Re: [FFmpeg-devel] [PATCH 2/3] avfilter/signature_lookup: Initialize bestmatch

[Michael Niedermayer <michael@niedermayer.cc>]

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On Mon, Apr 22, 2024 at 01:10:47AM +0200, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > Fixes: CID1500345 Uninitialized scalar variable
> > 
> > Sponsored-by: Sovereign Tech Fund
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavfilter/signature_lookup.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> > 
> > diff --git a/libavfilter/signature_lookup.c b/libavfilter/signature_lookup.c
> > index a3086b38cca..dc0a2ef2b24 100644
> > --- a/libavfilter/signature_lookup.c
> > +++ b/libavfilter/signature_lookup.c
> > @@ -535,16 +535,14 @@ static MatchingInfo lookup_signatures(AVFilterContext *ctx, SignatureContext *sc
> >  {
> >      CoarseSignature *cs, *cs2;
> >      MatchingInfo *infos;
> > -    MatchingInfo bestmatch;
> > +    MatchingInfo bestmatch = {0};
> >      MatchingInfo *i;
> >  
> >      cs = first->coarsesiglist;
> >      cs2 = second->coarsesiglist;
> >  
> >      /* score of bestmatch is 0, if no match is found */
> > -    bestmatch.score = 0;
> >      bestmatch.meandist = 99999;
> > -    bestmatch.whole = 0;
> >  
> >      fill_l1distlut(sc->l1distlut);
> >  
> 
> Does this fix an actual bug or just suppress a Coverity warning?

returning partially initialized structs is IMHO bad practice
it is strictly not a bug i guess.
But its similar to not initializing pointers to NULL and then
having to track if all paths initialize them before freeing.

This is similar. With passing partially initialized structs around,
one would have to ensure that nothing is touched that isnt initialized.
Ive marked the issue as false positive now as that is in fact more
correct.

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Complexity theory is the science of finding the exact solution to an
approximation. Benchmarking OTOH is finding an approximation of the exact

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