ffplay: dont destroy packet queues on stream change

This fixes occasional segfaults caused by lock request of the packet queue from
the reader thread.

Also don't allow to put frames into the queue when it's aborted, and don't try
to fill the queue with frames when it is aborted.

Signed-off-by: Marton Balint <cus@passwd.hu>

ffplay.c

@@ -303,13 +303,12 @@ void av_noreturn exit_program(int ret)
     exit(ret);
 }
 
-static int packet_queue_put(PacketQueue *q, AVPacket *pkt)
+static int packet_queue_put_private(PacketQueue *q, AVPacket *pkt)
 {
     AVPacketList *pkt1;
 
-    /* duplicate the packet */
-    if (pkt != &flush_pkt && av_dup_packet(pkt) < 0)
-        return -1;
+    if (q->abort_request)
+       return -1;
 
     pkt1 = av_malloc(sizeof(AVPacketList));
     if (!pkt1)
@@ -317,11 +316,7 @@ static int packet_queue_put(PacketQueue *q, AVPacket *pkt)
     pkt1->pkt = *pkt;
     pkt1->next = NULL;
 
-
-    SDL_LockMutex(q->mutex);
-
     if (!q->last_pkt)
-
         q->first_pkt = pkt1;
     else
         q->last_pkt->next = pkt1;
@@ -330,9 +325,25 @@ static int packet_queue_put(PacketQueue *q, AVPacket *pkt)
     q->size += pkt1->pkt.size + sizeof(*pkt1);
     /* XXX: should duplicate packet data in DV case */
     SDL_CondSignal(q->cond);
+    return 0;
+}
+
+static int packet_queue_put(PacketQueue *q, AVPacket *pkt)
+{
+    int ret;
 
+    /* duplicate the packet */
+    if (pkt != &flush_pkt && av_dup_packet(pkt) < 0)
+        return -1;
+
+    SDL_LockMutex(q->mutex);
+    ret = packet_queue_put_private(q, pkt);
     SDL_UnlockMutex(q->mutex);
-    return 0;
+
+    if (pkt != &flush_pkt && ret < 0)
+        av_free_packet(pkt);
+
+    return ret;
 }
 
 /* packet queue handling */
@@ -341,7 +352,7 @@ static void packet_queue_init(PacketQueue *q)
     memset(q, 0, sizeof(PacketQueue));
     q->mutex = SDL_CreateMutex();
     q->cond = SDL_CreateCond();
-    packet_queue_put(q, &flush_pkt);
+    q->abort_request = 1;
 }
 
 static void packet_queue_flush(PacketQueue *q)
@@ -361,7 +372,7 @@ static void packet_queue_flush(PacketQueue *q)
     SDL_UnlockMutex(q->mutex);
 }
 
-static void packet_queue_end(PacketQueue *q)
+static void packet_queue_destroy(PacketQueue *q)
 {
     packet_queue_flush(q);
     SDL_DestroyMutex(q->mutex);
@@ -379,6 +390,14 @@ static void packet_queue_abort(PacketQueue *q)
     SDL_UnlockMutex(q->mutex);
 }
 
+static void packet_queue_start(PacketQueue *q)
+{
+    SDL_LockMutex(q->mutex);
+    q->abort_request = 0;
+    packet_queue_put_private(q, &flush_pkt);
+    SDL_UnlockMutex(q->mutex);
+}
+
 /* return < 0 if aborted, 0 if no packet and > 0 if packet.  */
 static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block)
 {
@@ -877,6 +896,9 @@ static void stream_close(VideoState *is)
     is->abort_request = 1;
     SDL_WaitThread(is->read_tid, NULL);
     SDL_WaitThread(is->refresh_tid, NULL);
+    packet_queue_destroy(&is->videoq);
+    packet_queue_destroy(&is->audioq);
+    packet_queue_destroy(&is->subtitleq);
 
     /* free all pictures */
     for (i = 0; i < VIDEO_PICTURE_QUEUE_SIZE; i++) {
@@ -2343,20 +2365,20 @@ static int stream_component_open(VideoState *is, int stream_index)
         is->audio_diff_threshold = 2.0 * SDL_AUDIO_BUFFER_SIZE / wanted_spec.freq;
 
         memset(&is->audio_pkt, 0, sizeof(is->audio_pkt));
-        packet_queue_init(&is->audioq);
+        packet_queue_start(&is->audioq);
         SDL_PauseAudio(0);
         break;
     case AVMEDIA_TYPE_VIDEO:
         is->video_stream = stream_index;
         is->video_st = ic->streams[stream_index];
 
-        packet_queue_init(&is->videoq);
+        packet_queue_start(&is->videoq);
         is->video_tid = SDL_CreateThread(video_thread, is);
         break;
     case AVMEDIA_TYPE_SUBTITLE:
         is->subtitle_stream = stream_index;
         is->subtitle_st = ic->streams[stream_index];
-        packet_queue_init(&is->subtitleq);
+        packet_queue_start(&is->subtitleq);
 
         is->subtitle_tid = SDL_CreateThread(subtitle_thread, is);
         break;
@@ -2381,7 +2403,7 @@ static void stream_component_close(VideoState *is, int stream_index)
 
         SDL_CloseAudio();
 
-        packet_queue_end(&is->audioq);
+        packet_queue_flush(&is->audioq);
         av_free_packet(&is->audio_pkt);
         if (is->swr_ctx)
             swr_free(&is->swr_ctx);
@@ -2407,7 +2429,7 @@ static void stream_component_close(VideoState *is, int stream_index)
 
         SDL_WaitThread(is->video_tid, NULL);
 
-        packet_queue_end(&is->videoq);
+        packet_queue_flush(&is->videoq);
         break;
     case AVMEDIA_TYPE_SUBTITLE:
         packet_queue_abort(&is->subtitleq);
@@ -2422,7 +2444,7 @@ static void stream_component_close(VideoState *is, int stream_index)
 
         SDL_WaitThread(is->subtitle_tid, NULL);
 
-        packet_queue_end(&is->subtitleq);
+        packet_queue_flush(&is->subtitleq);
         break;
     default:
         break;
@@ -2625,9 +2647,9 @@ static int read_thread(void *arg)
 
         /* if the queue are full, no need to read more */
         if (   is->audioq.size + is->videoq.size + is->subtitleq.size > MAX_QUEUE_SIZE
-            || (   (is->audioq   .nb_packets > MIN_FRAMES || is->audio_stream < 0)
-                && (is->videoq   .nb_packets > MIN_FRAMES || is->video_stream < 0)
-                && (is->subtitleq.nb_packets > MIN_FRAMES || is->subtitle_stream < 0))) {
+            || (   (is->audioq   .nb_packets > MIN_FRAMES || is->audio_stream < 0 || is->audioq.abort_request)
+                && (is->videoq   .nb_packets > MIN_FRAMES || is->video_stream < 0 || is->videoq.abort_request)
+                && (is->subtitleq.nb_packets > MIN_FRAMES || is->subtitle_stream < 0 || is->subtitleq.abort_request))) {
             /* wait 10 ms */
             SDL_Delay(10);
             continue;
@@ -2732,6 +2754,10 @@ static VideoState *stream_open(const char *filename, AVInputFormat *iformat)
     is->subpq_mutex = SDL_CreateMutex();
     is->subpq_cond  = SDL_CreateCond();
 
+    packet_queue_init(&is->videoq);
+    packet_queue_init(&is->audioq);
+    packet_queue_init(&is->subtitleq);
+
     is->av_sync_type = av_sync_type;
     is->read_tid     = SDL_CreateThread(read_thread, is);
     if (!is->read_tid) {