linux-kernel - Re: [PATCH] Repalce strncmp by memcmp

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Message-ID: <20101129041359.GA6991@core.coreip.homeip.net>
Date:	Sun, 28 Nov 2010 20:13:59 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Pavel Vasilyev <pavel@...linux.ru>
Cc:	Ming Lei <tom.leiming@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Repalce strncmp by memcmp

On Mon, Nov 29, 2010 at 06:11:21AM +0300, Pavel Vasilyev wrote:
> On 29.11.2010 05:29, Ming Lei wrote:
> > Hi,
> >
> > 2010/11/29 Pavel Vasilyev <pavel@...linux.ru>:
> >>    This patch replace all strncmp(a, b, c) by  memcmp(a, b, c).
> >>
> >> I test on x86_64 (AMD Opteron 285).
> > In fact, memcmp doesn't handle case of tail of string, so
> > it is not safe to replace strncmp with memcmp
> >
> #include <stdio.h>
> #include <errno.h>
> 
> int main() {
> 
>    char *STR = "XXXX\0";
>    char *XXX = "XXXX";

Try comparing:

"XXXX\0YYYY" and
"XXXX\0ZZZZ"

and observe the difference.

-- 
Dmitry
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