ext/gconf/gstswitchsink.c: If the new kid element fails to change state for some reason forward the error message it ...

Original commit message from CVS:
* ext/gconf/gstswitchsink.c:
If the new kid element fails to change state for some reason
(e.g. esdsink not being able to connect to the sound server),
forward the error message it posted on the bus instead of just
posting a generic 'Internal state change error: please file a
bug' error message. Fixes #471364.

2 files changed, 36 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index a587f071..5fb65d31 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2007-09-06  Tim-Philipp Müller  <tim at centricular dot net>
+
+	* ext/gconf/gstswitchsink.c:
+	  If the new kid element fails to change state for some reason
+	  (e.g. esdsink not being able to connect to the sound server),
+	  forward the error message it posted on the bus instead of just
+	  posting a generic 'Internal state change error: please file a
+	  bug' error message. Fixes #471364.
+
 2007-09-05  Tim-Philipp Müller  <tim at centricular dot net>
 
 	* gst/qtdemux/Makefile.am:
diff --git a/ext/gconf/gstswitchsink.c b/ext/gconf/gstswitchsink.c
index a39d6e19..bc09f942 100644
--- a/ext/gconf/gstswitchsink.c
+++ b/ext/gconf/gstswitchsink.c
@@ -116,13 +116,14 @@ gst_switch_sink_dispose (GObject * object)
   GST_CALL_PARENT (G_OBJECT_CLASS, dispose, (object));
 }
 
-gboolean
+static gboolean
 gst_switch_commit_new_kid (GstSwitchSink * sink)
 {
   GstPad *targetpad;
   GstState kid_state;
   GstElement *new_kid, *old_kid;
   gboolean is_fakesink = FALSE;
+  GstBus *bus;
 
   /* need locking around member accesses */
   GST_OBJECT_LOCK (sink);
@@ -150,12 +151,37 @@ gst_switch_commit_new_kid (GstSwitchSink * sink)
     GST_DEBUG_OBJECT (sink, "Setting new kid");
   }
 
+  /* set temporary bus of our own to catch error messages from the child
+   * (could we just set our own bus on it, or would the state change messages
+   * from the not-yet-added element confuse the state change algorithm? Let's
+   * play it safe for now) */
+  bus = gst_bus_new ();
+  gst_element_set_bus (new_kid, bus);
+  gst_object_unref (bus);
+
   if (gst_element_set_state (new_kid, kid_state) == GST_STATE_CHANGE_FAILURE) {
+    GstMessage *msg;
+
+    /* check if child posted an error message and if so re-post it on our bus
+     * so that the application gets to see a decent error and not our generic
+     * fallback error message which is completely indecipherable to the user */
+    while ((msg = gst_bus_pop (GST_ELEMENT_BUS (new_kid)))) {
+      if (GST_MESSAGE_TYPE (msg) == GST_MESSAGE_ERROR) {
+        GST_INFO_OBJECT (sink, "Forwarding kid error: %" GST_PTR_FORMAT, msg);
+        gst_element_post_message (GST_ELEMENT (sink), msg);
+        break;
+      }
+      gst_message_unref (msg);
+    }
+    /* FIXME: need a translated error message that tells the user to check
+     * her GConf audio/video settings */
     GST_ELEMENT_ERROR (sink, CORE, STATE_CHANGE, (NULL),
         ("Failed to set state on new child."));
+    gst_element_set_bus (new_kid, NULL);
     gst_object_unref (new_kid);
     return FALSE;
   }
+  gst_element_set_bus (new_kid, NULL);
   gst_bin_add (GST_BIN (sink), new_kid);
 
   /* Now, replace the existing child */