Gregory Stark <st...@enterprisedb.com> writes:
> Teodor Sigaev <teo...@sigaev.ru> writes:
>
>> I reproduced the bug with a help of Grzegorz's point for 64-bit box. So,
>> patch
>> is attached and I'm going to commit it
> ...
>
>> ! Conf->flagval[(unsigned int) *s] = (unsigned char) val;
> ...
>> ! Conf->flagval[*(unsigned char*) s] = (unsigned char) val;
>
> Maybe I'm missing something but I don't understand how this fixes the problem.
Ah, I understand how this fixes the problem. You were casting to unsigned
*int* not unsigned char so it was sign extending first and then overflowing.
So char<255> was coming out as MAX_INT instead of 255.
#include <stdio.h>
main()
{
volatile signed char a = -1;
printf("ud=%ud\n", (unsigned int)a);
}
$ ./a.out
ud=4294967295d
If you just make these all casts to (unsigned char) it should work just as
well as the pointer type punning -- and be a whole lot less scary.
> What really boggles me is why you don't just use unsigned chars everywhere and
> remove all of these casts. or would that just move the casts to strcmp and
> company?
It still seems to me if you put a few "unsigned" in variable declarations you
could remove piles upon piles of casts and make all of the code more readable.
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
Ask me about EnterpriseDB's 24x7 Postgres support!
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