Blame debug/vsnprintf_chk.c

Packit 6c4009
/* Copyright (C) 1991-2018 Free Software Foundation, Inc.
Packit 6c4009
   This file is part of the GNU C Library.
Packit 6c4009
Packit 6c4009
   The GNU C Library is free software; you can redistribute it and/or
Packit 6c4009
   modify it under the terms of the GNU Lesser General Public
Packit 6c4009
   License as published by the Free Software Foundation; either
Packit 6c4009
   version 2.1 of the License, or (at your option) any later version.
Packit 6c4009
Packit 6c4009
   The GNU C Library is distributed in the hope that it will be useful,
Packit 6c4009
   but WITHOUT ANY WARRANTY; without even the implied warranty of
Packit 6c4009
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Packit 6c4009
   Lesser General Public License for more details.
Packit 6c4009
Packit 6c4009
   You should have received a copy of the GNU Lesser General Public
Packit 6c4009
   License along with the GNU C Library; if not, see
Packit 6c4009
   <http://www.gnu.org/licenses/>.  */
Packit 6c4009
Packit 6c4009
#include <stdarg.h>
Packit 6c4009
#include <stdio.h>
Packit 6c4009
#include "../libio/libioP.h"
Packit 6c4009
#include "../libio/strfile.h"
Packit 6c4009
Packit 6c4009
extern const struct _IO_jump_t _IO_strn_jumps libio_vtable attribute_hidden;
Packit 6c4009
Packit 6c4009
/* Write formatted output into S, according to the format
Packit 6c4009
   string FORMAT, writing no more than MAXLEN characters.  */
Packit 6c4009
/* VARARGS5 */
Packit 6c4009
int
Packit 6c4009
___vsnprintf_chk (char *s, size_t maxlen, int flags, size_t slen,
Packit 6c4009
		  const char *format, va_list args)
Packit 6c4009
{
Packit 6c4009
  /* XXX Maybe for less strict version do not fail immediately.
Packit 6c4009
     Though, maxlen is supposed to be the size of buffer pointed
Packit 6c4009
     to by s, so a conforming program can't pass such maxlen
Packit 6c4009
     to *snprintf.  */
Packit 6c4009
  if (__glibc_unlikely (slen < maxlen))
Packit 6c4009
    __chk_fail ();
Packit 6c4009
Packit 6c4009
  _IO_strnfile sf;
Packit 6c4009
  int ret;
Packit 6c4009
#ifdef _IO_MTSAFE_IO
Packit 6c4009
  sf.f._sbf._f._lock = NULL;
Packit 6c4009
#endif
Packit 6c4009
Packit 6c4009
  /* We need to handle the special case where MAXLEN is 0.  Use the
Packit 6c4009
     overflow buffer right from the start.  */
Packit 6c4009
  if (maxlen == 0)
Packit 6c4009
    {
Packit 6c4009
      s = sf.overflow_buf;
Packit 6c4009
      maxlen = sizeof (sf.overflow_buf);
Packit 6c4009
    }
Packit 6c4009
Packit 6c4009
  _IO_no_init (&sf.f._sbf._f, _IO_USER_LOCK, -1, NULL, NULL);
Packit 6c4009
  _IO_JUMPS (&sf.f._sbf) = &_IO_strn_jumps;
Packit 6c4009
  s[0] = '\0';
Packit 6c4009
Packit 6c4009
  /* For flags > 0 (i.e. __USE_FORTIFY_LEVEL > 1) request that %n
Packit 6c4009
     can only come from read-only format strings.  */
Packit 6c4009
  if (flags > 0)
Packit 6c4009
    sf.f._sbf._f._flags2 |= _IO_FLAGS2_FORTIFY;
Packit 6c4009
Packit 6c4009
  _IO_str_init_static_internal (&sf.f, s, maxlen - 1, s);
Packit 6c4009
  ret = _IO_vfprintf (&sf.f._sbf._f, format, args);
Packit 6c4009
Packit 6c4009
  if (sf.f._sbf._f._IO_buf_base != sf.overflow_buf)
Packit 6c4009
    *sf.f._sbf._f._IO_write_ptr = '\0';
Packit 6c4009
  return ret;
Packit 6c4009
}
Packit 6c4009
ldbl_hidden_def (___vsnprintf_chk, __vsnprintf_chk)
Packit 6c4009
ldbl_strong_alias (___vsnprintf_chk, __vsnprintf_chk)