gst/gstcaps.c: Clarify behaviour of _is_equal() when passing NULL parameters.

Original commit message from CVS:
* gst/gstcaps.c:
Clarify behaviour of _is_equal() when passing NULL parameters.

* gst/gstpad.c: (gst_pad_link_check_compatible_unlocked),
(gst_pad_set_caps):
Cleanups. Don't unref NULL caps.
When setting the same caps, protect caps of the pad with
proper lock.
Use full functionality of _is_equal() when comparing caps.

ChangeLog

@@ -1,3 +1,15 @@
+2006-01-20  Wim Taymans  <wim@fluendo.com>
+
+	* gst/gstcaps.c:
+	Clarify behaviour of _is_equal() when passing NULL parameters.
+
+	* gst/gstpad.c: (gst_pad_link_check_compatible_unlocked),
+	(gst_pad_set_caps):
+	Cleanups. Don't unref NULL caps.
+	When setting the same caps, protect caps of the pad with
+	proper lock.
+	Use full functionality of _is_equal() when comparing caps.
+
 2006-01-20  Jan Schmidt  <thaytan@mad.scientist.com>
 
 	* libs/gst/base/gstcollectpads.c: (gst_collect_pads_is_collected):

gst/gstcaps.c

@@ -875,7 +875,9 @@ gst_caps_is_subset (const GstCaps * subset, const GstCaps * superset)
  * <note>This function does not work reliably if optional properties for caps
  * are included on one caps and omitted on the other.</note>
  *
- * Returns: TRUE if both caps are equal
+ * This function deals correctly with passing NULL for any of the caps. 
+ *
+ * Returns: TRUE if both caps are equal. 
  */
 gboolean
 gst_caps_is_equal (const GstCaps * caps1, const GstCaps * caps2)

gst/gstpad.c

@@ -1510,10 +1510,12 @@ gst_pad_link_check_compatible_unlocked (GstPad * src, GstPad * sink)
 
   srccaps = gst_pad_get_caps_unlocked (src);
   sinkcaps = gst_pad_get_caps_unlocked (sink);
+
   GST_CAT_DEBUG (GST_CAT_CAPS, "src caps %" GST_PTR_FORMAT, srccaps);
   GST_CAT_DEBUG (GST_CAT_CAPS, "sink caps %" GST_PTR_FORMAT, sinkcaps);
 
-  /* if we have caps on both pads we can check the intersection */
+  /* if we have caps on both pads we can check the intersection. If one
+   * of the caps is NULL, we return TRUE. */
   if (srccaps && sinkcaps) {
     GstCaps *icaps;
 
@@ -1521,18 +1523,31 @@ gst_pad_link_check_compatible_unlocked (GstPad * src, GstPad * sink)
     gst_caps_unref (srccaps);
     gst_caps_unref (sinkcaps);
 
+    if (icaps == NULL)
+      goto was_null;
+
     GST_CAT_DEBUG (GST_CAT_CAPS,
         "intersection caps %p %" GST_PTR_FORMAT, icaps, icaps);
 
-    if (!icaps || gst_caps_is_empty (icaps)) {
+    if (gst_caps_is_empty (icaps))
-      GST_CAT_DEBUG (GST_CAT_CAPS, "intersection is empty");
+      goto was_empty;
-      gst_caps_unref (icaps);
+
-      return FALSE;
-    }
     gst_caps_unref (icaps);
   }
-
   return TRUE;
+
+  /* incompatible cases */
+was_null:
+  {
+    GST_CAT_DEBUG (GST_CAT_CAPS, "intersection gave NULL");
+    return FALSE;
+  }
+was_empty:
+  {
+    GST_CAT_DEBUG (GST_CAT_CAPS, "intersection is EMPTY");
+    gst_caps_unref (icaps);
+    return FALSE;
+  }
 }
 
 /* check if the grandparents of both pads are the same.
@@ -2136,12 +2151,11 @@ gst_pad_set_caps (GstPad * pad, GstCaps * caps)
   setcaps = GST_PAD_SETCAPSFUNC (pad);
 
   existing = GST_PAD_CAPS (pad);
-  if (caps == existing)
+  if (gst_caps_is_equal (caps, existing))
-    goto setting_same_caps;
-  else if (caps && existing && gst_caps_is_equal (caps, existing))
     goto setting_same_caps;
 
-  /* call setcaps function to configure the pad */
+  /* call setcaps function to configure the pad only if the
+   * caps is not NULL */
   if (setcaps != NULL && caps) {
     if (!GST_PAD_IS_IN_SETCAPS (pad)) {
       GST_OBJECT_FLAG_SET (pad, GST_PAD_IN_SETCAPS);
@@ -2167,10 +2181,11 @@ gst_pad_set_caps (GstPad * pad, GstCaps * caps)
 
 setting_same_caps:
   {
-    GST_OBJECT_UNLOCK (pad);
     gst_caps_replace (&GST_PAD_CAPS (pad), caps);
     GST_CAT_DEBUG_OBJECT (GST_CAT_CAPS, pad,
         "caps %" GST_PTR_FORMAT " same as existing, updating ptr only", caps);
+    GST_OBJECT_UNLOCK (pad);
+
     return TRUE;
   }
 /* errors */