From: Richard Henderson <rth@twiddle.net>
To: Andrea Arcangeli <andrea@suse.de>
Cc: Russell King <rmk@arm.linux.org.uk>,
Hubert Mantel <mantel@suse.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: Compatibility issue with 2.2.19pre7
Date: Tue, 23 Jan 2001 23:51:15 -0800 [thread overview]
Message-ID: <20010123235115.A14786@twiddle.net> (raw)
In-Reply-To: <20010110163158.F19503@athlon.random> <200101102209.f0AM9N803486@flint.arm.linux.org.uk> <20010111005924.L29093@athlon.random>
In-Reply-To: <20010111005924.L29093@athlon.random>
On Thu, Jan 11, 2001 at 12:59:24AM +0100, Andrea Arcangeli wrote:
> What I said is that I can write this C code:
>
> int x[2], * p = (int *) (((char *) &x)+1);
> main()
> {
> *p = 0;
> }
>
> This is legal C code.
Err, no. This is not "legal" by any stretch of the imagination.
This code has undefined behaviour.
As such, it may work, it may sigbus, it may write data at some
address unrelated to "x", or it may start World War III (with
appropriate hardware attached).
We aren't even obliged to allow this to compile.
r~
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next prev parent reply other threads:[~2001-01-24 7:51 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-10 0:37 Compatibility issue with 2.2.19pre7 Hubert Mantel
2001-01-10 0:43 ` Alan Cox
2001-01-10 6:54 ` Russell King
2001-01-10 15:31 ` Andrea Arcangeli
2001-01-10 22:09 ` Russell King
2001-01-10 23:59 ` Andrea Arcangeli
2001-01-11 7:34 ` Russell King
2001-01-11 10:33 ` Andi Kleen
2001-01-11 10:36 ` Russell King
2001-01-11 12:10 ` Manfred
2001-01-11 12:10 ` Andi Kleen
2001-01-11 12:29 ` Manfred
2001-01-11 13:27 ` Russell King
2001-01-24 7:51 ` Richard Henderson [this message]
2001-01-24 9:02 ` Andrea Arcangeli
2001-01-24 9:51 ` Richard Henderson
2001-01-24 12:21 ` Andrea Arcangeli
2001-01-24 17:49 ` Richard Henderson
2001-01-24 10:09 ` Thomas Pornin
2001-01-11 15:28 ` Trond Myklebust
2001-01-11 16:19 ` Manfred Spraul
2001-01-11 17:44 ` Trond Myklebust
2001-01-11 18:22 ` Trond Myklebust
2001-01-11 18:27 ` Andrea Arcangeli
2001-01-11 18:30 ` Trond Myklebust
2001-01-11 18:43 ` Andrea Arcangeli
2001-01-11 20:09 ` Russell King
2001-01-11 20:39 ` Trond Myklebust
2001-01-11 11:37 ` Trond Myklebust
-- strict thread matches above, loose matches on Subject: below --
2001-01-24 13:46 Jesse Pollard
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