mpdparser: Support multiple Period elements in external xml

External xml could have empty, one or multiple top-level "Period" elements.
Because xml parser cannot parse the multiple top-level elements
(i.e., no root element), we need to wrap a xml in order to make root element.
See also ISO/IEC 23009-1:2014 5.3.2.2

https://bugzilla.gnome.org/show_bug.cgi?id=774357

ext/dash/gstmpdparser.c

@@ -4186,19 +4186,23 @@ gst_mpd_client_setup_representation (GstMpdClient * client,
   return TRUE;
 }
 
+#define CUSTOM_WRAPPER_START "<custom_wrapper>"
+#define CUSTOM_WRAPPER_END "</custom_wrapper>"
+
 static GList *
 gst_mpd_client_fetch_external_period (GstMpdClient * client,
     GstPeriodNode * period_node, gboolean * error)
 {
   GstFragment *download;
+  GstAdapter *adapter;
   GstBuffer *period_buffer;
-  GstMapInfo map;
   GError *err = NULL;
   xmlDocPtr doc;
   GstUri *base_uri, *uri;
   gchar *query = NULL;
-  gchar *uri_string;
+  gchar *uri_string, *wrapper;
   GList *new_periods = NULL;
+  const gchar *data;
 
   *error = FALSE;
 
@@ -4248,34 +4252,65 @@ gst_mpd_client_fetch_external_period (GstMpdClient * client,
   period_buffer = gst_fragment_get_buffer (download);
   g_object_unref (download);
 
-  gst_buffer_map (period_buffer, &map, GST_MAP_READ);
+  /* external xml could have multiple period without root xmlNode.
+   * To avoid xml parsing error caused by no root node, wrapping it with
+   * custom root node */
+  adapter = gst_adapter_new ();
+
+  wrapper = g_new (gchar, strlen (CUSTOM_WRAPPER_START));
+  memcpy (wrapper, CUSTOM_WRAPPER_START, strlen (CUSTOM_WRAPPER_START));
+  gst_adapter_push (adapter,
+      gst_buffer_new_wrapped (wrapper, strlen (CUSTOM_WRAPPER_START)));
+
+  gst_adapter_push (adapter, period_buffer);
+
+  wrapper = g_strdup (CUSTOM_WRAPPER_END);
+  gst_adapter_push (adapter,
+      gst_buffer_new_wrapped (wrapper, strlen (CUSTOM_WRAPPER_END) + 1));
+
+  data = gst_adapter_map (adapter, gst_adapter_available (adapter));
 
   doc =
-      xmlReadMemory ((const gchar *) map.data, map.size, "noname.xml", NULL,
+      xmlReadMemory (data, gst_adapter_available (adapter), "noname.xml", NULL,
       XML_PARSE_NONET);
   if (doc) {
     xmlNode *root_element = xmlDocGetRootElement (doc);
-    if (root_element->type != XML_ELEMENT_NODE ||
-        xmlStrcmp (root_element->name, (xmlChar *) "Period") != 0) {
-      xmlFreeDoc (doc);
-      gst_buffer_unmap (period_buffer, &map);
-      gst_buffer_unref (period_buffer);
-      *error = TRUE;
-      return NULL;
-    }
+    xmlNode *iter;
 
-    gst_mpdparser_parse_period_node (&new_periods, root_element);
+    if (root_element->type != XML_ELEMENT_NODE)
+      goto error;
+
+    for (iter = root_element->children; iter; iter = iter->next) {
+      if (iter->type == XML_ELEMENT_NODE) {
+        if (xmlStrcmp (iter->name, (xmlChar *) "Period") == 0) {
+          gst_mpdparser_parse_period_node (&new_periods, iter);
+        } else {
+          goto error;
+        }
+      }
+    }
   } else {
     GST_ERROR ("Failed to parse period node XML");
-    gst_buffer_unmap (period_buffer, &map);
-    gst_buffer_unref (period_buffer);
+    gst_adapter_unmap (adapter);
+    gst_adapter_clear (adapter);
+    gst_object_unref (adapter);
     *error = TRUE;
     return NULL;
   }
-  gst_buffer_unmap (period_buffer, &map);
-  gst_buffer_unref (period_buffer);
+  xmlFreeDoc (doc);
+  gst_adapter_unmap (adapter);
+  gst_adapter_clear (adapter);
+  gst_object_unref (adapter);
 
