Re: Fix for Win32 division involving INT_MIN

Patch applied.  Backpatch to 8.1.X.

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Bruce Momjian wrote:
> Tom Lane wrote:
> > Bruce Momjian <pgman@candle.pha.pa.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
>
>   + If your life is a hard drive, Christ can be your backup. +


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

  + If your life is a hard drive, Christ can be your backup. +