From owner-freebsd-current@FreeBSD.ORG  Wed Sep 24 10:11:49 2003
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id 2A35A16A4D5; Wed, 24 Sep 2003 10:11:49 -0700 (PDT)
Received: from fledge.watson.org (fledge.watson.org [204.156.12.50])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id 070AE44029; Wed, 24 Sep 2003 10:11:41 -0700 (PDT)
	(envelope-from robert@fledge.watson.org)
Received: from fledge.watson.org (localhost [127.0.0.1])
	by fledge.watson.org (8.12.9/8.12.9) with ESMTP id h8OHBMgL069396;
	Wed, 24 Sep 2003 13:11:22 -0400 (EDT)
	(envelope-from robert@fledge.watson.org)
Received: from localhost (robert@localhost)h8OHBMhG069393;
	Wed, 24 Sep 2003 13:11:22 -0400 (EDT)
Date: Wed, 24 Sep 2003 13:11:21 -0400 (EDT)
From: Robert Watson <rwatson@freebsd.org>
X-Sender: robert@fledge.watson.org
To: Dan Nelson <dnelson@allantgroup.com>
In-Reply-To: <20030924170633.GA30073@dan.emsphone.com>
Message-ID: <Pine.NEB.3.96L.1030924131012.67029D-100000@fledge.watson.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
cc: deischen@freebsd.org
cc: Doug Barton <DougB@freebsd.org>
cc: Freebsd Current <current@freebsd.org>
Subject: Re: Fixing -pthreads (Re: ports and -current)
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 24 Sep 2003 17:11:49 -0000


On Wed, 24 Sep 2003, Dan Nelson wrote:

> Does it really matter if you end up linked to multiple threads
> libraries?  The first library providing a symbol wins, so the other
> shlibs just won't get used at all.  Libraries linked from the executable
> trump libraries linked from libraries, and LD_PRELOAD wins above all. 
> If one threads library exports a symbol not in the others, I'd call that
> an API bug in the first library. 
> 
> This should be no different from explicitly linking in dmalloc to
> override the malloc functions in libc, for example. 

One potential downside to the LD_PRELOAD approach is that it will only
work for applications that aren't setuid/setgid.  While today most of our
privileged and credential-munging applications aren't threaded, I'd like
to avoid precluding that in the future as much as possible.  What
mechanism should be used when LD_PRELOAD is being ignored due to
issetugid() returning true?

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Network Associates Laboratories