[FFmpeg-devel] [PATCHv2] avformat/mp3dec, rmdec: check return value of ffio_ensure_seekback

[wm4]

On Mon,  4 Jan 2016 17:50:01 -0800
Ganesh Ajjanagadde <gajjanagadde at gmail.com> wrote:

> ffio_ensure_seekback can fail due to e.g ENOMEM. This return value is
> checked here and a diagnostic is logged.
> 
> All usage of ffio_ensure_seekback in the codebase now has the return value checked.
> 
> Reviewed-by: wm4 <nfxjfg at googlemail.com>
> Reviewed-by: Ronald S. Bultje <rsbultje at gmail.com>
> Reviewed-by: Michael Niedermayer <michael at niedermayer.cc>
> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
> ---
>  libavformat/mp3dec.c | 13 +++++++++++--
>  libavformat/rmdec.c  |  3 ++-
>  2 files changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c
> index c76b21e..57ebcc8 100644
> --- a/libavformat/mp3dec.c
> +++ b/libavformat/mp3dec.c
> @@ -372,11 +372,19 @@ static int mp3_read_header(AVFormatContext *s)
>          uint32_t header, header2;
>          int frame_size;
>          if (!(i&1023))
> -            ffio_ensure_seekback(s->pb, i + 1024 + 4);
> +            if ((ret = ffio_ensure_seekback(s->pb, i + 1024 + 4)) < 0) {
> +                av_log(s, AV_LOG_WARNING,
> +                       "initial junk detection and skipping impossible due to: %s\n", av_err2str(ret));
> +                goto skip_fail;
> +            }
>          frame_size = check(s->pb, off + i, &header);
>          if (frame_size > 0) {
>              avio_seek(s->pb, off, SEEK_SET);
> -            ffio_ensure_seekback(s->pb, i + 1024 + frame_size + 4);
> +            if ((ret = ffio_ensure_seekback(s->pb, i + 1024 + frame_size + 4)) < 0) {
> +                av_log(s, AV_LOG_WARNING,
> +                       "initial junk detection and skipping impossible due to: %s\n", av_err2str(ret));
> +                goto skip_fail;
> +            }
>              if (check(s->pb, off + i + frame_size, &header2) >= 0 &&
>                  (header & SAME_HEADER_MASK) == (header2 & SAME_HEADER_MASK))
>              {
> @@ -387,6 +395,7 @@ static int mp3_read_header(AVFormatContext *s)
>          }
>          avio_seek(s->pb, off, SEEK_SET);
>      }
> +skip_fail:
>  
>      // the seek index is relative to the end of the xing vbr headers
>      for (i = 0; i < st->nb_index_entries; i++)
> diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c
> index 4e46a3d..470e227 100644
> --- a/libavformat/rmdec.c
> +++ b/libavformat/rmdec.c
> @@ -618,7 +618,8 @@ static int rm_read_header(AVFormatContext *s)
>              size = avio_rb32(pb);
>              codec_pos = avio_tell(pb);
>  
> -            ffio_ensure_seekback(pb, 4);
> +            if ((ret = ffio_ensure_seekback(pb, 4)) < 0)
> +                av_log(s, AV_LOG_WARNING, "seeking back impossible due to: %s\n", av_err2str(ret));
>              v = avio_rb32(pb);
>              if (v == MKBETAG('M', 'L', 'T', 'I')) {
>                  ret = rm_read_multi(s, s->pb, st, mime);

I maintain that this should not be done, because it makes the code
verbose for no reason. Or if you insist, do it in the ffio_ function
itself.