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56a2c21e0c
Instead of using the FIFO's memory address as part of its absolute path identity, just use an incrementing FIFO index instead. Note that this is not used for anything other than debugging (it helps you identify which file descriptors refer to the same FIFO by looking at /proc/PID/fds
120 lines
2.7 KiB
C++
120 lines
2.7 KiB
C++
#include <AK/HashTable.h>
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#include <AK/StdLibExtras.h>
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#include <Kernel/FileSystem/FIFO.h>
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#include <Kernel/FileSystem/FileDescription.h>
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#include <Kernel/Lock.h>
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#include <Kernel/Process.h>
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#include <Kernel/Thread.h>
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//#define FIFO_DEBUG
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Lockable<HashTable<FIFO*>>& all_fifos()
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{
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static Lockable<HashTable<FIFO*>>* s_table;
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if (!s_table)
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s_table = new Lockable<HashTable<FIFO*>>;
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return *s_table;
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}
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static int s_next_fifo_id = 1;
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NonnullRefPtr<FIFO> FIFO::create(uid_t uid)
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{
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return adopt(*new FIFO(uid));
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}
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NonnullRefPtr<FileDescription> FIFO::open_direction(FIFO::Direction direction)
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{
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auto description = FileDescription::create(*this);
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attach(direction);
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description->set_fifo_direction({}, direction);
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return description;
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}
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FIFO::FIFO(uid_t uid)
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: m_uid(uid)
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{
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LOCKER(all_fifos().lock());
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all_fifos().resource().set(this);
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m_fifo_id = ++s_next_fifo_id;
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}
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FIFO::~FIFO()
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{
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LOCKER(all_fifos().lock());
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all_fifos().resource().remove(this);
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}
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void FIFO::attach(Direction direction)
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{
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if (direction == Direction::Reader) {
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++m_readers;
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#ifdef FIFO_DEBUG
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kprintf("open reader (%u)\n", m_readers);
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#endif
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} else if (direction == Direction::Writer) {
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++m_writers;
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#ifdef FIFO_DEBUG
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kprintf("open writer (%u)\n", m_writers);
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#endif
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}
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}
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void FIFO::detach(Direction direction)
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{
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if (direction == Direction::Reader) {
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#ifdef FIFO_DEBUG
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kprintf("close reader (%u - 1)\n", m_readers);
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#endif
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ASSERT(m_readers);
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--m_readers;
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} else if (direction == Direction::Writer) {
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#ifdef FIFO_DEBUG
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kprintf("close writer (%u - 1)\n", m_writers);
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#endif
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ASSERT(m_writers);
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--m_writers;
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}
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}
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bool FIFO::can_read(const FileDescription&) const
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{
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return !m_buffer.is_empty() || !m_writers;
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}
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bool FIFO::can_write(const FileDescription&) const
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{
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return m_buffer.bytes_in_write_buffer() < 4096 || !m_readers;
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}
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ssize_t FIFO::read(FileDescription&, u8* buffer, ssize_t size)
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{
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if (!m_writers && m_buffer.is_empty())
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return 0;
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#ifdef FIFO_DEBUG
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dbgprintf("fifo: read(%u)\n", size);
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#endif
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ssize_t nread = m_buffer.read(buffer, size);
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#ifdef FIFO_DEBUG
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dbgprintf(" -> read (%c) %u\n", buffer[0], nread);
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#endif
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return nread;
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}
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ssize_t FIFO::write(FileDescription&, const u8* buffer, ssize_t size)
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{
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if (!m_readers) {
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current->process().send_signal(SIGPIPE, ¤t->process());
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return -EPIPE;
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}
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#ifdef FIFO_DEBUG
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dbgprintf("fifo: write(%p, %u)\n", buffer, size);
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#endif
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return m_buffer.write(buffer, size);
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}
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String FIFO::absolute_path(const FileDescription&) const
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{
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return String::format("fifo:%u", m_fifo_id);
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}
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