[FFmpeg-devel] [PATCH 1/2] avformat/aviobuf: fix avio_flush() for read streams

[wm4]

On Tue, 30 Sep 2014 01:02:45 +0200
Michael Niedermayer <michaelni at gmx.at> wrote:

> On Mon, Sep 29, 2014 at 07:41:27PM +0200, wm4 wrote:
> > avio_flush() did nothing useful for read streams. Fix it to behave as
> > expected, and discard the currently read buffer properly.
> > ---
> > Since avio_flush() was just broken for read streams, I don't think this
> > needs to be treated as an API-change.
> > ---
> >  libavformat/avio.h    | 8 ++++++--
> >  libavformat/aviobuf.c | 2 ++
> >  2 files changed, 8 insertions(+), 2 deletions(-)
> > 
> > diff --git a/libavformat/avio.h b/libavformat/avio.h
> > index 2210c01..86f754e 100644
> > --- a/libavformat/avio.h
> > +++ b/libavformat/avio.h
> > @@ -289,10 +289,14 @@ int url_feof(AVIOContext *s);
> >  int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
> >  
> >  /**
> > - * Force flushing of buffered data to the output s.
> > + * Force flushing of buffered data.
> >   *
> > - * Force the buffered data to be immediately written to the output,
> > + * For write streams, force the buffered data to be immediately written to the output,
> >   * without to wait to fill the internal buffer.
> > + *
> > + * For read streams, discard all currently buffered data, and advance the
> > + * reported file position to that of the underlying stream. This does not
> > + * read new data, and does not perform any seeks.
> >   */
> >  void avio_flush(AVIOContext *s);
> >  
> > diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
> > index 9795ba4..b8586bd 100644
> > --- a/libavformat/aviobuf.c
> > +++ b/libavformat/aviobuf.c
> > @@ -148,6 +148,8 @@ static void flush_buffer(AVIOContext *s)
> >          }
> >      }
> 
> this is calling writeout(), for a read flush

avio_close() called avio_flush() already. So I was assuming that it had
no bad consequences. On a closer look, this makes no sense though, and
writeout should only ever be called if write_flag is set.