LunaUX-Decompiler

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• A decompiler & disassembler for Luau (Roblox's Lua-based language). This project consists of an algorithm that takes raw Luau bytecode and attempts to reconstruct it into readable Luau source code or low level disassembly.

• Inspirated on Konstant, Oracle and medal, this decompiler was created to bring free decompilation service as medal or other decompilers.

Disclaimer: LunaUX is still in beta, it is not 100% perfect. This decompiler will receive regular updates to fix all those bugs.

Installing

• Windows

git clone https://github.com/boydev-1444/lunaux-decompiler.git
cd lunaux-decompiler
run.bat

• Linux

git clone https://github.com/boydev-1444/lunaux-decompiler.git 
cd lunaux-decompiler 
chmod +x run.sh 
./run.sh

API Script

• Paste it into an environment than supports request, base64encode or crypt library and getscriptbytecode

assert(request, "http request function missing")
assert(getscriptbytecode, "getscriptbytecode function missing")
local base64_encoder = (crypt and crypt.base64 and crypt.base64.encode) or base64encode
assert(base64_encoder, "base64encode function missing")
local http = game:GetService("HttpService")

local function apiRequest(bytecode, branch, scriptName)
	local response = request({
		Url = 'http://127.0.0.1:8000/' .. branch,
		Method = "POST",
		Headers = {
			["Content-Type"] = "application/json"
		},
		Body = http:JSONEncode({ bytecode = base64_encoder(bytecode), filename = scriptName })
	})
	if response.StatusCode ~= 200 then
		return `--[[ Server error (HTTP {response.StatusCode}:\n\t{response.Body}\n]]`
	end
	return response.Body
end

local function isValidScript(scriptInstance : BaseScript)
	return (scriptInstance.ClassName == "Script" and scriptInstance.RunContext == Enum.RunContext.Client) or scriptInstance.ClassName == "LocalScript" or scriptInstance.ClassName == "ModuleScript"
end

if getgenv then 
	getgenv().decompile = function(scriptPath : BaseScript)
		if typeof(scriptPath) ~= "Instance" then return "-- Invalid argument #1 to 'decompile' (Instance expected)" end
		if not isValidScript(scriptPath) then return "-- Server scripts are IMPOSSIBLE to decompile" end
		local OK, bytecode = pcall(getscriptbytecode, scriptPath)
		if not OK then return `--[[ Failed to get script bytecode:\n\t{bytecode}\n]]` end
		if type(bytecode) ~= "string" then return `--[[ Failed to get script bytecode, string type expected got {type(bytecode)} ]]` end
		if bytecode == "" then return "-- Empty bytecode" end
		return apiRequest(bytecode, "decompile", scriptPath.Name)
	end

	getgenv().disassemble = function(scriptPath : BaseScript)
		if typeof(scriptPath) ~= "Instance" then return "-- Invalid argument #1 to 'disassemble' (Instance expected)" end
		if not isValidScript(scriptPath) then return "-- Server scripts are IMPOSSIBLE to disassemble" end
		local OK, bytecode = pcall(getscriptbytecode, scriptPath)
		if not OK then return `--[[ Failed to get script bytecode:\n\t{bytecode}\n]]` end
		if type(bytecode) ~= "string" then return `--[[ Failed to get script bytecode, string type expected got {type(bytecode)} ]]` end
		if bytecode == "" then return "-- Empty bytecode" end
		return apiRequest(bytecode, "disassemble", scriptPath.Name) 
	end
end

API Options

• All decompiling options:
  • Semicolons : Add a semicolon for every line (Default: False)
  • StringInterpolation : Enables string interpolation between strings (Default: True)
  • UpvalueComment : Every upvalue used in a function (Default: True)
  • ShowLineDefined : Adds the original line defined of the prototype (Default: True)
  • ShowFunctionId : Adds the original function id in the bytecode (ShowlineDefined must be enabled; Default : False)
  • PreserveForStep : Keeps the step for the numeric loop including if is one (Default: False)
  • UseIfExpression : Uses if ... then ... else ... in assigns, if not enabled uses AND/OR operators (Default: True)

CLI Application

• Tool for fast analysis or other
  • Supports base64 encoded inputs or raw bytecodes

Options:
  -h, --help       Show this help message
  -v, --version    Show version information
  -ih, --hash      Show the current installer hash

Commands:
  run
    Start the LunaUX-Decompiler local server.

  * These commands support raw bytecode or Base64-encoded bytecode

  decomp, decompile <input_file> [output_directory]
      Decompile the specified bytecode file.
      If an output directory is provided, the result will be saved there;
      otherwise, it will be printed to the console.

  disasm, disassemble <input_file> [output_directory]
      Disassemble the specified bytecode file.
      If an output directory is provided, the result will be saved there;
      otherwise, it will be printed to the console.

Compiling CLI by yourself

• The CLI application is already compiled and you can find it in the releases tab.

• Windows

g++ CliApp.cpp -o CLI.exe -std=c++20 -O2 -s -lws2_32

• Linux

x86_64-w64-mingw32-g++ CliApp.cpp -o CLI.exe -std=c++20 -O2 -s -lws2_32