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Date:      Mon, 23 Aug 1999 22:12:38 +0200
From:      Mark Murray <mark@grondar.za>
To:        "Daniel C. Sobral" <dcs@newsguy.com>
Cc:        Greg Lehey <grog@lemis.com>, Poul-Henning Kamp <phk@critter.freebsd.dk>, Matthew Dillon <dillon@apollo.backplane.com>, FreeBSD Hackers <hackers@FreeBSD.org>, FreeBSD Committers <cvs-committers@FreeBSD.org>, Garrett Wollman <wollman@khavrinen.lcs.mit.edu>
Subject:   Re: Mandatory locking? 
Message-ID:  <199908232012.WAA78393@gratis.grondar.za>

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> > Now I suppose you're going to come and say that this is bad
> > programming, and advisory locking would do the job if the software is
> > written right.  Correct.  You could also use the same argument to say
> > that memory protection isn't necessary, because a correctly written
> > program doesn't overwrite other processes address space.  It's the
> > same thing: file protection belongs in the kernel.
> 
> Well, I'd say advisory lock does the job if the software is written
> right, and if the software is not written right, mandatory locking
> won't help.

Folk are all skirting around a very convenient (and necessary)
loophole; in cases where there _is_ mandatory locking, there
is always some meta-user which is allowed to violate this.

In process-space, this is the kernel. In file-space, this should
be root. Processes that require mandatory locking must revoke
superuser before attempting locks.

M
--
Mark Murray
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