ladybird/Kernel/TTY/MasterPTY.cpp
Tom 046d6855f5 Kernel: Move block condition evaluation out of the Scheduler
This makes the Scheduler a lot leaner by not having to evaluate
block conditions every time it is invoked. Instead evaluate them as
the states change, and unblock threads at that point.

This also implements some more waitid/waitpid/wait features and
behavior. For example, WUNTRACED and WNOWAIT are now supported. And
wait will now not return EINTR when SIGCHLD is delivered at the
same time.
2020-11-30 13:17:02 +01:00

149 lines
4.3 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "MasterPTY.h"
#include "PTYMultiplexer.h"
#include "SlavePTY.h"
#include <Kernel/Process.h>
#include <LibC/errno_numbers.h>
#include <LibC/signal_numbers.h>
#include <LibC/sys/ioctl_numbers.h>
//#define MASTERPTY_DEBUG
namespace Kernel {
MasterPTY::MasterPTY(unsigned index)
: CharacterDevice(200, index)
, m_slave(adopt(*new SlavePTY(*this, index)))
, m_index(index)
{
m_pts_name = String::format("/dev/pts/%u", m_index);
auto process = Process::current();
set_uid(process->uid());
set_gid(process->gid());
m_buffer.set_unblock_callback([this]() {
if (m_slave)
evaluate_block_conditions();
});
}
MasterPTY::~MasterPTY()
{
#ifdef MASTERPTY_DEBUG
dbg() << "~MasterPTY(" << m_index << ")";
#endif
PTYMultiplexer::the().notify_master_destroyed({}, m_index);
}
String MasterPTY::pts_name() const
{
return m_pts_name;
}
KResultOr<size_t> MasterPTY::read(FileDescription&, size_t, UserOrKernelBuffer& buffer, size_t size)
{
if (!m_slave && m_buffer.is_empty())
return 0;
return m_buffer.read(buffer, size);
}
KResultOr<size_t> MasterPTY::write(FileDescription&, size_t, const UserOrKernelBuffer& buffer, size_t size)
{
if (!m_slave)
return KResult(-EIO);
m_slave->on_master_write(buffer, size);
return size;
}
bool MasterPTY::can_read(const FileDescription&, size_t) const
{
if (!m_slave)
return true;
return !m_buffer.is_empty();
}
bool MasterPTY::can_write(const FileDescription&, size_t) const
{
return true;
}
void MasterPTY::notify_slave_closed(Badge<SlavePTY>)
{
#ifdef MASTERPTY_DEBUG
dbg() << "MasterPTY(" << m_index << "): slave closed, my retains: " << ref_count() << ", slave retains: " << m_slave->ref_count();
#endif
// +1 ref for my MasterPTY::m_slave
// +1 ref for FileDescription::m_device
if (m_slave->ref_count() == 2)
m_slave = nullptr;
}
ssize_t MasterPTY::on_slave_write(const UserOrKernelBuffer& data, ssize_t size)
{
if (m_closed)
return -EIO;
return m_buffer.write(data, size);
}
bool MasterPTY::can_write_from_slave() const
{
if (m_closed)
return true;
return m_buffer.space_for_writing();
}
KResult MasterPTY::close()
{
if (ref_count() == 2) {
InterruptDisabler disabler;
// After the closing FileDescription dies, slave is the only thing keeping me alive.
// From this point, let's consider ourselves closed.
m_closed = true;
m_slave->hang_up();
}
return KSuccess;
}
int MasterPTY::ioctl(FileDescription& description, unsigned request, FlatPtr arg)
{
REQUIRE_PROMISE(tty);
if (!m_slave)
return -EIO;
if (request == TIOCSWINSZ || request == TIOCGPGRP)
return m_slave->ioctl(description, request, arg);
return -EINVAL;
}
String MasterPTY::absolute_path(const FileDescription&) const
{
return String::format("ptm:%s", m_pts_name.characters());
}
}