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      1 /*	$NetBSD: strlcat.c,v 1.4 2013/01/23 07:57:27 matt Exp $	*/
      2 /*	$OpenBSD: strlcat.c,v 1.10 2003/04/12 21:56:39 millert Exp $	*/
      3 
      4 /*
      5  * Copyright (c) 1998 Todd C. Miller <Todd.Miller (at) 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 TODD C. MILLER DISCLAIMS ALL
     12  * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
     13  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL TODD C. MILLER BE LIABLE
     14  * FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
     16  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
     17  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     18  */
     19 
     20 #include "config.h"
     21 
     22 #if defined(LIBC_SCCS) && !defined(lint)
     23 __RCSID("$NetBSD: strlcat.c,v 1.4 2013/01/23 07:57:27 matt Exp $");
     24 #endif /* LIBC_SCCS and not lint */
     25 
     26 #include <sys/types.h>
     27 #include <assert.h>
     28 #include <string.h>
     29 
     30 #ifdef _LIBC
     31 # ifdef __weak_alias
     32 __weak_alias(strlcat, _strlcat)
     33 # endif
     34 #endif
     35 
     36 #if !HAVE_STRLCAT
     37 /*
     38  * Appends src to string dst of size siz (unlike strncat, siz is the
     39  * full size of dst, not space left).  At most siz-1 characters
     40  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
     41  * Returns strlen(src) + MIN(siz, strlen(initial dst)).
     42  * If retval >= siz, truncation occurred.
     43  */
     44 size_t
     45 strlcat(char *dst, const char *src, size_t siz)
     46 {
     47 #if 1
     48 	char *d = dst;
     49 	const char *s = src;
     50 	size_t n = siz;
     51 	size_t dlen;
     52 
     53 	_DIAGASSERT(dst != NULL);
     54 	_DIAGASSERT(src != NULL);
     55 
     56 	/* Find the end of dst and adjust bytes left but don't go past end */
     57 	while (n-- != 0 && *d != '\0')
     58 		d++;
     59 	dlen = d - dst;
     60 	n = siz - dlen;
     61 
     62 	if (n == 0)
     63 		return(dlen + strlen(s));
     64 	while (*s != '\0') {
     65 		if (n != 1) {
     66 			*d++ = *s;
     67 			n--;
     68 		}
     69 		s++;
     70 	}
     71 	*d = '\0';
     72 
     73 	return(dlen + (s - src));	/* count does not include NUL */
     74 #else
     75 	_DIAGASSERT(dst != NULL);
     76 	_DIAGASSERT(src != NULL);
     77 
     78 	/*
     79 	 * Find length of string in dst (maxing out at siz).
     80 	 */
     81 	size_t dlen = strnlen(dst, siz);
     82 
     83 	/*
     84 	 * Copy src into any remaining space in dst (truncating if needed).
     85 	 * Note strlcpy(dst, src, 0) returns strlen(src).
     86 	 */
     87 	return dlen + strlcpy(dst + dlen, src, siz - dlen);
     88 #endif
     89 }
     90 #endif
     91