xwayland-satellite/src/lib.rs

mod clientside;
mod data_device;
mod server;
pub mod xstate;

use crate::server::{PendingSurfaceState, ServerState};
use crate::xstate::XState;
use log::{error, info};
use rustix::event::{poll, PollFd, PollFlags};
use std::io::{BufRead, BufReader, Read, Write};
use std::os::fd::{AsFd, AsRawFd, BorrowedFd};
use std::os::unix::net::UnixStream;
use std::process::{Command, Stdio};
use std::sync::Arc;
use wayland_server::{Display, ListeningSocket};
use xcb::x;

pub trait XConnection: Sized + 'static {
    type ExtraData: FromServerState<Self>;
    type MimeTypeData: MimeTypeData;

    fn root_window(&self) -> x::Window;
    fn set_window_dims(&mut self, window: x::Window, dims: PendingSurfaceState);
    fn set_fullscreen(&mut self, window: x::Window, fullscreen: bool, data: Self::ExtraData);
    fn focus_window(&mut self, window: x::Window, data: Self::ExtraData);
    fn close_window(&mut self, window: x::Window, data: Self::ExtraData);
    fn raise_to_top(&mut self, window: x::Window);
}

pub trait FromServerState<C: XConnection> {
    fn create(state: &ServerState<C>) -> Self;
}

pub trait MimeTypeData {
    fn name(&self) -> &str;
    fn data(&self) -> &[u8];
}

type RealServerState = ServerState<Arc<xcb::Connection>>;

pub trait RunData {
    fn display(&self) -> Option<&str>;
    fn server(&self) -> Option<UnixStream> {
        None
    }
    fn created_server(&self) {}
    fn connected_server(&self) {}
    fn xwayland_ready(&self, _display: String) {}
}

pub fn main(data: impl RunData) -> Option<()> {
    let socket = ListeningSocket::bind_auto("wayland", 1..=128).unwrap();
    let mut display = Display::<RealServerState>::new().unwrap();
    let dh = display.handle();
    data.created_server();

    let mut server_state = RealServerState::new(dh, data.server());

    let (xsock_wl, xsock_xwl) = UnixStream::pair().unwrap();
    // Prevent creation of new Xwayland command from closing fd
    rustix::io::fcntl_setfd(&xsock_xwl, rustix::io::FdFlags::empty()).unwrap();

    let (ready_tx, ready_rx) = UnixStream::pair().unwrap();
    rustix::io::fcntl_setfd(&ready_tx, rustix::io::FdFlags::empty()).unwrap();
    let mut xwayland = Command::new("Xwayland");
    if let Some(display) = data.display() {
        xwayland.arg(display);
    }
    let mut xwayland = xwayland
        .args([
            "-rootless",
            "-wm",
            &xsock_xwl.as_raw_fd().to_string(),
            "-displayfd",
            &ready_tx.as_raw_fd().to_string(),
        ])
        .env("WAYLAND_DISPLAY", socket.socket_name().unwrap())
        .stderr(Stdio::piped())
        .spawn()
        .unwrap();

    let (mut finish_tx, mut finish_rx) = UnixStream::pair().unwrap();
    let stderr = xwayland.stderr.take().unwrap();
    std::thread::spawn(move || {
        let reader = BufReader::new(stderr);
        for line in reader.lines() {
            let line = line.unwrap();
            info!(target: "xwayland_process", "{line}");
        }
        let status = Box::new(xwayland.wait().unwrap());
        let status = Box::into_raw(status) as usize;
        finish_tx.write_all(&status.to_ne_bytes()).unwrap();
    });

    let mut ready_fds = [
        PollFd::new(&socket, PollFlags::IN),
        PollFd::new(&finish_rx, PollFlags::IN),
    ];

    let connection = match poll(&mut ready_fds, -1) {
        Ok(_) => {
            if !ready_fds[1].revents().is_empty() {
                let mut data = [0; (usize::BITS / 8) as usize];
                finish_rx.read_exact(&mut data).unwrap();
                let data = usize::from_ne_bytes(data);
                let status: Box<std::process::ExitStatus> =
                    unsafe { Box::from_raw(data as *mut _) };

                error!("Xwayland exited early with {status}");
                return None;
            }

            data.connected_server();
            socket.accept().unwrap().unwrap()
        }
        Err(e) => {
            panic!("first poll failed: {e:?}")
        }
    };
    drop(finish_rx);

    server_state.connect(connection);
    server_state.run();

    let mut xstate: Option<XState> = None;

    // Remove the lifetimes on our fds to avoid borrowing issues, since we know they will exist for
    // the rest of our program anyway
    let server_fd = unsafe { BorrowedFd::borrow_raw(server_state.clientside_fd().as_raw_fd()) };
    let display_fd = unsafe { BorrowedFd::borrow_raw(display.backend().poll_fd().as_raw_fd()) };

    let mut fds = [
        PollFd::from_borrowed_fd(server_fd, PollFlags::IN),
        PollFd::new(&xsock_wl, PollFlags::IN),
        PollFd::from_borrowed_fd(display_fd, PollFlags::IN),
        PollFd::new(&ready_rx, PollFlags::IN),
    ];

    let mut ready = false;
    loop {
        match poll(&mut fds, -1) {
            Ok(_) => {
                if !fds[3].revents().is_empty() {
                    ready = true;
                }
            }
            Err(other) => panic!("Poll failed: {other:?}"),
        }

        if xstate.is_none() && ready {
            let xstate = xstate.insert(XState::new(xsock_wl.as_fd()));
            let mut reader = BufReader::new(&ready_rx);
            let mut display = String::new();
            reader.read_line(&mut display).unwrap();
            display.pop();
            display.insert(0, ':');
            info!("Connected to Xwayland on {display}");
            data.xwayland_ready(display);
            server_state.set_x_connection(xstate.connection.clone());
            server_state.atoms = Some(xstate.atoms.clone());
        }

        if let Some(xstate) = &mut xstate {
            xstate.handle_events(&mut server_state);
        }

        display.dispatch_clients(&mut server_state).unwrap();
        server_state.run();
        display.flush_clients().unwrap();

        if let Some(xstate) = &mut xstate {
            if let Some(sel) = server_state.new_selection() {
                xstate.set_clipboard(sel);
            }
        }
    }
}