From owner-freebsd-hackers@FreeBSD.ORG  Sun Jul  2 14:34:37 2006
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
X-Original-To: freebsd-hackers@freebsd.org
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 133AE16A817
	for <freebsd-hackers@freebsd.org>; Sun,  2 Jul 2006 14:34:37 +0000 (UTC)
	(envelope-from Andre.Albsmeier@siemens.com)
Received: from david.siemens.de (david.siemens.de [192.35.17.14])
	by mx1.FreeBSD.org (Postfix) with ESMTP id B775243D62
	for <freebsd-hackers@freebsd.org>; Sun,  2 Jul 2006 14:34:27 +0000 (GMT)
	(envelope-from Andre.Albsmeier@siemens.com)
Received: from mail2.siemens.de (localhost [127.0.0.1])
	by david.siemens.de (8.12.6/8.12.6) with ESMTP id k62EYPvV022902;
	Sun, 2 Jul 2006 16:34:25 +0200
Received: from ims.mchp.siemens.de (ims.mchp.siemens.de [139.25.31.39])
	by mail2.siemens.de (8.12.6/8.12.6) with ESMTP id k62EYP0c015141;
	Sun, 2 Jul 2006 16:34:25 +0200
Received: from mail-ct.mchp.siemens.de (mail-ct.mchp.siemens.de [139.25.31.51])
	by ims.mchp.siemens.de  with ESMTP id k62EYOJQ020611;
	Sun, 2 Jul 2006 16:34:24 +0200 (MEST)
Received: from curry.mchp.siemens.de (curry [139.25.40.130])
	by mail-ct.mchp.siemens.de (8.12.11/8.12.11) with ESMTP id
	k62EYO1L006351; Sun, 2 Jul 2006 16:34:24 +0200 (MEST)
Received: (from localhost)
	by curry.mchp.siemens.de (8.13.6/8.13.6) id k62EYNJK086643;
Date: Sun, 2 Jul 2006 16:34:23 +0200
From: Andre Albsmeier <Andre.Albsmeier@siemens.com>
To: Matthias Andree <matthias.andree@gmx.de>
Message-ID: <20060702143423.GA1108@curry.mchp.siemens.de>
References: <20060628181045.GA54915@curry.mchp.siemens.de>
	<20060629054222.GA92895@leiferikson.flosken.lan>
	<m3bqsceyf2.fsf@merlin.emma.line.org>
	<20060629162319.GA94921@leiferikson.flosken.lan>
	<m33bdnhnv7.fsf@merlin.emma.line.org>
	<20060630045937.GB97868@leiferikson.flosken.lan>
	<417C9B11412FF8C17A1AD483@Zelazny>
	<m3hd21g1ss.fsf@merlin.emma.line.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <m3hd21g1ss.fsf@merlin.emma.line.org>
X-Echelon: <censored>
X-Advice: Drop that crappy M$-Outlook, I'm tired of your viruses!
User-Agent: Mutt/1.5.11
Cc: freebsd-hackers@freebsd.org, Pat Lashley <patl+freebsd@volant.org>,
	Johannes Weiner <hnazfoo@googlemail.com>, Andre.Albsmeier@siemens.com
Subject: Re: Return value of malloc(0)
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 02 Jul 2006 14:34:37 -0000

On Sat, 01-Jul-2006 at 10:35:47 +0200, Matthias Andree wrote:
> Pat Lashley <patl+freebsd@volant.org> writes:
> 
> > BUT, that said, the safest and most portable coding practice would be:
> >
> >        // The C standard does not require malloc(0) to return NULL;
> >        // but whatever it returns MUST NOT be dereferenced.
> >        ptr = ( size == 0 ) ? NULL : malloc( size ) ;
> 
> Safest (avoiding null derefence) would instead be:
> 
>        ptr = malloc(size ? size : 1);

I hacked malloc.c to do exactly this automatically, just for
testing. 15 Minutes after rebooting (and after doing a lot of 
desktop switching and opening and closing of windows) the
X-server ran out of memory :-).

I assume there are lots of programs out there which do
malloc(0) but only firefox (and apparently seamonkey)
dereference the returned non-NULL pointer and crash therefore.

	-Andre