ffplay: more robust mutex, condition variable handling

SDL_CreateMutex and SDL_CreateCond can fail:
https://wiki.libsdl.org/SDL_CreateMutex.
This patch makes handling more robust in one instance.

Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Marton Balint <cus@passwd.hu>

ffplay.c

@@ -451,12 +451,21 @@ static int packet_queue_put_nullpacket(PacketQueue *q, int stream_index)
 }
 
 /* packet queue handling */
-static void packet_queue_init(PacketQueue *q)
+static int packet_queue_init(PacketQueue *q)
 {
     memset(q, 0, sizeof(PacketQueue));
     q->mutex = SDL_CreateMutex();
+    if (!q->mutex) {
+        av_log(q, AV_LOG_FATAL, "SDL_CreateMutex(): %s\n", SDL_GetError());
+        return AVERROR(ENOMEM);
+    }
     q->cond = SDL_CreateCond();
+    if (!q->cond) {
+        av_log(q, AV_LOG_FATAL, "SDL_CreateCond(): %s\n", SDL_GetError());
+        return AVERROR(ENOMEM);
+    }
     q->abort_request = 1;
+    return 0;
 }
 
 static void packet_queue_flush(PacketQueue *q)
@@ -3136,9 +3145,10 @@ static VideoState *stream_open(const char *filename, AVInputFormat *iformat)
     if (frame_queue_init(&is->sampq, &is->audioq, SAMPLE_QUEUE_SIZE, 1) < 0)
         goto fail;
 
-    packet_queue_init(&is->videoq);
+    if (packet_queue_init(&is->videoq) < 0 ||
-    packet_queue_init(&is->audioq);
+        packet_queue_init(&is->audioq) < 0 ||
-    packet_queue_init(&is->subtitleq);
+        packet_queue_init(&is->subtitleq) < 0)
+        goto fail;
 
     is->continue_read_thread = SDL_CreateCond();