Node JS - read file properties - node.js

I'm developing a Desktop Application with NWJS and I need to get the file properties of an .exe File.
I've tried using the npm properties module https://github.com/gagle/node-properties, but I get an empty Object.
properties.parse('./unzipped/File.exe', { path: true }, function (err, obj) {
if (err) {
console.log(err);
}
console.log(obj);
});
I need to get the "File version" Property:
I've also tried using fs.stats and no luck.
Any ideas?

Unless you want to write some native C module, there is hacky way to get this done easily: using windows wmic command. This is the command to get version (found by googling):
wmic datafile where name='c:\\windows\\system32\\notepad.exe' get Version
so you can just run this command in node to get the job done:
var exec = require('child_process').exec
exec('wmic datafile where name="c:\\\\windows\\\\system32\\\\notepad.exe" get Version', function(err,stdout, stderr){
if(!err){
console.log(stdout)// parse this string for version
}
});

If you want the properties provided as an object, you can use get-file-properties. It uses wmic under the hood, but takes care of parsing the output into an easy to use typed object for your application's consumption.
import { getFileProperties, WmicDataObject } from 'get-file-properties'
async function demo() {
// Make sure to use double backslashes in your file path
const metadata: WmicDataObject = await getFileProperties('C:\\path\\to\\file.txt')
console.log(metadata.Version)
}
Disclaimer: I am the author of get-file-properties

Related

Electron app in production mode fails to run external script via child_process.spawnSync API in Mac but works perfectly in Linux

The app computes the sum of the exponentials of the two entered integers using an R code. The inputs are passed in the form of a JSON object to the R code via child_process.spawnSync API of node.js.
The app was packaged using electron-packager(v15.2.0) and its structure is as shown in the screenshot below. Source code to reproduce this issue can be obtained from this GitHub folder: https://github.com/wasimaftab/Utils/tree/master/test_js_r_interaction
index.js file contains the code to interact with R. Important note, you need to install rjson R package before attempting to run the electron app as it is used in R to extract the arguments from json object.
In Ubuntu (18.04) the output as expected, see the screenshot below,
The same code fails in Mac (Catalina 10.15.7) after packaging but, works perfectly in development mode, see the screenshot below.
The actual error is as follows:
Error: spawnSync Rscript ENOENT
at Object.spawnSync (internal/child_process.js:1041:20)
at Object.spawnSync (child_process.js:625:24)
at callSync (file:///Users/admin/Desktop/test_js_r_interaction/release-builds-mac/test_js_r_interaction-darwin-x64/test_js_r_interaction.app/Contents/Resources/app.asar/src/index.js:25:23)
at HTMLButtonElement.<anonymous> (file:///Users/admin/Desktop/test_js_r_interaction/release-builds-mac/test_js_r_interaction-darwin-x64/test_js_r_interaction.app/Contents/Resources/app.asar/src/index.js:84:20)
and the js code to interact with R is as follows:
const path = require("path");
const child_process = require('child_process');
const RSCRIPT = 'Rscript';
const defaultOptions = {
verboseResult: false
}
function parseStdout(output) {
try {
output = output.substr(output.indexOf('"{'), output.lastIndexOf('}"'));
return JSON.parse(JSON.parse(output));
} catch (err) {
return err;
}
}
function callSync(script, args, options) {
options = options || defaultOptions;
const result = args ?
child_process.spawnSync(RSCRIPT, [script, JSON.stringify(args)]) :
child_process.spawnSync(RSCRIPT, [script]);
if (result.status == 0) {
const ret = parseStdout(result.stdout.toString());
if (!(ret instanceof Error)) {
if (options.verboseResult) {
return {
pid: result.pid,
result: ret
};
} else {
return ret;
};
} else {
return {
pid: result.pid,
error: ret.message
};
}
} else if (result.status == 1) {
return {
pid: result.pid,
error: result.stderr.toString()
};
} else {
return {
pid: result.pid,
error: result.stderr.toString()
//error: result.stdout.toString()
};
}
}
I will appreciate any suggestion to fix this issue, thanks in advance
The error you're getting, ENOENT, suggests that your OS cannot find Rscript. This can result from the following scenarios:
Rscript is not even installed.
Rscript is installed, but not executable without a "shell". To check whether it is installed, open a Terminal and execute the command as your Electron application would.
If Rscript can be executed from within a Terminal, there could be something wrong with how the installation has set your paths up. There shouldn't be, really, but it might be necessary to execute spawnSync with additional options, such as { shell: true } to get the correct value of PATH.
If Rscript cannot be executed from within a Terminal, forcing Electron to spawn a shell via the above options (which really is what a Terminal does) will not solve this problem. In this case, try to use the complete path to Rscript as the command instead, if you happen to know where it should be installed.
If neither of those solutions help, try reinstalling Rscript altogether and try again. As I can see nothing which would be wrong with your code, I believe it is a problem of installation.
For more information on child_process.spawnSync (command, args, options), see its documentation.

