUN_SETUP },
-- 
2.5.0.256.g89f8063.dirty

Re: [PATCHv4 1/3] submodule: implement `list` as a builtin helper

[Junio C Hamano]

Stefan Beller <sbeller@google.com> writes:

> +static int module_list_compute(int argc, const char **argv,
> +				const char *prefix,
> +				struct pathspec *pathspec)
> +{
> +	int i, result = 0;
> +	char *max_prefix, *ps_matched = NULL;
> +	int max_prefix_len;
> +	parse_pathspec(pathspec, 0,
> +		       PATHSPEC_PREFER_FULL |
> +		       PATHSPEC_STRIP_SUBMODULE_SLASH_CHEAP,
> +		       prefix, argv);
> +
> +	/* Find common prefix for all pathspec's */
> +	max_prefix = common_prefix(pathspec);
> +	max_prefix_len = max_prefix ? strlen(max_prefix) : 0;
> +
> +	if (pathspec->nr)
> +		ps_matched = xcalloc(pathspec->nr, 1);
> +
> +	if (read_cache() < 0)
> +		die(_("index file corrupt"));
> +
> +	for (i = 0; i < active_nr; i++) {
> +		const struct cache_entry *ce = active_cache[i];
> +
> +		if (!match_pathspec(pathspec, ce->name, ce_namelen(ce),
> +				    max_prefix_len, ps_matched,
> +				    S_ISGITLINK(ce->ce_mode) | S_ISDIR(ce->ce_mode)))
> +			continue;
> +
> +		if (S_ISGITLINK(ce->ce_mode)) {
> +			ALLOC_GROW(ce_entries, ce_used + 1, ce_alloc);
> +			ce_entries[ce_used++] = ce;
> +		}
> +
> +		while (i + 1 < active_nr && !strcmp(ce->name, active_cache[i + 1]->name))
> +			/*
> +			 * Skip entries with the same name in different stages
> +			 * to make sure an entry is returned only once.
> +			 */
> +			i++;
> +	}

I hate myself not catching this earlier, but I suspect that this is
not quite a faithful rewrite of the original.  It changes behaviour
when a conflicted path records a non submodule in stage #1 and a
submodule in stage #2 (or stage #3), doesn't it?

The original scripted version will see the stage #1 entry and skips
it because it is not a submodule, then will see the stage #2 entry
and because the path is not yet in the %unmerged hash, and it will
push it to @out.

This loop instead sees a non-submodule entry at stage #1, skips it
(because it is not a submodule), then goes on to skip the entries
with the same name, including the stage #2 entry that _is_ a
submodule.

I think the clever "we are done with this entry, so let's skip all
others that have the same name" optimization should be done only
when we did handle an entry with the same name.  I.e. something like
this squashed in.
	
--------------------------------------------------

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 16d9abe..c4aff0c 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -39,12 +39,13 @@ static int module_list_compute(int argc, const char **argv,
 				    S_ISGITLINK(ce->ce_mode) | S_ISDIR(ce->ce_mode)))
 			continue;
 
-		if (S_ISGITLINK(ce->ce_mode)) {
-			ALLOC_GROW(ce_entries, ce_used + 1, ce_alloc);
-			ce_entries[ce_used++] = ce;
-		}
+		if (!S_ISGITLINK(ce->ce_mode))
+			continue;
 
-		while (i + 1 < active_nr && !strcmp(ce->name, active_cache[i + 1]->name))
+		ALLOC_GROW(ce_entries, ce_used + 1, ce_alloc);
+		ce_entries[ce_used++] = ce;
+		while (i + 1 < active_nr &&
+		       !strcmp(ce->name, active_cache[i + 1]->name))
 			/*
 			 * Skip entries with the same name in different stages
 			 * to make sure an entry is returned only once.

--------------------------------------------------

> +static int module_list(int argc, const char **argv, const char *prefix)
> +{
> +	int i;
> +	struct pathspec pathspec;
> +	const char *alternative_path;
> +
> +	struct option module_list_options[] = {
> +		OPT_STRING(0, "prefix", &alternative_path,
> +			   N_("path"),
> +			   N_("alternative anchor for relative paths")),
> +		OPT_END()
> +	};

Do we really need this alternative_path variable?  The "--prefix"
option that overrides the passed-in variable prefix would be easier
to understand if it touched the same variable, i.e.

