Re: [PATCH 4/9] util/oslib-win32: Return NULL on qemu_try_memalign() with zero size

[Richard Henderson]

On 3/3/22 06:55, Peter Maydell wrote:
> > Alternately, force size == 1, so that we always get a non-NULL value that can 
> > be freed.
> > That's a change on the POSIX side as well, of course.
>
> Yes, I had a look at what actual malloc() implementations tend
> to do, and the answer seems to be that forcing size to 1 gives
> less weird behaviour for the application. So here that would be
>
>     if (size == 0) {
>         size++;
>     }
>     ptr = _aligned_malloc(size, alignment);
>
> We don't need to do anything on the POSIX side (unless we want to
> enforce consistency of handling the size==0 case).

I would do this unconditionally.  The POSIX manpage says that either NULL or a unique 
pointer is a valid return value into *memptr here for size == 0.  What we want in our 
caller is NULL if and only if error.

> I'd quite like to get this series in before softfreeze (though mostly
> just for my personal convenience so it's not hanging around as a
> loose end I have to come back to after we reopen for 7.1). Does anybody
> object if I squash in that change and put this in a pullrequest,
> or would you prefer to see a v2 series first?

I'm happy with a squash and PR.


r~