debug/wcsncat_chk.c

   1 /* Copyright (C) 1995, 1996, 1997, 2005 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <wchar.h>
  21
  22
  23 /* Append no more than N wide-character of SRC onto DEST.  */
  24 wchar_t *
  25 __wcsncat_chk (wchar_t *dest, const wchar_t *src, size_t n, size_t destlen)
  26 {
  27   wchar_t c;
  28   wchar_t * const s = dest;
  29
  30   /* Find the end of DEST.  */
  31   do
  32     {
  33       if (__builtin_expect (destlen-- == 0, 0))
  34         __chk_fail ();
  35       c = *dest++;
  36     }
  37   while (c != L'\0');
  38
  39   /* Make DEST point before next character, so we can increment
  40      it while memory is read (wins on pipelined cpus).  */
  41   ++destlen;
  42   dest -= 2;
  43
  44   if (n >= 4)
  45     {
  46       size_t n4 = n >> 2;
  47       do
  48         {
  49           if (__builtin_expect (destlen-- == 0, 0))
  50             __chk_fail ();
  51           c = *src++;
  52           *++dest = c;
  53           if (c == L'\0')
  54             return s;
  55           if (__builtin_expect (destlen-- == 0, 0))
  56             __chk_fail ();
  57           c = *src++;
  58           *++dest = c;
  59           if (c == L'\0')
  60             return s;
  61           if (__builtin_expect (destlen-- == 0, 0))
  62             __chk_fail ();
  63           c = *src++;
  64           *++dest = c;
  65           if (c == L'\0')
  66             return s;
  67           if (__builtin_expect (destlen-- == 0, 0))
  68             __chk_fail ();
  69           c = *src++;
  70           *++dest = c;
  71           if (c == L'\0')
  72             return s;
  73         } while (--n4 > 0);
  74       n &= 3;
  75     }
  76
  77   while (n > 0)
  78     {
  79       if (__builtin_expect (destlen-- == 0, 0))
  80         __chk_fail ();
  81       c = *src++;
  82       *++dest = c;
  83       if (c == L'\0')
  84         return s;
  85       n--;
  86     }
  87
  88   if (c != L'\0')
  89     {
  90       if (__builtin_expect (destlen-- == 0, 0))
  91         __chk_fail ();
  92       *++dest = L'\0';
  93     }
  94
  95   return s;
  96 }