core: Only allow Pause() when state is PLAYING

cf. AVTransport:2 documentation, section 2.5.1, Figure 1 and section
2.4.11.

diff --git a/src/rygel/rygel-av-transport.vala b/src/rygel/rygel-av-transport.vala
index 1018ea4..1c1a777 100644 (file)
--- a/src/rygel/rygel-av-transport.vala
+++ b/src/rygel/rygel-av-transport.vala
@@ -390,6 +390,12 @@ internal class Rygel.AVTransport : Service {
             return;
         }
 
+        if (this.player.playback_state != "PLAYING") {
+            action.return_error (701, _("Transition not available"));
+
+            return;
+        }
+
         this.player.playback_state = "PAUSED_PLAYBACK";
 
         action.return ();