sys/libkern/strlcpy.c

   1 /*
   2  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. The name of the author may not be used to endorse or promote products
  14  *    derived from this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
  17  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  18  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
  19  * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  *
  27  * $OpenBSD: strlcpy.c,v 1.4 1999/05/01 18:56:41 millert Exp $
  28  * $FreeBSD: src/lib/libc/string/strlcpy.c,v 1.2.4.1 2001/07/09 23:30:06 obrien Exp $
  29  * $DragonFly: src/sys/libkern/strlcpy.c,v 1.5 2007/06/07 23:45:02 dillon Exp $
  30  */
  31
  32 #include <sys/types.h>
  33 #include <sys/libkern.h>
  34
  35 /*
  36  * Copy src to string dst of size siz.  At most siz-1 characters
  37  * will be copied.  Always NUL terminates (unless siz == 0).
  38  * Returns strlen(src); if retval >= siz, truncation occurred.
  39  */
  40 size_t
  41 strlcpy(char *dst, const char *src, size_t siz)
  42 {
  43         char *d = dst;
  44         const char *s = src;
  45         size_t n = siz;
  46
  47         /* Copy as many bytes as will fit */
  48         if (n != 0 && --n != 0) {
  49                 do {
  50                         if ((*d++ = *s++) == 0)
  51                                 break;
  52                 } while (--n != 0);
  53         }
  54
  55         /* Not enough room in dst, add NUL and traverse rest of src */
  56         if (n == 0) {
  57                 if (siz != 0)
  58                         *d = '\0';              /* NUL-terminate dst */
  59                 while (*s++)
  60                         ;
  61         }
  62
  63         return(s - src - 1);    /* count does not include NUL */
  64 }