string/strlcat.c

   1 /*
   2  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. The name of the author may not be used to endorse or promote products
  14  *    derived from this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
  17  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  18  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
  19  * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #if defined(LIBC_SCCS) && !defined(lint)
  29 static char *rcsid = "$OpenBSD: strlcat.c,v 1.2 1999/06/17 16:28:58 millert Exp $";
  30 #endif /* LIBC_SCCS and not lint */
  31 #ifndef lint
  32 static const char rcsid[] =
  33   "$FreeBSD: src/lib/libc/string/strlcat.c,v 1.2.4.2 2001/07/09 23:30:06 obrien Exp $";
  34 #endif
  35
  36 #include <sys/types.h>
  37 #include <string.h>
  38
  39 /*
  40  * Appends src to string dst of size siz (unlike strncat, siz is the
  41  * full size of dst, not space left).  At most siz-1 characters
  42  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
  43  * Returns strlen(initial dst) + strlen(src); if retval >= siz,
  44  * truncation occurred.
  45  */
  46 size_t strlcat(dst, src, siz)
  47         char *dst;
  48         const char *src;
  49         size_t siz;
  50 {
  51         register char *d = dst;
  52         register const char *s = src;
  53         register size_t n = siz;
  54         size_t dlen;
  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 }