[FFmpeg-devel] [PATCH] [v2] libavcodec/options.c: handle hw_frames_ctx where necessary

[Mark Thompson]

On 20/05/16 11:31, Andrey Turkin wrote:
> avcodec_copy_context didn't handle hw_frames_ctx references correctly which could cause crashes.
> ---
> 
> Changes from v1: reverted changes to avcodec_free_context
> 
> 
>  libavcodec/options.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/libavcodec/options.c b/libavcodec/options.c
> index ea2563b..08c2259 100644
> --- a/libavcodec/options.c
> +++ b/libavcodec/options.c
> @@ -197,6 +197,7 @@ int avcodec_copy_context(AVCodecContext *dest, const AVCodecContext *src)
>      av_freep(&dest->inter_matrix);
>      av_freep(&dest->extradata);
>      av_freep(&dest->subtitle_header);
> +    av_buffer_unref(&dest->hw_frames_ctx);
>  
>      memcpy(dest, src, sizeof(*dest));
>      av_opt_copy(dest, src);
> @@ -225,6 +226,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
>      dest->inter_matrix    = NULL;
>      dest->rc_override     = NULL;
>      dest->subtitle_header = NULL;
> +    dest->hw_frames_ctx   = NULL;
>  
>  #define alloc_and_copy_or_fail(obj, size, pad) \
>      if (src->obj && size > 0) { \
> @@ -245,6 +247,12 @@ FF_ENABLE_DEPRECATION_WARNINGS
>      av_assert0(dest->subtitle_header_size == src->subtitle_header_size);
>  #undef alloc_and_copy_or_fail
>  
> +    if (src->hw_frames_ctx) {
> +        dest->hw_frames_ctx = av_buffer_ref(src->hw_frames_ctx);
> +        if (!dest->hw_frames_ctx)
> +            goto fail;
> +    }
> +
>      return 0;
>  
>  fail:
> @@ -255,6 +263,7 @@ fail:
>      av_freep(&dest->subtitle_header);
>      dest->subtitle_header_size = 0;
>      dest->extradata_size = 0;
> +    av_buffer_unref(&dest->hw_frames_ctx);
>      av_opt_free(dest);
>      return AVERROR(ENOMEM);
>  }
> 

Looks fine; it does fix an immediate problem.

Note that development around hwcontext is mainly happening in libav, and this sort of copy support is not really an intended use.

<https://lists.libav.org/pipermail/libav-devel/2016-May/077006.html>

Thanks,

- Mark