From a55576d1fd25c7d67661630fc94367908802a496 Mon Sep 17 00:00:00 2001
From: Thibault Saunier <tsaunier@igalia.com>
Date: Tue, 3 Sep 2019 16:46:30 -0400
Subject: [PATCH] qtdemux: Specify REDIRECT information in error message

There are in the wild (mp4) streams that basically contain no tracks
but do have a redirect info[0], in which case, we won't be able
to expose any pad (there are no tracks) so we can't post anything but
an error on the bus, as:

- it can't send EOS downstream, it has no pad,
- posting an EOS message will be useless as PAUSED state can't be
  reached and there is no sink in the pipeline meaning GstBin will
  simply ignore it

The approach here is to to add details to the ERROR message with a
`redirect-location` field which elements like playbin handle and use right
away.

[0]: http://movietrailers.apple.com/movies/paramount/terminator-dark-fate/terminator-dark-fate-trailer-2_480p.mov
---
 gst/isomp4/qtdemux.c | 32 +++++++++++++++++++++++++-------
 gst/isomp4/qtdemux.h |  2 +-
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/gst/isomp4/qtdemux.c b/gst/isomp4/qtdemux.c
index ba4d43648a..8a6bf08c7c 100644
--- a/gst/isomp4/qtdemux.c
+++ b/gst/isomp4/qtdemux.c
@@ -526,6 +526,7 @@ GST_STATIC_PAD_TEMPLATE ("subtitle_%u",
 G_DEFINE_TYPE (GstQTDemux, gst_qtdemux, GST_TYPE_ELEMENT);
 
 static void gst_qtdemux_dispose (GObject * object);
+static void gst_qtdemux_finalize (GObject * object);
 
 static guint32
 gst_qtdemux_find_index_linear (GstQTDemux * qtdemux, QtDemuxStream * str,
@@ -628,6 +629,7 @@ gst_qtdemux_class_init (GstQTDemuxClass * klass)
   parent_class = g_type_class_peek_parent (klass);
 
   gobject_class->dispose = gst_qtdemux_dispose;
+  gobject_class->finalize = gst_qtdemux_finalize;
 
   gstelement_class->change_state = GST_DEBUG_FUNCPTR (gst_qtdemux_change_state);
 #if 0
@@ -683,6 +685,16 @@ gst_qtdemux_init (GstQTDemux * qtdemux)
   gst_qtdemux_reset (qtdemux, TRUE);
 }
 
+static void
+gst_qtdemux_finalize (GObject * object)
+{
+  GstQTDemux *qtdemux = GST_QTDEMUX (object);
+
+  g_free (qtdemux->redirect_location);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
 static void
 gst_qtdemux_dispose (GObject * object)
 {
@@ -711,10 +723,11 @@ gst_qtdemux_dispose (GObject * object)
 static void
 gst_qtdemux_post_no_playable_stream_error (GstQTDemux * qtdemux)
 {
-  if (qtdemux->posted_redirect) {
-    GST_ELEMENT_ERROR (qtdemux, STREAM, DEMUX,
+  if (qtdemux->redirect_location) {
+    GST_ELEMENT_ERROR_WITH_DETAILS (qtdemux, STREAM, DEMUX,
         (_("This file contains no playable streams.")),
-        ("no known streams found, a redirect message has been posted"));
+        ("no known streams found, a redirect message has been posted"),
+        ("redirect-location", G_TYPE_STRING, qtdemux->redirect_location, NULL));
   } else {
     GST_ELEMENT_ERROR (qtdemux, STREAM, DEMUX,
         (_("This file contains no playable streams.")),
@@ -2111,7 +2124,7 @@ gst_qtdemux_reset (GstQTDemux * qtdemux, gboolean hard)
     qtdemux->neededbytes = 16;
     qtdemux->todrop = 0;
     qtdemux->pullbased = FALSE;
-    qtdemux->posted_redirect = FALSE;
+    g_clear_pointer (&qtdemux->redirect_location, g_free);
     qtdemux->first_mdat = -1;
     qtdemux->header_size = 0;
     qtdemux->mdatoffset = -1;
@@ -6065,11 +6078,12 @@ gst_qtdemux_decorate_and_push_buffer (GstQTDemux * qtdemux,
     gst_buffer_unmap (buf, &map);
     if (url != NULL && strlen (url) != 0) {
       /* we have RTSP redirect now */
+      g_free (qtdemux->redirect_location);
+      qtdemux->redirect_location = g_strdup (url);
       gst_element_post_message (GST_ELEMENT_CAST (qtdemux),
           gst_message_new_element (GST_OBJECT_CAST (qtdemux),
               gst_structure_new ("redirect",
                   "new-location", G_TYPE_STRING, url, NULL)));
-      qtdemux->posted_redirect = TRUE;
     } else {
       GST_WARNING_OBJECT (qtdemux, "Redirect URI of stream is empty, not "
           "posting");
@@ -12915,7 +12929,9 @@ qtdemux_expose_streams (GstQTDemux * qtdemux)
             "new-location", G_TYPE_STRING,
             QTDEMUX_NTH_STREAM (qtdemux, 0)->redirect_uri, NULL));
     gst_element_post_message (GST_ELEMENT_CAST (qtdemux), m);
-    qtdemux->posted_redirect = TRUE;
+    g_free (qtdemux->redirect_location);
+    qtdemux->redirect_location =
+        g_strdup (QTDEMUX_NTH_STREAM (qtdemux, 0)->redirect_uri);
   }
 
   g_ptr_array_foreach (qtdemux->active_streams,
@@ -13968,9 +13984,11 @@ qtdemux_process_redirects (GstQTDemux * qtdemux, GList * references)
   g_list_free (references);
 
   GST_INFO_OBJECT (qtdemux, "posting redirect message: %" GST_PTR_FORMAT, s);
+  g_free (qtdemux->redirect_location);
+  qtdemux->redirect_location =
+      g_strdup (gst_structure_get_string (s, "new-location"));
   msg = gst_message_new_element (GST_OBJECT_CAST (qtdemux), s);
   gst_element_post_message (GST_ELEMENT_CAST (qtdemux), msg);
-  qtdemux->posted_redirect = TRUE;
 }
 
 /* look for redirect nodes, collect all redirect information and
diff --git a/gst/isomp4/qtdemux.h b/gst/isomp4/qtdemux.h
index f9731b2b8b..c5e85c7211 100644
--- a/gst/isomp4/qtdemux.h
+++ b/gst/isomp4/qtdemux.h
@@ -69,7 +69,7 @@ struct _GstQTDemux {
   /* TRUE if pull-based */
   gboolean pullbased;
 
-  gboolean posted_redirect;
+  gchar *redirect_location;
 
   /* Protect pad exposing from flush event */
   GMutex expose_lock;