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glibc  2.9
wcsncat_chk.c
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00001 /* Copyright (C) 1995, 1996, 1997, 2005 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <wchar.h>
00021 
00022 
00023 /* Append no more than N wide-character of SRC onto DEST.  */
00024 wchar_t *
00025 __wcsncat_chk (wchar_t *dest, const wchar_t *src, size_t n, size_t destlen)
00026 {
00027   wchar_t c;
00028   wchar_t * const s = dest;
00029 
00030   /* Find the end of DEST.  */
00031   do
00032     {
00033       if (__builtin_expect (destlen-- == 0, 0))
00034        __chk_fail ();
00035       c = *dest++;
00036     }
00037   while (c != L'\0');
00038 
00039   /* Make DEST point before next character, so we can increment
00040      it while memory is read (wins on pipelined cpus).  */
00041   ++destlen;
00042   dest -= 2;
00043 
00044   if (n >= 4)
00045     {
00046       size_t n4 = n >> 2;
00047       do
00048        {
00049          if (__builtin_expect (destlen-- == 0, 0))
00050            __chk_fail ();
00051          c = *src++;
00052          *++dest = c;
00053          if (c == L'\0')
00054            return s;
00055          if (__builtin_expect (destlen-- == 0, 0))
00056            __chk_fail ();
00057          c = *src++;
00058          *++dest = c;
00059          if (c == L'\0')
00060            return s;
00061          if (__builtin_expect (destlen-- == 0, 0))
00062            __chk_fail ();
00063          c = *src++;
00064          *++dest = c;
00065          if (c == L'\0')
00066            return s;
00067          if (__builtin_expect (destlen-- == 0, 0))
00068            __chk_fail ();
00069          c = *src++;
00070          *++dest = c;
00071          if (c == L'\0')
00072            return s;
00073        } while (--n4 > 0);
00074       n &= 3;
00075     }
00076 
00077   while (n > 0)
00078     {
00079       if (__builtin_expect (destlen-- == 0, 0))
00080        __chk_fail ();
00081       c = *src++;
00082       *++dest = c;
00083       if (c == L'\0')
00084        return s;
00085       n--;
00086     }
00087 
00088   if (c != L'\0')
00089     {
00090       if (__builtin_expect (destlen-- == 0, 0))
00091        __chk_fail ();
00092       *++dest = L'\0';
00093     }
00094 
00095   return s;
00096 }