Re: [Qemu-devel] Re: [PATCH 2/5] Support human unit formats in strtobytes, eg. 1.0G

[Anthony Liguori <anthony@codemonkey.ws>]

On 09/15/2010 10:45 AM, Paolo Bonzini wrote:
> On 09/15/2010 02:23 PM, Jes.Sorensen@redhat.com wrote:
>>       switch (*endptr++) {
>>       case 'K':
>>       case 'k':
>>           value<<= 10;
>>           break;
>>       case 0:
>> +        if (divider) {
>> +            value = 0;
>> +            break;
>> +        }
>>       case 'M':
>>       case 'm':
>>           value<<= 20;
>> @@ -284,9 +306,12 @@ uint64_t strtobytes(const char *nptr, char **end)
>>       default:
>>           value = 0;
>>       }
>> +    if (divider)
>> +        value /= divider;
>>
>
> This risks overflow if you do 1.00000000000000G or something similarly 
> braindead.  Do we loathe floating point so much that you cannot use 
> strtod, like

It should be strtod.  Only badness can happen otherwise.

Regards,

Anthony Liguori

>     endptr1 = nptr + strspn(s, "0123456789.");
>     switch (*endptr1)
>     {
>     case 0: divider = 1; break;
>     case 'm': divider = 1 << 20; break;
>     ...
>     default: /* error, including for 1.0e+5 and negative */
>     }
>     value = (uint64_t) (strtod(nptr, &endptr2) / divider);
>     if (endptr1 != endptr2) /* error, e.g. 1.2.3 */
>
>     return value;
> Paolo
>