compat/strlcpy.c

   1 /*      $OpenBSD: strlcpy.c,v 1.10 2005/08/08 08:05:37 espie Exp $      */
   2
   3 /*
   4  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include <sys/types.h>
  20 #include <string.h>
  21
  22 #include "compat.h"
  23
  24 /*
  25  * Copy src to string dst of size siz.  At most siz-1 characters
  26  * will be copied.  Always NUL terminates (unless siz == 0).
  27  * Returns strlen(src); if retval >= siz, truncation occurred.
  28  */
  29 size_t
  30 strlcpy(char *dst, const char *src, size_t siz)
  31 {
  32         char *d = dst;
  33         const char *s = src;
  34         size_t n = siz;
  35
  36         /* Copy as many bytes as will fit */
  37         if (n != 0 && --n != 0) {
  38                 do {
  39                         if ((*d++ = *s++) == 0)
  40                                 break;
  41                 } while (--n != 0);
  42         }
  43
  44         /* Not enough room in dst, add NUL and traverse rest of src */
  45         if (n == 0) {
  46                 if (siz != 0)
  47                         *d = '\0';              /* NUL-terminate dst */
  48                 while (*s++)
  49                         ;
  50         }
  51
  52         return(s - src - 1);    /* count does not include NUL */
  53 }