Re: Imminent bugfix release (1.97.1)

[Duboucher Thomas <thomas@duboucher.eu>]

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Vladimir 'phcoder' Serbinenko a écrit :
> Duboucher Thomas wrote:
>> Bean a écrit :
>>> Hi,
>>> This one work:
>>> int
>>> auth_strcmp (const char *s1, const char *s2)
>>> {
>>>   int result = 0;
>>>   while (1)
>>>     {
>>>       result += (*s1 != *s2);
>>>       if (*s1 == 0)
>>>     break;
>>>       s1++;
>>>       s2++;
>>>     }
>>>   return (result != 0);
>>> }
>>> The trick is to compare the ending '\0' as well, so that partial match
>>> is not satisfied.
>>
>>     Yep, I like this one, but I would prefer using an OR instead of an ADD
>> (with a highly hypothetical integer overflow :p) and because it's nicer
>> in terms of pure logic.
>>     "The comparison beetwen s1 and s2 is false if *s1 is different from
>> *s2, or recursively if the comparison beetwen s1+1 and s2+1 is false"
>>
>> int
>> auth_strcmp (const char *s1, const char *s2)
>> {
>>   int ret = 0;
>>
>>   for (;;)
>>   {
>>     ret |= (*s1 != *s2);
>>
>>     if (*s1 == '\0')
>>       break;
>>
>>     s1++;
>>     s2++;
>>   }
>>
>>   return ret;
>> }
>>
> 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

	Well, the only way to solve that problem would be IMHO to add a limit
to the size of s2, and use this maximum size as an end condition for the
'for' statement. Any better idea? :)

int
auth_strcmp (const char *s1, const char *s2)
{
  int ret, n;

  for (ret = n = 0; ret < PASSPHRASE_MAXSIZE; ret++)
  {
    ret |= (*s1 != *s2);

    if (*s1 == '\0')
      break;

    s1++;
    s2++;
  }

  return ret;
}

>>     Also, because s1 and s2 have two differents roles, I think it would be
>> best to give them names that better suits them. ;)
>>
>>     Thomas.
> 
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