RawConsole.Unix.cs

using System.Runtime.InteropServices;

internal static partial class RawConsole
{
    private const int STDIN_FILENO = 0;

    private static Termios origTermios;

    private static UnixRawStdinReader stdinReader = new UnixRawStdinReader(Console.InputEncoding);

    public static char ReadKeyUnix() 
    {
        return stdinReader.ReadChar();
    }

    private static void EnableRawModeUnix()
    {
        if (tcgetattr(STDIN_FILENO, ref origTermios) == -1)
        {
            throw new Exception($"Failed to call tcgetattr. Error code: {Marshal.GetLastSystemError()}.");
        }

        if(atexit(Marshal.GetFunctionPointerForDelegate(DisableRawModeUnix)) != 0)
        {
            throw new Exception($"Failed to register exit function (atexit). Error code: {Marshal.GetLastSystemError()}.");
        }

        Termios modTermios = origTermios;

        /* input modes: no break, no CR to NL, no parity check, no strip char, no start/stop output control. */
        modTermios.c_iflag &= (int)(~(InputFlags.BRKINT | InputFlags.ICRNL | InputFlags.INPCK | InputFlags.ISTRIP | InputFlags.IXON));
        /* output modes - disable post processing */
        modTermios.c_oflag &= (int)(~OutputFlags.OPOST);
        /* control modes - set 8 bit chars */
        modTermios.c_cflag |= (int)(ControlFlags.CS8);
        /* local modes - choing off, canonical off, no extended functions, no signal chars (^Z,^C) */
        modTermios.c_lflag &= (int)(~(LocalFlags.ECHO | LocalFlags.ICANON | LocalFlags.IEXTEN | LocalFlags.ISIG));

        modTermios.c_cc[(int)ControlCharacters.VMIN] = 0; /* Return each byte, or zero for timeout. */
        modTermios.c_cc[(int)ControlCharacters.VTIME] = 1; /* 100 ms timeout (unit is tens of second). */

        /* put terminal in raw mode after flushing */
        if (tcsetattr(STDIN_FILENO, (int)OptionalActions.TCSAFLUSH, ref modTermios) == -1)
        {
            throw new Exception($"Failed to call tcsetattr. Error code: {Marshal.GetLastSystemError()}");
        }
    }

    private static void DisableRawModeUnix()
    {
        if (tcsetattr(STDIN_FILENO, (int)OptionalActions.TCSAFLUSH, ref origTermios) == -1)
        {
            throw new Exception($"Failed to call tcsetattr. Error code: {Marshal.GetLastSystemError()}");
        }
    }

    [DllImport("libc", EntryPoint = "__cxa_atexit")]
    private static extern int atexit(IntPtr function);

    [DllImport("libc", SetLastError = true)]
    private static extern int tcgetattr(int fd, ref Termios termios);

    [DllImport("libc", SetLastError = true)]
    private static extern int tcsetattr(int fd, int optional_actions, ref Termios termios);


    [StructLayout(LayoutKind.Sequential)]
    private struct Termios
    {
        public Termios()
        {
            c_cc = new byte[32];
        }

        public int c_iflag;      /* input modes */
        public int c_oflag;      /* output modes */
        public int c_cflag;      /* control modes */
        public int c_lflag;      /* local modes */

        public byte c_line;	     /* line discipline */

        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
        public byte[] c_cc;      /* special characters */

        public int c_ispeed;     /* input speed */
        public int c_ospeed;     /* output speed */
    }

