On Tue, Nov 10, 2009 at 1:39 PM, Bean <bean12...@gmail.com> wrote:
> On Tue, Nov 10, 2009 at 5:34 AM, Vladimir 'phcoder' Serbinenko
> <phco...@gmail.com> wrote:
>> But now it has a technical problem: it may read post array definitions.
>> If any of post-array memory is MMIO or absent reading from it may have
>> peculiar consequences
>>> Also, because s1 and s2 have two differents roles, I think it would be
>>> best to give them names that better suits them. ;)
>
> Hi,
>
> Right, I think it'd be better to use fixed size array, perhaps we can
> define a type grub_password_t for it.
>
> BTW, with fixed size array, the following algorithm should run exactly
> the same amount of instruction each time:
>
> typedef char grub_password_t[1024];
>
> int
> grub_auth_strcmp (const grub_password_t s1, const grub_password_t s2)
> {
> int r1 = 0;
> int r2 = 0;
> int i, *p;
>
> p = &r1;
> for (i = 0; i < sizeof (grub_password_t); i++, s1++, s2++)
> {
> *p |= (*s1 ^ *s2);
> if (*s1 == '\0')
> p = &r2;
> }
>
> return (r1 != 0);
> }
Hi,
Oh sorry, this one still have some issue, this should work:
typedef char grub_password_t[1024];
int
grub_auth_strcmp (const grub_password_t s1, const grub_password_t s2)
{
int r1 = 0;
int r2 = 0;
int i, *p1, *p2;
p1 = p2 = &r1;
for (i = 0; i < sizeof (grub_password_t); i++, s1++, s2++)
{
*p1 |= (*s1 ^ *s2);
if (*s1 == '\0')
p1 = &r2;
else
p2 = &r2;
}
return (r1 != 0);
}
--
Bean
My repository: https://launchpad.net/burg
Document: https://help.ubuntu.com/community/Burg
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