Re: Imminent bugfix release (1.97.1)

[Darron Black <darron@griffin.net>]

richardvoigt@gmail.com wrote:
>> Hello,
>>
>> I'd be concerned about (s1 != s2).  Depending on how efficiently this
>> compiles, could not branch prediction make this faster for match vs. not
>> match, etc?.  I'd be worried about all the ways (and future ways) compilers
>> might help us and introduce time differences.
>>     
>
> I was avoiding suggesting new conditionals for that reason, but didn't
> see the one already there.  Good find.
>
>   
>> I'd feel most comfortable with the time delay, but why not stick to complete
>> artithmetic?
>>     
>
> I agree.  But I think you've inverted the return value (strcmp returns
> 0 on perfect match).
>
>   
Yeah, sorry.  That'd be a slightly larger security hole, eh? 

I meant to just show the "acc |= (*s1 ^ *s2);" line, but I decided to 
throw the rest in for context and didn't really check it.  I noticed 
that just AFTER sending.

>> int i;
>> int acc = 0;
>>
>> for(i=0;i<MAX_LEN;i++,s1++,s2++)
>> {
>>   acc |= (*s1 ^ *s2);
>>
>>   if (*s1 == 0)
>>      break;
>> }
>>
>> return (acc == 0);
>>
>>
>> Also, these strcmp functions don't properly return < or >.  Just = / !=.
>>  However, my context being so new is quite limited.
>>
>>
>> Darron
>>
>>
>>
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>>
>>     
>
>
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