--------------------------------------------------

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 16d9abe..387539f 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -65,10 +66,9 @@ static int module_list(int argc, const char **argv, const char *prefix)
 {
 	int i;
 	struct pathspec pathspec;
-	const char *alternative_path;
 
 	struct option module_list_options[] = {
-		OPT_STRING(0, "prefix", &alternative_path,
+		OPT_STRING(0, "prefix", &prefix,
 			   N_("path"),
 			   N_("alternative anchor for relative paths")),
 		OPT_END()
@@ -82,9 +82,7 @@ static int module_list(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, module_list_options,
 			     git_submodule_helper_usage, 0);
 
-	if (module_list_compute(argc, argv, alternative_path
-					    ? alternative_path
-					    : prefix, &pathspec) < 0) {
+	if (module_list_compute(argc, argv, prefix, &pathspec) < 0) {
 		printf("#unmatched\n");
 		return 1;
 	}

--------------------------------------------------

[PATCHv4 1/3] submodule: implement `list` as a builtin helper

[Stefan Beller]

Most of the submodule operations work on a set of submodules.
Calculating and using this set is usually done via:

       module_list "$@" | {
           while read mode sha1 stage sm_path
           do
                # the actual operation
           done
       }

Currently the function `module_list` is implemented in the
git-submodule.sh as a shell script wrapping a perl script.
The rewrite is in C, such that it is faster and can later be
easily adapted when other functions are rewritten in C.

git-submodule.sh, similar to the builtin commands, will navigate
to the top-most directory of the repository and keep the
subdirectory as a variable. As the helper is called from
within the git-submodule.sh script, we are already navigated
to the root level, but the path arguments are still relative
to the subdirectory we were in when calling git-submodule.sh.
That's why there is a `--prefix` option pointing to an alternative
path which to anchor relative path arguments.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 .gitignore                  |   1 +
 Makefile                    |   1 +
 builtin.h                   |   1 +
 builtin/submodule--helper.c | 137 ++++++++++++++++++++++++++++++++++++++++++++
 git-submodule.sh            |  54 ++---------------
 git.c                       |   1 +
 6 files changed, 147 insertions(+), 48 deletions(-)
 create mode 100644 builtin/submodule--helper.c

