pi-gui/src/bridge/runtime.js

import { chmod, lstat, mkdir, unlink } from "node:fs/promises";
import path from "node:path";
import { acquireBridgeLock } from "./instance-lock.js";
import { startUnixSocketServer } from "./unix-server.js";

const RUNTIME_DIRECTORY_MODE = 0o700;

export async function createRuntimePaths(
	runtimeDir = process.env.XDG_RUNTIME_DIR,
) {
	if (!runtimeDir || !path.isAbsolute(runtimeDir)) {
		throw new Error("XDG_RUNTIME_DIR must be an absolute path");
	}
	const directory = path.join(runtimeDir, "pi-status-bridge");
	await mkdir(directory, { recursive: true, mode: RUNTIME_DIRECTORY_MODE });
	await chmod(directory, RUNTIME_DIRECTORY_MODE);
	return {
		directory,
		socketPath: path.join(directory, "bridge.sock"),
		lockPath: path.join(directory, "bridge.lock"),
	};
}

async function removeStaleSocket(socketPath) {
	try {
		const socket = await lstat(socketPath);
		if (!socket.isSocket())
			throw new Error(`refusing to remove non-socket path: ${socketPath}`);
		await unlink(socketPath);
	} catch (error) {
		if (error?.code !== "ENOENT") throw error;
	}
}

export async function startBridgeServer({
	handleRequest,
	subscribe,
	runtimeDir,
	processAlive,
	maxFrameBytes,
}) {
	const paths = await createRuntimePaths(runtimeDir);
	const lock = await acquireBridgeLock({
		lockPath: paths.lockPath,
		socketPath: paths.socketPath,
		...(processAlive ? { processAlive } : {}),
	});

	try {
		await removeStaleSocket(paths.socketPath);
		const socketServer = await startUnixSocketServer({
			socketPath: paths.socketPath,
			handleRequest,
			...(subscribe ? { subscribe } : {}),
			...(maxFrameBytes ? { maxFrameBytes } : {}),
		});
		return {
			...paths,
			async close() {
				await socketServer.close();
				await lock.release();
			},
		};
	} catch (error) {
		await lock.release();
		throw error;
	}
}