Parent: #77

Summary

Implement UnixConsole using termios for raw mode and POSIX signals for resize detection.

Files to Create

• src/Termina/Platform/UnixConsole.cs

P/Invoke Requirements

termios

[DllImport("libc")]
static extern int tcgetattr(int fd, ref termios termios_p);

[DllImport("libc")]
static extern int tcsetattr(int fd, int optional_actions, ref termios termios_p);

Raw Mode Configuration

• Disable ICANON (line buffering)
• Disable ECHO (character echo)
• Disable ISIG (signal generation for Ctrl+C)
• Set VMIN=0, VTIME=0 for non-blocking reads

Input Polling

[DllImport("libc")]
static extern int poll(ref pollfd fds, uint nfds, int timeout);

Use poll() on stdin (fd 0) with timeout for cancellation support.

SIGWINCH Signal

[DllImport("libc")]
static extern int sigaction(int signum, ref sigaction act, ref sigaction oldact);

const int SIGWINCH = 28;

Register handler to emit resize events.

Key Behaviors

1. Initialize(): Save current termios, enter raw mode
2. ReadInputAsync(): Use poll() with timeout, then read() stdin bytes, parse ANSI sequences
3. Restore(): Reset termios to saved state
4. Resized: Emit on SIGWINCH signal

ANSI Sequence Parsing

Need to parse escape sequences for special keys:

• ESC[A = Up, ESC[B = Down, ESC[C = Right, ESC[D = Left
• ESC[1;5A = Ctrl+Up (modifier codes)
• Function keys, Home, End, etc.

Acceptance Criteria

• Raw mode enabled (no line buffering or echo)
• Event-driven input via poll()
• Cancellable via CancellationToken
• SIGWINCH signal handling for resize
• ANSI escape sequences parsed for special keys
• Terminal state properly restored on dispose
• Works on Linux and macOS