glibc/debug/strcat_chk.c

55 lines
1.4 KiB
C

/* Copyright (C) 1991-2020 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>
/* Append SRC on the end of DEST. */
char *
__strcat_chk (char *dest, const char *src, size_t destlen)
{
char *s1 = dest;
const char *s2 = src;
char c;
/* Find the end of the string. */
do
{
if (__glibc_unlikely (destlen-- == 0))
__chk_fail ();
c = *s1++;
}
while (c != '\0');
/* Make S1 point before the next character, so we can increment
it while memory is read (wins on pipelined cpus). */
++destlen;
s1 -= 2;
do
{
if (__glibc_unlikely (destlen-- == 0))
__chk_fail ();
c = *s2++;
*++s1 = c;
}
while (c != '\0');
return dest;
}