mirror of
https://github.com/CPunch/LuaPytecode.git
synced 2024-11-14 20:00:06 +00:00
307 lines
11 KiB
Python
307 lines
11 KiB
Python
'''
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Luac.py
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A Lua5.1 cross-platform bytecode deserializer. This module pulls int and size_t sizes from the
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chunk header, meaning it should be able to deserialize lua bytecode dumps from most platforms,
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regardless of the host machine.
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For details on the Lua5.1 bytecode format, I read [this PDF](https://archive.org/download/a-no-frills-intro-to-lua-5.1-vm-instructions/a-no-frills-intro-to-lua-5.1-vm-instructions_archive.torrent)
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as well as read the lundump.c source file from the Lua5.1 source.
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'''
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import struct
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import array
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from enum import IntEnum, Enum, auto
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class InstructionType(Enum):
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ABC = auto(),
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ABx = auto(),
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AsBx = auto()
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class ConstType(IntEnum):
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NIL = 0,
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BOOL = 1,
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NUMBER = 3,
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STRING = 4,
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class Instruction:
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def __init__(self, type: InstructionType, name: str) -> None:
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self.type = type
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self.name = name
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self.opcode: int = None
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self.A: int = None
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self.B: int = None
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self.C: int = None
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def toString(self):
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instr = "%10s" % self.name
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regs = ""
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if self.type == InstructionType.ABC:
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regs = "%d %d %d" % (self.A, self.B, self.C)
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elif self.type == InstructionType.ABx or self.type == InstructionType.AsBx:
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regs = "%d %d" % (self.A, self.B)
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return "%s : %s" % (instr, regs)
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class Constant:
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def __init__(self, type: ConstType, data) -> None:
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self.type = type
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self.data = data
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def toString(self):
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return "[" + self.type.name + "] " + str(self.data)
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class Local:
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def __init(self, name: str, start: int, end: int):
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self.name = name
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self.start = start
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self.end = end
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class Chunk:
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def __init__(self) -> None:
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self.constants: list[Constant] = []
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self.instructions: list[Instruction] = []
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self.protos: list[Chunk] = []
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self.name: str = "Unnamed proto"
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self.frst_line: int = 0
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self.last_line: int = 0
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self.numUpvals: int = 0
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self.numParams: int = 0
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self.isVarg: bool = False
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self.maxStack: int = 0
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self.upvalues: list[str] = []
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self.locals: list[Local] = []
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def appendInstruction(self, instr: Instruction):
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self.instructions.append(instr)
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def appendConstant(self, const: Constant):
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self.constants.append(const)
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def appendProto(self, proto):
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self.protos.append(proto)
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def print(self):
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print("\n==== [[" + str(self.name) + "'s constants]] ====\n")
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for z in range(len(self.constants)):
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i = self.constants[z]
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print(str(z) + ": " + i.toString())
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print("\n==== [[" + str(self.name) + "'s dissassembly]] ====\n")
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for i in range(len(self.instructions)):
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print("[%3d] %s" % (i, self.instructions[i].toString()))
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print("\n==== [[" + str(self.name) + "'s protos]] ====\n")
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for z in self.protos:
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z.print()
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instr_lookup_tbl = [
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Instruction(InstructionType.ABC, "MOVE"), Instruction(InstructionType.ABx, "LOADK"), Instruction(InstructionType.ABC, "LOADBOOL"),
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Instruction(InstructionType.ABC, "LOADNIL"), Instruction(InstructionType.ABC, "GETUPVAL"), Instruction(InstructionType.ABx, "GETGLOBAL"),
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Instruction(InstructionType.ABC, "GETTABLE"), Instruction(InstructionType.ABx, "SETGLOBAL"), Instruction(InstructionType.ABC, "SETUPVAL"),
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Instruction(InstructionType.ABC, "SETTABLE"), Instruction(InstructionType.ABC, "NEWTABLE"), Instruction(InstructionType.ABC, "SELF"),
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Instruction(InstructionType.ABC, "ADD"), Instruction(InstructionType.ABC, "SUB"), Instruction(InstructionType.ABC, "MUL"),
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Instruction(InstructionType.ABC, "DIV"), Instruction(InstructionType.ABC, "MOD"), Instruction(InstructionType.ABC, "POW"),
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Instruction(InstructionType.ABC, "UNM"), Instruction(InstructionType.ABC, "NOT"), Instruction(InstructionType.ABC, "LEN"),
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Instruction(InstructionType.ABC, "CONCAT"), Instruction(InstructionType.AsBx, "JMP"), Instruction(InstructionType.ABC, "EQ"),
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Instruction(InstructionType.ABC, "LT"), Instruction(InstructionType.ABC, "LE"), Instruction(InstructionType.ABC, "TEST"),
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Instruction(InstructionType.ABC, "TESTSET"), Instruction(InstructionType.ABC, "CALL"), Instruction(InstructionType.ABC, "TAILCALL"),
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Instruction(InstructionType.ABC, "RETURN"), Instruction(InstructionType.AsBx, "FORLOOP"), Instruction(InstructionType.AsBx, "FORPREP"),
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Instruction(InstructionType.ABC, "TFORLOOP"), Instruction(InstructionType.ABC, "SETLIST"), Instruction(InstructionType.ABC, "CLOSE"),
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Instruction(InstructionType.ABx, "CLOSURE"), Instruction(InstructionType.ABC, "VARARG")
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]
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# at [p]osition, with [s]ize of bits
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def _get_bits(num, p, s):
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# convert number into binary first
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binary = bin(num)
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# remove first two characters
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binary = binary[2:]
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# fill in missing bits
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for i in range(32 - len(binary)):
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binary = '0' + binary
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start = len(binary) - (p+s)
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end = len(binary) - p
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# extract k bit sub-string
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kBitSubStr = binary[start : end]
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# convert extracted sub-string into decimal again
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return (int(kBitSubStr,2))
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class LuaUndump:
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def __init__(self):
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self.rootChunk: Chunk = None
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self.index = 0
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@staticmethod
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def dis_chunk(chunk: Chunk):
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chunk.print()
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def loadBlock(self, sz) -> bytearray:
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if self.index + sz > len(self.bytecode):
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raise Exception("Malformed bytecode!")
