[FFmpeg-devel] [PATCH] lavf/utils: add error check in av_read_frame()

[Michael Niedermayer]

On Mon, Sep 24, 2012 at 12:43:36AM +0200, Stefano Sabatini wrote:
> In particular, fix crash when the input file contains no packets (e.g. an
> ffmeta input).
> ---
>  libavformat/utils.c |   17 ++++++++++++-----
>  1 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/libavformat/utils.c b/libavformat/utils.c
> index 6603483..4f3529a 100644
> --- a/libavformat/utils.c
> +++ b/libavformat/utils.c
> @@ -1409,11 +1409,18 @@ int av_read_frame(AVFormatContext *s, AVPacket *pkt)
>      AVStream *st;
>  
>      if (!genpts) {
> -        ret = s->packet_buffer ? read_from_packet_buffer(&s->packet_buffer,
> -                                                          &s->packet_buffer_end,
> -                                                          pkt) :
> -                                  read_frame_internal(s, pkt);
> -        goto return_packet;
> +        while (1) {
> +            ret = s->packet_buffer ?
> +                read_from_packet_buffer(&s->packet_buffer, &s->packet_buffer_end, pkt) :
> +                read_frame_internal(s, pkt);
> +            if (ret < 0) {
> +                if (ret == AVERROR(EAGAIN))
> +                    continue;
> +                else
> +                    return ret;
> +            }
> +            goto return_packet;
> +        }
>      }

this looks very wrong
and likely totally breaks non blocking reads as it busy loops


[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

When the tyrant has disposed of foreign enemies by conquest or treaty, and
there is nothing more to fear from them, then he is always stirring up
some war or other, in order that the people may require a leader. -- Plato
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