strlcat.cc (1743B)
1 /* $OpenBSD: strlcat.c,v 1.18 2016/10/16 17:37:39 dtucker Exp $ */ 2 3 /* 4 * Copyright (c) 1998, 2015 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 <stddef.h> 20 #include <string.h> 21 22 /* 23 * Appends src to string dst of size dsize (unlike strncat, dsize is the 24 * full size of dst, not space left). At most dsize-1 characters 25 * will be copied. Always NUL terminates (unless dsize <= strlen(dst)). 26 * Returns strlen(src) + MIN(dsize, strlen(initial dst)). 27 * If retval >= dsize, truncation occurred. 28 */ 29 size_t 30 strlcat(char *dst, const char *src, size_t dsize) 31 { 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 dlen = dst - odst; 41 n = dsize - dlen; 42 43 if (n-- == 0) 44 return(dlen + strlen(src)); 45 while (*src != '\0') { 46 if (n != 0) { 47 *dst++ = *src; 48 n--; 49 } 50 src++; 51 } 52 *dst = '\0'; 53 54 return(dlen + (src - osrc)); /* count does not include NUL */ 55 }