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temp = bytearray(self.bytecode[self.index:self.index+sz])
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self.index = self.index + sz
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return temp
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def get_byte(self) -> int:
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return self.loadBlock(1)[0]
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def get_int32(self) -> int:
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if (self.big_endian):
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return int.from_bytes(self.loadBlock(4), byteorder='big', signed=False)
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else:
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return int.from_bytes(self.loadBlock(4), byteorder='little', signed=False)
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def get_int(self) -> int:
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if (self.big_endian):
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return int.from_bytes(self.loadBlock(self.int_size), byteorder='big', signed=False)
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else:
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return int.from_bytes(self.loadBlock(self.int_size), byteorder='little', signed=False)
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def get_size_t(self) -> int:
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if (self.big_endian):
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return int.from_bytes(self.loadBlock(self.size_t), byteorder='big', signed=False)
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else:
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return int.from_bytes(self.loadBlock(self.size_t), byteorder='little', signed=False)
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def get_double(self) -> int:
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if self.big_endian:
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return struct.unpack('>d', self.loadBlock(8))[0]
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else:
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return struct.unpack('<d', self.loadBlock(8))[0]
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def get_string(self, size) -> str:
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if (size == None):
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size = self.get_size_t()
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if (size == 0):
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return ""
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return "".join(chr(x) for x in self.loadBlock(size))
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def decode_chunk(self):
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chunk = Chunk()
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chunk.name = self.get_string(None)
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chunk.frst_line = self.get_int()
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chunk.last_line = self.get_int()
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chunk.numUpvals = self.get_byte()
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chunk.numParams = self.get_byte()
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chunk.isVarg = (self.get_byte() != 0)
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chunk.maxStack = self.get_byte()
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if (not chunk.name == ""):
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chunk.name = chunk.name[1:-1]
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# parse instructions
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num = self.get_int()
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for i in range(num):
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data = self.get_int32()
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opcode = _get_bits(data, 0, 6)
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template = instr_lookup_tbl[opcode]
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instruction = Instruction(template.type, template.name)
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# i read the lopcodes.h file to get these bit position and sizes.
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instruction.opcode = opcode
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instruction.A = _get_bits(data, 6, 8) # starts after POS_OP + SIZE_OP (6), with a size of 8
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if instruction.type == InstructionType.ABC:
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instruction.B = _get_bits(data, 23, 9) # starts after POS_C + SIZE_C (23), with a size of 9
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instruction.C = _get_bits(data, 14, 9) # starts after POS_A + SIZE_A (14), with a size of 9
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elif instruction.type == InstructionType.ABx:
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instruction.B = _get_bits(data, 14, 18) # starts after POS_A + SIZE_A (14), with a size of 18
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elif instruction.type == InstructionType.AsBx:
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instruction.B = _get_bits(data, 14, 18) - 131071 # Bx is now signed, so just sub half of the MAX_UINT for 18 bits
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chunk.appendInstruction(instruction)
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# get constants
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num = self.get_int()
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for i in range(num):
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constant: Constant = None
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type = self.get_byte()
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if type == 0: #nil
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constant = Constant(ConstType.NIL, None)
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elif type == 1: # bool
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constant = Constant(ConstType.BOOL, (self.get_byte() != 0))
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elif type == 3: # number
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constant = Constant(ConstType.NUMBER, self.get_double())
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elif type == 4: # string
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constant = Constant(ConstType.STRING, self.get_string(None)[:-1])
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else:
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raise Exception("Unknown Datatype! [%d]" % type)
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chunk.appendConstant(constant)
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# parse protos
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num = self.get_int()
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for i in range(num):
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chunk.appendProto(self.decode_chunk())
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# debug stuff, maybe i'll add this to chunks to have better disassembly annotation in the future?
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# eh, for now just consume the bytes.
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# line numbers
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num = self.get_int()
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for i in range(num):
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self.get_int()
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# locals
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num = self.get_int()
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for i in range(num):
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self.get_string(None)[:-1] # local name
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self.get_int() # local start PC
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self.get_int() # local end PC
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# upvalues
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num = self.get_int()
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for i in range(num):
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self.get_string(None) # upvalue name
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return chunk
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def decode_rawbytecode(self, rawbytecode):
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# bytecode sanity checks
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if not rawbytecode[0:4] == b'\x1bLua':
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raise Exception("Lua Bytecode expected!")
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bytecode = array.array('b', rawbytecode)
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return self.decode_bytecode(bytecode)
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def decode_bytecode(self, bytecode):
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self.bytecode = bytecode
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# aligns index, skips header
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self.index = 4
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self.vm_version = self.get_byte()
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self.bytecode_format = self.get_byte()
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self.big_endian = (self.get_byte() == 0)
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self.int_size = self.get_byte()
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self.size_t = self.get_byte()
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self.instr_size = self.get_byte() # gets size of instructions
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self.l_number_size = self.get_byte() # size of lua_Number
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self.integral_flag = self.get_byte()
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self.rootChunk = self.decode_chunk()
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return self.rootChunk
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def loadFile(self, luaCFile):
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with open(luaCFile, 'rb') as luac_file:
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bytecode = luac_file.read()
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return self.decode_rawbytecode(bytecode)
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def print_dissassembly(self):
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LuaUndump.dis_chunk(self.rootChunk)
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