Node script for hashing J2ME JAR files, excluding editable parts

jarhasher.js

// MULTI-CORE J2ME JAR HASHER | EXCLUDES EVERYTHING INSIDE MANIFEST FOLDER TO IGNORE MANIFEST-ONLY-CHANGES | (c) Remixer Dec 2019 | License: CC BY-NC 4.0
// usage: node jarhasher.js "C:/path/to/folder_with_jar_files_only_with_forward_slashes" CPU_LOGICAL_CORES HASHLIMIT
// output: 2 files hashed.json, corrupted.json
// output format: [["filename","md5","sha1"],...]

const os = require('os')
const JSZip = require("jszip");
const fs = require("fs")
const crypto = require('crypto')
const cluster = require('cluster');
const path = require('path')

// configuration
const DIR = process.argv[2] || 'C:/Users/Admin/Downloads/J2ME'
const HASHLIMIT = process.argv[4] || Infinity //hash only n files in JAR instead of all of them
const CPUCORES = process.argv[3] || os.cpus().length / 2 //It's recommended to set PHYSICAL core count

function zipHash(fn){
    return new Promise((rs,rj)=>{
        fs.readFile(path.posix.join(DIR,fn),(err,f)=>{
            JSZip.loadAsync(f).then(function (zip) {
                let files = Object.values(zip.files).sort((a,b)=>a.name.localeCompare(b.name))
                let md5 = crypto.createHash("md5");
                let sha = crypto.createHash("sha1");
                for(let i=0,l=files.length;i<l;i++){
                    if(files[i].name.slice(0,8).toLowerCase() != 'meta-inf'){
                        if(i==HASHLIMIT) break
                        let b = new Buffer(4)
                        b.writeInt32LE(files[i]._data.crc32)
                        md5.update(b)
                        sha.update(b)
                    }
                }
                let md5h = md5.digest().toString('hex')
                let shah = sha.digest().toString('hex')
                rs([fn,md5h,shah])
            }).catch(e=>{
                corrupted.push(fn)
                rj()
            });
        })
    })
}

function arrSplit(arr,chunkSize){
    return new Array(Math.ceil(arr.length / chunkSize)).fill().map(_ => arr.splice(0,chunkSize))
}

const progress = []
let allData = []
let corrupted = []
let jobsDone = 0

if (cluster.isMaster) {
    //main process
    let t1 = Date.now()
    let fl = fs.readdirSync(DIR).filter(x=>x.toLowerCase().endsWith('jar'))
    let arrs = arrSplit(fl,Math.ceil(fl.length/CPUCORES))
    for(let y=0;y<CPUCORES;y++){
        let fr = cluster.fork()
        progress.push(0)
        fr.on('message',(msg)=>{
            if('progress' in msg){
                progress[msg.id-1] = msg.progress
                process.title = 'Hashing: '+progress.map(x=>x+'%').join(' | ')
                return
            }
            console.log(`worker #${msg.id} is done!`)
            allData = [].concat(allData,msg.data)
            corrupted = [].concat(corrupted, msg.corrupted)
            jobsDone++
            if(jobsDone == CPUCORES){
                let t2 = Date.now()
                console.log(`job's done in ${(t2-t1)} ms, hashed ${allData.length} files, found ${corrupted.length} corrupted files`);
                fs.writeFileSync('hashed.json',JSON.stringify(allData))
                fs.writeFileSync('corrupted.json',JSON.stringify(corrupted))
                process.exit()
            }
        })
        fr.send({files:arrs[y]});
    }
} else {
    process.on('message', async (msg)=>{
        console.log(`Worker #${cluster.worker.id} started.`)
        let results = []
        for(let j=0,l=msg.files.length;j<l;j++){
            let file = msg.files[j]
            let hash = await zipHash(file).catch(e=>console.error(file+' failed, archive corrupted'))
            if(hash){
                results.push(hash)
            }
            if(j % 100 == 0){
                process.send({progress:Math.round(j*100/l),id:cluster.worker.id})
            }
        }
        process.send({data: results,corrupted: corrupted,id:cluster.worker.id})
    })
}

package.json

{
  "name": "multicore-jar-hasher",
  "version": "1.0.1",
  "description": "script for hashing J2ME JAR files, excluding editable parts",
  "main": "jarhasher.js",
  "dependencies": {
    "jszip": "^3.2.2"
  },
  "devDependencies": {},
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Remixer Dec",
  "license": "MIT"
}