glibc/debug/vswprintf_chk.c

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/* Copyright (C) 1991-2013 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
<http://www.gnu.org/licenses/>. */
#include <stdarg.h>
#include <wchar.h>
#include "../libio/libioP.h"
#include "../libio/strfile.h"
/* Write formatted output into S, according to the format
string FORMAT, writing no more than MAXLEN characters. */
/* VARARGS5 */
int
__vswprintf_chk (wchar_t *s, size_t maxlen, int flags, size_t slen,
const wchar_t *format, va_list args)
{
/* XXX Maybe for less strict version do not fail immediately.
Though, maxlen is supposed to be the size of buffer pointed
to by s, so a conforming program can't pass such maxlen
to *snprintf. */
if (__builtin_expect (slen < maxlen, 0))
__chk_fail ();
_IO_wstrnfile sf;
struct _IO_wide_data wd;
int ret;
#ifdef _IO_MTSAFE_IO
sf.f._sbf._f._lock = NULL;
#endif
/* We need to handle the special case where MAXLEN is 0. Use the
overflow buffer right from the start. */
if (__builtin_expect (maxlen == 0, 0))
/* Since we have to write at least the terminating L'\0' a buffer
length of zero always makes the function fail. */
return -1;
_IO_no_init (&sf.f._sbf._f, _IO_USER_LOCK, 0, &wd, &_IO_wstrn_jumps);
_IO_fwide (&sf.f._sbf._f, 1);
s[0] = L'\0';
/* For flags > 0 (i.e. __USE_FORTIFY_LEVEL > 1) request that %n
can only come from read-only format strings. */
if (flags > 0)
sf.f._sbf._f._flags2 |= _IO_FLAGS2_FORTIFY;
_IO_wstr_init_static (&sf.f._sbf._f, s, maxlen - 1, s);
ret = _IO_vfwprintf ((_IO_FILE *) &sf.f._sbf, format, args);
if (sf.f._sbf._f._wide_data->_IO_buf_base == sf.overflow_buf)
/* ISO C99 requires swprintf/vswprintf to return an error if the
output does not fit int he provided buffer. */
return -1;
/* Terminate the string. */
*sf.f._sbf._f._wide_data->_IO_write_ptr = '\0';
return ret;
}
libc_hidden_def (__vswprintf_chk)