src/port/strlcat.c

   1 /*
   2  * src/port/strlcat.c
   3  *
   4  *      $OpenBSD: strlcat.c,v 1.13 2005/08/08 08:05:37 espie Exp $      */
   5
   6 /*
   7  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
   8  *
   9  * Permission to use, copy, modify, and distribute this software for any
  10  * purpose with or without fee is hereby granted, provided that the above
  11  * copyright notice and this permission notice appear in all copies.
  12  *
  13  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  14  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  15  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  16  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  17  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  18  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  19  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  20  */
  21
  22 #include "c.h"
  23
  24
  25 /*
  26  * Appends src to string dst of size siz (unlike strncat, siz is the
  27  * full size of dst, not space left).  At most siz-1 characters
  28  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
  29  * Returns strlen(src) + MIN(siz, strlen(initial dst)).
  30  * If retval >= siz, truncation occurred.
  31  */
  32 size_t
  33 strlcat(char *dst, const char *src, size_t siz)
  34 {
  35         char       *d = dst;
  36         const char *s = src;
  37         size_t          n = siz;
  38         size_t          dlen;
  39
  40         /* Find the end of dst and adjust bytes left but don't go past end */
  41         while (n-- != 0 && *d != '\0')
  42                 d++;
  43         dlen = d - dst;
  44         n = siz - dlen;
  45
  46         if (n == 0)
  47                 return (dlen + strlen(s));
  48         while (*s != '\0')
  49         {
  50                 if (n != 1)
  51                 {
  52                         *d++ = *s;
  53                         n--;
  54                 }
  55                 s++;
  56         }
  57         *d = '\0';
  58
  59         return (dlen + (s - src));      /* count does not include NUL */
  60 }