glibc/debug/wcsncat_chk.c

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/* Copyright (C) 1995-2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <wchar.h>
/* Append no more than N wide-character of SRC onto DEST. */
wchar_t *
__wcsncat_chk (wchar_t *dest, const wchar_t *src, size_t n, size_t destlen)
{
wchar_t c;
wchar_t * const s = dest;
/* Find the end of DEST. */
do
{
if (__glibc_unlikely (destlen-- == 0))
__chk_fail ();
c = *dest++;
}
while (c != L'\0');
/* Make DEST point before next character, so we can increment
it while memory is read (wins on pipelined cpus). */
++destlen;
dest -= 2;
if (n >= 4)
{
size_t n4 = n >> 2;
do
{
if (__glibc_unlikely (destlen-- == 0))
__chk_fail ();
c = *src++;
*++dest = c;
if (c == L'\0')
return s;
if (__glibc_unlikely (destlen-- == 0))
__chk_fail ();
c = *src++;
*++dest = c;
if (c == L'\0')
return s;
if (__glibc_unlikely (destlen-- == 0))
__chk_fail ();
c = *src++;
*++dest = c;
if (c == L'\0')
return s;
if (__glibc_unlikely (destlen-- == 0))
__chk_fail ();
c = *src++;
*++dest = c;
if (c == L'\0')
return s;
} while (--n4 > 0);
n &= 3;
}
while (n > 0)
{
if (__glibc_unlikely (destlen-- == 0))
__chk_fail ();
c = *src++;
*++dest = c;
if (c == L'\0')
return s;
n--;
}
if (c != L'\0')
{
if (__glibc_unlikely (destlen-- == 0))
__chk_fail ();
*++dest = L'\0';
}
return s;
}