submodule--helper: fix obscure leak in module_add()

Fix an obscure leak in module_add(), if the "git add" command we were
piping to failed we'd fail to strbuf_release(&sb). This fixes a leak
introduced in a6226fd (submodule--helper: convert the bulk of
cmd_add() to C, 2021-08-10).

In fixing it move to a "goto cleanup" pattern, and since we need to
introduce a "ret" variable to do that let's also get rid of the
intermediate "exit_code" variable. The initialization to "-1" in
a6226fd has always been redundant, we'd only use the "exit_code"
value after assigning the return value of pipe_command() to it.

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Reviewed-by: Glen Choo <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: avar

builtin/submodule--helper.c

@@ -3293,6 +3293,8 @@ static int module_add(int argc, const char **argv, const char *prefix)
 		N_("git submodule add [<options>] [--] <repository> [<path>]"),
 		NULL
 	};
+	struct strbuf sb = STRBUF_INIT;
+	int ret = 1;
 
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
 
@@ -3342,21 +3344,17 @@ static int module_add(int argc, const char **argv, const char *prefix)
 	die_on_repo_without_commits(add_data.sm_path);
 
 	if (!force) {
-		int exit_code = -1;
-		struct strbuf sb = STRBUF_INIT;
 		struct child_process cp = CHILD_PROCESS_INIT;
 
 		cp.git_cmd = 1;
 		cp.no_stdout = 1;
 		strvec_pushl(&cp.args, "add", "--dry-run", "--ignore-missing",
 			     "--no-warn-embedded-repo", add_data.sm_path, NULL);
-		if ((exit_code = pipe_command(&cp, NULL, 0, NULL, 0, &sb, 0))) {
+		if ((ret = pipe_command(&cp, NULL, 0, NULL, 0, &sb, 0))) {
 			strbuf_complete_line(&sb);
 			fputs(sb.buf, stderr);
-			free(add_data.sm_path);
-			return exit_code;
+			goto cleanup;
 		}
-		strbuf_release(&sb);
 	}
 
 	if(!add_data.sm_name)
@@ -3371,15 +3369,17 @@ static int module_add(int argc, const char **argv, const char *prefix)
 	add_data.progress = !!progress;
 	add_data.dissociate = !!dissociate;
 
-	if (add_submodule(&add_data)) {
-		free(add_data.sm_path);
-		return 1;
-	}
+	if (add_submodule(&add_data))
+		goto cleanup;
 	configure_added_submodule(&add_data);
+
+	ret = 0;
+cleanup:
 	free(add_data.sm_path);
 	free(to_free);
+	strbuf_release(&sb);
 
-	return 0;
+	return ret;
 }
 
 #define SUPPORT_SUPER_PREFIX (1<<0)