libc/upstream-openbsd/lib/libc/string/memrchr.c

/*	$OpenBSD: memrchr.c,v 1.3 2015/08/31 02:53:57 guenther Exp $	*/

/*
 * Copyright (c) 2007 Todd C. Miller <Todd.Miller@courtesan.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <string.h>

/*
 * Reverse memchr()
 * Find the last occurrence of 'c' in the buffer 's' of size 'n'.
 */
void *
memrchr(const void *s, int c, size_t n) __overloadable
{
	const unsigned char *cp;

	if (n != 0) {
		cp = (unsigned char *)s + n;
		do {
			if (*(--cp) == (unsigned char)c)
				return((void *)cp);
		} while (--n != 0);
	}
	return(NULL);
}
DEF_WEAK(memrchr);