update: pass const string to update_enqueue()

Duplicate the path string within update.c, do not expect an allocated
string as parameter.

src/command.c

@@ -1018,12 +1018,12 @@ handle_playlistmove(struct client *client, G_GNUC_UNUSED int argc, char *argv[])
 static enum command_return
 handle_update(struct client *client, G_GNUC_UNUSED int argc, char *argv[])
 {
-	char *path = NULL;
+	const char *path = NULL;
 	unsigned ret;
 
 	assert(argc <= 2);
 	if (argc == 2)
-		path = g_strdup(argv[1]);
+		path = argv[1];
 
 	ret = update_enqueue(path);
 	if (ret > 0) {

src/update.c

@@ -790,7 +790,8 @@ static void * update_task(void *_path)
 	return NULL;
 }
 
-static void spawn_update_task(char *path)
+static void
+spawn_update_task(const char *path)
 {
 	GError *e = NULL;
 
@@ -798,15 +799,18 @@ static void spawn_update_task(char *path)
 
 	progress = UPDATE_PROGRESS_RUNNING;
 	modified = false;
-	if (!(update_thr = g_thread_create(update_task, path, TRUE, &e)))
+
+	update_thr = g_thread_create(update_task, g_strdup(path), TRUE, &e);
+	if (update_thr == NULL)
 		g_error("Failed to spawn update task: %s", e->message);
+
 	if (++update_task_id > update_task_id_max)
 		update_task_id = 1;
 	g_debug("spawned thread for update job id %i", update_task_id);
 }
 
 unsigned
-update_enqueue(char *path)
+update_enqueue(const char *path)
 {
 	assert(g_thread_self() == main_task);
 
@@ -816,17 +820,16 @@ update_enqueue(char *path)
 	if (progress != UPDATE_PROGRESS_IDLE) {
 		unsigned next_task_id;
 
-		if (update_paths_nr == G_N_ELEMENTS(update_paths)) {
-			g_free(path);
+		if (update_paths_nr == G_N_ELEMENTS(update_paths))
 			return 0;
-		}
 
 		assert(update_paths_nr < G_N_ELEMENTS(update_paths));
-		update_paths[update_paths_nr++] = path;
+		update_paths[update_paths_nr++] = g_strdup(path);
 		next_task_id = update_task_id + update_paths_nr;
 
 		return next_task_id > update_task_id_max ?  1 : next_task_id;
 	}
+
 	spawn_update_task(path);
 
 	idle_add(IDLE_UPDATE);
@@ -884,6 +887,7 @@ static void update_finished_event(void)
 		memmove(&update_paths[0], &update_paths[1],
 		        --update_paths_nr * sizeof(char *));
 		spawn_update_task(path);
+		g_free(path);
 	} else {
 		progress = UPDATE_PROGRESS_IDLE;
 

src/update.h

@@ -27,12 +27,14 @@ void update_global_finish(void);
 unsigned
 isUpdatingDB(void);
 
-/*
- * returns the positive update job ID on success,
- * returns 0 if busy
- * @path will be freed by this function and should not be reused
+/**
+ * Add this path to the database update queue.
+ *
+ * @param path a path to update; if NULL or an empty string,
+ * the whole music directory is updated
+ * @return the job id, or 0 on error
  */
 unsigned
-update_enqueue(char *path);
+update_enqueue(const char *path);
 
 #endif