newlib/libc/string/wcslcat.c

   1 /*
   2 FUNCTION
   3         <<wcslcat>>---concatenate wide-character strings to specified length
   4
   5 SYNOPSIS
   6         #include <wchar.h>
   7         size_t wcslcat(wchar_t *<[dst]>, const wchar_t *<[src]>, size_t <[siz]>);
   8
   9 DESCRIPTION
  10         The <<wcslcat>> function appends wide characters from <[src]> to
  11         end of the <[dst]> wide-character string so that the resultant
  12         wide-character string is not more than <[siz]> wide characters
  13         including the terminating null wide-character code.  A terminating
  14         null wide character is always added unless <[siz]> is 0.  Thus,
  15         the maximum number of wide characters that can be appended from
  16         <[src]> is <[siz]> - 1. If copying takes place between objects
  17         that overlap, the behaviour is undefined.
  18
  19 RETURNS
  20         Wide-character string length of initial <[dst]> plus the
  21         wide-character string length of <[src]> (does not include
  22         terminating null wide-characters).  If the return value is
  23         greater than or equal to <[siz]>, then truncation occurred and
  24         not all wide characters from <[src]> were appended.
  25
  26 PORTABILITY
  27 No supporting OS subroutines are required.
  28 */
  29
  30 /*      $OpenBSD: wcslcat.c,v 1.7 2019/01/25 00:19:25 millert Exp $     */
  31
  32 /*
  33  * Copyright (c) 1998, 2015 Todd C. Miller <millert@openbsd.org>
  34  *
  35  * Permission to use, copy, modify, and distribute this software for any
  36  * purpose with or without fee is hereby granted, provided that the above
  37  * copyright notice and this permission notice appear in all copies.
  38  *
  39  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  40  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  41  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  42  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  43  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  44  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  45  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  46  */
  47
  48 #include <sys/types.h>
  49 #include <wchar.h>
  50
  51 /*
  52  * Appends src to string dst of size dsize (unlike strncat, dsize is the
  53  * full size of dst, not space left).  At most dsize-1 characters
  54  * will be copied.  Always NUL terminates (unless dsize <= wcslen(dst)).
  55  * Returns wcslen(src) + MIN(dsize, wcslen(initial dst)).
  56  * If retval >= siz, truncation occurred.
  57  */
  58 size_t
  59 wcslcat (wchar_t *dst,
  60         const wchar_t *src,
  61         size_t dsize)
  62 {
  63         const wchar_t *odst = dst;
  64         const wchar_t *osrc = src;
  65         size_t n = dsize;
  66         size_t dlen;
  67
  68         /* Find the end of dst and adjust bytes left but don't go past end. */
  69         while (n-- != 0 && *dst != L'\0')
  70                 dst++;
  71         dlen = dst - odst;
  72         n = dsize - dlen;
  73
  74         if (n-- == 0)
  75                 return(dlen + wcslen(src));
  76         while (*src != L'\0') {
  77                 if (n != 0) {
  78                         *dst++ = *src;
  79                         n--;
  80                 }
  81                 src++;
  82         }
  83         *dst = L'\0';
  84
  85         return(dlen + (src - osrc));    /* count does not include NUL */
  86 }