[FFmpeg-devel] & vs. &&

[Reimar Döffinger]

On Tue, Oct 13, 2009 at 08:33:36AM +0200, Benoit Fouet wrote:
> On 2009-10-12 18:52, Reimar D?ffinger wrote:
> > On Mon, Oct 12, 2009 at 06:41:20PM +0200, Benoit Fouet wrote:
> >>> So, I have a patch now:
> >>> Index: libavformat/aviobuf.c
> >>> ===================================================================
> >>> --- libavformat/aviobuf.c       (revision 20209)
> >>> +++ libavformat/aviobuf.c       (working copy)
> >>> @@ -590,7 +590,7 @@ int url_setbufsize(ByteIOContext *s, int
> >>>  int url_resetbuf(ByteIOContext *s, int flags)
> >>>  {
> >>>      URLContext *h = s->opaque;
> >>> -    if ((flags & URL_RDWR) || (h && h->flags != flags && !h->flags &
> >>> URL_RDWR))
> >>> +    if ((flags & URL_RDWR) || (h && h->flags != flags && !(h->flags &
> >>> URL_RDWR)))
> >>>          return AVERROR(EINVAL);
> >>>
> >>>      if (flags & URL_WRONLY) {
> >>>
> >>>
> >>> This is crashing the following command line on my machine (triggered by
> >>> make test), can anybody reproduce ?
> >>>
> >>> $ gdb --args ./ffmpeg_g -v 0 -y -flags +bitexact -dct fastint -idct
> >>> simple -sws_flags +accurate_rnd+bitexact -t 1 -qscale 10 -f image2
> >>> -vcodec pgmyuv -i ./tests/vsynth1/%02d.pgm -f s16le -i
> >>> ././tests/data/asynth1.sw -acodec mp2
> >>> ././tests/data/b-lavf.nut                                                                                                                                                        
> >>>
> >> The problem seems to be in the handling of buf_end.
> >> When entering put_buffer() from libavformat/nutenc.c:389, the
> >> ByteIOContext is as follows:
> >> {buffer = 0xa465324 "\003",
> >>  buffer_size = 1024,
> >>  buf_ptr = 0xa465324 "\003",
> >>  buf_end = 0x0,
> > 
> > That is almost certainly due to url_resetbuf failing (and I don't think
> > there is any use of it that actually checks for failure).
> > You could try if using
> > if ((flags & URL_RDWR) || (h && (h->flags & (URL_RDONLY | URL_WRONLY | URL_RDWR)) != flags && !(h->flags & URL_RDWR)))
> > helps any...
> 
> it doesn't. url_resetbuf is not even called before the crash (maybe it's
>  a problem)

Hm? How can a change to url_resetbuf make a difference if url_resetbuf
was never called? I think there's something wrong with how you tested...