Back to index

glibc  2.9
ioftell.c
Go to the documentation of this file.
00001 /* Copyright (C) 1993, 1995-2000, 2001, 2002, 2003, 2004
00002    Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.
00019 
00020    As a special exception, if you link the code in this file with
00021    files compiled with a GNU compiler to produce an executable,
00022    that does not cause the resulting executable to be covered by
00023    the GNU Lesser General Public License.  This exception does not
00024    however invalidate any other reasons why the executable file
00025    might be covered by the GNU Lesser General Public License.
00026    This exception applies to code released by its copyright holders
00027    in files containing the exception.  */
00028 
00029 #include "libioP.h"
00030 #include <stdlib.h>
00031 #include <errno.h>
00032 /* ANSI explicily requires setting errno to a positive value on failure. */
00033 
00034 long int
00035 _IO_ftell (fp)
00036      _IO_FILE *fp;
00037 {
00038   _IO_off64_t pos;
00039   CHECK_FILE (fp, -1L);
00040   _IO_acquire_lock (fp);
00041   pos = _IO_seekoff_unlocked (fp, 0, _IO_seek_cur, 0);
00042   if (_IO_in_backup (fp) && pos != _IO_pos_BAD)
00043     {
00044       if (_IO_vtable_offset (fp) != 0 || fp->_mode <= 0)
00045        pos -= fp->_IO_save_end - fp->_IO_save_base;
00046     }
00047   _IO_release_lock (fp);
00048   if (pos == _IO_pos_BAD)
00049     {
00050 #ifdef EIO
00051       if (errno == 0)
00052        __set_errno (EIO);
00053 #endif
00054       return -1L;
00055     }
00056   if ((_IO_off64_t) (long int) pos != pos)
00057     {
00058 #ifdef EOVERFLOW
00059       __set_errno (EOVERFLOW);
00060 #endif
00061       return -1L;
00062     }
00063   return pos;
00064 }
00065 INTDEF(_IO_ftell)
00066 
00067 #ifdef weak_alias
00068 weak_alias (_IO_ftell, ftell)
00069 #endif