1/* An fseeko() function that, together with fflush(), is POSIX compliant.
2   Copyright (C) 2007 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#undef fseeko
27#if !HAVE_FSEEKO
28# undef fseek
29# define fseeko fseek
30#endif
31
32int
33rpl_fseeko (FILE *fp, off_t offset, int whence)
34{
35#if LSEEK_PIPE_BROKEN
36  /* mingw gives bogus answers rather than failure on non-seekable files.  */
37  if (lseek (fileno (fp), 0, SEEK_CUR) == -1)
38    return EOF;
39#endif
40
41  /* These tests are based on fpurge.c.  */
42#if defined _IO_ferror_unlocked     /* GNU libc, BeOS */
43  if (fp->_IO_read_end == fp->_IO_read_ptr
44      && fp->_IO_write_ptr == fp->_IO_write_base
45      && fp->_IO_save_base == NULL)
46#elif defined __sferror             /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
47# if defined __NetBSD__ || defined __OpenBSD__ /* NetBSD, OpenBSD */
48   /* See <http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup>
49      and <http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup> */
50#  define fp_ub ((struct { struct __sbuf _ub; } *) fp->_ext._base)->_ub
51# else                                         /* FreeBSD, MacOS X, Cygwin */
52#  define fp_ub fp->_ub
53# endif
54# if defined __SL64 && defined __SCLE /* Cygwin */
55  if ((fp->_flags & __SL64) == 0)
56    {
57      /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit
58	 mode; but has an fseeko that requires 64-bit mode.  */
59      FILE *tmp = fopen ("/dev/null", "r");
60      if (!tmp)
61	return -1;
62      fp->_flags |= __SL64;
63      fp->_seek64 = tmp->_seek64;
64      fclose (tmp);
65    }
66# endif
67  if (fp->_p == fp->_bf._base
68      && fp->_r == 0
69      && fp->_w == ((fp->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
70		    ? fp->_bf._size
71		    : 0)
72      && fp_ub._base == NULL)
73#elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, mingw */
74# if defined __sun && defined _LP64 /* Solaris/{SPARC,AMD64} 64-bit */
75#  define fp_ ((struct { unsigned char *_ptr; \
76			 unsigned char *_base; \
77			 unsigned char *_end; \
78			 long _cnt; \
79			 int _file; \
80			 unsigned int _flag; \
81		       } *) fp)
82  if (fp_->_ptr == fp_->_base
83      && (fp_->_ptr == NULL || fp_->_cnt == 0))
84# else
85  if (fp->_ptr == fp->_base
86      && (fp->_ptr == NULL || fp->_cnt == 0))
87# endif
88#elif defined __UCLIBC__            /* uClibc */
89  if (((fp->__modeflags & __FLAG_WRITING) == 0
90       || fp->__bufpos == fp->__bufstart)
91      && ((fp->__modeflags & (__FLAG_READONLY | __FLAG_READING)) == 0
92	  || fp->__bufpos == fp->__bufread))
93#elif defined __QNX__               /* QNX */
94  if ((fp->_Mode & _MWRITE ? fp->_Next == fp->_Buf : fp->_Next == fp->_Rend)
95      && fp->_Rback == fp->_Back + sizeof (fp->_Back)
96      && fp->_Rsave == NULL)
97#else
98  #error "Please port gnulib fseeko.c to your platform! Look at the code in fpurge.c, then report this to bug-gnulib."
99#endif
100    {
101      off_t pos = lseek (fileno (fp), offset, whence);
102      if (pos == -1)
103	{
104#if defined __sferror               /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
105	  fp->_flags &= ~__SOFF;
106#endif
107	  return -1;
108	}
109      else
110	{
111#if defined __sferror               /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
112	  fp->_offset = pos;
113	  fp->_flags |= __SOFF;
114#endif
115	  return 0;
116	}
117    }
118  else
119    return fseeko (fp, offset, whence);
120}
121