1/* An fseeko() function that, together with fflush(), is POSIX compliant.
2   Copyright (C) 2007-2014 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, or (at your option)
7   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 along
15   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 off_t, lseek, _POSIX_VERSION.  */
23#include <unistd.h>
24
25#include "stdio-impl.h"
26
27int
28fseeko (FILE *fp, off_t offset, int whence)
29#undef fseeko
30#if !HAVE_FSEEKO
31# undef fseek
32# define fseeko fseek
33#endif
34#if _GL_WINDOWS_64_BIT_OFF_T
35# undef fseeko
36# if HAVE__FSEEKI64 /* msvc, mingw64 */
37#  define fseeko _fseeki64
38# else /* mingw */
39#  define fseeko fseeko64
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 EOF;
47#endif
48
49  /* These tests are based on fpurge.c.  */
50#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
51  if (fp->_IO_read_end == fp->_IO_read_ptr
52      && fp->_IO_write_ptr == fp->_IO_write_base
53      && fp->_IO_save_base == NULL)
54#elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin */
55# if defined __SL64 && defined __SCLE /* Cygwin */
56  if ((fp->_flags & __SL64) == 0)
57    {
58      /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit
59         mode; but has an fseeko that requires 64-bit mode.  */
60      FILE *tmp = fopen ("/dev/null", "r");
61      if (!tmp)
62        return -1;
63      fp->_flags |= __SL64;
64      fp->_seek64 = tmp->_seek64;
65      fclose (tmp);
66    }
67# endif
68  if (fp_->_p == fp_->_bf._base
69      && fp_->_r == 0
70      && fp_->_w == ((fp_->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
71                     ? fp_->_bf._size
72                     : 0)
73      && fp_ub._base == NULL)
74#elif defined __EMX__               /* emx+gcc */
75  if (fp->_ptr == fp->_buffer
76      && fp->_rcount == 0
77      && fp->_wcount == 0
78      && fp->_ungetc_count == 0)
79#elif defined __minix               /* Minix */
80  if (fp_->_ptr == fp_->_buf
81      && (fp_->_ptr == NULL || fp_->_count == 0))
82#elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw, NonStop Kernel */
83  if (fp_->_ptr == fp_->_base
84      && (fp_->_ptr == NULL || fp_->_cnt == 0))
85#elif defined __UCLIBC__            /* uClibc */
86  if (((fp->__modeflags & __FLAG_WRITING) == 0
87       || fp->__bufpos == fp->__bufstart)
88      && ((fp->__modeflags & (__FLAG_READONLY | __FLAG_READING)) == 0
89          || fp->__bufpos == fp->__bufread))
90#elif defined __QNX__               /* QNX */
91  if ((fp->_Mode & 0x2000 /* _MWRITE */ ? fp->_Next == fp->_Buf : fp->_Next == fp->_Rend)
92      && fp->_Rback == fp->_Back + sizeof (fp->_Back)
93      && fp->_Rsave == NULL)
94#elif defined __MINT__              /* Atari FreeMiNT */
95  if (fp->__bufp == fp->__buffer
96      && fp->__get_limit == fp->__bufp
97      && fp->__put_limit == fp->__bufp
98      && !fp->__pushed_back)
99#elif defined EPLAN9                /* Plan9 */
100  if (fp->rp == fp->buf
101      && fp->wp == fp->buf)
102#elif FUNC_FFLUSH_STDIN < 0 && 200809 <= _POSIX_VERSION
103  /* Cross-compiling to some other system advertising conformance to
104     POSIX.1-2008 or later.  Assume fseeko and fflush work as advertised.
105     If this assumption is incorrect, please report the bug to
106     bug-gnulib.  */
107  if (0)
108#else
109  #error "Please port gnulib fseeko.c to your platform! Look at the code in fseeko.c, then report this to bug-gnulib."
110#endif
111    {
112      /* We get here when an fflush() call immediately preceded this one (or
113         if ftell() has created buffers but no I/O has occurred on a
114         newly-opened stream).  We know there are no buffers.  */
115      off_t pos = lseek (fileno (fp), offset, whence);
116      if (pos == -1)
117        {
118#if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin */
119          fp_->_flags &= ~__SOFF;
120#endif
121          return -1;
122        }
123
124#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
125      fp->_flags &= ~_IO_EOF_SEEN;
126      fp->_offset = pos;
127#elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin */
128# if defined __CYGWIN__
129      /* fp_->_offset is typed as an integer.  */
130      fp_->_offset = pos;
131# else
132      /* fp_->_offset is an fpos_t.  */
133      {
134        /* Use a union, since on NetBSD, the compilation flags
135           determine whether fpos_t is typedef'd to off_t or a struct
136           containing a single off_t member.  */
137        union
138          {
139            fpos_t f;
140            off_t o;
141          } u;
142        u.o = pos;
143        fp_->_offset = u.f;
144      }
145# endif
146      fp_->_flags |= __SOFF;
147      fp_->_flags &= ~__SEOF;
148#elif defined __EMX__               /* emx+gcc */
149      fp->_flags &= ~_IOEOF;
150#elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw, NonStop Kernel */
151      fp->_flag &= ~_IOEOF;
152#elif defined __MINT__              /* Atari FreeMiNT */
153      fp->__offset = pos;
154      fp->__eof = 0;
155#endif
156      return 0;
157    }
158  return fseeko (fp, offset, whence);
159}
160