Fix #839: use stack allocated memory to handle TIG_LS_REMOTE

Remove argv_from_env and use memory from the stack to parse the
TIG_LS_REMOTE environment variable in reload_refs.

include/tig/argv.h

@@ -28,7 +28,6 @@ char *argv_to_string_alloc(const char *argv[], const char *sep);
 bool argv_to_string_quoted(const char *argv[SIZEOF_ARG], char *buf, size_t buflen, const char *sep);
 bool argv_from_string_no_quotes(const char *argv[SIZEOF_ARG], int *argc, char *cmd);
 bool argv_from_string(const char *argv[SIZEOF_ARG], int *argc, char *cmd);
-bool argv_from_env(const char **argv, const char *name);
 void argv_free(const char *argv[]);
 size_t argv_size(const char **argv);
 bool argv_append(const char ***argv, const char *arg);

src/argv.c

@@ -172,17 +172,6 @@ argv_from_string(const char *argv[SIZEOF_ARG], int *argc, char *cmd)
 	return split_argv_string(argv, argc, cmd, false);
 }
 
-bool
-argv_from_env(const char **argv, const char *name)
-{
-	char *env = argv ? getenv(name) : NULL;
-	int argc = 0;
-
-	if (env && *env)
-		env = strdup(env);
-	return !env || argv_from_string(argv, &argc, env);
-}
-
 void
 argv_free(const char *argv[])
 {

src/refdb.c

@@ -314,15 +314,18 @@ reload_refs(bool force)
 	const char *ls_remote_argv[SIZEOF_ARG] = {
 		"git", "show-ref", "--head", "--dereference", NULL
 	};
-	static bool init = false;
+	char ls_remote_cmd[SIZEOF_STR];
 	struct ref_opt opt = { repo.remote, repo.head, WATCH_NONE };
 	struct repo_info old_repo = repo;
 	enum status_code code;
+	const char *env = getenv("TIG_LS_REMOTE");
 
-	if (!init) {
-		if (!argv_from_env(ls_remote_argv, "TIG_LS_REMOTE"))
-			return ERROR_OUT_OF_MEMORY;
-		init = true;
+	if (env && *env) {
+		int argc = 0;
+
+		string_ncopy(ls_remote_cmd, env, strlen(env));
+		if (!argv_from_string(ls_remote_argv, &argc, ls_remote_cmd))
+			return error("Failed to parse TIG_LS_REMOTE: %s", env);
 	}
 
 	if (!*repo.git_dir)