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Running stateful commands in PowerShell through Node.js

Context: I have a javascript file that activates PowerShell's native SpeechSynthesizer module. The script receives a message and passes that through to PowerShell, where it is rendered as speech.
Problem: there is horrible latency (~5sec) between execution and response. This is because the script creates an entirely new PowerShell session and SpeechSynthesizer object with every execution.
Objective: I want to change the script so that a single PowerShell session and SpeechSynthesizer object is persisted and used across multiple sessions. I believe this will eradicate the latency completely.
Limiting Factor: this modification requires making the PowerShell execution stateful. Currently, I don't know how to incorporate stateful commands for the PowerShell in a javascript file.
Code:
const path = require('path');
const Max = require('max-api');
const { exec } = require('child_process');
// This will be printed directly to the Max console
Max.post(`Loaded the ${path.basename(__filename)} script`);
const execCommand = command => {
// Max.post(`Running command: ${command}`);
exec(command, {'shell':'powershell.exe'}, (err, stdout, stderr) => {
if (err) {
// node couldn't execute the command
Max.error(stderr);
Max.error(err);
return;
}
// the *entire* stdout and stderr (buffered)
Max.outletBang()
});
}
// Use the 'outlet' function to send messages out of node.script's outlet
Max.addHandler("speak", (msg) => {
let add = 'Add-Type -AssemblyName System.speech'
let create = '\$speak = New-Object System.Speech.Synthesis.SpeechSynthesizer'
let speak = `\$speak.Speak(\'${msg}\')`
let command = ([add,create,speak]).join('; ')
execCommand(command)
});
Objective, Re-stated: I want to move the add and create commands to a 'create' handler which will only be ran once. The speak command will be run an arbitrary amount of times afterward.
Attempted Solution: I've found one package (https://github.com/bitsofinfo/powershell-command-executor) that supposedly supports stateful PowerShell commands, but it's very complicated. Also, the author mentions a risk of command injection and other insecurities, of which I have no knowledge of.
Any and all suggestions are welcome. Thanks!

copyFileSync not copying file and not throwing error

I'm running a function which I've written in JavaScript inside a nodejs/Electron client.
This function is meant to copy a file from the users flash drive to their c:/Windows/System32 (The file is being copied there so that it can be ran from Command Prompt manually next time the computer is touched without having to switch directories)
The problem is, the files are not being copied, and copyFileSync is not throwing an error.
Here is the code I'm specifically having a problem with:
try {
console.log('copying t.bat');
fs.copyFileSync(remote.app.getAppPath() + '\\app\\files\\scripts\\files\\t.bat', 'C:\\Windows\\System32\\t.bat');
} catch(err) {
console.log('could not copy t.bat', err);
$('#mfail_title').text('Could not copy t.bat file');
$('#mfail_data').text(err);
UIkit.modal("#master_fail").show();
return false;
}
As you can see, I have copyFileSync inside a TRY CATCH block. I know this code is running because in the console I get copying t.bat, but nothing else.
How can I get my files to copy, or at least throw an error when it cannot?
This client is running inside OOBE mode on various Windows 10 machines, therefore always has administrator access.
I've tried updating to the async version of copyFile, but I'm having the same issue. Here is my code
var source = remote.app.getAppPath() + '\\app\\files\\scripts\\files\\t.bat';
var destination = 'C:\\Windows\\System32\\t.bat';
fs.copyFile(source, destination, (err) => {
if (err) {
console.log(err);
} else {
source = remote.app.getAppPath() + '\\app\\files\\scripts\\files\\p.bat';
destination = 'C:\\Windows\\System32\\p.bat';
fs.copyFile(source, destination, (err) => {
if (err) {
console.log(err);
} else {
source = remote.app.getAppPath() + '\\app\\files\\scripts\\files\\p.bat';
destination = 'C:\\Windows\\System32\\p.bat';
child = spawn("powershell.exe",['-ExecutionPolicy', 'ByPass', '-File', remote.app.getAppPath() + '\\app\\files\\scripts\\' + type + '.ps1']);
}
});
}
});
This should copy a file, then when it's complete it should copy another file, once that is complete, it should run a powershell script.
Each copyFile checks for an error before moving on, but it never throws an error, and the file is never copied.

I had a similar issue earlier, In which an Antivirus(Comodo) was not allowing electron app to access the hard drive.
Copy and other file operations were successful in that case as well, because electron in such case access the corresponding sandbox
Please check this is not the case with you.
You can actually access 'fs' in console from electron and check other things in the file system.

