Reforger PAK Unpacker (Node.js)

Node.js library to extract files from Arma Reforger .pak archive files.

Features

• Extract all files from PAK archives
• Extract specific files by name
• List all files in an archive
• Support for Zlib compressed files
• Async and sync APIs
• Easy integration into Express.js or other Node.js applications

Installation

npm install

Usage

Basic Example - Extract All Files

const { PakUnpacker } = require('./PakUnpacker');

async function extractPak() {
    const unpacker = new PakUnpacker('path/to/file.pak');
    await unpacker.load();

    console.log(`Found ${unpacker.entries.length} files`);

    await unpacker.extract('./output');
    console.log('Extraction complete!');
}

extractPak();

List Files in Archive

const { PakUnpacker } = require('./PakUnpacker');

async function listFiles() {
    const unpacker = new PakUnpacker('path/to/file.pak');
    await unpacker.load();

    const files = unpacker.listFiles();
    files.forEach(file => {
        console.log(`${file.name} - ${file.size} bytes (${file.compressed ? 'Compressed' : 'Uncompressed'})`);
    });
}

listFiles();

Extract a Specific File

const { PakUnpacker } = require('./PakUnpacker');

async function extractFile() {
    const unpacker = new PakUnpacker('path/to/file.pak');
    await unpacker.load();

    const fileData = await unpacker.getFile('config.json');

    if (fileData) {
        console.log('File content:', fileData.toString('utf8'));
    } else {
        console.log('File not found');
    }
}

extractFile();

Synchronous API

const { PakUnpacker } = require('./PakUnpacker');

function extractPakSync() {
    const unpacker = new PakUnpacker('path/to/file.pak');
    unpacker.loadSync();

    console.log(`Found ${unpacker.entries.length} files`);

    unpacker.extractSync('./output');
    console.log('Extraction complete!');
}

extractPakSync();

API Integration Example

Express.js REST API

const express = require('express');
const { PakUnpacker } = require('./PakUnpacker');
const app = express();

// List all files in a PAK archive
app.get('/api/pak/:pakName/files', async (req, res) => {
    try {
        const unpacker = new PakUnpacker(`./paks/${req.params.pakName}.pak`);
        await unpacker.load();

        const files = unpacker.listFiles();
        res.json({ success: true, files });
    } catch (error) {
        res.status(500).json({ success: false, error: error.message });
    }
});

// Extract a specific file
app.get('/api/pak/:pakName/extract/:fileName(*)', async (req, res) => {
    try {
        const unpacker = new PakUnpacker(`./paks/${req.params.pakName}.pak`);
        await unpacker.load();

        const fileData = await unpacker.getFile(req.params.fileName);

        if (fileData) {
            res.setHeader('Content-Type', 'application/octet-stream');
            res.send(fileData);
        } else {
            res.status(404).json({ success: false, error: 'File not found' });
        }
    } catch (error) {
        res.status(500).json({ success: false, error: error.message });
    }
});

app.listen(3000, () => {
    console.log('Server running on port 3000');
});

PAK File Format

Reforger PAK files have the following structure:

1. FORM Block: Header with size (Big Endian Int32)
2. HEAD Block: 32 bytes header data
3. DATA Block: Size + data block
4. Entries Block: Directory and file entries

Entry Types

• Type 0: Directory (with child count)
• Type 1: File (with offset, size, original size, compression info)

Compression

• None (0x00): No compression
• Zlib (0x106): Deflate compression with 2-byte Zlib header

API Reference

Class: PakUnpacker

Constructor

new PakUnpacker(filePath)

• filePath (string): Path to the .pak file

Methods

async load()

Load and parse the PAK file asynchronously.

loadSync()

Load and parse the PAK file synchronously (blocking).

async extract(dstDir)

Extract all files to the destination directory.

• dstDir (string): Destination directory path

extractSync(dstDir)

Extract all files synchronously.

• dstDir (string): Destination directory path

async getFile(fileName)

Get a specific file's data by name.

• fileName (string): Name or partial name of the file
• Returns: Promise<Buffer|null>

getFileSync(fileName)

Get a specific file's data synchronously.

• fileName (string): Name or partial name of the file
• Returns: Buffer|null

listFiles()

List all files in the PAK archive.

• Returns: Array of objects with {name, size, originalSize, compressed} properties

Properties

• entries (Array): Array of PakEntryFile objects
• formSize (number): Size of the FORM block
• dataSize (number): Size of the DATA block
• entriesSize (number): Size of the entries block

Requirements

• Node.js >= 14.0.0
• No external dependencies (uses built-in modules only)

License

MIT

Credits

Converted from the original C# implementation.