Re: [PATCH v17 02/14] util/cutils: Use qemu_strtold_finite to parse size

[Tao Xu]

On 11/25/2019 2:56 PM, Markus Armbruster wrote:
> Tao Xu <address@hidden> writes:
>
> > Support full 64bit precision, modify related test cases.
>
> That's not true in general: long double need not be any wider than
> double.
>
> It might be true on the host machines we support, but I don't know.  If
> we decide to rely on it, we better make the build fail when the host
> machine doesn't meet our expectations, preferably in configure.
[...]
> > -    if ((val * mul >= 0xfffffffffffffc00) || val < 0) {
> > +    /* Values > UINT64_MAX overflow uint64_t */
> > +    if ((val * mul > UINT64_MAX) || val < 0) {
> >           retval = -ERANGE;
> >           goto out;
> >       }
>
> Not portable.  If it was, we'd have made this changd long ago :)

OK. So the suitable solution is what you suggested in v14?

"A possible alternative is to parse the numeric part both as a double 
and as a 64 bit unsigned integer, then use whatever consumes more 
characters.  This enables providing full 64 bits unless you actually use
a fraction."

I will try this way.