Looks to me as if you're using fs on then renderer process (client side) which will not work (assuming that your fs is the node.js fs module and (*)). Your first script seems to use jQuery (hints for renderer) and the second one uses remote in the first line.
fs can only (*) be used on the main process and you'll need to create an IRC channel and do something like:
ircRenderer.sendSync('copy-file-sync', {from: '/from/path', to: '/to/path'})
and, of course, implement the handler for that quickly invented 'copy-file' channel on the main process.
(*) Edit: I haven't played around a lot with nodeIntegration = true, so fs may or may not work on the renderer process with that flag set on the BrowserWindow. But the irc messaging should definitely work and if not, the problem is outside electron, probably related to file permissions.

WebSocket connection closes after calling child process

Here's the setup: I create simple WebSocket Server using the ws library. I then attach a listener for when the client sends me the URL of a PDF to transform. I download it locally then I call another command to transform it:
const download = require("download");
wss.on("connection", ws => {
ws.onmessage = async msg => {
await download(msg.data, destination, {
filename: fileName
});
transformPDF(ws, msg.data);
};
// ...
});
After that, the transformPDF function calls the spawn command to execute a command line binary. I parse the percentage done from the stdout and then try to emit it to the client. But even before this, the connection has been closed and I'm not sure why:
const { spawn } = require("child_process");
const transformPDF = (ws, url) => {
// ...
const child = spawn("k2pdfopt", settings);
child.stdout.on("data", data => {
// ...
ws.send(percentageDone); // <--- connection is broken before this is called
});
};
I have tried to make the transformPDF function a promise and then awaiting it. I have also tried adding an optional detached option to the spawn process. I'm not really sure why it's closing since I've also successfully replaced the command k2pdfopt with something like a lengthy find, and that worked just fine (although it did batch all of the data in the stdout before calling ws.send).
Any help or insight on why it's closing is much appreciated.

Turns out that when I was creating a child process, it was resetting the Visual Studio Code live-server extension that I had running the index.html. That explains why I was also getting a status code of 1001, which I found out most likely means the client refreshed.
I fixed the issue by simply installing the node package live-server and running my index.html from a different terminal.

Electron - Invalid package on unzip

For around 3 weeks I've been working on an Electron app and finally decided to get around to adding update checking. For my research, the standard way to do this in Electron (using Squirrel) requires the user to physically install the application onto their computer. I would rather not do this, and keep everything as portable as possible. I then decided to try making my own update script by having the program download the update.zip, and extract it to overwrite the existing files. This works well, up until the very end. At the very end of the extraction, I receive a Invalid package error, and the actual app.asar file is missing, rendering the application useless.
I am using this to download and extract the updates:
function downloadFile(url, target, fileName, cb) { // Downloads
var req = request({
method: 'GET',
uri: url
});
var out = fs.createWriteStream(target+'/'+fileName);
req.pipe(out);
req.on('end', function() {
unzip(target+'/'+fileName, target, function() {
if (cb) {
cb();
}
});
});
}
function unzip(file, target, cb) { // Unzips
var out = fs.createReadStream(file);
out.pipe(unzipper.Extract({ path: target })).on('finish', function () {
dialog.showMessageBox({
type: 'question',
message: 'Finished extracting to `'+target+'`'
});
if (cb) {
cb();
}
});
}
And call it with:
downloadFile('http://example.com/update.zip', path.join(__dirname, './'), 'update.zip', function() { // http://example.com/update.zip is not the real source
app.relaunch();
app.quit();
});
And I use the unzipper NPM package (https://www.npmjs.com/package/unzipper).
The code works perfectly for all other zips, but it fails when trying to extract a zip containing an Electron app.
Anything I'm doing wrong, or maybe a different package that properly supports extracting zips with .asar files?
Edit 1
I just found https://www.npmjs.com/package/electron-basic-updater, which does not throw the same JavaScript error however it still does not extract the .asar files correctly, and will throw it's own error. Since the .asar is still missing, the app is still useless after the "update"

Thanks to your link to electron-basic-updater, I have found this issue mentioned there: https://github.com/TamkeenLMS/electron-basic-updater/issues/4.
They refer to the issue in the electron app: https://github.com/electron/electron/issues/9304.
Finally, in the end of the second topic there's a solution:
This is due to the electron fs module treating asar files as directories rather than files. To make the unzip process work you need to do one of two things:
Set process.noAsar = true
Use original-fs instead of fs
I have seen the people working with original-fs. But it looked like a big trouble to me.
So I tried setting process.noAsar = true (and then process.noAsar = false after unzipping) - and that worked like a charm.

