3 files changed, 235 insertions, 0 deletions
diff --git a/src/ipc/client.rs b/src/ipc/client.rs
new file mode 100644
index 00000000..c09ef84e
--- /dev/null
+++ b/src/ipc/client.rs
@@ -0,0 +1,106 @@
+use std::env;
+use std::io::{Read, Write};
+use std::net::Shutdown;
+use std::os::unix::net::UnixStream;
+
+use anyhow::{bail, Context};
+use niri_ipc::{Mode, Output, Request, Response};
+
+use crate::Msg;
+
+pub fn handle_msg(msg: Msg, json: bool) -> anyhow::Result<()> {
+    let socket_path = env::var_os(niri_ipc::SOCKET_PATH_ENV).with_context(|| {
+        format!(
+            "{} is not set, are you running this within niri?",
+            niri_ipc::SOCKET_PATH_ENV
+        )
+    })?;
+
+    let mut stream =
+        UnixStream::connect(socket_path).context("error connecting to {socket_path}")?;
+
+    let request = match msg {
+        Msg::Outputs => Request::Outputs,
+    };
+    let mut buf = serde_json::to_vec(&request).unwrap();
+    stream
+        .write_all(&buf)
+        .context("error writing IPC request")?;
+    stream
+        .shutdown(Shutdown::Write)
+        .context("error closing IPC stream for writing")?;
+
+    buf.clear();
+    stream
+        .read_to_end(&mut buf)
+        .context("error reading IPC response")?;
+
+    let response = serde_json::from_slice(&buf).context("error parsing IPC response")?;
+    match msg {
+        Msg::Outputs => {
+            #[allow(irrefutable_let_patterns)]
+            let Response::Outputs(outputs) = response
+            else {
+                bail!("unexpected response: expected Outputs, got {response:?}");
+            };
+
+            if json {
+                let output =
+                    serde_json::to_string(&outputs).context("error formatting response")?;
+                println!("{output}");
+                return Ok(());
+            }
+
+            let mut outputs = outputs.into_iter().collect::<Vec<_>>();
+            outputs.sort_unstable_by(|a, b| a.0.cmp(&b.0));
+
+            for (connector, output) in outputs.into_iter() {
+                let Output {
+                    name,
+                    make,
+                    model,
+                    physical_size,
+                    modes,
+                    current_mode,
+                } = output;
+
+                println!(r#"Output "{connector}" ({make} - {model} - {name})"#);
+
+                if let Some(current) = current_mode {
+                    let mode = *modes
+                        .get(current)
+                        .context("invalid response: current mode does not exist")?;
+                    let Mode {
+                        width,
+                        height,
+                        refresh_rate,
+                    } = mode;
+                    let refresh = refresh_rate as f64 / 1000.;
+                    println!("  Current mode: {width}x{height} @ {refresh:.3} Hz");
+                } else {
+                    println!("  Disabled");
+                }
+
+                if let Some((width, height)) = physical_size {
+                    println!("  Physical size: {width}x{height} mm");
+                } else {
+                    println!("  Physical size: unknown");
+                }
+
+                println!("  Available modes:");
+                for mode in modes {
+                    let Mode {
+                        width,
+                        height,
+                        refresh_rate,
+                    } = mode;
+                    let refresh = refresh_rate as f64 / 1000.;
+                    println!("    {width}x{height}@{refresh:.3}");
+                }
+                println!();
+            }
+        }
+    }
+
+    Ok(())
+}
diff --git a/src/ipc/mod.rs b/src/ipc/mod.rs
new file mode 100644
index 00000000..c07f47e0
--- /dev/null
+++ b/src/ipc/mod.rs
@@ -0,0 +1,2 @@
+pub mod client;
+pub mod server;
diff --git a/src/ipc/server.rs b/src/ipc/server.rs
