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

[Paolo Bonzini <pbonzini@redhat.com>]

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

     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