   return new_periods;
+
+error:
+  xmlFreeDoc (doc);
+  gst_adapter_unmap (adapter);
+  gst_adapter_clear (adapter);
+  gst_object_unref (adapter);
+  *error = TRUE;
+  return NULL;
 }
 
 gboolean

ext/dash/gstmpdparser.h

@@ -29,6 +29,7 @@
 
 #include <gst/gst.h>
 #include <gst/uridownloader/gsturidownloader.h>
+#include <gst/base/gstadapter.h>
 
 G_BEGIN_DECLS
 

tests/check/Makefile.am

@@ -470,8 +470,9 @@ elements_mpegtsmux_LDADD = $(GST_PLUGINS_BASE_LIBS) $(GST_VIDEO_LIBS) $(GST_BASE
 elements_uvch264demux_CFLAGS = -DUVCH264DEMUX_DATADIR="$(srcdir)/elements/uvch264demux_data" \
 				$(AM_CFLAGS)
 
-elements_dash_mpd_CFLAGS = $(AM_CFLAGS) $(GST_PLUGINS_BAD_CFLAGS) $(LIBXML2_CFLAGS)
-elements_dash_mpd_LDADD = $(LDADD) $(LIBXML2_LIBS) \
+elements_dash_mpd_CFLAGS = $(GST_BASE_CFLAGS) $(AM_CFLAGS) $(GST_PLUGINS_BAD_CFLAGS) $(LIBXML2_CFLAGS) \
+	-DDASH_MPD_DATADIR="$(srcdir)/elements/dash_mpd_data"
+elements_dash_mpd_LDADD = $(GST_BASE_LIBS) $(LDADD) $(LIBXML2_LIBS) \
 	$(top_builddir)/gst-libs/gst/uridownloader/libgsturidownloader-@GST_API_VERSION@.la
 elements_dash_mpd_SOURCES = elements/dash_mpd.c
 

tests/check/elements/dash_mpd.c

@@ -5528,6 +5528,107 @@ GST_START_TEST (dash_mpdparser_maximum_segment_duration)
 
 GST_END_TEST;
 
