debug/vswprintf_chk.c

   1 /* Copyright (C) 1991,1995,1997,1998,2004,2005 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <stdarg.h>
  20 #include <wchar.h>
  21 #include "../libio/libioP.h"
  22 #include "../libio/strfile.h"
  23
  24
  25 /* Write formatted output into S, according to the format
  26    string FORMAT, writing no more than MAXLEN characters.  */
  27 /* VARARGS5 */
  28 int
  29 __vswprintf_chk (wchar_t *s, size_t maxlen, int flags, size_t slen,
  30                  const wchar_t *format, va_list args)
  31 {
  32   /* XXX Maybe for less strict version do not fail immediately.
  33      Though, maxlen is supposed to be the size of buffer pointed
  34      to by s, so a conforming program can't pass such maxlen
  35      to *snprintf.  */
  36   if (__builtin_expect (slen < maxlen, 0))
  37     __chk_fail ();
  38
  39   _IO_wstrnfile sf;
  40   struct _IO_wide_data wd;
  41   int ret;
  42 #ifdef _IO_MTSAFE_IO
  43   sf.f._sbf._f._lock = NULL;
  44 #endif
  45
  46   /* We need to handle the special case where MAXLEN is 0.  Use the
  47      overflow buffer right from the start.  */
  48   if (__builtin_expect (maxlen == 0, 0))
  49     /* Since we have to write at least the terminating L'\0' a buffer
  50        length of zero always makes the function fail.  */
  51     return -1;
  52
  53   _IO_no_init (&sf.f._sbf._f, _IO_USER_LOCK, 0, &wd, &_IO_wstrn_jumps);
  54   _IO_fwide (&sf.f._sbf._f, 1);
  55   s[0] = L'\0';
  56
  57   /* For flags > 0 (i.e. __USE_FORTIFY_LEVEL > 1) request that %n
  58      can only come from read-only format strings.  */
  59   if (flags > 0)
  60     sf.f._sbf._f._flags2 |= _IO_FLAGS2_FORTIFY;
  61
  62   _IO_wstr_init_static (&sf.f._sbf._f, s, maxlen - 1, s);
  63   ret = _IO_vfwprintf ((_IO_FILE *) &sf.f._sbf, format, args);
  64
  65   if (sf.f._sbf._f._wide_data->_IO_buf_base == sf.overflow_buf)
  66     /* ISO C99 requires swprintf/vswprintf to return an error if the
  67        output does not fit int he provided buffer.  */
  68     return -1;
  69
  70   /* Terminate the string.  */
  71   *sf.f._sbf._f._wide_data->_IO_write_ptr = '\0';
  72
  73   return ret;
  74 }
  75 libc_hidden_def (__vswprintf_chk)