Re: Zero-length allocation with posix_memalign()

> Fabian Keil wrote:
> > Rémi Denis-Courmont, one of the vlc developers, pointed out
> > that passing a zero size to posix_memalign() should actually
> > work, though:
> >
> > | In principle, while useless, there is no reason why allocating an empty
> > | picture should not be possible. posix_memalign() does support zero-length
> > | allocation anyway:
> > | http://www.opengroup.org/onlinepubs/9699919799/functions/posix_memalign.html
> > | | If the size of the space requested is 0, the behavior is
> > | | implementation-defined; the value returned in memptr shall be either a
> > | | null pointer or a unique pointer.
>
> Standards: So many to choose from.  This behavior for posix_memalign was
> only defined as of the 2008 standard (see the Issue 7 notes for
> posix_memalign):
>
> https://www.opengroup.org/austin/interps/uploads/40/14543/AI-152.txt
>
> Such requirements are unfortunate, because they induce a performance
> penalty for every call, just so that programs can avoid proper handling
> of edge cases in the rare situations for which such edge cases are a
> real possibility.
>
> I will add the pessimization to posix_memalign once the 8.0 freeze is
> over.  It will be quite some time before this behavior becomes
> ubiquitous, so in the meanwhile it's probably a good idea to modify vlc
> to avoid such allocation requests.