usr/src/boot/lib/libc/string/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 <sys/cdefs.h>
  20 __FBSDID("$FreeBSD$");
  21
  22 #include <sys/types.h>
  23 #include <string.h>
  24
  25 /*
  26  * Copy string src to buffer dst of size dsize.  At most dsize-1
  27  * chars will be copied.  Always NUL terminates (unless dsize == 0).
  28  * Returns strlen(src); if retval >= dsize, truncation occurred.
  29  */
  30 size_t
  31 strlcpy(char * __restrict dst, const char * __restrict src, size_t dsize)
  32 {
  33         const char *osrc = src;
  34         size_t nleft = dsize;
  35
  36         /* Copy as many bytes as will fit. */
  37         if (nleft != 0) {
  38                 while (--nleft != 0) {
  39                         if ((*dst++ = *src++) == '\0')
  40                                 break;
  41                 }
  42         }
  43
  44         /* Not enough room in dst, add NUL and traverse rest of src. */
  45         if (nleft == 0) {
  46                 if (dsize != 0)
  47                         *dst = '\0';            /* NUL-terminate dst */
  48                 while (*src++)
  49                         ;
  50         }
  51
  52         return(src - osrc - 1); /* count does not include NUL */
  53 }