1 /* $OpenBSD: strlcat.c,v 1.15 2015/03/02 21:41:08 millert Exp $ */ 2 3 /* 4 * SPDX-License-Identifier: ISC 5 * 6 * Copyright (c) 1998, 2015 Todd C. Miller <Todd.Miller@courtesan.com> 7 * 8 * Permission to use, copy, modify, and distribute this software for any 9 * purpose with or without fee is hereby granted, provided that the above 10 * copyright notice and this permission notice appear in all copies. 11 * 12 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 13 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 14 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 15 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 16 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 17 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 18 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 19 */ 20 21 #include <stdio.h> 22 #include <string.h> 23 24 #include <ssp/string.h> 25 26 /* 27 * Appends src to string dst of size dsize (unlike strncat, dsize is the 28 * full size of dst, not space left). At most dsize-1 characters 29 * will be copied. Always NUL terminates (unless dsize <= strlen(dst)). 30 * Returns strlen(src) + MIN(dsize, strlen(initial dst)). 31 * If retval >= dsize, truncation occurred. 32 */ 33 size_t 34 __strlcat_chk(char * __restrict dst, const char * __restrict src, size_t dsize, 35 size_t dbufsize) 36 { 37 const char *odst = dst; 38 const char *osrc = src; 39 size_t n = dsize; 40 size_t dlen; 41 42 if (dsize > dbufsize) 43 __chk_fail(); 44 45 /* Find the end of dst and adjust bytes left but don't go past end. */ 46 while (n-- != 0 && *dst != '\0') { 47 dst++; 48 } 49 50 dlen = dst - odst; 51 n = dsize - dlen; 52 53 if (n-- == 0) 54 return (dlen + strlen(src)); 55 while (*src != '\0') { 56 if (n != 0) { 57 if (dbufsize-- == 0) 58 __chk_fail(); 59 *dst++ = *src; 60 n--; 61 } 62 63 src++; 64 } 65 66 if (dbufsize-- == 0) 67 __chk_fail(); 68 *dst = '\0'; 69 return (dlen + (src - osrc)); /* count does not include NUL */ 70 } 71