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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 "MasterPTY.h"
28#include "PTYMultiplexer.h"
29#include "SlavePTY.h"
30#include <Kernel/Process.h>
31#include <LibC/errno_numbers.h>
32#include <LibC/signal_numbers.h>
33#include <LibC/sys/ioctl_numbers.h>
34
35//#define MASTERPTY_DEBUG
36
37namespace Kernel {
38
39MasterPTY::MasterPTY(unsigned index)
40 : CharacterDevice(200, index)
41 , m_slave(adopt(*new SlavePTY(*this, index)))
42 , m_index(index)
43{
44 m_pts_name = String::format("/dev/pts/%u", m_index);
45 set_uid(Process::current->uid());
46 set_gid(Process::current->gid());
47}
48
49MasterPTY::~MasterPTY()
50{
51#ifdef MASTERPTY_DEBUG
52 dbg() << "~MasterPTY(" << m_index << ")";
53#endif
54 PTYMultiplexer::the().notify_master_destroyed({}, m_index);
55}
56
57String MasterPTY::pts_name() const
58{
59 return m_pts_name;
60}
61
62ssize_t MasterPTY::read(FileDescription&, u8* buffer, ssize_t size)
63{
64 if (!m_slave && m_buffer.is_empty())
65 return 0;
66 return m_buffer.read(buffer, size);
67}
68
69ssize_t MasterPTY::write(FileDescription&, const u8* buffer, ssize_t size)
70{
71 if (!m_slave)
72 return -EIO;
73 m_slave->on_master_write(buffer, size);
74 return size;
75}
76
77bool MasterPTY::can_read(const FileDescription&) const
78{
79 if (!m_slave)
80 return true;
81 return !m_buffer.is_empty();
82}
83
84bool MasterPTY::can_write(const FileDescription&) const
85{
86 return true;
87}
88
89void MasterPTY::notify_slave_closed(Badge<SlavePTY>)
90{
91#ifdef MASTERPTY_DEBUG
92 dbg() << "MasterPTY(" << m_index << "): slave closed, my retains: " << ref_count() << ", slave retains: " << m_slave->ref_count();
93#endif
94 // +1 ref for my MasterPTY::m_slave
95 // +1 ref for FileDescription::m_device
96 if (m_slave->ref_count() == 2)
97 m_slave = nullptr;
98}
99
100ssize_t MasterPTY::on_slave_write(const u8* data, ssize_t size)
101{
102 if (m_closed)
103 return -EIO;
104 m_buffer.write(data, size);
105 return size;
106}
107
108bool MasterPTY::can_write_from_slave() const
109{
110 if (m_closed)
111 return true;
112 return m_buffer.space_for_writing();
113}
114
115void MasterPTY::close()
116{
117 if (ref_count() == 2) {
118 InterruptDisabler disabler;
119 // After the closing FileDescription dies, slave is the only thing keeping me alive.
120 // From this point, let's consider ourselves closed.
121 m_closed = true;
122
123 m_slave->hang_up();
124 }
125}
126
127int MasterPTY::ioctl(FileDescription& description, unsigned request, unsigned arg)
128{
129 REQUIRE_PROMISE(tty);
130 if (!m_slave)
131 return -EIO;
132 if (request == TIOCSWINSZ || request == TIOCGPGRP)
133 return m_slave->ioctl(description, request, arg);
134 return -EINVAL;
135}
136
137String MasterPTY::absolute_path(const FileDescription&) const
138{
139 return String::format("ptm:%s", m_pts_name.characters());
140}
141
142}