lib/libc/string/strlcpy.c

   1 /*      $OpenBSD: strlcpy.c,v 1.4 1999/05/01 18:56:41 millert Exp $     */
   2
   3 /*
   4  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. The name of the author may not be used to endorse or promote products
  16  *    derived from this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
  19  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  20  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
  21  * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  22  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  23  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  24  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  25  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  26  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  27  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  *
  29  * $OpenBSD: strlcpy.c,v 1.4 1999/05/01 18:56:41 millert Exp $
  30  * $FreeBSD: src/lib/libc/string/strlcpy.c,v 1.2.4.1 2001/07/09 23:30:06 obrien Exp $
  31  * $DragonFly: src/lib/libc/string/strlcpy.c,v 1.4 2005/09/18 16:32:34 asmodai Exp $
  32  */
  33
  34 #include <sys/types.h>
  35 #include <string.h>
  36
  37 /*
  38  * Copy src to string dst of size siz.  At most siz-1 characters
  39  * will be copied.  Always NUL terminates (unless siz == 0).
  40  * Returns strlen(src); if retval >= siz, truncation occurred.
  41  */
  42 size_t strlcpy(char *dst, const char *src, size_t siz)
  43 {
  44         char *d = dst;
  45         const char *s = src;
  46         size_t n = siz;
  47
  48         /* Copy as many bytes as will fit */
  49         if (n != 0 && --n != 0) {
  50                 do {
  51                         if ((*d++ = *s++) == 0)
  52                                 break;
  53                 } while (--n != 0);
  54         }
  55
  56         /* Not enough room in dst, add NUL and traverse rest of src */
  57         if (n == 0) {
  58                 if (siz != 0)
  59                         *d = '\0';              /* NUL-terminate dst */
  60                 while (*s++)
  61                         ;
  62         }
  63
  64         return(s - src - 1);    /* count does not include NUL */
  65 }