[FFmpeg-devel] [PATCH] lavfi: avfilter_merge_formats: handle case where inputs are same.

[Mina Nagy Zaki]

On Thursday 09 June 2011 12:37:18 Stefano Sabatini wrote:
> On date Thursday 2011-06-09 11:10:09 +0300, Mina Nagy Zaki encoded:
> > ---
> > 
> >  libavfilter/formats.c |    2 ++
> >  1 files changed, 2 insertions(+), 0 deletions(-)
> > 
> > diff --git a/libavfilter/formats.c b/libavfilter/formats.c
> > index ec7fca3..58593fc 100644
> > --- a/libavfilter/formats.c
> > +++ b/libavfilter/formats.c
> > @@ -44,6 +44,8 @@ AVFilterFormats *avfilter_merge_formats(AVFilterFormats
> > *a, AVFilterFormats *b)
> > 
> >      AVFilterFormats *ret;
> >      unsigned i, j, k = 0;
> > 
> > +    if (a == b) return a;
> > +
> > 
> >      ret = av_mallocz(sizeof(AVFilterFormats));
> >      
> >      /* merge list of formats */
> 
> Looks OK (I'd just add a note in the commit message that this is not
> changing behavior, but just optimizing the case where the two merged
> lists are the same one). I'll apply soon if I see no comments.

To be more clear, this actually fixes a double-free crash if lists are the same 
due to the two merge_ref() calls at the end of the (useless) merging that 
happens.

-- 
Mina