+/*
+ * Test parsing of Perioud using @xlink:href attribute
+ */
+
+#define STRINGIFY_(x) #x
+#define STRINGIFY(x) STRINGIFY_ (x)
+#define REMOTEDIR STRINGIFY (DASH_MPD_DATADIR)
+#define XLINK_SINGLE_PERIOD_FILENAME REMOTEDIR "/xlink_single_period.period"
+#define XLINK_DOUBLE_PERIOD_FILENAME REMOTEDIR "/xlink_double_period.period"
+
+GST_START_TEST (dash_mpdparser_xlink_period)
+{
+  GstPeriodNode *periodNode;
+  GstUriDownloader *downloader;
+  GstMpdClient *mpdclient;
+  GList *period_list, *iter;
+  gboolean ret;
+  gchar *xml_joined, *file_uri_single_period, *file_uri_double_period;
+  const gchar *xml_frag_start =
+      "<?xml version=\"1.0\"?>"
+      "<MPD xmlns=\"urn:mpeg:dash:schema:mpd:2011\""
+      "     profiles=\"urn:mpeg:dash:profile:isoff-main:2011\">"
+      "  <Period id=\"Period0\"" "duration=\"PT5S\"></Period>";
+
+  const gchar *xml_uri_front = "  <Period xlink:href=\"";
+
+  const gchar *xml_uri_rear =
+      "\""
+      "          xlink:actuate=\"onRequest\""
+      "          xmlns:xlink=\"http://www.w3.org/1999/xlink\"></Period>";
+
+  const gchar *xml_frag_end = "</MPD>";
+
+  /* XLINK_ONE_PERIOD_FILENAME
+   *
+   * <Period id="xlink-single-period-Period1" duration="PT10S" xmlns="urn:mpeg:dash:schema:mpd:2011"></Period>
+   */
+
+  /* XLINK_TWO_PERIODS_FILENAME
+   *
+   * <Period id="xlink-double-period-Period1" duration="PT10S" xmlns="urn:mpeg:dash:schema:mpd:2011"></Period>
+   * <Period id="xlink-double-period-Period2" duration="PT20S" xmlns="urn:mpeg:dash:schema:mpd:2011"></Period>
+   */
+
+
+  mpdclient = gst_mpd_client_new ();
+  downloader = gst_uri_downloader_new ();
+
+  gst_mpd_client_set_uri_downloader (mpdclient, downloader);
+
+  file_uri_single_period =
+      gst_filename_to_uri (XLINK_SINGLE_PERIOD_FILENAME, NULL);
+  file_uri_double_period =
+      gst_filename_to_uri (XLINK_DOUBLE_PERIOD_FILENAME, NULL);
+
+  /* constructs inital mpd using external xml uri */
+  xml_joined = g_strjoin ("", xml_frag_start,
+      xml_uri_front, (const char *) file_uri_single_period, xml_uri_rear,
+      xml_uri_front, (const char *) file_uri_double_period, xml_uri_rear,
+      xml_frag_end, NULL);
+
+  ret = gst_mpd_parse (mpdclient, xml_joined, (gint) strlen (xml_joined));
+  assert_equals_int (ret, TRUE);
+
+  period_list = mpdclient->mpd_node->Periods;
+  /* only count periods on initial mpd (external xml does not parsed yet) */
+  assert_equals_int (g_list_length (period_list), 3);
+
+  /* process the xml data */
+  ret = gst_mpd_client_setup_media_presentation (mpdclient, GST_CLOCK_TIME_NONE,
+      -1, NULL);
+  assert_equals_int (ret, TRUE);
+
+  period_list = mpdclient->mpd_node->Periods;
+  assert_equals_int (g_list_length (period_list), 4);
+
+  iter = period_list;
+  periodNode = (GstPeriodNode *) iter->data;
+  assert_equals_string (periodNode->id, "Period0");
+
+  iter = iter->next;
+  periodNode = (GstPeriodNode *) iter->data;
+  assert_equals_string (periodNode->id, "xlink-single-period-Period1");
+
+  iter = iter->next;
+  periodNode = (GstPeriodNode *) iter->data;
+  assert_equals_string (periodNode->id, "xlink-double-period-Period1");
+
+  iter = iter->next;
+  periodNode = (GstPeriodNode *) iter->data;
+  assert_equals_string (periodNode->id, "xlink-double-period-Period2");
+
+  gst_mpd_client_free (mpdclient);
+  g_object_unref (downloader);
+  g_free (file_uri_single_period);
+  g_free (file_uri_double_period);
+  g_free (xml_joined);
+}
+
+GST_END_TEST;
+
 /*
  * create a test suite containing all dash testcases
  */
@@ -5654,6 +5755,9 @@ dash_suite (void)
   tcase_add_test (tc_simpleMPD, dash_mpdparser_various_duration_formats);
   tcase_add_test (tc_simpleMPD, dash_mpdparser_default_presentation_delay);
 
+  /* tests checking xlink attributes */
+  tcase_add_test (tc_simpleMPD, dash_mpdparser_xlink_period);
+
   /* tests checking the MPD management
    * (eg. setting active streams, obtaining attributes values)
    */

tests/check/elements/dash_mpd_data/xlink_double_period.period

@@ -0,0 +1,2 @@
+<Period id="xlink-double-period-Period1" duration="PT10S" xmlns="urn:mpeg:dash:schema:mpd:2011"></Period>
+<Period id="xlink-double-period-Period2" duration="PT20S" xmlns="urn:mpeg:dash:schema:mpd:2011"></Period>

tests/check/elements/dash_mpd_data/xlink_single_period.period

@@ -0,0 +1 @@
+<Period id="xlink-single-period-Period1" duration="PT10S" xmlns="urn:mpeg:dash:schema:mpd:2011"></Period>