src/common/strlcat.c

   1 /*      $OpenBSD: strlcat.c,v 1.8 2001/05/13 15:40:15 deraadt Exp $     */
   2
   3 /*
   4  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. The name of the author may not be used to endorse or promote products
  16  *    derived from this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
  19  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  20  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
  21  * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  22  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  23  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  24  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  25  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  26  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  27  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char *rcsid = "$OpenBSD: strlcat.c,v 1.8 2001/05/13 15:40:15 deraadt Exp $";
  32 #endif /* LIBC_SCCS and not lint */
  33
  34 #include <sys/types.h>
  35 #include <string.h>
  36
  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         register char *d = dst;
  48         register const char *s = src;
  49         register size_t n = siz;
  50         size_t dlen;
  51
  52         /* Find the end of dst and adjust bytes left but don't go past end */
  53         while (n-- != 0 && *d != '\0')
  54                 d++;
  55         dlen = d - dst;
  56         n = siz - dlen;
  57
  58         if (n == 0)
  59                 return(dlen + strlen(s));
  60         while (*s != '\0') {
  61                 if (n != 1) {
  62                         *d++ = *s;
  63                         n--;
  64                 }
  65                 s++;
  66         }
  67         *d = '\0';
  68
  69         return(dlen + (s - src));       /* count does not include NUL */
  70 }