missing/strlcpy.c

   1 /*      $OpenBSD: strlcpy.c,v 1.12 2015/01/15 03:54:12 millert Exp $    */
   2
   3 /*
   4  * Copyright (c) 1998, 2015 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 "ruby/missing.h"
  20 #include <sys/types.h>
  21 #include <string.h>
  22
  23 /*
  24  * Copy string src to buffer dst of size dsize.  At most dsize-1
  25  * chars will be copied.  Always NUL terminates (unless dsize == 0).
  26  * Returns strlen(src); if retval >= dsize, truncation occurred.
  27  */
  28 size_t
  29 strlcpy(char *dst, const char *src, size_t dsize)
  30 {
  31         const char *osrc = src;
  32         size_t nleft = dsize;
  33
  34         /* Copy as many bytes as will fit. */
  35         if (nleft != 0) {
  36                 while (--nleft != 0) {
  37                         if ((*dst++ = *src++) == '\0')
  38                                 break;
  39                 }
  40         }
  41
  42         /* Not enough room in dst, add NUL and traverse rest of src. */
  43         if (nleft == 0) {
  44                 if (dsize != 0)
  45                         *dst = '\0';            /* NUL-terminate dst */
  46                 while (*src++)
  47                         ;
  48         }
  49
  50         return(src - osrc - 1); /* count does not include NUL */
  51 }