[FFmpeg-devel] [PATCH] avformat/matroskadec: retain error codes in matroska_resync() and matroska_read_packet()

[Michael Niedermayer]

On Wed, Aug 10, 2016 at 10:24:08AM -0700, Sophia Wang wrote:
> Signed-off-by: Sophia Wang <skw at google.com>
> ---
>  libavformat/matroskadec.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
> index d07a092..8c809ad 100644
> --- a/libavformat/matroskadec.c
> +++ b/libavformat/matroskadec.c
> @@ -738,13 +738,16 @@ static int matroska_read_close(AVFormatContext *s);
>  static int matroska_resync(MatroskaDemuxContext *matroska, int64_t last_pos)
>  {
>      AVIOContext *pb = matroska->ctx->pb;
> +    int64_t ret;
>      uint32_t id;
>      matroska->current_id = 0;
>      matroska->num_levels = 0;
>  
>      /* seek to next position to resync from */
> -    if (avio_seek(pb, last_pos + 1, SEEK_SET) < 0)
> -        goto eof;
> +    if ((ret = avio_seek(pb, last_pos + 1, SEEK_SET)) < 0) {
> +        matroska->done = 1;
> +        return ret;
> +    }
>  
>      id = avio_rb32(pb);
>  
> @@ -760,7 +763,6 @@ static int matroska_resync(MatroskaDemuxContext *matroska, int64_t last_pos)
>          id = (id << 8) | avio_r8(pb);
>      }
>  
> -eof:
>      matroska->done = 1;
>      return AVERROR_EOF;
>  }

> @@ -3322,13 +3324,16 @@ static int matroska_parse_cluster(MatroskaDemuxContext *matroska)
>  static int matroska_read_packet(AVFormatContext *s, AVPacket *pkt)
>  {
>      MatroskaDemuxContext *matroska = s->priv_data;
> +    int ret;
>  
>      while (matroska_deliver_packet(matroska, pkt)) {
>          int64_t pos = avio_tell(matroska->ctx->pb);
>          if (matroska->done)
>              return AVERROR_EOF;
> -        if (matroska_parse_cluster(matroska) < 0)
> -            matroska_resync(matroska, pos);
> +        if (matroska_parse_cluster(matroska) < 0) {
> +            if ((ret = matroska_resync(matroska, pos)) < 0)
> +                return ret;
> +        }
>      }

is it possible that matroska_parse_cluster() adds packets to
matroska->packets and then fails?
if so and if matroska_resync subsequently fails too
the previous code would have returned the packet in
matroska_deliver_packet() the new code would not i think unless
i miss something
(the application would likley not call matroska_read_packet() again
after it signaled EOF, and might or might not after an error even
though there would the still be buffered packets prior to the error

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No great genius has ever existed without some touch of madness. -- Aristotle
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