From owner-freebsd-hackers@FreeBSD.ORG  Thu Jun 29 17:29:21 2006
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From: Matthias Andree <matthias.andree@gmx.de>
To: freebsd-hackers@freebsd.org
In-Reply-To: <20060629162319.GA94921@leiferikson.flosken.lan> (Johannes
	Weiner's message of "Thu, 29 Jun 2006 18:23:19 +0200")
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Date: Thu, 29 Jun 2006 19:29:16 +0200
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Subject: Re: Return value of malloc(0)
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Johannes Weiner <hnazfoo@googlemail.com> writes:

> On Thu, Jun 29, 2006 at 06:09:37PM +0200, Matthias Andree wrote:
>
>> The value returned from malloc(0) must not be dereferenced whatever it
>> was. It was 0x800, which doesn't count as "failure".
>
> But this would be appropriate for catching the error:
>
> if ((foo = malloc(0)) == foo)
> 	/* make noise */
>
> wouldn't it?

No, sir. Operator precedence: assign first, and then compare, thus the
comparison will always be true (else you'd be comparing to undefined
values, which isn't any better).  You might as well write:

 foo = malloc(0);
 /* make noise */

There is no way to see a 0x800 return from malloc(0) as "error".

-- 
Matthias Andree