1/* This is part of libio/iostream, providing -*- C++ -*- input/output.
2Copyright (C) 1993 Free Software Foundation
3
4This file is part of the GNU IO Library.  This library is free
5software; you can redistribute it and/or modify it under the
6terms of the GNU General Public License as published by the
7Free Software Foundation; either version 2, or (at your option)
8any later version.
9
10This library is distributed in the hope that it will be useful,
11but WITHOUT ANY WARRANTY; without even the implied warranty of
12MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13GNU General Public License for more details.
14
15You should have received a copy of the GNU General Public License
16along with this library; see the file COPYING.  If not, write to the Free
17Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
18
19As a special exception, if you link this library with files
20compiled with a GNU compiler to produce an executable, this does not cause
21the resulting executable to be covered by the GNU General Public License.
22This exception does not however invalidate any other reasons why
23the executable file might be covered by the GNU General Public License. */
24
25/* Written by Per Bothner (bothner@cygnus.com). */
26
27#ifdef __GNUG__
28#pragma implementation
29#endif
30
31#include "libioP.h"
32#include <stdiostream.h>
33
34// A stdiobuf is "tied" to a FILE object (as used by the stdio package).
35// Thus a stdiobuf is always synchronized with the corresponding FILE,
36// though at the cost of some overhead.  (If you use the implementation
37// of stdio supplied with this library, you don't need stdiobufs.)
38// This implementation inherits from filebuf, but implement the virtual
39// functions sys_read/..., using the stdio functions fread/... instead
40// of the low-level read/... system calls.  This has the advantage that
41// we get all of the nice filebuf semantics automatically, though
42// with some overhead.
43
44
45#ifndef SEEK_SET
46#define SEEK_SET 0
47#endif
48#ifndef SEEK_CUR
49#define SEEK_CUR 1
50#endif
51#ifndef SEEK_END
52#define SEEK_END 2
53#endif
54
55stdiobuf::stdiobuf(FILE *f) : filebuf(fileno(f))
56{
57    _file = f;
58    // Turn off buffer in stdiobuf.  Instead, rely on buffering in (FILE).
59    // Thus the stdiobuf will be synchronized with the FILE.
60    setbuf(NULL, 0);
61}
62
63stdiobuf::~stdiobuf()
64{
65  /* Only needed if we're buffered.  Not buffered is the default. */
66  _IO_do_flush((_IO_FILE*)this);
67}
68
69streamsize stdiobuf::sys_read(char* buf, streamsize size)
70{
71  // A minor optimization, but it makes a noticable difference.
72  // A bigger optimization would be to write stdiobuf::underflow,
73  // but that has some modularity disadvantages.  Re-evaluate that
74  // after we have gotten rid of the double indirection.  FIXME
75  if (size == 1)
76    {
77      register int ch = getc(_file);
78      if (ch == EOF)
79	return 0;
80      *buf = (char)ch;
81      return 1;
82    }
83  else
84    return fread(buf, 1, size, _file);
85}
86
87streamsize stdiobuf::sys_write(const char *buf, streamsize n)
88{
89    _IO_ssize_t count = fwrite(buf, 1, n, _file);
90    if (_offset >= 0)
91	_offset += n;
92    return count;
93}
94
95streampos stdiobuf::sys_seek(streamoff offset, _seek_dir dir)
96{
97    // Normally, equivalent to: fdir=dir
98    int fdir =
99	(dir == ios::beg) ? SEEK_SET :
100        (dir == ios::cur) ? SEEK_CUR :
101        (dir == ios::end) ? SEEK_END :
102        dir;
103    return fseek(_file, offset, fdir);
104}
105
106int stdiobuf::sys_close()
107{
108    int status = fclose(_file);
109    _file = NULL;
110    return status;
111}
112
113int stdiobuf::sync()
114{
115  if (_IO_do_flush((_IO_FILE*)this))
116    return EOF;
117  if (!(xflags() & _IO_NO_WRITES))
118    if (fflush(_file))
119      return EOF;
120  return 0;
121}
122
123int stdiobuf::overflow(int c /* = EOF*/)
124{
125    if (filebuf::overflow(c) == EOF)
126	return EOF;
127    if (c != EOF)
128	return c;
129    return fflush(_file);
130}
131
132streamsize stdiobuf::xsputn(const char* s, streamsize n)
133{
134  if (buffered ())
135    {
136      // The filebuf implementation of sputn loses.
137      return streambuf::xsputn(s, n);
138    }
139  else
140    return fwrite (s, 1, n, _file);
141}
142
143void stdiobuf::buffered (int b)
144{
145  if (b)
146    {
147      if (_flags & _IO_UNBUFFERED)
148	{ /* Was unbuffered, make it buffered. */
149	  _flags &= ~_IO_UNBUFFERED;
150	}
151    }
152  else
153    {
154      if (!(_flags & _IO_UNBUFFERED))
155	{ /* Was buffered, make it unbuffered. */
156	  setbuf(NULL, 0);
157	}
158    }
159}
160