CoD LuaJIT Decompiler

A fork of marsinator358's luajit-decompiler-v2 project geared specifically towards decompiling Call of Duty (CoD) lua bytecode.

The original project did have a branch dedicated to adding support for CoD (and this fork has it as a base), but the project still felt like a catch-all for luajit and was missing some specializations that could clean up the decomps.

Simple Usage

If you're on Windows, simply download the executable from the Releases tab and drag-and-drop your bytecode files onto the executable to begin the decompilation process.

CLI Usage

Use -h or -? to show the help menu

 > dist/bin/cod-luajit-decompiler -h
Usage: cod-luajit-decompiler [--help] [--output OUTPUT_PATH] [--extension EXTENSION] [--bit-length BIT_LENGTH] [--force_overwrite] [--ignore_debug_info] [--minimize_diffs] [--new-xhash-enum] [--uleb-hash] INPUT_PATH

Decompile Call of Duty LuaJIT bytecode into readable Lua source.

Positional arguments:
  INPUT_PATH                File or directory containing LuaJIT bytecode

Optional arguments:
  -h, --help                shows help message and exits
  -o, --output OUTPUT_PATH  Override default output directory
  -e, --extension           Only decompile files with the specified extension [nargs=0..1] [default: ".lua"]
  -b, --bit-length          Set package-index hash width in bits (0-64) [nargs=0..1] [default: 64]
  -f, --force_overwrite     Always overwrite existing files
  -i, --ignore_debug_info   Ignore bytecode debug info
  -m, --minimize_diffs      Optimize output formatting to help minimize diffs
  --new-xhash-enum          Use the 0x84 XHashType enum for 0x83 bytecode
  --uleb-hash               Read 0x84 hashes as two ULEB128 values

--new-xhash-enum only affects 0x83 bytecode; --uleb-hash only affects 0x84 bytecode. Both options are ignored for other versions.

For a directory input, output defaults to <input-directory>/output and keeps the input-relative directory tree. For a file input, output defaults to an output directory beside the file. Relative --output paths are resolved from the current working directory, and missing output directories are created.

To resolve hashes, place WNI v1 (.wni) package-index files in a PackageIndex directory beside the executable (see projects like GreyhoundPackageIndex for example wnis). Subdirectories are scanned recursively. --bit-length has no effect when this directory is absent.

If PackageIndex/.bit_length exists, its decimal value overrides --bit-length. It must be between 0 and 64. (This behavior is custom to this project, but will not affect any other projects that use the wni format)

Example:

 > cat PackageIndex/.bit_length
───────┬─────────────────────────────────────────────────────────────────────────
       │ File: PackageIndex/.bit_length
───────┼─────────────────────────────────────────────────────────────────────────
   1   │ 64
───────┴─────────────────────────────────────────────────────────────────────────

Batch runs continue after individual file failures and finish with a summary. The command exits unsuccessfully if any file fails.

Build Requirements

• Clang with a C++23 standard library that supports <print> (libstdc++ 14, libc++, or the MSVC STL)
• CMake 3.20 or newer

Build and Install

Windows

cmake -S . -B build -T ClangCL
cmake --build build --config Release --parallel
cmake --install build --config Release --prefix dist

The executable is installed to dist/bin/cod-luajit-decompiler.exe.

Linux

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=clang++
cmake --build build --parallel
cmake --install build --prefix dist

The executable is installed to dist/bin/cod-luajit-decompiler.

MacOS

Mac is unsupported right now. Feel free to modify this project to include support for MacOS and open a PR.

Feel free to report any issues you have.

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This project uses an boolean expression decompilation algorithm that is based on this paper:
www.cse.iitd.ac.in/~sak/reports/isec2016-paper.pdf