Commander throws error for command with description

Here is a simple example of adding command in nodejs using commander:
'use strict';
const {Command} = require('commander');
const run = () => {
const program = new Command();
console.log('CMD');
program.command('cmd [opts...]')
.action((opts) => {
console.log('OPTS');
});
program.parse(process.argv);
};
run();
In this case everything works fine, but when I'm adding description and options, commander throws an error:
program.command('cmd [opts...]', 'DESCRIPTION', {isDefault: true})
node test-commander.js cmd opts
test-commander-cmd(1) does not exist, try --help
My env:
node v8.9.3
npm 5.3.0
commander 2.12.2
That is the declared behavior of commander. From the npm page under Git-style sub-commands...
When .command() is invoked with a description argument, no .action(callback) should be called to handle sub-commands, otherwise there will be an error. This tells commander that you're going to use separate executables for sub-commands, much like git(1) and other popular tools.
The commander will try to search the executables in the directory of the entry script (like ./examples/pm) with the name program-command, like pm-install, pm-search.
So, when you add a description like you have, it'll assume you have another executable file called test-commander-cmd for the sub command.
If commander's behavior is not what you were expecting, I might recommend looking into a package I published, called wily-cli... only if you're not committed to commander, of course ;)
Assuming your code rests in file.js, your example with wily-cli would look like this...
const cli = require('wily-cli');
const run = () => {
cli
.command('cmd [opts...]', 'DESCRIPTION', (options, parameters) => { console.log(parameters.opts); })
.defaultCommand('cmd');
};
run();
// "node file.js option1 option2" will output "[ 'option1', 'option2' ]"

reading a packaged file in aws lambda package

I have a very simple node lambda function which reads the contents of packaged file in it. I upload the code as zip file. The directory structure is as follows.
index.js
readme.txt
Then have in my index.js file:
fs.readFile('/var/task/readme.txt', function (err, data) {
if (err) throw err;
});
I keep getting the following error NOENT: no such file or directory, open '/var/task/readme.txt'.
I tried ./readme.txt also.
What am I missing ?
Try this, it works for me:
'use strict'
let fs = require("fs");
let path = require("path");
exports.handler = (event, context, callback) => {
// To debug your problem
console.log(path.resolve("./readme.txt"));
// Solution is to use absolute path using `__dirname`
fs.readFile(__dirname +'/readme.txt', function (err, data) {
if (err) throw err;
});
};
to debug why your code is not working, add below link in your handler
console.log(path.resolve("./readme.txt"));
On AWS Lambda node process might be running from some other folder and it looks for readme.txt file from that folder as you have provided relative path, solution is to use absolute path.
What worked for me was the comment by Vadorrequest to use process.env.LAMBDA_TASK_ROOT. I wrote a function to get a template file in a /templates directory when I'm running it locally on my machine with __dirname or with the process.env.LAMBDA_TASK_ROOT variable when running on Lambda:
function loadTemplateFile(templateName) {
const fileName = `./templates/${templateName}`
let resolved
if (process.env.LAMBDA_TASK_ROOT) {
resolved = path.resolve(process.env.LAMBDA_TASK_ROOT, fileName)
} else {
resolved = path.resolve(__dirname, fileName)
}
console.log(`Loading template at: ${resolved}`)
try {
const data = fs.readFileSync(resolved, 'utf8')
return data
} catch (error) {
const message = `Could not load template at: ${resolved}, error: ${JSON.stringify(error, null, 2)}`
console.error(message)
throw new Error(message)
}
}
This is an oldish question but comes up first when attempting to sort out whats going on with file paths on Lambda.
Additional Steps for Serverless Framework
For anyone using Serverless framework to deploy (which probably uses webpack to build) you will also need to add the following to your webpack config file (just after target: node):
// assume target: 'node', is here
node: {
__dirname: false,
},
Without this piece using __dirname with Serverless will STILL not get you the desired absolute directory path.
I went through this using serverless framework and it really was the file that was not sent in the compression. Just add the following line in serverless.yml:
package:
individually: false
include:
- src/**
const filepath = path.resolve('../../filename.text');
const fileData2 = fs.readFileSync(process.env.LAMBDA_TASK_ROOT + filepath, 'utf-8');
I was using fs.promises.readFile(). Couldn't get it to error out at out. The file was there, and LAMBDA_TASK_ROOT seemed right to me as well. After I changed to fs.readFileSync(), it worked.
I hade the same problem and I tried applying all these wonderful solutions above - which didn't work.
The problem was that I setup one of the folder name with one letter in upper case which was really lowercase.
So when I tried to fetch the content of /src/SOmething/some_file.txt
While the folder was really /src/Something/ - I got this error...
Windows (local environment) is case insensitive while AWS is not!!!....

