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https://github.com/LadybirdBrowser/ladybird.git
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d0f314b23c
There is a slight race condition in our implementation of write(). We call File::can_write() before attempting to write to it (blocking if it returns false). If it returns true, we assume that we can write to the file, and our code assumes that File::write() cannot possibly fail by being blocked. There is, however, the rare case where another process writes to the file and prevents further writes in between the call to Files::can_write() and File::write() in the first process. This would result in the first process calling File::write() when it cannot be written to. We fix this by adding a mechanism for File::can_write() to signal that it was blocked, making it the responsibilty of File::write() to check whether it can write and then finally making sys$write() check if the write failed due to it being blocked.
141 lines
3.8 KiB
C++
141 lines
3.8 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <Kernel/Devices/CharacterDevice.h>
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#include <Kernel/IO.h>
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namespace Kernel {
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#define SERIAL_COM1_ADDR 0x3F8
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#define SERIAL_COM2_ADDR 0x2F8
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#define SERIAL_COM3_ADDR 0x3E8
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#define SERIAL_COM4_ADDR 0x2E8
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class SerialDevice final : public CharacterDevice {
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AK_MAKE_ETERNAL
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public:
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SerialDevice(IOAddress base_addr, unsigned minor);
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virtual ~SerialDevice() override;
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// ^CharacterDevice
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virtual bool can_read(const FileDescription&, size_t) const override;
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virtual KResultOr<size_t> read(FileDescription&, u64, UserOrKernelBuffer&, size_t) override;
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virtual bool can_write(const FileDescription&, size_t) const override;
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virtual KResultOr<size_t> write(FileDescription&, u64, const UserOrKernelBuffer&, size_t) override;
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void put_char(char);
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enum InterruptEnable {
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LowPowerMode = 0x01 << 5,
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SleepMode = 0x01 << 4,
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ModemStatusInterrupt = 0x01 << 3,
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ReceiverLineStatusInterrupt = 0x01 << 2,
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TransmitterHoldingRegisterEmptyInterrupt = 0x01 << 1,
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ReceivedDataAvailableInterrupt = 0x01 << 0
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};
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enum Baud {
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Baud50 = 2304,
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Baud110 = 1047,
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Baud220 = 524,
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Baud300 = 384,
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Baud600 = 192,
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Baud1200 = 96,
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Baud2400 = 48,
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Baud4800 = 24,
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Baud9600 = 12,
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Baud19200 = 6,
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Baud38400 = 3,
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Baud57600 = 2,
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Baud115200 = 1
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};
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enum ParitySelect {
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None = 0x00 << 3,
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Odd = 0x01 << 3,
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Even = 0x03 << 3,
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Mark = 0x05 << 3,
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Space = 0x07 << 3
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};
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enum StopBits {
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One = 0x00 << 2,
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Two = 0x01 << 2
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};
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enum WordLength {
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FiveBits = 0x00,
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SixBits = 0x01,
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SevenBits = 0x02,
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EightBits = 0x03
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};
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enum FIFOControl {
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EnableFIFO = 0x01 << 0,
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ClearReceiveFIFO = 0x01 << 1,
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ClearTransmitFIFO = 0x01 << 2,
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Enable64ByteFIFO = 0x01 << 5,
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TriggerLevel1 = 0x00 << 6,
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TriggerLevel2 = 0x01 << 6,
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TriggerLevel3 = 0x02 << 6,
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TriggerLevel4 = 0x03 << 6
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};
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enum ModemControl {
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AutoflowControlEnabled = 0x01 << 5,
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LoopbackMode = 0x01 << 4,
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AuxiliaryOutput2 = 0x01 << 3,
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AuxiliaryOutput1 = 0x01 << 2,
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RequestToSend = 0x01 << 1,
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DataTerminalReady = 0x01 << 0
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};
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enum LineStatus {
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ErrorInReceivedFIFO = 0x01 << 7,
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EmptyDataHoldingRegisters = 0x01 << 6,
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EmptyTransmitterHoldingRegister = 0x01 << 5,
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BreakInterrupt = 0x01 << 4,
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FramingError = 0x01 << 3,
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ParityError = 0x01 << 2,
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OverrunError = 0x01 << 1,
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DataReady = 0x01 << 0
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};
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// ^Device
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virtual mode_t required_mode() const override { return 0620; }
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virtual String device_name() const override;
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private:
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friend class PCISerialDevice;
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// ^CharacterDevice
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virtual const char* class_name() const override { return "SerialDevice"; }
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void initialize();
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void set_interrupts(bool interrupt_enable);
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void set_baud(Baud);
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void set_fifo_control(u8 fifo_control);
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void set_line_control(ParitySelect, StopBits, WordLength);
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void set_break_enable(bool break_enable);
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void set_modem_control(u8 modem_control);
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u8 get_line_status() const;
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IOAddress m_base_addr;
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bool m_interrupt_enable { false };
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u8 m_fifo_control { 0 };
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Baud m_baud { Baud38400 };
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ParitySelect m_parity_select { None };
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StopBits m_stop_bits { One };
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WordLength m_word_length { EightBits };
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bool m_break_enable { false };
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u8 m_modem_control { 0 };
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bool m_last_put_char_was_carriage_return { false };
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SpinLock<u8> m_serial_lock;
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};
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}
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