sys/libkern/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  * $OpenBSD: strlcat.c,v 1.2 1999/06/17 16:28:58 millert Exp $
  28  * $FreeBSD: src/lib/libc/string/strlcat.c,v 1.2.4.2 2001/07/09 23:30:06 obrien Exp $
  29  * $DragonFly: src/sys/libkern/strlcat.c,v 1.5 2007/06/07 23:45:02 dillon Exp $
  30  */
  31
  32 #include <sys/types.h>
  33 #include <sys/libkern.h>
  34
  35 /*
  36  * Appends src to string dst of size siz (unlike strncat, siz is the
  37  * full size of dst, not space left).  At most siz-1 characters
  38  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
  39  * Returns strlen(initial dst) + strlen(src); if retval >= siz,
  40  * truncation occurred.
  41  */
  42 size_t
  43 strlcat(char *dst, const char *src, size_t siz)
  44 {
  45         char *d = dst;
  46         const char *s = src;
  47         size_t n = siz;
  48         size_t dlen;
  49
  50         /* Find the end of dst and adjust bytes left but don't go past end */
  51         while (n-- != 0 && *d != '\0')
  52                 d++;
  53         dlen = d - dst;
  54         n = siz - dlen;
  55
  56         if (n == 0)
  57                 return(dlen + strlen(s));
  58         while (*s != '\0') {
  59                 if (n != 1) {
  60                         *d++ = *s;
  61                         n--;
  62                 }
  63                 s++;
  64         }
  65         *d = '\0';
  66
  67         return(dlen + (s - src));       /* count does not include NUL */
  68 }