GRF Loader

GRF is an archive file format that supports lossless data compression used on Ragnarok Online to store game assets. A GRF file may contain one or more files or directories that may have been compressed (deflate) and encrypted (variant of DES).

Features

• ✅ GRF version 0x200 support
• ✅ Works in both Node.js and browser environments
• ✅ DES decryption support
• ✅ Korean filename encoding (CP949/EUC-KR) with auto-detection
• ✅ Mojibake detection and fixing
• ✅ Case-insensitive path resolution
• ✅ Collision-safe indexing (no lost files)
• ✅ Memory efficient (streams data without loading entire file)
• ❌ Custom encryption not supported

Installation

npm install @chicowall/grf-loader

Quick Start

Node.js

import { GrfNode } from '@chicowall/grf-loader';
import { openSync } from 'fs';

const fd = openSync('path/to/data.grf', 'r');
const grf = new GrfNode(fd);

await grf.load();

// Get file
const { data, error } = await grf.getFile('data\\sprite\\monster.spr');

Browser

import { GrfBrowser } from '@chicowall/grf-loader';

const file = document.querySelector('input[type="file"]').files[0];
const grf = new GrfBrowser(file);

await grf.load();

Configuration Options

const grf = new GrfNode(fd, {
  // Filename encoding: 'auto' | 'cp949' | 'euc-kr' | 'utf-8' | 'latin1'
  filenameEncoding: 'auto',

  // Auto-detection threshold for bad characters (default: 1%)
  autoDetectThreshold: 0.01,

  // Maximum uncompressed file size (default: 256MB)
  maxFileUncompressedBytes: 256 * 1024 * 1024,

  // Maximum entries allowed (default: 500,000)
  maxEntries: 500000
});

API Reference

File Operations

// Get file data
const { data, error } = await grf.getFile('data\\clientinfo.xml');

// Check if file exists (case-insensitive)
grf.hasFile('DATA\\CLIENTINFO.XML'); // true

// Get file entry metadata
const entry = grf.getEntry('data\\clientinfo.xml');
// { type, offset, realSize, compressedSize, lengthAligned, rawNameBytes }

// Resolve path (handles case-insensitivity and collisions)
const result = grf.resolvePath('DATA\\Sprite\\Test.spr');
// { status: 'found' | 'not_found' | 'ambiguous', matchedPath?, candidates? }

Search API

// Find files with multiple filters
const files = grf.find({
  ext: 'spr',              // Filter by extension
  contains: 'monster',      // Filter by substring (case-insensitive)
  endsWith: 'poring.spr',  // Filter by path ending
  regex: /^data\\sprite/,  // Filter by regex
  limit: 100               // Max results
});

// Get all files by extension (fast, uses index)
const sprites = grf.getFilesByExtension('spr');
const textures = grf.getFilesByExtension('bmp');

// List all unique extensions
const extensions = grf.listExtensions();
// ['spr', 'act', 'bmp', 'wav', ...]

// List all files
const allFiles = grf.listFiles();

Statistics

const stats = grf.getStats();
// {
//   fileCount: 203092,
//   badNameCount: 4,        // Files with encoding issues
//   collisionCount: 0,      // Normalized path collisions
//   extensionStats: Map,    // Extension -> count
//   detectedEncoding: 'cp949'
// }

// Get detected encoding
const encoding = grf.getDetectedEncoding(); // 'cp949' | 'utf-8' | ...

Encoding Utilities

import {
  isMojibake,
  fixMojibake,
  normalizeFilename,
  normalizeEncodingPath,
  countBadChars,
  hasIconvLite
} from '@chicowall/grf-loader';

// Detect mojibake (CP949 misread as Windows-1252)
isMojibake('À¯ÀúÀÎÅÍÆäÀ̽º'); // true
isMojibake('유저인터페이스');     // false

// Fix mojibake
fixMojibake('À¯ÀúÀÎÅÍÆäÀ̽º'); // '유저인터페이스'

// Normalize entire path
normalizeEncodingPath('data\\texture\\À¯ÀúÀÎÅÍÆäÀ̽º\\test.bmp');
// 'data\\texture\\유저인터페이스\\test.bmp'

// Count problematic characters
countBadChars('test�file.txt'); // 1 (U+FFFD replacement char)

// Check if iconv-lite is available (Node.js only)
hasIconvLite(); // true in Node.js, false in browser

Korean Encoding Support

GRF files from Korean Ragnarok Online clients use CP949 encoding for filenames. This library automatically detects and handles Korean encoding:

// Auto-detection (default)
const grf = new GrfNode(fd, { filenameEncoding: 'auto' });

// Force CP949
const grf = new GrfNode(fd, { filenameEncoding: 'cp949' });

// Reload with different encoding
await grf.reloadWithEncoding('euc-kr');

Encoding Detection Results

| Scenario | Detection | Result | |----------|-----------|--------| | Korean GRF | cp949 | ✅ Proper Korean display | | English GRF | utf-8 | ✅ ASCII preserved | | Mixed content | cp949 | ✅ Both work |

Error Handling

import { GrfError, GRF_ERROR_CODES } from '@chicowall/grf-loader';

try {
  await grf.load();
} catch (e) {
  if (e instanceof GrfError) {
    switch (e.code) {
      case 'INVALID_MAGIC':
        console.log('Not a GRF file');
        break;
      case 'UNSUPPORTED_VERSION':
        console.log('Only version 0x200 supported');
        break;
      case 'CORRUPT_TABLE':
        console.log('File table is corrupted');
        break;
      case 'LIMIT_EXCEEDED':
        console.log('File exceeds size limit');
        break;
    }
  }
}

Error Codes

| Code | Description | |------|-------------| | INVALID_MAGIC | File is not a GRF (invalid signature) | | UNSUPPORTED_VERSION | GRF version not 0x200 | | NOT_LOADED | GRF not loaded yet | | FILE_NOT_FOUND | Requested file not in archive | | AMBIGUOUS_PATH | Multiple files match (collision) | | DECOMPRESS_FAIL | Decompression failed | | CORRUPT_TABLE | File table is corrupted | | LIMIT_EXCEEDED | Size/count limit exceeded |

Validation Tools

Validate a Single GRF

npm run validate:grf -- path/to/data.grf auto 100

Validate All GRFs in a Folder

npm run validate:all -- path/to/grf/folder auto

Output example:

================================================================================
SUMMARY
================================================================================
GRFs loaded:        3/3
Total files:        655,144
Bad U+FFFD:         12
Bad C1 Control:     40
Read tests passed:  300
Read tests failed:  0

Encoding Health:    99.99% (655,092/655,144 clean)

Examples

Extract All Files

npx ts-node examples/extract-all.ts path/to/data.grf output-directory

List All Files by Extension

const grf = new GrfNode(fd);
await grf.load();

// Get all sprite files
const sprites = grf.getFilesByExtension('spr');
console.log(`Found ${sprites.length} sprite files`);

// Get extension statistics
const stats = grf.getStats();
for (const [ext, count] of stats.extensionStats) {
  console.log(`${ext}: ${count} files`);
}

Handle Case-Insensitive Lookups

// All of these resolve to the same file:
await grf.getFile('data\\sprite\\monster.spr');
await grf.getFile('DATA\\SPRITE\\MONSTER.SPR');
await grf.getFile('data/sprite/monster.spr');

Browser Limitations

• iconv-lite is not available in browsers
• CP949 extended characters may show as C1 control characters
• Use hasIconvLite() to check availability

License

MIT