matroskademux: Handle element's duration query.

This is small regression from commit f7abd81a.

When calling `gst_element_query()` no pad is associated with that query, but the
current code always forwards the query to the associated pad, which is NULL in
previous case. This patch checks for the pad before forwarding the query.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3404>

diff --git a/subprojects/gst-plugins-good/gst/matroska/matroska-demux.c b/subprojects/gst-plugins-good/gst/matroska/matroska-demux.c
index 773a306..38e4e4d 100644 (file)
--- a/subprojects/gst-plugins-good/gst/matroska/matroska-demux.c
+++ b/subprojects/gst-plugins-good/gst/matroska/matroska-demux.c
@@ -1839,9 +1839,10 @@ gst_matroska_demux_query (GstMatroskaDemux * demux, GstPad * pad,
 
       gst_query_parse_duration (query, &format, NULL);
 
-      res = TRUE;
       if (format == GST_FORMAT_TIME) {
-        res = gst_pad_query_default (pad, GST_OBJECT_CAST (demux), query);
+        res = FALSE;
+        if (pad)
+          res = gst_pad_query_default (pad, GST_OBJECT_CAST (demux), query);
         if (!res) {
           GST_OBJECT_LOCK (demux);
           gst_query_set_duration (query, GST_FORMAT_TIME,
@@ -1852,6 +1853,8 @@ gst_matroska_demux_query (GstMatroskaDemux * demux, GstPad * pad,
         }
       } else if (format == GST_FORMAT_DEFAULT && context
           && context->default_duration) {
+        res = TRUE;
+
         GST_OBJECT_LOCK (demux);
         gst_query_set_duration (query, GST_FORMAT_DEFAULT,
             demux->common.segment.duration / context->default_duration);