    /// <summary>
    /// Linux\general flags sysdeps\unix\sysv\linux\bits\termios-c_iflag.h
    /// </summary>
    [Flags]
    enum InputFlags : int
    {
        IGNBRK = 1 << 0, /* Ignore break condition.  */
        BRKINT = 1 << 1, /* Signal interrupt on break.  */
        IGNPAR = 1 << 2, /* Ignore characters with parity errors.  */
        PARMRK = 1 << 3, /* Mark parity and framing errors.  */
        INPCK = 1 << 4, /* Enable input parity check.  */
        ISTRIP = 1 << 5, /* Strip 8th bit off characters.  */
        INLCR = 1 << 6, /* Map NL to CR on input.  */
        IGNCR = 1 << 7, /* Ignore CR.  */
        ICRNL = 1 << 8, /* Map CR to NL on input.  */
        IUCLC = 1 << 9, /* Map uppercase characters to lowercase on input (not in POSIX).  */
        IXON = 1 << 10, /* Enable start/stop output control.  */
        IXANY = 1 << 11, /* Enable any character to restart output.  */
        IXOFF = 1 << 12, /* Enable start/stop input control.  */
        IMAXBEL = 1 << 13, /* Ring bell when input queue is full (not in POSIX).  */
        IUTF8 = 1 << 14, /* Input is UTF8 (not in POSIX).  */
    }

    /// <summary>
    /// Linux\general flags sysdeps\unix\sysv\linux\bits\termios-c_oflag.h
    /// </summary>
    [Flags]
    enum OutputFlags : int
    {
        OPOST = 1 << 0, /* Post-process output.  */
        OLCUC = 1 << 1, /* Map lowercase characters to uppercase on out (= in POSIX).  */
        ONLCR = 1 << 2, /* Map NL to CR-NL on output.  */
        OCRNL = 1 << 3, /* Map CR to NL on output.  */
        ONOCR = 1 << 4, /* No CR output at column 0.  */
        ONLRE = 1 << 5, /* NL performs CR function.  */
        OFILL = 1 << 6, /* Use fill characters for delay.  */
        OFDEL = 1 << 7, /* Fill is DEL.  */
        NLDLY = 1 << 8,  /* Select newline delays:  */
        NL0 = 0,        /* Newline type 0.  */
        NL1 = 1 << 8,   /* Newline type 1.  */
        CRDLY = CR0 | CR1 | CR2,  /* Select carriage-return delays:  */
        CR0 = 0,        /* Carriage-return delay type 0.  */
        CR1 = 1 << 9,   /* Carriage-return delay type 1.  */
        CR2 = 1 << 10,  /* Carriage-return delay type 2.  */
        CR3 = CR1 | CR2,/* Carriage-return delay type 3.  */
        TABDLY = TAB0 | TAB2 | TAB3,  /* Select horizontal-tab delays:  */
        TAB0 = 0,  /* Horizontal-tab delay type 0.  */
        TAB1 = 1 << 11,  /* Horizontal-tab delay type 1.  */
        TAB2 = 1 << 12,  /* Horizontal-tab delay type 2.  */
        TAB3 = TAB1 | TAB2,  /* Expand tabs to spaces.  */
        BSDLY = 1 << 13, /* Select backspace delays:  */
        BS0 = 0, /* Backspace-delay type 0.  */
        BS1 = 1 << 13, /* Backspace-delay type 1.  */
        FFDLY = 1 << 15, /* Select form-feed delays:  */
        FF0 = 0, /* Form-feed delay type 0.  */
        FF1 = 1 << 15, /* Form-feed delay type 1.  */
        VTDLY = 1 << 14, /* Select vertical-tab delays:  */
        VT0 = 0, /* Vertical-tab delay type 0.  */
        VT1 = 1 << 14, /* Vertical-tab delay type 1.  */
        XTABS = TAB3
    }

    /// <summary>
    /// Linux\general flags sysdeps\unix\sysv\linux\bits\termios-c_cflag.h
    /// </summary>
    [Flags]
    enum ControlFlags : int
    {
        CSIZE = CS5 | CS6 | CS7 | CS8,  /* Number of bits per byte (mask).  */
        CS5 = 0,            /* 5 bits per byte.  */
        CS6 = 1 << 4,       /* 6 bits per byte.  */
        CS7 = 1 << 5,       /* 7 bits per byte.  */
        CS8 = CS6 | CS7,    /* 8 bits per byte.  */
        CSTOPB = 1 << 6,    /* Two stop bits instead of one.  */
        CREAD = 1 << 7,     /* Enable receiver.  */
        PARENB = 1 << 8,    /* Parity enable.  */
        PARODD = 1 << 9,    /* Odd parity instead of even.  */
        HUPCL = 1 << 10,    /* Hang up on last close.  */
        CLOCAL = 1 << 11,   /* Ignore modem status lines.  */
    }

