tzip

A Rust library for creating and validating TorrentZip-format ZIP files.

What is TorrentZip?

TorrentZip is a ZIP file format specification that ensures byte-identical output across different systems and tools. This is critical for:

• ROM preservation - Verify file integrity with hash comparison
• Distributed systems - BitTorrent/P2P sharing benefits from identical files
• Reproducible builds - Same input always produces the same output

Features

• ✅ Byte-identical output - Matches original trrntzip tools exactly
• ✅ Full validation - Verify existing TorrentZip files
• ✅ Zero unsafe code - 100% safe Rust
• ✅ No dependencies on external tools - Pure Rust + zlib

Usage

Creating a TorrentZip

use tzip::TorrentZipWriter;

let mut buffer = Vec::new();
{
    let mut tz = TorrentZipWriter::new(&mut buffer);
    tz.add_file("game.bin", &rom_data)?;
    tz.add_file("bios.bin", &bios_data)?;
    tz.finish()?;
}

// buffer now contains a valid TorrentZip file
std::fs::write("output.zip", &buffer)?;

Validating a TorrentZip

use tzip::TorrentZipValidator;

let data = std::fs::read("archive.zip")?;
let result = TorrentZipValidator::validate(&data)?;

if result.is_valid {
    println!("Valid TorrentZip! CRC32: {:08X}", result.computed_crc32);
} else {
    for error in result.errors {
        eprintln!("Validation error: {:?}", error);
    }
}

Convenience Function

use tzip::create_torrentzip;

let files = vec![
    ("rom1.bin", &rom1_data[..]),
    ("rom2.bin", &rom2_data[..]),
];

let zip_data = create_torrentzip(files)?;

TorrentZip Specification

This crate implements the full TorrentZip specification:

Why These Constraints?

• Fixed timestamp - Eliminates time-based differences between builds
• Max compression - Consistent DEFLATE output via zlib
• Sorted files - Deterministic file ordering
• Archive comment - Self-verifying checksum of structure

Testing

The test suite includes 21 tests covering:

• Byte-identical output comparison with original trrntzip
• Determinism (same input → same output, run 5 times)
• Validation of valid TorrentZip files
• Detection of invalid/corrupted files
• Case-insensitive file sorting

cargo test --release

Compatibility

This crate produces byte-identical output to the original C trrntzip tool by using:

• flate2 with zlib backend (same DEFLATE implementation)
• Matching VERSION_MADE_BY = 0 in central directory headers

Files created by this crate are fully compatible with:

• trrntzip (original C tool)
• trrntzip .NET port
• Any standard ZIP utility

License

MIT OR Apache-2.0

Credits

Based on the TorrentZip specification and PKWARE APPNOTE 6.3.0.