pad: not only describe conditions in the docs, also check them in the code

When blocking pads, check if the pad is in the rigt direction. Log some info
for the developer and return FALSE, instead of just locking up.

diff --git a/gst/gstpad.c b/gst/gstpad.c
index a0040f8..01937e6 100644 (file)
--- a/gst/gstpad.c
+++ b/gst/gstpad.c
@@ -1038,7 +1038,7 @@ gst_pad_is_active (GstPad * pad)
  *  and sink pads in pull mode.
  * </note>
  *
- * Returns: TRUE if the pad could be blocked. This function can fail if the
+ * Returns: %TRUE if the pad could be blocked. This function can fail if the
  * wrong parameters were passed or the pad was already in the requested state.
  *
  * MT safe.
@@ -1061,6 +1061,15 @@ gst_pad_set_blocked_async_full (GstPad * pad, gboolean blocked,
   if (G_UNLIKELY (was_blocked == blocked))
     goto had_right_state;
 
+  if (G_UNLIKELY (
+          (GST_PAD_ACTIVATE_MODE (pad) == GST_ACTIVATE_PUSH) &&
+          (GST_PAD_DIRECTION (pad) != GST_PAD_SRC)))
+    goto wrong_direction;
+  if (G_UNLIKELY (
+          (GST_PAD_ACTIVATE_MODE (pad) == GST_ACTIVATE_PULL) &&
+          (GST_PAD_DIRECTION (pad) != GST_PAD_SINK)))
+    goto wrong_direction;
+
   if (blocked) {
     GST_CAT_LOG_OBJECT (GST_CAT_SCHEDULING, pad, "blocking pad");
 
@@ -1104,6 +1113,8 @@ gst_pad_set_blocked_async_full (GstPad * pad, gboolean blocked,
 
   return TRUE;
 
+/* Errors */
+
 had_right_state:
   {
     GST_CAT_LOG_OBJECT (GST_CAT_SCHEDULING, pad,
@@ -1112,6 +1123,14 @@ had_right_state:
 
     return FALSE;
   }
+wrong_direction:
+  {
+    GST_CAT_INFO_OBJECT (GST_CAT_SCHEDULING, pad, "pad block on the wrong pad, "
+        "block src pads in push mode and sink pads in pull mode.");
+    GST_OBJECT_UNLOCK (pad);
+
+    return FALSE;
+  }
 }
 
 /**