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[glibc.git] / libio / ftello.c
blob2d8a8a7167a8f911c6e85363eb1ef212a04b749a
1 /* Copyright (C) 1993, 1995, 1996, 1997, 1998 Free Software Foundation, Inc.
2 This file is part of the GNU IO Library.
4 This library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU General Public License as
6 published by the Free Software Foundation; either version 2, or (at
7 your option) any later version.
9 This library is distributed in the hope that it will be useful, but
10 WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this library; see the file COPYING. If not, write to
16 the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
17 MA 02111-1307, USA.
19 As a special exception, if you link this library with files
20 compiled with a GNU compiler to produce an executable, this does
21 not cause the resulting executable to be covered by the GNU General
22 Public License. This exception does not however invalidate any
23 other reasons why the executable file might be covered by the GNU
24 General Public License. */
26 #include <stdio.h>
27 #include <libioP.h>
28 #include <errno.h>
31 off_t
32 ftello (fp)
33 _IO_FILE *fp;
35 _IO_pos_t pos;
36 CHECK_FILE (fp, -1L);
37 _IO_cleanup_region_start ((void (*) __P ((void *))) _IO_funlockfile, fp);
38 _IO_flockfile (fp);
39 pos = _IO_seekoff (fp, 0, _IO_seek_cur, 0);
40 if (_IO_in_backup (fp))
41 pos -= fp->_IO_save_end - fp->_IO_save_base;
42 _IO_funlockfile (fp);
43 _IO_cleanup_region_end (0);
44 if (pos == _IO_pos_BAD)
46 #ifdef EIO
47 if (errno == 0)
48 __set_errno (EIO);
49 #endif
50 return -1L;
52 return _IO_pos_as_off (pos);