1/* Retrieve information about a FILE stream.
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 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 "freadahead.h"
21
22size_t
23freadahead (FILE *fp)
24{
25#if defined _IO_ferror_unlocked     /* GNU libc, BeOS */
26  if (fp->_IO_write_ptr > fp->_IO_write_base)
27    return 0;
28  return fp->_IO_read_end - fp->_IO_read_ptr;
29#elif defined __sferror             /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
30  if ((fp->_flags & __SWR) != 0 || fp->_r < 0)
31    return 0;
32  return fp->_r;
33#elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, mingw */
34# if defined __sun && defined _LP64 /* Solaris/{SPARC,AMD64} 64-bit */
35#  define fp_ ((struct { unsigned char *_ptr; \
36			 unsigned char *_base; \
37			 unsigned char *_end; \
38			 long _cnt; \
39			 int _file; \
40			 unsigned int _flag; \
41		       } *) fp)
42  if ((fp_->_flag & _IOWRT) != 0)
43    return 0;
44  return fp_->_cnt;
45# else
46  if ((fp->_flag & _IOWRT) != 0)
47    return 0;
48  return fp->_cnt;
49# endif
50#elif defined __UCLIBC__            /* uClibc */
51# ifdef __STDIO_BUFFERS
52  if (fp->__modeflags & __FLAG_WRITING)
53    return 0;
54  return fp->__bufread - fp->__bufpos;
55# else
56  return 0;
57# endif
58#elif defined __QNX__               /* QNX */
59  if ((fp->_Mode & 0x2000 /* _MWRITE */) != 0)
60    return 0;
61  /* fp->_Buf <= fp->_Next <= fp->_Rend */
62  return fp->_Rend - fp->_Next;
63#else
64 #error "Please port gnulib freadahead.c to your platform! Look at the definition of fflush, fread on your system, then report this to bug-gnulib."
65#endif
66}
67