@rize-io/active-win/lib/linux.js

Get metadata about the active window (title, id, bounds, owner, URL, etc)

'use strict';
const {promisify} = require('util');
const fs = require('fs');
const childProcess = require('child_process');

const execFile = promisify(childProcess.execFile);
const readFile = promisify(fs.readFile);
const readlink = promisify(fs.readlink);

const xpropBin = 'xprop';
const xwininfoBin = 'xwininfo';
const xpropActiveArgs = ['-root', '\t$0', '_NET_ACTIVE_WINDOW'];
const xpropOpenArgs = ['-root', '_NET_CLIENT_LIST_STACKING'];
const xpropDetailsArgs = ['-id'];

const processOutput = output => {
	const result = {};

	for (const row of output.trim().split('\n')) {
		if (row.includes('=')) {
			const [key, value] = row.split('=');
			result[key.trim()] = value.trim();
		} else if (row.includes(':')) {
			const [key, value] = row.split(':');
			result[key.trim()] = value.trim();
		}
	}

	return result;
};

const parseLinux = ({stdout, boundsStdout, activeWindowId}) => {
	const result = processOutput(stdout);
	const bounds = processOutput(boundsStdout);

	const windowIdProperty = 'WM_CLIENT_LEADER(WINDOW)';
	const resultKeys = Object.keys(result);
	const windowId = (resultKeys.indexOf(windowIdProperty) > 0 &&
		Number.parseInt(result[windowIdProperty].split('#').pop(), 16)) || activeWindowId;

	const processId = Number.parseInt(result['_NET_WM_PID(CARDINAL)'], 10);

	if (Number.isNaN(processId)) {
		throw new Error('Failed to parse process ID'); // eslint-disable-line unicorn/prefer-type-error
	}

	return {
		platform: 'linux',
		title: JSON.parse(result['_NET_WM_NAME(UTF8_STRING)'] || result['WM_NAME(STRING)']) || null,
		id: windowId,
		owner: {
			name: JSON.parse(result['WM_CLASS(STRING)'].split(',').pop()),
			processId
		},
		bounds: {
			x: Number.parseInt(bounds['Absolute upper-left X'], 10),
			y: Number.parseInt(bounds['Absolute upper-left Y'], 10),
			width: Number.parseInt(bounds.Width, 10),
			height: Number.parseInt(bounds.Height, 10)
		}
	};
};

const getActiveWindowId = activeWindowIdStdout => Number.parseInt(activeWindowIdStdout.split('\t')[1], 16);

const getMemoryUsageByPid = async pid => {
	const statm = await readFile(`/proc/${pid}/statm`, 'utf8');
	return Number.parseInt(statm.split(' ')[1], 10) * 4096;
};

const getMemoryUsageByPidSync = pid => {
	const statm = require('fs').readFileSync(`/proc/${pid}/statm`, 'utf8');
	return Number.parseInt(statm.split(' ')[1], 10) * 4096;
};

const getPathByPid = pid => {
	return readlink(`/proc/${pid}/exe`);
};

const getPathByPidSync = pid => {
	try {
		return fs.readlinkSync(`/proc/${pid}/exe`);
	} catch {}
};

async function getWindowInformation(windowId) {
	const [{stdout}, {stdout: boundsStdout}] = await Promise.all([
		execFile(xpropBin, [...xpropDetailsArgs, windowId], {env: {...process.env, LC_ALL: 'C.utf8'}}),
		execFile(xwininfoBin, [...xpropDetailsArgs, windowId])
	]);

	const data = parseLinux({
		windowId,
		boundsStdout,
		stdout
	});
	const [memoryUsage, path] = await Promise.all([
		getMemoryUsageByPid(data.owner.processId),
		getPathByPid(data.owner.processId).catch(() => {})
	]);
	data.memoryUsage = memoryUsage;
	data.owner.path = path;
	return data;
}

function getWindowInformationSync(windowId) {
	const stdout = childProcess.execFileSync(xpropBin, [...xpropDetailsArgs, windowId], {encoding: 'utf8', env: {...process.env, LC_ALL: 'C.utf8'}});
	const boundsStdout = childProcess.execFileSync(xwininfoBin, [...xpropDetailsArgs, windowId], {encoding: 'utf8'});

	const data = parseLinux({
		windowId,
		boundsStdout,
		stdout
	});
	data.memoryUsage = getMemoryUsageByPidSync(data.owner.processId);
	data.owner.path = getPathByPidSync(data.owner.processId);
	return data;
}

module.exports = async () => {
	try {
		const {stdout: activeWindowIdStdout} = await execFile(xpropBin, xpropActiveArgs);
		const activeWindowId = getActiveWindowId(activeWindowIdStdout);

		if (!activeWindowId) {
			return;
		}

		return getWindowInformation(activeWindowId);
	} catch {
		return undefined;
	}
};

module.exports.sync = () => {
	try {
		const activeWindowIdStdout = childProcess.execFileSync(xpropBin, xpropActiveArgs, {encoding: 'utf8'});
		const activeWindowId = getActiveWindowId(activeWindowIdStdout);

		if (!activeWindowId) {
			return;
		}

		return getWindowInformationSync(activeWindowId);
	} catch {
		return undefined;
	}
};

module.exports.getOpenWindows = async () => {
	try {
		const {stdout: openWindowIdStdout} = await execFile(xpropBin, xpropOpenArgs);
		// Get open windows Ids
		const windowsIds = openWindowIdStdout.split('#')[1].trim().replace('\n', '').split(',');

		if (!windowsIds || windowsIds.length === 0) {
			return;
		}

		const openWindows = [];

		for await (const windowId of windowsIds) {
			openWindows.push(await getWindowInformation(Number.parseInt(windowId, 16)));
		}

		return openWindows;
	} catch {
		return undefined;
	}
};

module.exports.getOpenWindowsSync = () => {
	try {
		const openWindowIdStdout = childProcess.execFileSync(xpropBin, xpropOpenArgs, {encoding: 'utf8'});
		const windowsIds = openWindowIdStdout.split('#')[1].trim().replace('\n', '').split(',');

		if (!windowsIds || windowsIds.length === 0) {
			return;
		}

		const openWindows = [];

		for (const windowId of windowsIds) {
			const windowInformation = getWindowInformationSync(Number.parseInt(windowId, 16));
			openWindows.push(windowInformation);
		}

		return openWindows;
	} catch (error) {
		console.log(error);
		return undefined;
	}
};