[FFmpeg-devel] [PATCH] Check for the isatty function

[Martin Storsjö]

On Wed, 22 Jul 2009, M?ns Rullg?rd wrote:

> Martin Storsj? <martin at martin.st> writes:
> 
> > On Tue, 14 Jul 2009, Ramiro Polla wrote:
> >
> >> 2009/7/14 M?ns Rullg?rd <mans at mansr.com>:
> >> > Martin Storsj? <martin at martin.st> writes:
> >> >
> >> >> diff --git a/ffmpeg.c b/ffmpeg.c
> >> >> index ca083de..15b1dcd 100644
> >> >> --- a/ffmpeg.c
> >> >> +++ b/ffmpeg.c
> >> >> @@ -3978,8 +3978,10 @@ int main(int argc, char **argv)
> >> >> ? ? ?avdevice_register_all();
> >> >> ? ? ?av_register_all();
> >> >>
> >> >> +#if HAVE_ISATTY
> >> >> ? ? ?if(isatty(STDIN_FILENO))
> >> >> ? ? ? ? ?url_set_interrupt_cb(decode_interrupt_cb);
> >> >> +#endif
> >> >>
> >> >> ? ? ?for(i=0; i<CODEC_TYPE_NB; i++){
> >> >> ? ? ? ? ?avcodec_opts[i]= avcodec_alloc_context2(i);
> >> >
> >> > Fine by me.
> >> >
> >> > That said, why do we do this only if stdin is a terminal?
> >> 
> >> I don't know, Michael added that. If we set it unconditionally, won't
> >> this interfere with pipe inputs?
> >
> > Yes, it would probably interfere with pipes.
> >
> > Another solution would be:
> >
> > #ifdef HAVE_ISATTY
> >     if (isatty(STDIN_FILENO))
> > #endif
> >         url_set_interrupt_cb(decode_interrupt_cb);
> >
> > That is, if isatty isn't available, one can perhaps assume that stdin 
> > isn't a pipe.
> >
> > OTOH, the initial version is safer in this aspect. If I understood issue66 
> > correctly, this is only needed to be able to abort by pressing 'q' while 
> > opening the file, so skipping if it if unsure (as in the initial patch) 
> > should be quite safe.
> 
> I didn't mean to imply that the patch was wrong.  I just wasn't sure
> why the original code was that way in the first place.

Yeah, I dug around to look up things, both to clarify it to myself and to 
others, and to prod this thread back to life again...

// Martin