strlcat.c (1789B)
1 2 /* $OpenBSD: strlcat.c,v 1.15 2015/03/02 21:41:08 millert Exp $ */ 3 4 /* 5 * Copyright (c) 1998, 2015 Todd C. Miller <Todd.Miller@courtesan.com> 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 */ 19 20 #include <string.h> 21 22 #include "strlcat.h" 23 24 /* 25 * Appends src to string dst of size dsize (unlike strncat, dsize is the 26 * full size of dst, not space left). At most dsize-1 characters 27 * will be copied. Always NUL terminates (unless dsize <= strlen(dst)). 28 * Returns strlen(src) + MIN(dsize, strlen(initial dst)). 29 * If retval >= dsize, truncation occurred. 30 */ 31 size_t strlcat(char* dst, const char* src, size_t dsize) { 32 const char* odst = dst; 33 const char* osrc = src; 34 size_t n = dsize; 35 size_t dlen; 36 37 /* Find the end of dst and adjust bytes left but don't go past end. */ 38 while (n-- != 0 && *dst != '\0') { 39 dst++; 40 } 41 dlen = dst - odst; 42 n = dsize - dlen; 43 44 if (n-- == 0) { 45 return (dlen + strlen(src)); 46 } 47 while (*src != '\0') { 48 if (n != 0) { 49 *dst++ = *src; 50 n--; 51 } 52 src++; 53 } 54 *dst = '\0'; 55 56 return (dlen + (src - osrc)); /* count does not include NUL */ 57 }