linux-kernel - Re: [linux-pm] [PATCH] ACPI: replace strlen("string") with sizeof("string") -1

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Message-ID: <Pine.LNX.4.44L0.1208061028160.1649-100000@iolanthe.rowland.org>
Date:	Mon, 6 Aug 2012 10:36:57 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Pavel Machek <pavel@....cz>
cc:	Len Brown <lenb@...nel.org>, <linux-acpi@...r.kernel.org>,
	<linux-pm@...ts.linux-foundation.org>,
	<linux-kernel@...r.kernel.org>, Len Brown <len.brown@...el.com>,
	Pavel Vasilyev <pavel@...linux.ru>
Subject: Re: [linux-pm] [PATCH] ACPI: replace strlen("string") with
 sizeof("string") -1

On Mon, 6 Aug 2012, Pavel Machek wrote:

> On Thu 2012-07-26 21:39:38, Len Brown wrote:
> > ...both give the number of chars in the string
> > without the '\0', as strncmp() wants,
> > but sizeof() is compile-time.
> 
> What about introducing something like streq() to do this
> automatically? This is ugly....
> 
> #define streq(a, b) ... if (_buildin_constant(b)) ...
> 
> ?
> 
> > -	if (!strncmp(val, "enable", strlen("enable"))) {
> > +	if (!strncmp(val, "enable", sizeof("enable") - 1)) {

While you're at it, there's no point using strncmp when you know the 
length of one of the strings beforehand.  Just use memcmp, and don't 
subtract 1 from the sizeof value.

Alan Stern

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