libio/ioftell.c

   1 /* Copyright (C) 1993, 1995-2000, 2001, 2002, 2003, 2004
   2    Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.
  19
  20    As a special exception, if you link the code in this file with
  21    files compiled with a GNU compiler to produce an executable,
  22    that does not cause the resulting executable to be covered by
  23    the GNU Lesser General Public License.  This exception does not
  24    however invalidate any other reasons why the executable file
  25    might be covered by the GNU Lesser General Public License.
  26    This exception applies to code released by its copyright holders
  27    in files containing the exception.  */
  28
  29 #include "libioP.h"
  30 #include <stdlib.h>
  31 #include <errno.h>
  32 /* ANSI explicily requires setting errno to a positive value on failure. */
  33
  34 long int
  35 _IO_ftell (fp)
  36      _IO_FILE *fp;
  37 {
  38   _IO_off64_t pos;
  39   CHECK_FILE (fp, -1L);
  40   _IO_acquire_lock (fp);
  41   pos = _IO_seekoff_unlocked (fp, 0, _IO_seek_cur, 0);
  42   if (_IO_in_backup (fp) && pos != _IO_pos_BAD)
  43     {
  44       if (_IO_vtable_offset (fp) != 0 || fp->_mode <= 0)
  45         pos -= fp->_IO_save_end - fp->_IO_save_base;
  46     }
  47   _IO_release_lock (fp);
  48   if (pos == _IO_pos_BAD)
  49     {
  50 #ifdef EIO
  51       if (errno == 0)
  52         __set_errno (EIO);
  53 #endif
  54       return -1L;
  55     }
  56   if ((_IO_off64_t) (long int) pos != pos)
  57     {
  58 #ifdef EOVERFLOW
  59       __set_errno (EOVERFLOW);
  60 #endif
  61       return -1L;
  62     }
  63   return pos;
  64 }
  65 INTDEF(_IO_ftell)
  66
  67 #ifdef weak_alias
  68 weak_alias (_IO_ftell, ftell)
  69 #endif