avcodec/mss4: Fix memleaks upon allocation error

During init the mts2 decoder allocates several VLCs and then several
buffers in a loop; if one of the latter allocations fails, only the VLCs
are freed, not any buffers that might already have been successfully
allocated. This commit fixes this by setting the
FF_CODEC_CAP_INIT_CLEANUP flag.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavcodec/mss4.c

@@ -648,7 +648,6 @@ static av_cold int mss4_decode_init(AVCodecContext *avctx)
 
     if (mss4_init_vlcs(c)) {
         av_log(avctx, AV_LOG_ERROR, "Cannot initialise VLCs\n");
-        mss4_free_vlcs(c);
         return AVERROR(ENOMEM);
     }
     for (i = 0; i < 3; i++) {
@@ -656,16 +655,13 @@ static av_cold int mss4_decode_init(AVCodecContext *avctx)
         c->prev_dc[i]   = av_malloc_array(c->dc_stride[i], sizeof(**c->prev_dc));
         if (!c->prev_dc[i]) {
             av_log(avctx, AV_LOG_ERROR, "Cannot allocate buffer\n");
-            mss4_free_vlcs(c);
             return AVERROR(ENOMEM);
         }
     }
 
     c->pic = av_frame_alloc();
-    if (!c->pic) {
-        mss4_decode_end(avctx);
+    if (!c->pic)
         return AVERROR(ENOMEM);
-    }
 
     avctx->pix_fmt     = AV_PIX_FMT_YUV444P;
 
@@ -682,4 +678,5 @@ AVCodec ff_mts2_decoder = {
     .close          = mss4_decode_end,
     .decode         = mss4_decode_frame,
     .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
 };