os/strlcpy.c

   1 /*
   2  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND TODD C. MILLER DISCLAIMS ALL
   9  * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  10  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL TODD C. MILLER BE LIABLE
  11  * FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  13  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  14  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 #ifdef HAVE_DIX_CONFIG_H
  18 #include <dix-config.h>
  19 #endif
  20
  21 #include <sys/types.h>
  22 #include <string.h>
  23 #include "os.h"
  24
  25 #ifndef HAVE_STRLCPY
  26 /*
  27  * Copy src to string dst of size siz.  At most siz-1 characters
  28  * will be copied.  Always NUL terminates (unless siz == 0).
  29  * Returns strlen(src); if retval >= siz, truncation occurred.
  30  */
  31 size_t
  32 strlcpy(char *dst, const char *src, size_t siz)
  33 {
  34     register char *d = dst;
  35     register const char *s = src;
  36     register size_t n = siz;
  37
  38     /* Copy as many bytes as will fit */
  39     if (n != 0 && --n != 0) {
  40         do {
  41             if ((*d++ = *s++) == 0)
  42                 break;
  43         } while (--n != 0);
  44     }
  45
  46     /* Not enough room in dst, add NUL and traverse rest of src */
  47     if (n == 0) {
  48         if (siz != 0)
  49             *d = '\0';          /* NUL-terminate dst */
  50         while (*s++);
  51     }
  52
  53     return s - src - 1;         /* count does not include NUL */
  54 }
  55 #endif