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From: sja@tekla.fi (Sakari Jalovaara)
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Date: Fri, 18 Oct 1996 13:31:12 +0300
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To: current@freebsd.org
Subject: Re: Weirdness in current
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>> >Stack corruption bugs are a *bugger* to find.
>
> Port your software to SunOS/Slolaris and run Purify on it. :)

Hey, don't laugh!  I've ported plenty of stuff to HP just to
run under Purify.

Going through all FreeBSD userland stuff with Purify would be a useful
project (and a BIG one).  One would need to port libraries and
executables to SunOS, HP-UX and/or NT.

(Purify for Losedows NT just came out; see www.pureatria.com.)

>> I once made a gross hack on a Pyramid, such that checksum of the stack
>> was made at every function call and record written to file at the
>> return recording match/nomatch.
>
> This is basically what Purify does..

The mechanism is different (at least from the manual I've read);
the stack checksum trick would find different kinds of errors
from what Purify catches.

Purify uses a memory coloring sceme and object code modification
to figure out what bytes in memory shouldn't be accessed.
									++sja