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/* Copyright (C) 1991-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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
<https://www.gnu.org/licenses/>. */
#include <string.h>
#include <memcopy.h>
char *
__strncat_chk (char *s1, const char *s2, size_t n, size_t s1len)
{
char c;
char *s = s1;
/* Find the end of S1. */
do
{
if (__glibc_unlikely (s1len-- == 0))
__chk_fail ();
c = *s1++;
}
while (c != '\0');
/* Make S1 point before next character, so we can increment
it while memory is read (wins on pipelined cpus). */
++s1len;
s1 -= 2;
if (n >= 4)
{
size_t n4 = n >> 2;
do
{
if (__glibc_unlikely (s1len-- == 0))
__chk_fail ();
c = *s2++;
*++s1 = c;
if (c == '\0')
return s;
if (__glibc_unlikely (s1len-- == 0))
__chk_fail ();
c = *s2++;
*++s1 = c;
if (c == '\0')
return s;
if (__glibc_unlikely (s1len-- == 0))
__chk_fail ();
c = *s2++;
*++s1 = c;
if (c == '\0')
return s;
if (__glibc_unlikely (s1len-- == 0))
__chk_fail ();
c = *s2++;
*++s1 = c;
if (c == '\0')
return s;
} while (--n4 > 0);
n &= 3;
}
while (n > 0)
{
if (__glibc_unlikely (s1len-- == 0))
__chk_fail ();
c = *s2++;
*++s1 = c;
if (c == '\0')
return s;
n--;
}
if (c != '\0')
{
if (__glibc_unlikely (s1len-- == 0))
__chk_fail ();
*++s1 = '\0';
}
return s;
}
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