On Tue, Oct 27, 2015 at 08:18:34PM -0400, Ganesh Ajjanagadde wrote: > av_gcd is now always defined regardless of input. This documents this > change in the "documented API". Two benefits (closely related): > 1. The function is robust, and there is no need to worry about INT64_MIN, etc. > > 2. Clients of av_gcd, like av_reduce, can now be made fully correct. > Currently, > av_reduce can trigger undefined behavior if e.g num is INT64_MIN due to > integer overflow in the FFABS. Furthermore, this undefined behavior is > completely undocumented, and could be a fuzzer's paradise. The FFABS was > needed in the past as > av_gcd was undefined for negative inputs. In order to make av_reduce > robust, it is essential to guarantee that av_gcd works for all int64_t. > > Signed-off-by: Ganesh Ajjanagadde <gajjanaga...@gmail.com> > --- > libavutil/mathematics.h | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/libavutil/mathematics.h b/libavutil/mathematics.h > index ac94488..6fc2577 100644 > --- a/libavutil/mathematics.h > +++ b/libavutil/mathematics.h > @@ -77,9 +77,9 @@ enum AVRounding { > }; > > /** > - * Return the greatest common divisor of a and b. > - * If both a and b are 0 or either or both are <0 then behavior is > - * undefined. > + * Compute the greatest common divisor of a and b. > + * > + * @return gcd of a and b up to sign; if a and b are both zero returns 0 > */ > int64_t av_const av_gcd(int64_t a, int64_t b);
LGTM thanks [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Why not whip the teacher when the pupil misbehaves? -- Diogenes of Sinope
signature.asc
Description: Digital signature
_______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel