update: job ID must be positive

The documentation for directory_update_init() was incorrect: a job ID
must be positive, not non-negative.  If the update queue is full and
no job was created, it makes more sense to return 0 instead of -1,
because it is more consistent with the return value of isUpdatingDB().

4 files changed, 8 insertions, 10 deletions

diff --git a/src/command.c b/src/command.c
index aafb88418..541a71a50 100644
--- a/src/command.c
+++ b/src/command.c
@@ -788,14 +788,12 @@ static int handlePlaylistMove(int fd, mpd_unused int *permission,
 
 static int print_update_result(int fd, int ret)
 {
-	if (ret >= 0) {
+	if (ret > 0) {
 		fdprintf(fd, "updating_db: %i\n", ret);
 		return 0;
 	}
-	if (ret == -2)
-		commandError(fd, ACK_ERROR_ARG, "invalid path");
-	else
-		commandError(fd, ACK_ERROR_UPDATE_ALREADY, "already updating");
+	assert(!ret);
+	commandError(fd, ACK_ERROR_UPDATE_ALREADY, "already updating");
 	return -1;
 }
 
diff --git a/src/database.c b/src/database.c
index 3a1667bb6..ea78940f8 100644
--- a/src/database.c
+++ b/src/database.c
@@ -40,7 +40,7 @@ void db_init(void)
 {
 	music_root = directory_new("", NULL);
 
-	if (directory_update_init(NULL) < 0)
+	if (!directory_update_init(NULL))
 		FATAL("directory update failed\n");
 
 	do {
diff --git a/src/update.c b/src/update.c
index f5619a1d4..7dc50b5aa 100644
--- a/src/update.c
+++ b/src/update.c
@@ -418,9 +418,9 @@ int directory_update_init(char *path)
 		int next_task_id;
 
 		if (!path)
-			return -1;
+			return 0;
 		if (update_paths_nr == ARRAY_SIZE(update_paths))
-			return -1;
+			return 0;
 		assert(update_paths_nr < ARRAY_SIZE(update_paths));
 		update_paths[update_paths_nr++] = path;
 		next_task_id = update_task_id + update_paths_nr;
diff --git a/src/update.h b/src/update.h
index 0c0d74416..5c7277e32 100644
--- a/src/update.h
+++ b/src/update.h
@@ -23,8 +23,8 @@
 int isUpdatingDB(void);
 
 /*
- * returns the non-negative update job ID on success,
- * returns -1 if busy
+ * returns the positive update job ID on success,
+ * returns 0 if busy
  * @path will be freed by this function and should not be reused
  */
 int directory_update_init(char *path);