linux-kernel - Re: kfree(0)

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Message-ID: <Pine.LNX.4.64.0708151217120.5639@fbirervta.pbzchgretzou.qr>
Date:	Wed, 15 Aug 2007 12:20:27 +0200 (CEST)
From:	Jan Engelhardt <jengelh@...putergmbh.de>
To:	Rene Herman <rene.herman@...il.com>
cc:	Jason Uhlenkott <jasonuhl@...onuhl.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Tim Bird <tim.bird@...sony.com>,
	linux kernel <linux-kernel@...r.kernel.org>
Subject: Re: kfree(0) - ok?


On Aug 15 2007 11:58, Rene Herman wrote:
>> > > > > NULL is not 0 though.
>> > > > It is.  Its representation isn't guaranteed to be all-bits-zero,
>> > > 
>
> He said the null _pointer_ isn't guaranteed to be all-bits zero. And it
> isn't. Read the standard or the faq.

0 is all-bits-zero.
NULL is 0. ("It is.", above)

Transitively, this would make NULL all-bits-zero.
I might have missed something, though, perhaps that the cast to void* makes it
intransitive.
But leave it at whatever the standard says.

>> > > > but the constant value 0 when used in pointer context is always a
>> > > > null pointer (and in fact the standard requires that NULL be
>> > > > #defined as 0 or a cast thereof).

	Jan
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