Re: [PATCH 11/11] cutils: Improve qemu_strtosz handling of fractions

[Hanna Czenczek <hreitz@redhat.com>]

On 10.05.23 09:46, Hanna Czenczek wrote:
> On 09.05.23 23:28, Eric Blake wrote:

[...]

>> But I think the solution to that is not to treat underflow as valf =
>> 0, but rather to alter this snippet:
>>
>> -            valf = (uint64_t)(fraction * 0x1p64);
>> +            /*
>> +             * If fraction was non-zero, add slop small enough that 
>> it doesn't
>> +             * impact rounding, but does let us reject 
>> "1..00000000000000000001B".
>> +             */
>> +            valf = (uint64_t)(fraction * 0x1p64) | !fraction;
>>
>> so that between the ERANGE branch and this slop, valf is guaranteed
>> non-zero if fraction contained any non-zero digits.
>
> I’d make it a logical || instead of |, but that sounds good, yes.

Sent too soon – exactly when sending I realized that I’m very wrong.  
Still, I wouldn’t just | the 1 on, and rather make take the LoC to make it

valf = (uint64_t)(fraction * 0x1p64);
if (!valf && fraction) {
     /*
      * If fraction was non-zero, add slop small enough that it doesn't
      * impact rounding, but does let us reject "1..00000000000000000001B".
      */
     valf = 1;
}