gc: replace config subprocesses with API calls

The 'git maintenance [un]register' commands set or unset the multi-
valued maintenance.repo config key with the absolute path of the current
repository. These are set in the global config file.

Instead of calling a subcommand and creating a new process, create the
proper API calls to git_config_set_multivar_in_file_gently(). It
requires loading the filename for the global config file (and erroring
out if now $HOME value is set). We also need to be careful about using
CONFIG_REGEX_NONE when adding the value and using
CONFIG_FLAGS_FIXED_VALUE when removing the value. In both cases, we
check that the value already exists (this check already existed for
'unregister').

Also, remove the transparent translation of the error code from the
config API to the exit code of 'git maintenance'. Instead, use die() to
recover from failures at that level. In the case of 'unregister
--force', allow the CONFIG_NOTHING_SET error code to be a success. This
allows a possible race where another process removes the config value.
The end result is that the config value is not set anymore, so we can
treat this as a success.

Reported-by: SZEDER Gábor <[email protected]>
Signed-off-by: Derrick Stolee <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: derrickstolee

builtin/gc.c

@@ -1470,11 +1470,12 @@ static int maintenance_register(int argc, const char **argv, const char *prefix)
 	struct option options[] = {
 		OPT_END(),
 	};
-	int rc;
+	int found = 0;
+	const char *key = "maintenance.repo";
 	char *config_value;
-	struct child_process config_set = CHILD_PROCESS_INIT;
-	struct child_process config_get = CHILD_PROCESS_INIT;
 	char *maintpath = get_maintpath();
+	struct string_list_item *item;
+	const struct string_list *list;
 
 	argc = parse_options(argc, argv, prefix, options,
 			     builtin_maintenance_register_usage, 0);
@@ -1491,31 +1492,35 @@ static int maintenance_register(int argc, const char **argv, const char *prefix)
 	else
 		git_config_set("maintenance.strategy", "incremental");
 
-	config_get.git_cmd = 1;
-	strvec_pushl(&config_get.args, "config", "--global", "--get",
-		     "--fixed-value", "maintenance.repo", maintpath, NULL);
-	config_get.out = -1;
-
-	if (start_command(&config_get)) {
-		rc = error(_("failed to run 'git config'"));
-		goto done;
+	list = git_config_get_value_multi(key);
+	if (list) {
+		for_each_string_list_item(item, list) {
+			if (!strcmp(maintpath, item->string)) {
+				found = 1;
+				break;
+			}
+		}
 	}
 
-	/* We already have this value in our config! */
-	if (!finish_command(&config_get)) {
-		rc = 0;
-		goto done;
+	if (!found) {
+		int rc;
+		char *user_config, *xdg_config;
+		git_global_config(&user_config, &xdg_config);
+		if (!user_config)
+			die(_("$HOME not set"));
+		rc = git_config_set_multivar_in_file_gently(
+			user_config, "maintenance.repo", maintpath,
+			CONFIG_REGEX_NONE, 0);
+		free(user_config);
+		free(xdg_config);
+
+		if (rc)
+			die(_("unable to add '%s' value of '%s'"),
+			    key, maintpath);
 	}
 
-	config_set.git_cmd = 1;
-	strvec_pushl(&config_set.args, "config", "--add", "--global", "maintenance.repo",
-		     maintpath, NULL);
-
-	rc = run_command(&config_set);
-
-done:
 	free(maintpath);
-	return rc;
+	return 0;
 }
 
 static char const * const builtin_maintenance_unregister_usage[] = {
@@ -1533,8 +1538,6 @@ static int maintenance_unregister(int argc, const char **argv, const char *prefi
 		OPT_END(),
 	};
 	const char *key = "maintenance.repo";
-	int rc = 0;
-	struct child_process config_unset = CHILD_PROCESS_INIT;
 	char *maintpath = get_maintpath();
 	int found = 0;
 	struct string_list_item *item;
@@ -1557,17 +1560,27 @@ static int maintenance_unregister(int argc, const char **argv, const char *prefi
 	}
 
 	if (found) {
-		config_unset.git_cmd = 1;
-		strvec_pushl(&config_unset.args, "config", "--global", "--unset",
-			     "--fixed-value", key, maintpath, NULL);
-
-		rc = run_command(&config_unset);
+		int rc;
+		char *user_config, *xdg_config;
+		git_global_config(&user_config, &xdg_config);
+		if (!user_config)
+			die(_("$HOME not set"));
+		rc = git_config_set_multivar_in_file_gently(
+			user_config, key, NULL, maintpath,
+			CONFIG_FLAGS_MULTI_REPLACE | CONFIG_FLAGS_FIXED_VALUE);
+		free(user_config);
+		free(xdg_config);
+
+		if (rc &&
+		    (!force || rc == CONFIG_NOTHING_SET))
+			die(_("unable to unset '%s' value of '%s'"),
+			    key, maintpath);
 	} else if (!force) {
 		die(_("repository '%s' is not registered"), maintpath);
 	}
 
 	free(maintpath);
-	return rc;
+	return 0;
 }
 
 static const char *get_frequency(enum schedule_priority schedule)