I'm working on a node-webkit app that performs filesystem operations. I need to be able to check if the file is being used by another process before deleting (unlinking).
If I only use the fs.unlink method, the system will wait until the file stops being used before removing it completely. What I want is that if the file is being used, don't wait until it's released, but cancel the whole operation and don't delete it.
Thanks.
Assuming you're on a *nix system something like this should work. Obviously this is overly simplified as far as error and path checking. There may very well be a better way to do this but I might as well start the discussion with this:
var fs = require('fs'),
exec = require('child_process').exec;
function unlinkIfUnused(path) {
exec('lsof ' + path, function(err, stdout, stderr) {
if (stdout.length === 0) {
console.log(path, " not in use. unlinking...");
// fs.unlink...
} else {
console.log(path, "IN USE. Ignoring...");
}
});
}
unlinkIfUnused('/home/jack/testlock.txt');
Related
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!
I've been worked on a vue project.
This vue project use the nodejs API I've created, in simple way, they are two entire differents project which are not located in the same directory and they are launched separately.
The problem is whenever I debug a route with node --inspect --debug-break event_type.controller.js for example named:
"/eventtype/create"
exports.create = (req, res) => {
const userId = jwt.getUserId(req.headers.authorization);
if (userId == null) {
res.status(401).send(Response.response401());
return;
}
// Validate request
if (!req.body.label || !req.body.calendarId) {
res.status(400).send(Response.response400());
return;
}
const calendarId = req.body.calendarId; // Calendar id
// Save to database
EventType.create({
label: req.body.label,
}).then((eventType) => {
Calendar.findByPk(calendarId).then((calendar) => {
eventType.addCalendar(calendar); // Add a Calendar
res.status(201).send(eventType);
}).catch((err) => {
res.status(500).send(Response.response500(err.message));
});
}).catch((err) => {
res.status(500).send(Response.response500(err.message));
});
};
Even if I create a breakpoint on const userId = jwt.getUserId(req.headers.authorization);
and from my vue app I trigger the api createEventType event, my break point is not passed.
Also when I press f8 after the breakpoint on my first line with the debugger, my file close automatically.
I do not use VS Code but Vim for coding but I've heard that maybe Vs Code could allow a simplified way to debug nodesjs application.
NOTE: I use the V8 node debugger.
For newer NodeJS versions (> 7.0.0) you need to use
node --inspect-brk event_type.controller.js
instead of
node --inspect --debug-break event_type.controller.js
to break on the first line of the application code. See https://nodejs.org/api/debugger.html#debugger_advanced_usage for more information.
The solution (even if it's not really a solution) has been to add console.log to the line I wanted to debug.
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.
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.
I started developing tests for a website application and I have some problems.
I'm using Node.js, webdriver, chromedriver and selenium rc.
The questions are:
1. How do I make a screenshot and save it in the same folder as the script.
2. Is there a way to save the test logs for a test case? For example, if check for an element on the page and don't find it, how do I output that?
For saving the test logs you typically use a test runner. When you check if an element is on the page and you can't find it then you raise an exception (typically an assertion error) and the test runner will record this and mark it as a failed test. In the documentation they suggest you use Mocha.
As for saving a screenshot to disk, the the api looks like this
driver.takeScreenshot().then(
function(image, err) {
require('fs').writeFile('out.png', image, 'base64', function(err) {
console.log(err);
});
}
);
Adapting aychedee's answer into a complete promise that will resolve after the file is written and reject on write failure:
const fsp = require('fs').promises
function takeScreenshot(driver, file){
return driver.takeScreenshot()
.then(image => fsp.writeFile(file, image, 'base64'))
}
Or in an ESM async function
import { writeFile } from 'node:fs/promises'
async function takeScreenshot(driver, file){
let image = await driver.takeScreenshot()
await writeFile(file, image, 'base64')
}
Just for the record, this is how you take a screenshot with WebdriverJS:
var webdriverjs = require('webdriverjs'),
client = webdriverjs.remote({
desiredCapabilities: {
browserName: 'chrome'
}
});
client
.init()
.url('http://google.com')
.saveScreenshot(__dirname + '/googleScreenshot.png')
.end();
You can also use WebdriverCSS to take screenshots. It is a plugin for WebdriverJS to do CSS regression tests. It is pretty much the same like PhantomCSS.