diff --git a/.gitignore b/.gitignore
index 4fd81ba..1c2f832 100644
--- a/.gitignore
+++ b/.gitignore
@@ -155,6 +155,7 @@
 /git-status
 /git-stripspace
 /git-submodule
+/git-submodule--helper
 /git-svn
 /git-symbolic-ref
 /git-tag
diff --git a/Makefile b/Makefile
index 24b636d..d434e73 100644
--- a/Makefile
+++ b/Makefile
@@ -901,6 +901,7 @@ BUILTIN_OBJS += builtin/shortlog.o
 BUILTIN_OBJS += builtin/show-branch.o
 BUILTIN_OBJS += builtin/show-ref.o
 BUILTIN_OBJS += builtin/stripspace.o
+BUILTIN_OBJS += builtin/submodule--helper.o
 BUILTIN_OBJS += builtin/symbolic-ref.o
 BUILTIN_OBJS += builtin/tag.o
 BUILTIN_OBJS += builtin/unpack-file.o
diff --git a/builtin.h b/builtin.h
index 839483d..924e6c4 100644
--- a/builtin.h
+++ b/builtin.h
@@ -119,6 +119,7 @@ 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_status(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);
 extern int cmd_tag(int argc, const char **argv, const char *prefix);
 extern int cmd_tar_tree(int argc, const char **argv, const char *prefix);
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
new file mode 100644
index 0000000..16d9abe
--- /dev/null
+++ b/builtin/submodule--helper.c
@@ -0,0 +1,137 @@
+#include "builtin.h"
+#include "cache.h"
+#include "parse-options.h"
+#include "quote.h"
+#include "pathspec.h"
+#include "dir.h"
+#include "utf8.h"
+
+static const struct cache_entry **ce_entries;
+static int ce_alloc, ce_used;
+
+static int module_list_compute(int argc, const char **argv,
+				const char *prefix,
+				struct pathspec *pathspec)
+{
+	int i, result = 0;
+	char *max_prefix, *ps_matched = NULL;
+	int max_prefix_len;
+	parse_pathspec(pathspec, 0,
+		       PATHSPEC_PREFER_FULL |
+		       PATHSPEC_STRIP_SUBMODULE_SLASH_CHEAP,
+		       prefix, argv);
+
+	/* Find common prefix for all pathspec's */
+	max_prefix = common_prefix(pathspec);
+	max_prefix_len = max_prefix ? strlen(max_prefix) : 0;
+
+	if (pathspec->nr)
+		ps_matched = xcalloc(pathspec->nr, 1);
+
+	if (read_cache() < 0)
+		die(_("index file corrupt"));
+
+	for (i = 0; i < active_nr; i++) {
+		const struct cache_entry *ce = active_cache[i];
+
+		if (!match_pathspec(pathspec, ce->name, ce_namelen(ce),
+				    max_prefix_len, ps_matched,
+				    S_ISGITLINK(ce->ce_mode) | S_ISDIR(ce->ce_mode)))
+			continue;
+
+		if (S_ISGITLINK(ce->ce_mode)) {
+			ALLOC_GROW(ce_entries, ce_used + 1, ce_alloc);
+			ce_entries[ce_used++] = ce;
+		}
+
+		while (i + 1 < active_nr && !strcmp(ce->name, active_cache[i + 1]->name))
+			/*
+			 * Skip entries with the same name in different stages
+			 * to make sure an entry is returned only once.
+			 */
+			i++;
+	}
+	free(max_prefix);
+
+	if (ps_matched && report_path_error(ps_matched, pathspec, prefix))
+		result = -1;
+
+	free(ps_matched);
+
+	return result;
+}
+
+static int module_list(int argc, const char **argv, const char *prefix)
+{
+	int i;
+	struct pathspec pathspec;
+	const char *alternative_path;
+
+	struct option module_list_options[] = {
+		OPT_STRING(0, "prefix", &alternative_path,
+			   N_("path"),
+			   N_("alternative anchor for relative paths")),
+		OPT_END()
+	};
+
+	const char *const git_submodule_helper_usage[] = {
+		N_("git submodule--helper list [--prefix=<path>] [<path>...]"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, module_list_options,
+			     git_submodule_helper_usage, 0);
+
+	if (module_list_compute(argc, argv, alternative_path
+					    ? alternative_path
+					    : prefix, &pathspec) < 0) {
+		printf("#unmatched\n");
+		return 1;
+	}
+
+	for (i = 0; i < ce_used; i++) {
+		const struct cache_entry *ce = ce_entries[i];
+
+		if (ce_stage(ce))
+			printf("%06o %s U\t", ce->ce_mode, sha1_to_hex(null_sha1));
+		else
+			printf("%06o %s %d\t", ce->ce_mode, sha1_to_hex(ce->sha1), ce_stage(ce));
+
+		utf8_fprintf(stdout, "%s\n", ce->name);
+	}
+	return 0;
+}
+
+
+struct cmd_struct {
+	const char *cmd;
+	int (*fct)(int, const char **, const char *);
+};
+
+static struct cmd_struct commands[] = {
+	{"list", module_list},
+};
+
+int cmd_submodule__helper(int argc, const char **argv, const char *prefix)
+{
+	int i;
+	if (argc < 2)
+		goto out;
+
+	for (i = 0; i < ARRAY_SIZE(commands); i++)
+		if (!strcmp(argv[1], commands[i].cmd))
+			return commands[i].fct(argc - 1, argv + 1, prefix);
+
+out:
+	if (argc > 1)
+		fprintf(stderr, _("fatal: '%s' is not a valid submodule--helper "
+				  "subcommand, which are:\n"), argv[1]);
+	else
+		fprintf(stderr, _("fatal: submodule--helper subcommand must be "
+				  "called with a subcommand, which are:\n"));
+
+	for (i = 0; i < ARRAY_SIZE(commands); i++)
+		fprintf(stderr, "\t%s\n", commands[i].cmd);
+
+	exit(129);
+}
diff --git a/git-submodule.sh b/git-submodule.sh
index 36797c3..95c04fc 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -145,48 +145,6 @@ relative_path ()
 	echo "$result$target"
 }
 
