repak

Python bindings for repak, a Rust library for reading and writing Unreal Engine .pak files.

Installation

# Using pip
pip install repak

# Using uv
uv add repak

# Using poetry
poetry add repak

Prebuilt wheels are published for Linux, macOS and Windows. A single abi3 wheel per platform covers CPython 3.10 and newer, including 3.14. No Rust toolchain is required.

Reading

import repak

with repak.PakBuilder().reader("game.pak") as pak:
    print(pak.version, pak.mount_point)

    for path in pak:
        print(path)

    data = pak.get("Content/Asset.uasset")
    pak.read_file("Content/Asset.uasset", "Asset.uasset")
    pak.unpack("out")

PakReader supports len(), in and iteration over entry paths. A pak may also be read from memory by passing bytes instead of a path.

Entries are stored relative to the pak's mount point, so a pak mounted at ../../../Game/Content/Sub/ holds them under bare names like Asset.uasset. files() joins the mount point back on and drops the leading ../, giving the path the entry actually mounts at:

with repak.PakBuilder().reader("game.pak") as pak:
    pak.mount_point  # '../../../Game/Content/Sub/'
    pak.files()  # ['Game/Content/Sub/Asset.uasset', ...]
    pak.entries()  # ['Asset.uasset', ...]

get(), read_file() and in accept either form. unpack() recreates the mounted layout.

Writing

import repak

builder = repak.PakBuilder().compression([repak.Compression.ZLIB])

with builder.writer("mod.pak") as pak:
    pak.write_file("Content/Asset.uasset", data)

The index is written when the with block exits. Without a context manager, call write_index() yourself. Entries are only compressed if the builder was given a compression algorithm.

To append to an existing pak, turn a reader into a writer:

import repak

reader = repak.PakBuilder().reader("mod.pak")
with reader.into_writer("mod.pak") as pak:
    pak.write_file("Content/Extra.uasset", data)

Encryption

import repak

pak = repak.PakBuilder().key("0x0123456789abcdef...").reader("game.pak")

The key is a 256 bit AES key given as bytes, a hex string with an optional 0x prefix, or base64.

Oodle

Oodle works out of the box:

import repak

builder = repak.PakBuilder().compression([repak.Compression.OODLE])

The Oodle library is proprietary and cannot be shipped inside the wheel, so repak downloads it on first use, the first time an Oodle pak is read or written.

To avoid the download, or when the install directory is not writable, point REPAK_OODLE_PATH at a copy you already have. That also lets you substitute a different Oodle version:

export REPAK_OODLE_PATH=/opt/oodle/liboo2corelinux64.so.9

repak.oodle_library_path() returns the path in use. If the library cannot be fetched or loaded, Oodle operations raise repak.OodleError.

Errors

All failures raise repak.RepakError or one of its subclasses: MissingEntryError, VersionError, EncryptionError and CompressionError. Filesystem failures raise the usual OSError.

Versioning

The package version tracks the version of the upstream repak crate it wraps. Fixes to the bindings alone are released as post releases, for example 0.2.3.post1.

Upstream resolves the Oodle library relative to the running executable, which inside a Python extension is the interpreter and is often not writable. vendor/oodle_loader replaces that crate through a cargo [patch] entry so the path is resolvable, without forking repak itself.

Development

The preferred dev environment requires Python 3.14 and Rust nightly toolchain, pinned in rust-toolchain.toml.

uv sync
uv run pytest
uv run ruff check
uv run ruff format
uv run pyright
cargo clippy --all-targets
cargo fmt

uv sync compiles the extension module. Use uv run maturin develop --uv to rebuild it after changing Rust code.

License

This project is licensed under the MIT License. See the LICENSE file for details.