avcodec/omx: Check initializing mutexes/conditions

The earlier code did not properly check these initializations:
It only recorded whether the part of init where these initializations
are has been reached, but it did not check whether the initializations
were successful, although destroying them would be undefined behaviour
if they had not been initialized successfully.
Furthermore cleanup() always locked a mutex regardless of whether there
was any attempt to initialize these mutexes at all.

Reviewed-by: Martin Storsjö <martin@martin.st>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/omx.c

@@ -43,6 +43,7 @@
 #include "avcodec.h"
 #include "h264.h"
 #include "internal.h"
+#include "pthread_internal.h"
 
 #ifdef OMX_SKIP64BIT
 static OMX_TICKS to_omx_ticks(int64_t value)
@@ -218,7 +219,7 @@ typedef struct OMXCodecContext {
     OMX_STATETYPE state;
     OMX_ERRORTYPE error;
 
-    int mutex_cond_inited;
+    unsigned mutex_cond_inited_cnt;
 
     int eos_sent, got_eos;
 
@@ -229,6 +230,12 @@ typedef struct OMXCodecContext {
     int profile;
 } OMXCodecContext;
 
+#define NB_MUTEX_CONDS 6
+#define OFF(field) offsetof(OMXCodecContext, field)
+DEFINE_OFFSET_ARRAY(OMXCodecContext, omx_codec_context, mutex_cond_inited_cnt,
+                    (OFF(input_mutex), OFF(output_mutex), OFF(state_mutex)),
+                    (OFF(input_cond),  OFF(output_cond),  OFF(state_cond)));
+
 static void append_buffer(pthread_mutex_t *mutex, pthread_cond_t *cond,
                           int* array_size, OMX_BUFFERHEADERTYPE **array,
                           OMX_BUFFERHEADERTYPE *buffer)
@@ -591,6 +598,9 @@ static av_cold void cleanup(OMXCodecContext *s)
 {
     int i, executing;
 
+    /* If the mutexes/condition variables have not been properly initialized,
+     * nothing has been initialized and locking the mutex might be unsafe. */
+    if (s->mutex_cond_inited_cnt == NB_MUTEX_CONDS) {
     pthread_mutex_lock(&s->state_mutex);
     executing = s->state == OMX_StateExecuting;
     pthread_mutex_unlock(&s->state_mutex);
@@ -620,20 +630,13 @@ static av_cold void cleanup(OMXCodecContext *s)
 
     omx_deinit(s->omx_context);
     s->omx_context = NULL;
-    if (s->mutex_cond_inited) {
-        pthread_cond_destroy(&s->state_cond);
-        pthread_mutex_destroy(&s->state_mutex);
-        pthread_cond_destroy(&s->input_cond);
-        pthread_mutex_destroy(&s->input_mutex);
-        pthread_cond_destroy(&s->output_cond);
-        pthread_mutex_destroy(&s->output_mutex);
-        s->mutex_cond_inited = 0;
-    }
     av_freep(&s->in_buffer_headers);
     av_freep(&s->out_buffer_headers);
     av_freep(&s->free_in_buffers);
     av_freep(&s->done_out_buffers);
     av_freep(&s->output_buf);
+    }
+    ff_pthread_free(s, omx_codec_context_offsets);
 }
 
 static av_cold int omx_encode_init(AVCodecContext *avctx)
@@ -644,17 +647,14 @@ static av_cold int omx_encode_init(AVCodecContext *avctx)
     OMX_BUFFERHEADERTYPE *buffer;
     OMX_ERRORTYPE err;
 
+    /* cleanup relies on the mutexes/conditions being initialized first. */
+    ret = ff_pthread_init(s, omx_codec_context_offsets);
+    if (ret < 0)
+        return ret;
     s->omx_context = omx_init(avctx, s->libname, s->libprefix);
     if (!s->omx_context)
         return AVERROR_ENCODER_NOT_FOUND;
 
-    pthread_mutex_init(&s->state_mutex, NULL);
-    pthread_cond_init(&s->state_cond, NULL);
-    pthread_mutex_init(&s->input_mutex, NULL);
-    pthread_cond_init(&s->input_cond, NULL);
-    pthread_mutex_init(&s->output_mutex, NULL);
-    pthread_cond_init(&s->output_cond, NULL);
-    s->mutex_cond_inited = 1;
     s->avctx = avctx;
     s->state = OMX_StateLoaded;
     s->error = OMX_ErrorNone;