-#
-# Get submodule info for registered submodules
-# $@ = path to limit submodule list
-#
-module_list()
-{
-	eval "set $(git rev-parse --sq --prefix "$wt_prefix" -- "$@")"
-	(
-		git ls-files -z --error-unmatch --stage -- "$@" ||
-		echo "unmatched pathspec exists"
-	) |
-	@@PERL@@ -e '
-	my %unmerged = ();
-	my ($null_sha1) = ("0" x 40);
-	my @out = ();
-	my $unmatched = 0;
-	$/ = "\0";
-	while (<STDIN>) {
-		if (/^unmatched pathspec/) {
-			$unmatched = 1;
-			next;
-		}
-		chomp;
-		my ($mode, $sha1, $stage, $path) =
-			/^([0-7]+) ([0-9a-f]{40}) ([0-3])\t(.*)$/;
-		next unless $mode eq "160000";
-		if ($stage ne "0") {
-			if (!$unmerged{$path}++) {
-				push @out, "$mode $null_sha1 U\t$path\n";
-			}
-			next;
-		}
-		push @out, "$_\n";
-	}
-	if ($unmatched) {
-		print "#unmatched\n";
-	} else {
-		print for (@out);
-	}
-	'
-}
-
 die_if_unmatched ()
 {
 	if test "$1" = "#unmatched"
@@ -532,7 +490,7 @@ cmd_foreach()
 	# command in the subshell (and a recursive call to this function)
 	exec 3<&0
 
-	module_list |
+	git submodule--helper list --prefix "$wt_prefix"|
 	while read mode sha1 stage sm_path
 	do
 		die_if_unmatched "$mode"
@@ -592,7 +550,7 @@ cmd_init()
 		shift
 	done
 
-	module_list "$@" |
+	git submodule--helper list --prefix "$wt_prefix" "$@" |
 	while read mode sha1 stage sm_path
 	do
 		die_if_unmatched "$mode"
@@ -674,7 +632,7 @@ cmd_deinit()
 		die "$(eval_gettext "Use '.' if you really want to deinitialize all submodules")"
 	fi
 
-	module_list "$@" |
+	git submodule--helper list --prefix "$wt_prefix" "$@" |
 	while read mode sha1 stage sm_path
 	do
 		die_if_unmatched "$mode"
@@ -790,7 +748,7 @@ cmd_update()
 	fi
 
 	cloned_modules=
-	module_list "$@" | {
+	git submodule--helper list --prefix "$wt_prefix" "$@" | {
 	err=
 	while read mode sha1 stage sm_path
 	do
@@ -1222,7 +1180,7 @@ cmd_status()
 		shift
 	done
 
-	module_list "$@" |
+	git submodule--helper list --prefix "$wt_prefix" "$@" |
 	while read mode sha1 stage sm_path
 	do
 		die_if_unmatched "$mode"
@@ -1299,7 +1257,7 @@ cmd_sync()
 		esac
 	done
 	cd_to_toplevel
-	module_list "$@" |
+	git submodule--helper list --prefix "$wt_prefix" "$@" |
 	while read mode sha1 stage sm_path
 	do
 		die_if_unmatched "$mode"
diff --git a/git.c b/git.c
index 55c327c..deecba0 100644
--- a/git.c
+++ b/git.c
@@ -469,6 +469,7 @@ static struct cmd_struct commands[] = {
 	{ "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 	{ "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 	{ "stripspace", cmd_stripspace },
+	{ "submodule--helper", cmd_submodule__helper, RUN_SETUP },
 	{ "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 	{ "tag", cmd_tag, RUN_SETUP },
 	{ "unpack-file", cmd_unpack_file, RUN_SETUP },
-- 
2.5.0.256.g89f8063.dirty

Re: [PATCHv4 1/3] submodule: implement `list` as a builtin helper

[Stefan Beller]

please ignore.

Re: [PATCHv4 1/3] submodule: implement `list` as a builtin helper

[Eric Sunshine]

On Tue, Sep 1, 2015 at 2:24 PM, Stefan Beller <sbeller@google.com> wrote:
> Most of the submodule operations work on a set of submodules.
> Calculating and using this set is usually done via:
>
>        module_list "$@" | {
>            while read mode sha1 stage sm_path
>            do
>                 # the actual operation
>            done
>        }
>
> Currently the function `module_list` is implemented in the
> git-submodule.sh as a shell script wrapping a perl script.
> The rewrite is in C, such that it is faster and can later be
> easily adapted when other functions are rewritten in C.
>
> [...]
>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---
> +struct cmd_struct {
> +       const char *cmd;
> +       int (*fct)(int, const char **, const char *);

It would be better to stick with a more idiomatic name such as 'f' or
'func' than invent an entirely new one ('fct').

