feat: add nested Phase 0 compositor

compositor/src/main.rs

@@ -1,3 +1,49 @@
-fn main() {
-    println!("Ferese Phase 0 scaffold");
+#![allow(irrefutable_let_patterns)]
+
+mod handlers;
+mod input;
+mod state;
+mod winit;
+
+use std::{error::Error, process::Command};
+
+use smithay::reexports::{calloop::EventLoop, wayland_server::Display};
+pub use state::Ferese;
+use tracing::{info, warn};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    init_logging();
+
+    let mut event_loop: EventLoop<Ferese> = EventLoop::try_new()?;
+    let display: Display<Ferese> = Display::new()?;
+    let mut state = Ferese::new(&mut event_loop, display)?;
+    winit::init(&mut event_loop, &mut state)?;
+
+    // SAFETY: the backend has already read the host display and Ferese is
+    // single-threaded before the event loop and optional child start.
+    unsafe { std::env::set_var("WAYLAND_DISPLAY", &state.socket_name) };
+
+    info!(socket = ?state.socket_name, "Ferese is accepting Wayland clients");
+    spawn_client_from_args();
+    event_loop.run(None, &mut state, |_| {})?;
+    Ok(())
+}
+
+fn init_logging() {
+    let filter = tracing_subscriber::EnvFilter::try_from_default_env()
+        .unwrap_or_else(|_| tracing_subscriber::EnvFilter::new("ferese=info"));
+    tracing_subscriber::fmt().with_env_filter(filter).init();
+}
+
+fn spawn_client_from_args() {
+    let mut args = std::env::args_os().skip(1);
+    let Some(program) = args.next() else {
+        info!("no client requested; pass one after `--`, for example `-- foot`");
+        return;
+    };
+
+    match Command::new(&program).args(args).spawn() {
+        Ok(child) => info!(program = ?program, pid = child.id(), "spawned nested client"),
+        Err(error) => warn!(program = ?program, %error, "failed to spawn nested client"),
+    }
 }