update: validate in command.c and fix small memory leak

If update_task was called with "" as its path argument, that
string would never get freed because it false positived.

Instead, never pass "" to update_task and trip an assertion
if we do.

2 files changed, 17 insertions, 6 deletions

diff --git a/src/command.c b/src/command.c
index f583f82a1..04e85c6fe 100644
--- a/src/command.c
+++ b/src/command.c
@@ -802,9 +802,15 @@ static int handleUpdate(int fd, mpd_unused int *permission,
 	char *path = NULL;
 
 	assert(argc <= 2);
-	if (argc == 2 && !(path = sanitizePathDup(argv[1]))) {
-		commandError(fd, ACK_ERROR_ARG, "invalid path");
-		return -1;
+	if (argc == 2) {
+		if (!(path = sanitizePathDup(argv[1]))) {
+			commandError(fd, ACK_ERROR_ARG, "invalid path");
+			return -1;
+		}
+		if (path_is_music_root(path)) {
+			free(path);
+			path = NULL;
+		}
 	}
 	return print_update_result(fd, directory_update_init(path));
 }
diff --git a/src/update.c b/src/update.c
index 72f4b943b..6c8b6e7bc 100644
--- a/src/update.c
+++ b/src/update.c
@@ -349,9 +349,12 @@ static void updatePath(const char *utf8path)
 
 static void * update_task(void *_path)
 {
-	if (_path && !path_is_music_root(_path)) {
-		updatePath(_path);
-		free(_path);
+	char *utf8path = _path;
+
+	if (utf8path) {
+		assert(*utf8path);
+		updatePath(utf8path);
+		free(utf8path);
 	} else {
 		struct stat st;
 
@@ -386,6 +389,8 @@ unsigned directory_update_init(char *path)
 {
 	assert(pthread_equal(pthread_self(), main_task));
 
+	assert(!path || (path && *path));
+
 	if (progress != UPDATE_PROGRESS_IDLE) {
 		unsigned next_task_id;