1/* An fseeko() function that, together with fflush(), is POSIX compliant.
2   Copyright (C) 2007-2009 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, write to the Free Software Foundation,
16   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
17
18#include <config.h>
19
20/* Specification.  */
21#include <stdio.h>
22
23/* Get off_t and lseek.  */
24#include <unistd.h>
25
26#include "stdio-impl.h"
27
28#undef fseeko
29#if !HAVE_FSEEKO
30# undef fseek
31# define fseeko fseek
32#endif
33
34int
35rpl_fseeko (FILE *fp, off_t offset, int whence)
36{
37#if LSEEK_PIPE_BROKEN
38  /* mingw gives bogus answers rather than failure on non-seekable files.  */
39  if (lseek (fileno (fp), 0, SEEK_CUR) == -1)
40    return EOF;
41#endif
42
43  /* These tests are based on fpurge.c.  */
44#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
45  if (fp->_IO_read_end == fp->_IO_read_ptr
46      && fp->_IO_write_ptr == fp->_IO_write_base
47      && fp->_IO_save_base == NULL)
48#elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
49# if defined __SL64 && defined __SCLE /* Cygwin */
50  if ((fp->_flags & __SL64) == 0)
51    {
52      /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit
53	 mode; but has an fseeko that requires 64-bit mode.  */
54      FILE *tmp = fopen ("/dev/null", "r");
55      if (!tmp)
56	return -1;
57      fp->_flags |= __SL64;
58      fp->_seek64 = tmp->_seek64;
59      fclose (tmp);
60    }
61# endif
62  if (fp_->_p == fp_->_bf._base
63      && fp_->_r == 0
64      && fp_->_w == ((fp_->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
65		     ? fp_->_bf._size
66		     : 0)
67      && fp_ub._base == NULL)
68#elif defined __EMX__               /* emx+gcc */
69  if (fp->_ptr == fp->_buffer
70      && fp->_rcount == 0
71      && fp->_wcount == 0
72      && fp->_ungetc_count == 0)
73#elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw */
74  if (fp_->_ptr == fp_->_base
75      && (fp_->_ptr == NULL || fp_->_cnt == 0))
76#elif defined __UCLIBC__            /* uClibc */
77  if (((fp->__modeflags & __FLAG_WRITING) == 0
78       || fp->__bufpos == fp->__bufstart)
79      && ((fp->__modeflags & (__FLAG_READONLY | __FLAG_READING)) == 0
80	  || fp->__bufpos == fp->__bufread))
81#elif defined __QNX__               /* QNX */
82  if ((fp->_Mode & 0x2000 /* _MWRITE */ ? fp->_Next == fp->_Buf : fp->_Next == fp->_Rend)
83      && fp->_Rback == fp->_Back + sizeof (fp->_Back)
84      && fp->_Rsave == NULL)
85#elif defined __MINT__              /* Atari FreeMiNT */
86  if (fp->__bufp == fp->__buffer
87      && fp->__get_limit == fp->__bufp
88      && fp->__put_limit == fp->__bufp
89      && !fp->__pushed_back)
90#else
91  #error "Please port gnulib fseeko.c to your platform! Look at the code in fpurge.c, then report this to bug-gnulib."
92#endif
93    {
94      /* We get here when an fflush() call immediately preceded this one.  We
95	 know there are no buffers.
96	 POSIX requires us to modify the file descriptor's position.
97	 But we cannot position beyond end of file here.  */
98      off_t pos =
99	lseek (fileno (fp),
100	       whence == SEEK_END && offset > 0 ? 0 : offset,
101	       whence);
102      if (pos == -1)
103	{
104#if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
105	  fp_->_flags &= ~__SOFF;
106#endif
107	  return -1;
108	}
109
110#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
111      fp->_flags &= ~_IO_EOF_SEEN;
112#elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
113      fp_->_offset = pos;
114      fp_->_flags |= __SOFF;
115      fp_->_flags &= ~__SEOF;
116#elif defined __EMX__               /* emx+gcc */
117      fp->_flags &= ~_IOEOF;
118#elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw */
119      fp->_flag &= ~_IOEOF;
120#elif defined __MINT__              /* Atari FreeMiNT */
121      fp->__offset = pos;
122      fp->__eof = 0;
123#endif
124      /* If we were not requested to position beyond end of file, we're
125	 done.  */
126      if (!(whence == SEEK_END && offset > 0))
127	return 0;
128    }
129  return fseeko (fp, offset, whence);
130}
131