RE: generic strncpy - off-by-one error

[Peter Kjellerstedt]

> -----Original Message-----
> From: Daniel Forrest [mailto:forrest@xxxxxxxxxxxxx] 
> Sent: Saturday, August 16, 2003 10:41
> To: Peter Kjellerstedt
> Cc: 'Timothy Miller'; 'Willy Tarreau'; linux-kernel mailing list
> Subject: Re: generic strncpy - off-by-one error
> 
> On Sat, Aug 16, 2003 at 10:15:14AM +0200, Peter Kjellerstedt wrote:
> > 
> > Here is the code that I used:
> > 
> > char *strncpy(char *dest, const char *src, size_t count)
> > {
> > 	char *tmp = dest;
> > 
> > 	while (count && *src) {
> > 		*tmp++ = *src++;
> > 		count--;
> > 	}
> > 
> > 	if (count) {
> > 		size_t count2;
> > 
> > 		while (count & (sizeof(long) - 1)) {
> 
> Shouldn't this be:
> 
> 		while (tmp & (sizeof(long) - 1)) {

Actually, it should be:

	while (count && ((long)tmp & (sizeof(long) - 1)))

> > 			*tmp++ = '\0';
> > 			count--;
> > 		}
> > 
> > 		count2 = count / sizeof(long);
> > 		while (count2) {
> > 			*((long *)tmp)++ = '\0';
> > 			count2--;
> > 		}
> > 
> > 		count &= (sizeof(long) - 1);
> > 		while (count) {
> > 			*tmp++ = '\0';
> > 			count--;
> > 		}
> > 	}
> > 
> > 	return dest;
> > }
> 
> -- 
> Dan

//Peter
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