Re: Fix for Win32 division involving INT_MIN

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > With no Win32 exception detection code in sight, I propose the following
> > patch to prevent server crashes for unusual INT_MIN integer division.
>
> The overflow code tries hard to avoid assuming it knows what INT_MIN and
> INT_MAX are --- this is maybe not so important for int4 but it is for
> int8 (because of our support for int8-less machines). I don't
> immediately see how to make this test without assuming you know the
> value of INT_MIN, but we ought to try to come up with one.
>
> We do see funny behavior on Intel chips even without Windows, so it'd
> be better to not #ifdef WIN32 but use the same overflow test for
> everyone.

> I would imagine the same problem arises with int8, has anyone checked?

Seems int8 is OK on Win32:

postgres=# SELECT (-9223372036854775808) / (-1);
ERROR: bigint out of range

> Also, the overflow tests in the intNmul routines seem vulnerable.

I reproduced the crash using int4 multiplication. Again int8
multiplication seemed OK.

I tried int2 and that seemed OK.

Updated patch attached.

--
Bruce Momjian http://candle.pha.pa.us
EnterpriseDB http://www.enterprisedb.com

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