[FFmpeg-devel] [PATCH 1/2] avformat/wtvdec: Forward errors when reading packet

[Peter Ross]

On Tue, Feb 18, 2020 at 12:36:00PM +0000, Andreas Rheinhardt wrote:
> Andreas Rheinhardt:
> > wtvfile_read_packet did not abide by the requirements of an
> > AVIOContext's read_packet-function: If it did not read anything,
> > it returned zero, which currently leads to a warning in read_packet_wrapper
> > in aviobuf.c. Said warning will be an av_assert2 as soon as
> > FF_API_OLD_AVIO_EOF_0 is zero (probably the next major version bump).
> > So instead forward the error code from the underlying protocol.
> > 
> > This error/assert is triggered in the wtv-demux FATE test.
> > 
> > Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> > ---
> > This patch supersedes [1]. The difference to the previous version is
> > that I have changed the return value from "nread ? nread : n ? :
> > AVERROR_EOF" to "nread ? nread : n". This can only make a difference if
> > buf_size (the size of the data to be read) is zero and I now think that
> > this should simply not happen: It would be possible by calling
> > avio_read_partial with a desired size of 0 and if the AVIOContext's
> > write_flag is set, but avio_read_partial is not called with one of
> > wtvdec's custom AVIOContexts (not to mention that if this were a
> > problem, it should probably be fixed in avio_read_partial).
> > 
> > [1]: https://patchwork.ffmpeg.org/project/ffmpeg/patch/20190821090438.10260-4-andreas.rheinhardt@gmail.com/
> > 
> >  libavformat/wtvdec.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> > 
> > diff --git a/libavformat/wtvdec.c b/libavformat/wtvdec.c
> > index 67d934f074..83f510b92f 100644
> > --- a/libavformat/wtvdec.c
> > +++ b/libavformat/wtvdec.c
> > @@ -71,7 +71,7 @@ static int wtvfile_read_packet(void *opaque, uint8_t *buf, int buf_size)
> >  {
> >      WtvFile *wf = opaque;
> >      AVIOContext *pb = wf->pb_filesystem;
> > -    int nread = 0;
> > +    int nread = 0, n = 0;
> >  
> >      if (wf->error || pb->error)
> >          return -1;
> > @@ -80,7 +80,6 @@ static int wtvfile_read_packet(void *opaque, uint8_t *buf, int buf_size)
> >  
> >      buf_size = FFMIN(buf_size, wf->length - wf->position);
> >      while(nread < buf_size) {
> > -        int n;
> >          int remaining_in_sector = (1 << wf->sector_bits) - (wf->position & ((1 << wf->sector_bits) - 1));
> >          int read_request        = FFMIN(buf_size - nread, remaining_in_sector);
> >  
> > @@ -100,7 +99,7 @@ static int wtvfile_read_packet(void *opaque, uint8_t *buf, int buf_size)
> >              }
> >          }
> >      }
> > -    return nread;
> > +    return nread ? nread : n;
> >  }
> >  
> >  /**
> > 
> 
> Ping.

looks good. please apply.

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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