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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include "PTYMultiplexer.h"
28#include "MasterPTY.h"
29#include <Kernel/FileSystem/FileDescription.h>
30#include <Kernel/Process.h>
31#include <LibC/errno_numbers.h>
32
33//#define PTMX_DEBUG
34
35namespace Kernel {
36
37static const unsigned s_max_pty_pairs = 8;
38static PTYMultiplexer* s_the;
39
40PTYMultiplexer& PTYMultiplexer::the()
41{
42 ASSERT(s_the);
43 return *s_the;
44}
45
46PTYMultiplexer::PTYMultiplexer()
47 : CharacterDevice(5, 2)
48{
49 s_the = this;
50 m_freelist.ensure_capacity(s_max_pty_pairs);
51 for (int i = s_max_pty_pairs; i > 0; --i)
52 m_freelist.unchecked_append(i - 1);
53}
54
55PTYMultiplexer::~PTYMultiplexer()
56{
57}
58
59KResultOr<NonnullRefPtr<FileDescription>> PTYMultiplexer::open(int options)
60{
61 LOCKER(m_lock);
62 if (m_freelist.is_empty())
63 return KResult(-EBUSY);
64 auto master_index = m_freelist.take_last();
65 auto master = adopt(*new MasterPTY(master_index));
66#ifdef PTMX_DEBUG
67 dbg() << "PTYMultiplexer::open: Vending master " << master->index();
68#endif
69 auto description = FileDescription::create(move(master));
70 description->set_rw_mode(options);
71 description->set_file_flags(options);
72 return description;
73}
74
75void PTYMultiplexer::notify_master_destroyed(Badge<MasterPTY>, unsigned index)
76{
77 LOCKER(m_lock);
78 m_freelist.append(index);
79#ifdef PTMX_DEBUG
80 dbg() << "PTYMultiplexer: " << index << " added to freelist";
81#endif
82}
83
84}