[OpenBIOS] [PATCH 9/10] Divide by zero check

[Mark Cave-Ayland]

On 09/08/11 22:55, William Hahne wrote:

> It is possible for BootX to purposefully divide by zero expecting 0 as
> the result.
>
> Index: kernel/forth.c
> ===================================================================
> --- kernel/forth.c (revision 1041)
> +++ kernel/forth.c (working copy)
> @@ -1157,6 +1157,12 @@
>   {
> const ucell b = POP();
> const ducell a = DPOP();
> +
> + if (b == 0) { // can't divide by zero
> +            PUSH(0);
> +            DPUSH(0);
> +            return;
> + }
>   #ifdef NEED_FAKE_INT128_T
>           if (a.hi != 0) {
>               fprintf(stderr, "mudivmod called (0x%016llx %016llx /
> 0x%016llx)\n",

There is something wrong here: nothing will purposefully divide by zero 
as it will invoke a trap somewhere. Again, I think this is hiding 
another bug somewhere and is not necessarily the correct fix.


ATB,

Mark.

-- 
Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
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