new file mode 100644
index 00000000..d493e861
--- /dev/null
+++ b/src/ipc/server.rs
@@ -0,0 +1,127 @@
+use std::cell::RefCell;
+use std::collections::HashMap;
+use std::os::unix::net::{UnixListener, UnixStream};
+use std::path::PathBuf;
+use std::rc::Rc;
+use std::{env, io, process};
+
+use anyhow::Context;
+use calloop::io::Async;
+use directories::BaseDirs;
+use futures_util::io::{AsyncReadExt, BufReader};
+use futures_util::{AsyncBufReadExt, AsyncWriteExt};
+use niri_ipc::{Request, Response};
+use smithay::reexports::calloop::generic::Generic;
+use smithay::reexports::calloop::{Interest, LoopHandle, Mode, PostAction};
+use smithay::reexports::rustix::fs::unlink;
+
+use crate::niri::State;
+
+pub struct IpcServer {
+    pub socket_path: PathBuf,
+}
+
+struct ClientCtx {
+    ipc_outputs: Rc<RefCell<HashMap<String, niri_ipc::Output>>>,
+}
+
+impl IpcServer {
+    pub fn start(
+        event_loop: &LoopHandle<'static, State>,
+        wayland_socket_name: &str,
+    ) -> anyhow::Result<Self> {
+        let _span = tracy_client::span!("Ipc::start");
+
+        let socket_name = format!("niri.{wayland_socket_name}.{}.sock", process::id());
+        let mut socket_path = socket_dir();
+        socket_path.push(socket_name);
+
+        let listener = UnixListener::bind(&socket_path).context("error binding socket")?;
+        listener
+            .set_nonblocking(true)
+            .context("error setting socket to non-blocking")?;
+
+        let source = Generic::new(listener, Interest::READ, Mode::Level);
+        event_loop
+            .insert_source(source, |_, socket, state| {
+                match socket.accept() {
+                    Ok((stream, _)) => on_new_ipc_client(state, stream),
+                    Err(e) if e.kind() == io::ErrorKind::WouldBlock => (),
+                    Err(e) => return Err(e),
+                }
+
+                Ok(PostAction::Continue)
+            })
+            .unwrap();
+
+        Ok(Self { socket_path })
+    }
+}
+
+impl Drop for IpcServer {
+    fn drop(&mut self) {
+        let _ = unlink(&self.socket_path);
+    }
+}
+
+fn socket_dir() -> PathBuf {
+    BaseDirs::new()
+        .as_ref()
+        .and_then(|x| x.runtime_dir())
+        .map(|x| x.to_owned())
+        .unwrap_or_else(env::temp_dir)
+}
+
+fn on_new_ipc_client(state: &mut State, stream: UnixStream) {
+    let _span = tracy_client::span!("on_new_ipc_client");
+    trace!("new IPC client connected");
+
+    let stream = match state.niri.event_loop.adapt_io(stream) {
+        Ok(stream) => stream,
+        Err(err) => {
+            warn!("error making IPC stream async: {err:?}");
+            return;
+        }
+    };
+
+    let ctx = ClientCtx {
+        ipc_outputs: state.backend.ipc_outputs(),
+    };
+
+    let future = async move {
+        if let Err(err) = handle_client(ctx, stream).await {
+            warn!("error handling IPC client: {err:?}");
+        }
+    };
+    if let Err(err) = state.niri.scheduler.schedule(future) {
+        warn!("error scheduling IPC stream future: {err:?}");
+    }
+}
+
+async fn handle_client(ctx: ClientCtx, stream: Async<'_, UnixStream>) -> anyhow::Result<()> {
+    let (read, mut write) = stream.split();
+    let mut buf = String::new();
+
+    // Read a single line to allow extensibility in the future to keep reading.
+    BufReader::new(read)
+        .read_line(&mut buf)
+        .await
+        .context("error reading request")?;
+
+    let request: Request = serde_json::from_str(&buf).context("error parsing request")?;
+
+    let response = match request {
+        Request::Outputs => {
+            let ipc_outputs = ctx.ipc_outputs.borrow().clone();
+            Response::Outputs(ipc_outputs)
+        }
+    };
+
+    let buf = serde_json::to_vec(&response).context("error formatting response")?;
+    write
+        .write_all(&buf)
+        .await
+        .context("error writing response")?;
+
+    Ok(())
+}