> +};
> +
> +static struct cmd_struct commands[] = {
> +       {"list", module_list},
> +};
> +
> +int cmd_submodule__helper(int argc, const char **argv, const char *prefix)
> +{
> +       int i;
> +       if (argc < 2)
> +               goto out;
> +
> +       for (i = 0; i < ARRAY_SIZE(commands); i++)
> +               if (!strcmp(argv[1], commands[i].cmd))
> +                       return commands[i].fct(argc - 1, argv + 1, prefix);
> +
> +out:
> +       if (argc > 1)
> +               fprintf(stderr, _("fatal: '%s' is not a valid submodule--helper "
> +                                 "subcommand, which are:\n"), argv[1]);
> +       else
> +               fprintf(stderr, _("fatal: submodule--helper subcommand must be "
> +                                 "called with a subcommand, which are:\n"));
> +
> +       for (i = 0; i < ARRAY_SIZE(commands); i++)
> +               fprintf(stderr, "\t%s\n", commands[i].cmd);

A couple observations:

1. git-submodule--helper isn't the only Git command featuring
subcommands which could benefit from this dispatching and error
reporting code, so making it re-usable would be sensible rather than
hiding it away inside this one (very low-level, not user-facing)
command. If you go that route, it would deserve its own patch series,
and well thought out design and interface. However...

2. I realize that the suggestion of listing available subcommands was
put forth tentatively by Junio[1], but it seems overkill for a command
like this which is not user-facing, and is inconsistent with other
subcommand-bearing commands. At this stage, it should be sufficient
merely to emit a plain error message (without any usage information):

    unrecognized subcommand: %s

    missing subcommand

at which point the user can consult the man page or "git
subcommand--helper -h" to find out what went wrong.

[1]: http://article.gmane.org/gmane.comp.version-control.git/276935

> +
> +       exit(129);
> +}

Re: [PATCHv4 1/3] submodule: implement `list` as a builtin helper

[Junio C Hamano]

Junio C Hamano <gitster@pobox.com> writes:

> Stefan Beller <sbeller@google.com> writes:
>
>> +static int module_list_compute(int argc, const char **argv,
>> +				const char *prefix,
>> +				struct pathspec *pathspec)
>> +{
>> ...
>> +	for (i = 0; i < active_nr; i++) {
>> +		const struct cache_entry *ce = active_cache[i];
>> +
>> +		if (!match_pathspec(pathspec, ce->name, ce_namelen(ce),
>> +				    max_prefix_len, ps_matched,
>> +				    S_ISGITLINK(ce->ce_mode) | S_ISDIR(ce->ce_mode)))
>> +			continue;

Another minor thing I noticed here is that ce->ce_mode would never
be S_ISDIR().

It is not immediately clear if it is necessary to pass is_dir=true
upon S_ISGITLINK(ce->ce_mode) to match_pathspec(), but I think that
is probably a right thing to do.  The only difference this makes, I
think, is when a pathspec ends with a slash.  E.g. when you have a
submodule at path ce->ce_name == "dir" and the caller says "dir/".
Then DO_MATCH_DIRECTORY logic would say "dir/" does match "dir".

So taken together with the remainder of the loop, perhaps

        for (i = 0; i < active_nr; i++) {
                ce = active_cache[i];

                if (!S_ISGITLINK(ce->ce_mode) ||
                    !match_pathspec(..., is_dir=1))
                        continue;

                ALLOC_GROW(ce_entries, ce_nr + 1, ce_alloc);
                ce_entries[ce_nr++] = ce;
                while (...)
                        skip the entries with the same name;
        }

would be what we want.  Pathspec matching is much more expensive
than ce_mode check, and after passing that check, you know the last
parameter to the match_pathspec() at that point, so the above
structure would also make sense from performance point of view, I
think.  And of course, the structure makes it clear that we only
care about GITLINK entries and nothing else in this loop, so it is
good from readability point of view, too.