On Mon, May 16, 2022 at 01:05:28PM +0200, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > Maybe helps coverity
> > Helps: CID1433771
> >
> > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
> > ---
> > libavcodec/mpeg4videodec.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
> > index e2bde73639..715cb606c9 100644
> > --- a/libavcodec/mpeg4videodec.c
> > +++ b/libavcodec/mpeg4videodec.c
> > @@ -1981,7 +1981,8 @@ static int mpeg4_decode_studio_block(MpegEncContext
> > *s, int32_t block[64], int n
> > return AVERROR_INVALIDDATA;
> > j = scantable[idx++];
> > block[j] = get_xbits(&s->gb, additional_code_len);
> > - } else if (group == 21) {
> > + } else {
> > + av_assert2(group == 21);
> > /* Escape */
> > if (idx > 63)
> > return AVERROR_INVALIDDATA;
>
> This also reminds me of an old attempt of mine to add an AV_UNREACHABLE
> macro for such scenarios:
> https://github.com/mkver/FFmpeg/commits/unreachable. There are two
> reasons why I never sent it to the ML:> a) It uses ASSERT_LEVEL (i.e. with a high ASSERT_LEVEL it degenarates > into an actual assert). But this is only defined internally, so useless > to an API user. Therefore I wonder whether this should be in a public > header (the same issue exists for av_assert1 and av_assert2). for av_assertX to be usefull to a user app, the developer of that app needs to be able to set ASSERT_LEVEL. It would be less useful if it was fixed to the value ffmpeg used in its built The developer should be able to set ASSERT_LEVEL before the include or with -D but some other way could be added too > b) Both Clang and MSVC have something more, namely a > __builtin_assume(cond) resp. __assume(cond). I was unsure whether this > should not be added, too. It could be translated to "if (!(cond)) > __builtin_unreachable()" to GCC, but would be more natural in general. > (Of course, cond must not have any side effects.) [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Nations do behave wisely once they have exhausted all other alternatives. -- Abba Eban
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