[RFC PATCH v2 1/4] tag: use a "goto cleanup" pattern, leak less memory

[Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx>]

Change cmd_tag() to free its "struct string_list"'s instead of using
an UNLEAK() pattern. This changes code added in 886e1084d78 (builtin/:
add UNLEAKs, 2017-10-01).

As shown in the context of the deceleration of the "struct
msg_arg" (which I'm changing to use a designated initializer while at
it, and to show the context in this change), that struct is just a
thin wrapper around an int and "struct strbuf".

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx>
---
 builtin/tag.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/builtin/tag.c b/builtin/tag.c
index 6535ed27ee9..ad6c9855914 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -432,7 +432,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 	int annotate = 0, force = 0;
 	int cmdmode = 0, create_tag_object = 0;
 	const char *msgfile = NULL, *keyid = NULL;
-	struct msg_arg msg = { 0, STRBUF_INIT };
+	struct msg_arg msg = { .buf = STRBUF_INIT };
 	struct ref_transaction *transaction;
 	struct strbuf err = STRBUF_INIT;
 	struct ref_filter filter;
@@ -482,6 +482,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 		OPT_BOOL('i', "ignore-case", &icase, N_("sorting and filtering are case insensitive")),
 		OPT_END()
 	};
+	int ret = 0;
 
 	setup_ref_filter_porcelain_msg();
 
@@ -529,7 +530,6 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 	ref_sorting_set_sort_flags_all(sorting, REF_SORTING_ICASE, icase);
 	filter.ignore_case = icase;
 	if (cmdmode == 'l') {
-		int ret;
 		if (column_active(colopts)) {
 			struct column_options copts;
 			memset(&copts, 0, sizeof(copts));
@@ -540,7 +540,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 		ret = list_tags(&filter, sorting, &format);
 		if (column_active(colopts))
 			stop_column_filter();
-		return ret;
+		goto cleanup;
 	}
 	if (filter.lines != -1)
 		die(_("-n option is only allowed in list mode"));
@@ -552,12 +552,15 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 		die(_("--points-at option is only allowed in list mode"));
 	if (filter.reachable_from || filter.unreachable_from)
 		die(_("--merged and --no-merged options are only allowed in list mode"));
-	if (cmdmode == 'd')
-		return delete_tags(argv);
+	if (cmdmode == 'd') {
+		ret = delete_tags(argv);
+		goto cleanup;
+	}
 	if (cmdmode == 'v') {
 		if (format.format && verify_ref_format(&format))
 			usage_with_options(git_tag_usage, options);
-		return for_each_tag_name(argv, verify_tag, &format);
+		ret = for_each_tag_name(argv, verify_tag, &format);
+		goto cleanup;
 	}
 
 	if (msg.given || msgfile) {
@@ -626,10 +629,11 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 		printf(_("Updated tag '%s' (was %s)\n"), tag,
 		       find_unique_abbrev(&prev, DEFAULT_ABBREV));
 
-	UNLEAK(buf);
-	UNLEAK(ref);
-	UNLEAK(reflog_msg);
-	UNLEAK(msg);
-	UNLEAK(err);
-	return 0;
+cleanup:
+	strbuf_release(&buf);
+	strbuf_release(&ref);
+	strbuf_release(&reflog_msg);
+	strbuf_release(&msg.buf);
+	strbuf_release(&err);
+	return ret;
 }
-- 
2.33.1.1338.g20da966911a