libio/ioftell.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 <errno.h>
  27 /* ANSI explicily requires setting errno to a positive value on failure. */
  28
  29 long int
  30 _IO_ftell (fp)
  31      _IO_FILE* fp;
  32 {
  33   _IO_pos_t pos;
  34   CHECK_FILE (fp, -1L);
  35   __libc_cleanup_region_start ((void (*) __P ((void *))) _IO_funlockfile, fp);
  36   _IO_flockfile (fp);
  37   pos = _IO_seekoff (fp, 0, _IO_seek_cur, 0);
  38   __libc_cleanup_region_end (1);
  39   if (pos == _IO_pos_BAD)
  40     {
  41 #ifdef EIO
  42       if (errno == 0)
  43         __set_errno (EIO);
  44 #endif
  45       return -1L;
  46     }
  47   return _IO_pos_as_off (pos);
  48 }
  49
  50 weak_alias (_IO_ftell, ftell)