Re: generic strncpy - off-by-one error

From: Timothy Miller <miller@techsource.com>
To: Daniel Forrest <forrest@lmcg.wisc.edu>
Cc: Peter Kjellerstedt <peter.kjellerstedt@axis.com>,
	"'Willy Tarreau'" <willy@w.ods.org>,
	linux-kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: generic strncpy - off-by-one error
Date: Mon, 18 Aug 2003 12:40:37 -0400	[thread overview]
Message-ID: <3F410185.2090804@techsource.com> (raw)
In-Reply-To: 20030816050415.A6986@rda07.lmcg.wisc.edu

Daniel Forrest wrote:

>  
> -	if (count) {
> +	if (count >= sizeof(long)) {
>  		size_t count2;
>  

I like this size check here, but the comparison should be to some number 
greater than sizeof(long).  There is a threshold below which it's not 
worth it to do all of the extra loops.  If you're going to fill only 
four bytes, it's probably best to do it just using the last loop.

Maybe through some trial and error, we could determine what that 
threshold is.  I'm betting it's something around 2* or 3* word size.

[snip]

> +
> +	while (count) {
> +		*tmp++ = '\0';
> +		count--;
>  	}
>  
>  	return dest;
>  }
> 