How can I parse a string into appropriate arguments for child_process.spawn?

I want to be able to take a command string, for example:
some/script --option="Quoted Option" -d --another-option 'Quoted Argument'
And parse it into something that I can send to child_process.spawn:
spawn("some/script", ["--option=\"Quoted Option\"", "-d", "--another-option", "Quoted Argument"])
All of the parsing libraries I've found (e.g. minimist, etc.) do too much here by parsing it into some kind of options object, etc. I basically want the equivalent of whatever Node does to create process.argv in the first place.
This seems like a frustrating hole in the native APIs since exec takes a string, but doesn't execute as safely as spawn. Right now I'm hacking around this by using:
spawn("/bin/sh", ["-c", commandString])
However, I don't want this to be tied to UNIX so strongly (ideally it'd work on Windows too). Halp?
Standard Method (no library)
You don't have to parse the command string into arguments, there's an option on child_process.spawn named shell.
options.shell
If true, runs command inside of a shell.
Uses /bin/sh on UNIX, and cmd.exe on Windows.
Example:
let command = `some_script --option="Quoted Option" -d --another-option 'Quoted Argument'`
let process = child_process.spawn(command, [], { shell: true }) // use `shell` option
process.stdout.on('data', (data) => {
console.log(data)
})
process.stderr.on('data', (data) => {
console.log(data)
})
process.on('close', (code) => {
console.log(code)
})
The minimist-string package might be just what you're looking for.
Here's some sample code that parses your sample string -
const ms = require('minimist-string')
const sampleString = 'some/script --option="Quoted Option" -d --another-option \'Quoted Argument\'';
const args = ms(sampleString);
console.dir(args)
This piece of code outputs this -
{
_: [ 'some/script' ],
option: 'Quoted Option',
d: true,
'another-option': 'Quoted Argument'
}

NodeJS not spawning child process except in tests

I have the following NodeJS code:
var spawn = require('child_process').spawn;
var Unzipper = {
unzip: function(src, dest, callback) {
var self = this;
if (!fs.existsSync(dest)) {
fs.mkdir(dest);
}
var unzip = spawn('unzip', [ src, '-d', dest ]);
unzip.stdout.on('data', function (data) {
self.stdout(data);
});
unzip.stderr.on('data', function (data) {
self.stderr(data);
callback({message: "There was an error executing an unzip process"});
});
unzip.on('close', function() {
callback();
});
}
};
I have a NodeUnit test that executes successfully. Using phpStorm to debug the test the var unzip is assigned correctly
However if I run the same code as part of a web service, the spawn call doesn't return properly and the server crashes on trying to attach an on handler to the nonexistent stdout property of the unzip var.
I've tried running the program outside of phpStorm, however it crashes on the command line as well for the same reason. I'm suspecting it's a permissions issue that the tests don't have to deal with. A web server spawning processes could cause chaos in a production environment, therefore some extra permissions might be needed, but I haven't been able to find (or I've missed) documentation to support my hypothesis.
I'm running v0.10.3 on OSX Snow Leopard (via MacPorts).
Why can't I spawn the child process correctly?
UPDATES
For #jonathan-wiepert
I'm using Prototypical inheritance so when I create an "instance" of Unzipper I set stdout and stderr ie:
var unzipper = Unzipper.spawn({
stdout: function(data) { util.puts(data); },
stderr: function(data) { util.puts(data); }
});
This is similar to the concept of "constructor injection". As for your other points, thanks for the tips.
The error I'm getting is:
project/src/Unzipper.js:15
unzip.stdout.on('data', function (data) {
^
TypeError: Cannot call method 'on' of undefined
As per my debugging screenshots, the object that is returned from the spawn call is different under different circumstances. My test passes (it checks that a ZIP can be unzipped correctly) so the problem occurs when running this code as a web service.
The problem was that the spawn method created on the Object prototype (see this article on Protypical inheritance) was causing the child_process.spawn function to be replaced, so the wrong function was being called.
I saved child_process.spawn into a property on the Unzipper "class" before it gets clobbered and use that property instead.

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