1/* An ftello() function that works around platform bugs.
2   Copyright (C) 2007, 2009-2014 Free Software Foundation, Inc.
3
4   This program is free software: you can redistribute it and/or modify
5   it under the terms of the GNU General Public License as published by
6   the Free Software Foundation; either version 3 of the License, or
7   (at your option) any later version.
8
9   This program is distributed in the hope that it will be useful,
10   but WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12   GNU General Public License for more details.
13
14   You should have received a copy of the GNU General Public License
15   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
16
17#include <config.h>
18
19/* Specification.  */
20#include <stdio.h>
21
22/* Get lseek.  */
23#include <unistd.h>
24
25#include "stdio-impl.h"
26
27off_t
28ftello (FILE *fp)
29#undef ftello
30#if !HAVE_FTELLO
31# undef ftell
32# define ftello ftell
33#endif
34#if _GL_WINDOWS_64_BIT_OFF_T
35# undef ftello
36# if HAVE__FTELLI64 /* msvc, mingw64 */
37#  define ftello _ftelli64
38# else /* mingw */
39#  define ftello ftello64
40# endif
41#endif
42{
43#if LSEEK_PIPE_BROKEN
44  /* mingw gives bogus answers rather than failure on non-seekable files.  */
45  if (lseek (fileno (fp), 0, SEEK_CUR) == -1)
46    return -1;
47#endif
48
49#if FTELLO_BROKEN_AFTER_SWITCHING_FROM_READ_TO_WRITE /* Solaris */
50  /* The Solaris stdio leaves the _IOREAD flag set after reading from a file
51     reaches EOF and the program then starts writing to the file.  ftello
52     gets confused by this.  */
53  if (fp_->_flag & _IOWRT)
54    {
55      off_t pos;
56
57      /* Call ftello nevertheless, for the side effects that it does on fp.  */
58      ftello (fp);
59
60      /* Compute the file position ourselves.  */
61      pos = lseek (fileno (fp), (off_t) 0, SEEK_CUR);
62      if (pos >= 0)
63        {
64          if ((fp_->_flag & _IONBF) == 0 && fp_->_base != NULL)
65            pos += fp_->_ptr - fp_->_base;
66        }
67      return pos;
68    }
69#endif
70
71#if defined __SL64 && defined __SCLE /* Cygwin */
72  if ((fp->_flags & __SL64) == 0)
73    {
74      /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit
75         mode; but has an ftello that requires 64-bit mode.  */
76      FILE *tmp = fopen ("/dev/null", "r");
77      if (!tmp)
78        return -1;
79      fp->_flags |= __SL64;
80      fp->_seek64 = tmp->_seek64;
81      fclose (tmp);
82    }
83#endif
84  return ftello (fp);
85}
86