src/port/strlcpy.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * strlcpy.c
   4  *        strncpy done right
   5  *
   6  * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
   7  *
   8  *
   9  * IDENTIFICATION
  10  *        src/port/strlcpy.c
  11  *
  12  * This file was taken from OpenBSD and is used on platforms that don't
  13  * provide strlcpy().  The OpenBSD copyright terms follow.
  14  *-------------------------------------------------------------------------
  15  */
  16
  17 /*      $OpenBSD: strlcpy.c,v 1.11 2006/05/05 15:27:38 millert Exp $    */
  18
  19 /*
  20  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
  21  *
  22  * Permission to use, copy, modify, and distribute this software for any
  23  * purpose with or without fee is hereby granted, provided that the above
  24  * copyright notice and this permission notice appear in all copies.
  25  *
  26  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  27  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  28  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  29  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  30  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  31  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  32  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  33  */
  34
  35 #include "c.h"
  36
  37
  38 /*
  39  * Copy src to string dst of size siz.  At most siz-1 characters
  40  * will be copied.  Always NUL terminates (unless siz == 0).
  41  * Returns strlen(src); if retval >= siz, truncation occurred.
  42  * Function creation history:  http://www.gratisoft.us/todd/papers/strlcpy.html
  43  */
  44 size_t
  45 strlcpy(char *dst, const char *src, size_t siz)
  46 {
  47         char       *d = dst;
  48         const char *s = src;
  49         size_t          n = siz;
  50
  51         /* Copy as many bytes as will fit */
  52         if (n != 0)
  53         {
  54                 while (--n != 0)
  55                 {
  56                         if ((*d++ = *s++) == '\0')
  57                                 break;
  58                 }
  59         }
  60
  61         /* Not enough room in dst, add NUL and traverse rest of src */
  62         if (n == 0)
  63         {
  64                 if (siz != 0)
  65                         *d = '\0';                      /* NUL-terminate dst */
  66                 while (*s++)
  67                         ;
  68         }
  69
  70         return (s - src - 1);           /* count does not include NUL */
  71 }