Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!lll-crg!mordor!sri-spam!sri-unix!hplabs!decwrl!ucbvax!sdcsvax!coleman
From: coleman@sdcsvax.UCSD.EDU (Don Coleman)
Newsgroups: comp.unix.wizards
Subject: Re: brk's zero-fill behavior on VAXen
Message-ID: <2204@sdcsvax.UCSD.EDU>
Date: Wed, 12-Nov-86 21:40:52 EST
Article-I.D.: sdcsvax.2204
Posted: Wed Nov 12 21:40:52 1986
Date-Received: Thu, 13-Nov-86 07:38:38 EST
References: <7208@elsie.UUCP> <544@mcgill-vision.UUCP>
Reply-To: coleman@sdcsvax.UUCP (Don Coleman)
Organization: UCSD Emu project
Lines: 15


The reason VAXen zero-fill brk'ed data is for security(it wouldn't be good
for a snoopy user to watch until somebody exits vi after editing a 
very private file, and then do lots of brks, and get access to the 'dirty'
pages that the vi was using...).

There are also a lot of other benefits in terms of the predictability of 
programs when they fail, and it makes core images quite a bit cleaner.

But this is *not* something to depend on.  I doubt you'll find it in
the SVID(This of course assumes that you care what's in the SVID).

don
coleman@sdcsvax.ucsd.edu
Newsgroups: net.unix-wizards