libio/fileno.c

   1 /*
   2 Copyright (C) 1993, 1995, 1996 Free Software Foundation, Inc.
   3
   4 This file is part of the GNU IO Library.  This library is free
   5 software; you can redistribute it and/or modify it under the
   6 terms of the GNU General Public License as published by the
   7 Free Software Foundation; either version 2, or (at your option)
   8 any later version.
   9
  10 This library is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this library; see the file COPYING.  If not, write to the Free
  17 Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18
  19 As a special exception, if you link this library with files
  20 compiled with a GNU compiler to produce an executable, this does not cause
  21 the resulting executable to be covered by the GNU General Public License.
  22 This exception does not however invalidate any other reasons why
  23 the executable file might be covered by the GNU General Public License. */
  24
  25 #include "libioP.h"
  26 #include "stdio.h"
  27
  28 int
  29 fileno (fp)
  30      _IO_FILE* fp;
  31 {
  32   CHECK_FILE (fp, EOF);
  33
  34   if (!(fp->_flags & _IO_IS_FILEBUF))
  35     return EOF;
  36
  37   return _IO_fileno (fp);
  38 }
  39
  40 #ifdef _IO_MTSAFE_IO
  41 /* The fileno implementation for libio does not require locking because
  42    it only accesses once a single variable and this is already atomic
  43    (at least at thread level).  */
  44
  45 weak_alias (fileno_unlocked, fileno)
  46 weak_alias (fileno_locked, fileno)
  47 #endif