gst/matroska/matroska-mux.c: Add locking to the global array of used track UIDs to prevent random crashes if more tha...

Original commit message from CVS:
* gst/matroska/matroska-mux.c: (gst_matroska_mux_create_uid),
(gst_matroska_mux_reset), (gst_matroska_mux_start):
Add locking to the global array of used track UIDs to prevent random
crashes if more than a single matrosmux instance is used.
Use 64 bit values for the track UIDs.
Use the global GRandom of GLib instead of creating our own one
for the few random numbers we need every single time.

1 files changed, 15 insertions, 27 deletions

diff --git a/gst/matroska/matroska-mux.c b/gst/matroska/matroska-mux.c
index 1582b671..39a95b2d 100644
--- a/gst/matroska/matroska-mux.c
+++ b/gst/matroska/matroska-mux.c
@@ -1,6 +1,7 @@
 /* GStreamer Matroska muxer/demuxer
  * (c) 2003 Ronald Bultje <rbultje@ronald.bitfreak.net>
  * (c) 2005 Michal Benes <michal.benes@xeris.cz>
+ * (c) 2008 Sebastian Dröge <sebastian.droege@collabora.co.uk>
  *
  * matroska-mux.c: matroska file/stream muxer
  *
@@ -140,6 +141,7 @@ GST_STATIC_PAD_TEMPLATE ("subtitle_%d",
     GST_STATIC_CAPS_ANY);
 
 static GArray *used_uids;
+G_LOCK_DEFINE_STATIC (used_uids);
 
 static void gst_matroska_mux_add_interfaces (GType type);
 
@@ -174,7 +176,7 @@ static void gst_matroska_mux_get_property (GObject * object,
 static void gst_matroska_mux_reset (GstElement * element);
 
 /* uid generation */
-static guint32 gst_matroska_mux_create_uid ();
+static guint64 gst_matroska_mux_create_uid ();
 
 static gboolean theora_streamheader_to_codecdata (const GValue * streamheader,
     GstMatroskaTrackContext * context);
@@ -301,27 +303,30 @@ gst_matroska_mux_finalize (GObject * object)
  *
  * Returns: New track UID.
  */
-static guint32
+static guint64
 gst_matroska_mux_create_uid (void)
 {
-  guint32 uid = 0;
+  guint64 uid = 0;
 
-  GRand *rand = g_rand_new ();
+  G_LOCK (used_uids);
+
+  if (!used_uids)
+    used_uids = g_array_sized_new (FALSE, FALSE, sizeof (guint64), 10);
 
-  /* FIXME: array needs locking or moved into instance structure */
   while (!uid) {
     guint i;
 
-    uid = g_rand_int (rand);
+    uid = (((guint64) g_random_int ()) << 32) | g_random_int ();
     for (i = 0; i < used_uids->len; i++) {
-      if (g_array_index (used_uids, guint32, i) == uid) {
+      if (g_array_index (used_uids, guint64, i) == uid) {
         uid = 0;
         break;
       }
     }
     g_array_append_val (used_uids, uid);
   }
-  g_free (rand);
+
+  G_UNLOCK (used_uids);
   return uid;
 }
 
@@ -407,13 +412,6 @@ gst_matroska_mux_reset (GstElement * element)
   mux->time_scale = GST_MSECOND;
   mux->duration = 0;
 
-  /* reset uid array */
-  if (used_uids) {
-    g_array_free (used_uids, TRUE);
-  }
-  /* arbitrary size, 10 should be enough in most cases */
-  used_uids = g_array_sized_new (FALSE, FALSE, sizeof (guint32), 10);
-
   /* reset cluster */
   mux->cluster = 0;
   mux->cluster_time = 0;
@@ -1376,7 +1374,6 @@ static void
 gst_matroska_mux_start (GstMatroskaMux * mux)
 {
   GstEbmlWrite *ebml = mux->ebml_write;
-
   guint32 seekhead_id[] = { GST_MATROSKA_ID_SEGMENTINFO,
     GST_MATROSKA_ID_TRACKS,
     GST_MATROSKA_ID_CUES,
@@ -1384,18 +1381,11 @@ gst_matroska_mux_start (GstMatroskaMux * mux)
     0
   };
   guint64 master, child;
-
   GSList *collected;
-
   int i;
-
   guint tracknum = 1;
-
   GstClockTime duration = 0;
-
-  guint32 *segment_uid = (guint32 *) g_malloc (16);
-
-  GRand *rand = g_rand_new ();
+  guint32 segment_uid[4];
   GTimeVal time = { 0, 0 };
 
   /* we start with a EBML header */
@@ -1424,12 +1414,10 @@ gst_matroska_mux_start (GstMatroskaMux * mux)
   mux->info_pos = ebml->pos;
   master = gst_ebml_write_master_start (ebml, GST_MATROSKA_ID_SEGMENTINFO);
   for (i = 0; i < 4; i++) {
-    segment_uid[i] = g_rand_int (rand);
+    segment_uid[i] = g_random_int ();
   }
-  g_free (rand);
   gst_ebml_write_binary (ebml, GST_MATROSKA_ID_SEGMENTUID,
       (guint8 *) segment_uid, 16);
-  g_free (segment_uid);
   gst_ebml_write_uint (ebml, GST_MATROSKA_ID_TIMECODESCALE, mux->time_scale);
   mux->duration_pos = ebml->pos;
   /* get duration */