[FFmpeg-devel] Fix coredump when writing trailer to file with no streams added

[Michael Niedermayer]

On Thu, Jun 19, 2008 at 01:40:06PM -0400, Art Clarke wrote:
> Hi there,
> 
> Ffmpeg core-dumps if you do an av_write_header() and then an
> av_write_trailer() without first adding at least one stream to the output
> file.
> 
> While in theory users should NEVER output a file with no streams in it,
> core-dumping seems like the wrong thing to do.  The fix just checks to make
> sure there is at least one stream before we start returning cached packets
> to write.
> 
> Also attached is a test case file that generates the crash before the fix,
> and shows that everything runs smoothly after the fix.
> 
> Please let me know if this passes the bar for a fix, is rejected, or if in
> between, what I need to do to fix it up right.
> 
> Thanks,
> 
> - Art

> Index: libavformat/utils.c
> ===================================================================
> --- libavformat/utils.c	(revision 13819)
> +++ libavformat/utils.c	(working copy)
> @@ -2551,7 +2551,7 @@
>          pktl= pktl->next;
>      }
>  
> -    if(s->nb_streams == stream_count || (flush && stream_count)){
> +    if(stream_count && s->nb_streams == stream_count || (flush && stream_count)){

this check can be simplified

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I hate to see young programmers poisoned by the kind of thinking
Ulrich Drepper puts forward since it is simply too narrow -- Roman Shaposhnik
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