1 /* $OpenBSD: strnlen.c,v 1.7 2016/10/14 18:19:04 dtucker Exp $ */ 2 3 /* 4 * Copyright (c) 2010 Todd C. Miller <Todd.Miller@courtesan.com> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <sys/types.h> 20 21 #include <string.h> 22 #include <stdint.h> 23 24 size_t 25 strnlen(const char *str, size_t maxlen) 26 { 27 const char *cp; 28 29 for (cp = str; maxlen != 0 && *cp != '\0'; cp++, maxlen--) 30 ; 31 32 /* 33 * Cast pointers to unsigned type before calculation, to avoid signed 34 * overflow when the string ends where the MSB has changed. 35 */ 36 return (size_t)((uintptr_t)cp - (uintptr_t)str); 37 } 38 DEF_WEAK(strnlen); 39