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/*
* 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 <AK/HashTable.h>
#include <AK/Singleton.h>
#include <AK/StdLibExtras.h>
#include <AK/StringView.h>
#include <Kernel/FileSystem/FIFO.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Lock.h>
#include <Kernel/Process.h>
#include <Kernel/Thread.h>
//#define FIFO_DEBUG
namespace Kernel {
static AK::Singleton<Lockable<HashTable<FIFO*>>> s_table;
static Lockable<HashTable<FIFO*>>& all_fifos()
{
return *s_table;
}
static int s_next_fifo_id = 1;
NonnullRefPtr<FIFO> FIFO::create(uid_t uid)
{
return adopt(*new FIFO(uid));
}
NonnullRefPtr<FileDescription> FIFO::open_direction(FIFO::Direction direction)
{
auto description = FileDescription::create(*this);
attach(direction);
description->set_fifo_direction({}, direction);
return description;
}
NonnullRefPtr<FileDescription> FIFO::open_direction_blocking(FIFO::Direction direction)
{
Locker locker(m_open_lock);
auto description = open_direction(direction);
if (direction == Direction::Reader) {
m_read_open_queue.wake_all();
if (m_writers == 0) {
locker.unlock();
m_write_open_queue.wait_on(nullptr, "FIFO");
locker.lock();
}
}
if (direction == Direction::Writer) {
m_write_open_queue.wake_all();
if (m_readers == 0) {
locker.unlock();
m_read_open_queue.wait_on(nullptr, "FIFO");
locker.lock();
}
}
return description;
}
FIFO::FIFO(uid_t uid)
: m_uid(uid)
{
LOCKER(all_fifos().lock());
all_fifos().resource().set(this);
m_fifo_id = ++s_next_fifo_id;
// Use the same block condition for read and write
m_buffer.set_unblock_callback([this]() {
evaluate_block_conditions();
});
}
FIFO::~FIFO()
{
LOCKER(all_fifos().lock());
all_fifos().resource().remove(this);
}
void FIFO::attach(Direction direction)
{
if (direction == Direction::Reader) {
++m_readers;
#ifdef FIFO_DEBUG
klog() << "open reader (" << m_readers << ")";
#endif
} else if (direction == Direction::Writer) {
++m_writers;
#ifdef FIFO_DEBUG
klog() << "open writer (" << m_writers << ")";
#endif
}
evaluate_block_conditions();
}
void FIFO::detach(Direction direction)
{
if (direction == Direction::Reader) {
#ifdef FIFO_DEBUG
klog() << "close reader (" << m_readers << " - 1)";
#endif
ASSERT(m_readers);
--m_readers;
} else if (direction == Direction::Writer) {
#ifdef FIFO_DEBUG
klog() << "close writer (" << m_writers << " - 1)";
#endif
ASSERT(m_writers);
--m_writers;
}
evaluate_block_conditions();
}
bool FIFO::can_read(const FileDescription&, size_t) const
{
return !m_buffer.is_empty() || !m_writers;
}
bool FIFO::can_write(const FileDescription&, size_t) const
{
return m_buffer.space_for_writing() || !m_readers;
}
KResultOr<size_t> FIFO::read(FileDescription&, size_t, UserOrKernelBuffer& buffer, size_t size)
{
if (!m_writers && m_buffer.is_empty())
return 0;
return m_buffer.read(buffer, size);
}
KResultOr<size_t> FIFO::write(FileDescription&, size_t, const UserOrKernelBuffer& buffer, size_t size)
{
if (!m_readers) {
Thread::current()->send_signal(SIGPIPE, Process::current());
return -EPIPE;
}
return m_buffer.write(buffer, size);
}
String FIFO::absolute_path(const FileDescription&) const
{
return String::format("fifo:%u", m_fifo_id);
}
KResult FIFO::stat(::stat& st) const
{
memset(&st, 0, sizeof(st));
st.st_mode = S_IFIFO;
return KSuccess;
}
}
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