How to inject module from different app in Node.js

I've two node apps/services that are running together,
1. main app
2. second app
The main app is responsible to show all the data from diffrent apps at the end. Now I put some code of the second app in the main app and now its working, but I want it to be decoupled. I mean that the code of the secnod app will not be in the main app (by somehow to inject it on runtime )
like the second service is registered to the main app in inject the code of it.
the code of it is just two modules ,is it possible to do it in nodejs ?
const Socket = require('socket.io-client');
const client = require("./config.json");
module.exports = (serviceRegistry, wsSocket) =>{
var ws = null;
var consumer = () => {
var registration = serviceRegistry.get("tweets");
console.log("Service: " + registration);
//Check if service is online
if (registration === null) {
if (ws != null) {
ws.close();
ws = null;
console.log("Closed websocket");
}
return
}
var clientName = `ws://localhost:${registration.port}/`
if (client.hosted) {
clientName = `ws://${client.client}/`;
}
//Create a websocket to communicate with the client
if (ws == null) {
console.log("Created");
ws = Socket(clientName, {
reconnect: false
});
ws.on('connect', () => {
console.log("second service is connected");
});
ws.on('tweet', function (data) {
wsSocket.emit('tweet', data);
});
ws.on('disconnect', () => {
console.log("Disconnected from blog-twitter")
});
ws.on('error', (err) => {
console.log("Error connecting socket: " + err);
});
}
}
//Check service availability
setInterval(consumer, 20 * 1000);
}
In the main module I put this code and I want to decouple it by inject it somehow on runtime ? example will be very helpful ...

You will have to use vm module to achieve this. More technical info here https://nodejs.org/api/vm.html. Let me explain how you can use this:
You can use the API vm.script to create compiled js code from the code which you want run later. See the description from official documentation
Creating a new vm.Script object compiles code but does not run it. The
compiled vm.Script can be run later multiple times. It is important to
note that the code is not bound to any global object; rather, it is
bound before each run, just for that run.
Now when you want to insert or run this code, you can use script.runInContext API.
Another good example from their official documentation:
'use strict';
const vm = require('vm');
let code =
`(function(require) {
const http = require('http');
http.createServer( (request, response) => {
response.writeHead(200, {'Content-Type': 'text/plain'});
response.end('Hello World\\n');
}).listen(8124);
console.log('Server running at http://127.0.0.1:8124/');
})`;
vm.runInThisContext(code)(require);
Another example of using js file directly:
var app = fs.readFileSync(__dirname + '/' + 'app.js');
vm.runInThisContext(app);
You can use this approach for the conditional code which you want to insert.

You can create a package from one of your apps and then reference the package in the other app.
https://docs.npmjs.com/getting-started/creating-node-modules

There are several ways to decouple two applications. One easy way is with pub/sub pattern (in case you don't need a response).
(Now if you have an application that is very couple, it will be very difficult to decouple it unless you do some refactoring.)
zeromq offers a very good implementation of pub/sub and is very fast.
e.g.
import zmq from "zmq";
socket.connect('tcp://127.0.0.1:5545');
socket.subscribe('sendConfirmation');
socket.on('message', function (topic, message) {
// you can get the data from message.
// something like:
const msg = message.toString('ascii');
const data = JSON.parse(msg);
// do some actions.
// .....
});
//don't forget to close the socket.
process.on('SIGINT', () => {
debug("... closing the socket ....");
socket.close();
process.exit();
});
//-----------------------------------------
import zmq from "zmq";
socket.bind('tcp://127.0.0.1:5545');
socket.send(['sendConfirmation', someData]);
process.on('SIGINT', function() {
socket.close();
});
This way you could have two different containers (docker) for your modules, just be sure to open the corresponding port.
What i don't understand, is why you inject wsSocket and also you create a new Socket. Probably what I would do is just to send the
socket id, and then just use it like:
const _socketId = "/#" + data.socketId;
io.sockets.connected[socketId].send("some message");
You could also use another solution like kafka instead of zmq, just consider that is slower but it will keep the logs.
Hope this can get you an idea of how to solve your problem.

You can use npm link feature.
The linking process consists of two steps:
Declaring a module as a global link by running npm link in the module’s root folder
Installing the linked modules in your target module(app) by running npm link in the target folder
This works pretty well unless one of your local modules depends on another local module. In this case, linking fails because it cannot find the dependent module. In order to solve this issue, one needs to link the dependent module to the parent module and then install the parent into the app.
https://docs.npmjs.com/cli/link