debug/wcscat_chk.c

   1 /* Copyright (C) 1995-2015 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <wchar.h>
  20
  21
  22 /* Append SRC on the end of DEST.  Check for overflows.  */
  23 wchar_t *
  24 __wcscat_chk (wchar_t *dest, const wchar_t *src, size_t destlen)
  25 {
  26   wchar_t *s1 = dest;
  27   const wchar_t *s2 = src;
  28   wchar_t c;
  29
  30   /* Find the end of the string.  */
  31   do
  32     {
  33       if (__glibc_unlikely (destlen-- == 0))
  34         __chk_fail ();
  35       c = *s1++;
  36     }
  37   while (c != L'\0');
  38
  39   /* Make S1 point before the next character, so we can increment
  40      it while memory is read (wins on pipelined cpus).  */
  41   s1 -= 2;
  42   ++destlen;
  43
  44   do
  45     {
  46       if (__glibc_unlikely (destlen-- == 0))
  47         __chk_fail ();
  48       c = *s2++;
  49       *++s1 = c;
  50     }
  51   while (c != L'\0');
  52
  53   return dest;
  54 }