    /// <summary>
    /// Linux\general flags sysdeps\unix\sysv\linux\bits\termios-c_lflag.h
    /// </summary>
    [Flags]
    enum LocalFlags : int
    {
        ISIG = (1 << 0), /* Enable signals.  */
        ICANON = (1 << 1), /* Canonical input (erase and kill processing).  */
        XCASE = (1 << 2),
        ECHO = (1 << 3), /* Enable echo.  */
        ECHOE = (1 << 4), /* Echo erase character as error-correcting backspace.  */
        ECHOK = (1 << 5), /* Echo KILL.  */
        ECHONL = (1 << 6), /* Echo NL.  */
        NOFLSH = (1 << 7), /* Disable flush after interrupt or quit.  */
        TOSTOP = (1 << 8), /* Send SIGTTOU for background output.  */
        ECHOCTL = (1 << 9), /* If ECHO is also set, terminal special characters
                            other than TAB, NL, START, and STOP are echoed as
                            ^X, where X is the character with ASCII code 0x40
                            greater than the special character
                            (not in POSIX).  */
        ECHOPRT = (1 << 10), /* If ICANON and ECHO are also set, characters are
                            printed as they are being erased
                            (not in POSIX).  */
        ECHOKE = (1 << 11), /* If ICANON is also set, KILL is echoed by erasing
                            each character on the line, as specified by ECHOE
                            and ECHOPRT (not in POSIX).  */
        FLUSHO = (1 << 12), /* Output is being flushed.  This flag is toggled by
                            typing the DISCARD character (not in POSIX).  */
        PENDIN = (1 << 14), /* All characters in the input queue are reprinted
                            when the next character is read
                            (not in POSIX).  */
        IEXTEN = (1 << 15), /* Enable implementation-defined input processing.  */
        EXTPROC = (1 << 16)
    }

    enum ControlCharacters : byte
    {
        VINTR = 0,  /* Interrupt character [ISIG].  */
        VQUIT = 1,  /* Quit character [ISIG].  */
        VERASE = 2, /* Erase character [ICANON].  */
        VKILL = 3,  /* Kill-line character [ICANON].  */
        VEOF = 4,   /* End-of-file character [ICANON].  */
        VTIME = 5,  /* Time-out value (tenths of a second) [!ICANON].  */
        VMIN = 6,   /* Minimum number of bytes read at once [!ICANON].  */
        VSWTC = 7,  /* Switch character (SWTCH).  Used in System V to switch shells in shell layers, a predecessor to shell job control.*/
        VSTART = 8, /* Start (X-ON) character [IXON, IXOFF].  */
        VSTOP = 9,  /* Stop (X-OFF) character [IXON, IXOFF].  */
        VSUSP = 10, /* Suspend character [ISIG].  */
        VEOL = 11,  /* End-of-line character [ICANON].  */
        VREPRINT = 12,  /* Reprint-line character [ICANON].  */
        VDISCARD = 13,  /* Discard character [IEXTEN].  */
        VWERASE = 14,   /* Word-erase character [ICANON].  */
        VLNEXT = 15,    /* Literal-next character [IEXTEN].  */
        VEOL2 = 16      /* Second EOL character [ICANON].  */
    }

    enum OptionalActions
    {
        /* Change immediately.  */
        TCSANOW = 0,
        /* Change when pending output is written.  */
        TCSADRAIN = 1,
        /* Flush pending input before changing.  */
        TCSAFLUSH = 2,
        /* Flag: Don't alter hardware state.  */
        TCSASOFT = 0x10
    }
}