Re: [PATCH 0/9] QEMU file cleanups

[Peter Xu]

On Thu, May 04, 2023 at 04:56:46PM +0200, Juan Quintela wrote:
> Peter Xu <peterx@redhat.com> wrote:
> > On Thu, May 04, 2023 at 01:38:32PM +0200, Juan Quintela wrote:
> >> - convince and review code to see that everything is uint64_t.
> >
> > One general question to patches regarding this - what's the major benefit
> > of using uint64_t?
> >
> > It doubles the possible numbers to hold, but it's already 64bits so I don't
> > think it matters a lot.
> 
> We were checking for negatives even when that can't be.
> And we are doing this dance of
> 
> int64_t x, y;
> uint64_t a, b;
> 
> x = a;
> b = y;
> 
> This is always confusing and not always right.

Yeah this is confusing, but if anything can go wrong with this I assume we
could have some bigger problem anyway..

> 
> > The thing is we're removing some code trying to
> > detect negative which seems to be still helpful to detect e.g. overflows
> > (even though I don't think it'll happen).  I just still think it's good to
> > know when overflow happens, and not sure what I missed on benefits of using
> > unsigned here.
> 
> If you grep through the code, you see that half of the things are
> int64_t and the other half is uint64_t.  I find it always confusing.

Right, I'm personally curious whether we should just use int64_t always
unless necessary. :) Another good thing with int64_t is it's also suitable
for error report when used in retvals.

But no strong opinion here, I don't think that's a huge deal for now.
Having such an alignment on types makes sense to me.

Thanks,

-- 
Peter Xu