strlcat.c (1723B)
1 /* $OpenBSD: strlcat.c,v 1.15 2015/03/02 21:41:08 millert 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 <string.h> 20 21 /* 22 * Appends src to string dst of size dsize (unlike strncat, dsize is the 23 * full size of dst, not space left). At most dsize-1 characters 24 * will be copied. Always NUL terminates (unless dsize <= strlen(dst)). 25 * Returns strlen(src) + MIN(dsize, strlen(initial dst)). 26 * If retval >= dsize, truncation occurred. 27 */ 28 size_t 29 strlcat(char *dst, const char *src, size_t dsize) 30 { 31 const char *odst = dst; 32 const char *osrc = src; 33 size_t n = dsize; 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 && *dst != '\0') 38 dst++; 39 dlen = dst - odst; 40 n = dsize - dlen; 41 42 if (n-- == 0) 43 return(dlen + strlen(src)); 44 while (*src != '\0') { 45 if (n != 0) { 46 *dst++ = *src; 47 n--; 48 } 49 src++; 50 } 51 *dst = '\0'; 52 53 return(dlen + (src - osrc)); /* count does not include NUL */ 54 }