1 /* $OpenBSD: strlcat.c,v 1.7 2014/06/10 04:16:57 deraadt Exp $ */ 2 3 /* 4 * Copyright (c) 1998 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 <lib/libkern/libkern.h> 20 21 /* 22 * Appends src to string dst of size siz (unlike strncat, siz is the 23 * full size of dst, not space left). At most siz-1 characters 24 * will be copied. Always NUL terminates (unless siz <= strlen(dst)). 25 * Returns strlen(src) + MIN(siz, strlen(initial dst)). 26 * If retval >= siz, truncation occurred. 27 */ 28 size_t 29 strlcat(char *dst, const char *src, size_t siz) 30 { 31 char *d = dst; 32 const char *s = src; 33 size_t n = siz; 34 size_t dlen; 35 36 /* Find the end of dst and adjust bytes left but don't go past end */ 37 while (n-- != 0 && *d != '\0') 38 d++; 39 dlen = d - dst; 40 n = siz - dlen; 41 42 if (n == 0) 43 return(dlen + strlen(s)); 44 while (*s != '\0') { 45 if (n != 1) { 46 *d++ = *s; 47 n--; 48 } 49 s++; 50 } 51 *d = '\0'; 52 53 return(dlen + (s - src)); /* count does not include NUL */ 54 } 55