1/* Copyright (C) 1995-2022 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <wchar.h>
19
20
21/* Append SRC on the end of DEST. Check for overflows. */
22wchar_t *
23__wcscat_chk (wchar_t *dest, const wchar_t *src, size_t destlen)
24{
25 wchar_t *s1 = dest;
26 const wchar_t *s2 = src;
27 wchar_t c;
28
29 /* Find the end of the string. */
30 do
31 {
32 if (__glibc_unlikely (destlen-- == 0))
33 __chk_fail ();
34 c = *s1++;
35 }
36 while (c != L'\0');
37
38 /* Make S1 point before the next character, so we can increment
39 it while memory is read (wins on pipelined cpus). */
40 s1 -= 2;
41 ++destlen;
42
43 do
44 {
45 if (__glibc_unlikely (destlen-- == 0))
46 __chk_fail ();
47 c = *s2++;
48 *++s1 = c;
49 }
50 while (c != L'\0');
51
52 return dest;
53}
54

source code of glibc/debug/wcscat_chk.c