lavc: Check codec_whitelist early in avcodec_open2()

This ensures that if a codec isn't on codec_whitelist, trying to open it
will not trigger ff_codec_close(), which could invalidate useful
information still present in the context.

Signed-off-by: Dale Curtis <dalecurtis@chromium.org>
Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavcodec/avcodec.c

@@ -174,6 +174,14 @@ int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *code
     if (avctx->extradata_size < 0 || avctx->extradata_size >= FF_MAX_EXTRADATA_SIZE)
         return AVERROR(EINVAL);
 
+    if ((ret = av_opt_set_dict(avctx, options)) < 0)
+        return ret;
+
+    if (avctx->codec_whitelist && av_match_list(codec->name, avctx->codec_whitelist, ',') <= 0) {
+        av_log(avctx, AV_LOG_ERROR, "Codec (%s) not on whitelist \'%s\'\n", codec->name, avctx->codec_whitelist);
+        return AVERROR(EINVAL);
+    }
+
     avci = av_codec_is_decoder(codec) ?
         ff_decode_internal_alloc()    :
         ff_encode_internal_alloc();
@@ -207,14 +215,6 @@ int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *code
     } else {
         avctx->priv_data = NULL;
     }
-    if ((ret = av_opt_set_dict(avctx, options)) < 0)
-        goto free_and_end;
-
-    if (avctx->codec_whitelist && av_match_list(codec->name, avctx->codec_whitelist, ',') <= 0) {
-        av_log(avctx, AV_LOG_ERROR, "Codec (%s) not on whitelist \'%s\'\n", codec->name, avctx->codec_whitelist);
-        ret = AVERROR(EINVAL);
-        goto free_and_end;
-    }
 
     // only call ff_set_dimensions() for non H.264/VP6F/DXV codecs so as not to overwrite previously setup dimensions
     if (!(avctx->coded_width && avctx->coded_height && avctx->width && avctx->height &&