LuaPytecode/luac.py

557 lines
19 KiB
Python

'''
l(un)dump.py
A Lua5.1 cross-platform bytecode deserializer && serializer. This module pulls int and size_t sizes from the
chunk header, meaning it should be able to deserialize lua bytecode dumps from most platforms,
regardless of the host machine.
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)
as well as read the lundump.c source file from the Lua5.1 source.
'''
import struct
import array
from enum import IntEnum, Enum, auto
class InstructionType(Enum):
ABC = auto(),
ABx = auto(),
AsBx = auto()
class Opcodes(IntEnum):
MOVE = 0,
LOADK = 1,
LOADBOOL = 2,
LOADNIL = 3,
GETUPVAL = 4,
GETGLOBAL = 5,
GETTABLE = 6,
SETGLOBAL = 7,
SETUPVAL = 8,
SETTABLE = 9,
NEWTABLE = 10,
SELF = 11,
ADD = 12,
SUB = 13,
MUL = 14,
DIV = 15,
MOD = 16,
POW = 17,
UNM = 18,
NOT = 19,
LEN = 20,
CONCAT = 21,
JMP = 22,
EQ = 23,
LT = 24,
LE = 25,
TEST = 26,
TESTSET = 27,
CALL = 28,
TAILCALL = 29,
RETURN = 30,
FORLOOP = 31,
FORPREP = 32,
TFORLOOP = 33,
SETLIST = 34,
CLOSE = 35,
CLOSURE = 36,
VARARG = 37
class ConstType(IntEnum):
NIL = 0,
BOOL = 1,
NUMBER = 3,
STRING = 4,
_RKBCInstr = [Opcodes.SETTABLE, Opcodes.ADD, Opcodes.SUB, Opcodes.MUL, Opcodes.DIV, Opcodes.MOD, Opcodes.POW, Opcodes.EQ, Opcodes.LT]
_RKCInstr = [Opcodes.GETTABLE, Opcodes.SELF]
_KBx = [Opcodes.LOADK, Opcodes.GETGLOBAL, Opcodes.SETGLOBAL]
_LUAMAGIC = b'\x1bLua'
# is an 'RK' value a K? (result is true for K, false for R)
def whichRK(rk: int):
return (rk & (1 << 8)) > 0
# read an RK as a K
def readRKasK(rk: int):
return (rk & ~(1 << 8))
class Instruction:
def __init__(self, type: InstructionType, name: str) -> None:
self.type = type
self.name = name
self.opcode: int = None
self.A: int = None
self.B: int = None
self.C: int = None
# 'RK's are special in because can be a register or a konstant. a bitflag is read to determine which
def __formatRK(self, rk: int) -> str:
if whichRK(rk):
return "K[" + str(readRKasK(rk)) + "]"
else:
return "R[" + str(rk) + "]"
def toString(self):
instr = "%10s" % self.name
regs = ""
if self.type == InstructionType.ABC:
# by default, treat them as registers
A = "%d" % self.A
B = "%d" % self.B
C = "%d" % self.C
# these opcodes have RKs for B & C
if self.opcode in _RKBCInstr:
A = "R[%d]" % self.A
B = self.__formatRK(self.B)
C = self.__formatRK(self.C)
elif self.opcode in _RKCInstr: # just for C
A = "R[%d]" % self.A
C = self.__formatRK(self.C)
regs = "%6s %6s %6s" % (A, B, C)
elif self.type == InstructionType.ABx or self.type == InstructionType.AsBx:
A = "R[%d]" % self.A
B = "%d" % self.B
if self.opcode in _KBx:
B = "K[%d]" % self.B
regs = "%6s %6s" % (A, B)
return "%s : %s" % (instr, regs)
def getAnnotation(self, chunk):
if self.opcode == Opcodes.MOVE:
return "move R[%d] into R[%d]" % (self.B, self.A)
elif self.opcode == Opcodes.LOADK:
return "load %s into R[%d]" % (chunk.getConstant(self.B).toCode(), self.A)
elif self.opcode == Opcodes.GETGLOBAL:
return 'move _G[%s] into R[%d]' % (chunk.getConstant(self.B).toCode(), self.A)
elif self.opcode == Opcodes.ADD:
return 'add %s to %s, place into R[%d]' % (self.__formatRK(self.C), self.__formatRK(self.B), self.A)
elif self.opcode == Opcodes.SUB:
return 'sub %s from %s, place into R[%d]' % (self.__formatRK(self.C), self.__formatRK(self.B), self.A)
elif self.opcode == Opcodes.MUL:
return 'mul %s to %s, place into R[%d]' % (self.__formatRK(self.C), self.__formatRK(self.B), self.A)
elif self.opcode == Opcodes.DIV:
return 'div %s from %s, place into R[%d]' % (self.__formatRK(self.C), self.__formatRK(self.B), self.A)
elif self.opcode == Opcodes.CONCAT:
count = self.C - self.B + 1
return "concat %d values from R[%d] to R[%d], store into R[%d]" % (count, self.B, self.C, self.A)
else:
return ""
class Constant:
def __init__(self, type: ConstType, data) -> None:
self.type = type
self.data = data
def toString(self):
return "[%s] %s" % (self.type.name, str(self.data))
# format the constant so that it is parsable by lua
def toCode(self):
if self.type == ConstType.STRING:
return "\"" + self.data + "\""
elif self.type == ConstType.BOOL:
if self.data:
return "true"
else:
return "false"
elif self.type == ConstType.NUMBER:
return "%g" % self.data
else:
return "nil"
class Local:
def __init__(self, name: str, start: int, end: int):
self.name = name
self.start = start
self.end = end
class Chunk:
def __init__(self) -> None:
self.constants: list[Constant] = []
self.instructions: list[Instruction] = []
self.protos: list[Chunk] = []
self.name: str = "Unnamed proto"
self.frst_line: int = 0
self.last_line: int = 0
self.numUpvals: int = 0
self.numParams: int = 0
self.isVarg: bool = False
self.maxStack: int = 0
self.upvalues: list[str] = []
self.lineNums: list[int] = []
self.locals: list[Local] = []
def appendInstruction(self, instr: Instruction):
self.instructions.append(instr)
def appendConstant(self, const: Constant):
self.constants.append(const)
def appendProto(self, proto):
self.protos.append(proto)
def appendLine(self, line: int):
self.lineNums.append(line)
def appendLocal(self, local: Local):
self.locals.append(local)
def appendUpval(self, upval: str):
self.upvalues.append(upval)
def findLocal(self, pc: int) -> Local:
for l in self.locals:
if l.start <= pc and l.end >= pc:
return l
# there's no local information (may have been stripped)
return None
def getConstant(self, indx: int) -> Constant:
return self.constants[indx]
def print(self):
print("\n==== [[" + str(self.name) + "'s constants]] ====\n")
for i in range(len(self.constants)):
print("%d: %s" % (i, self.constants[i].toString()))
print("\n==== [[" + str(self.name) + "'s locals]] ====\n")
for i in range(len(self.locals)):
print("R[%d]: %s" % (i, self.locals[i].name))
print("\n==== [[" + str(self.name) + "'s dissassembly]] ====\n")
for i in range(len(self.instructions)):
print("[%3d] %-40s ; %s" % (i, self.instructions[i].toString(), self.instructions[i].getAnnotation(self)))
if len(self.protos) > 0:
print("\n==== [[" + str(self.name) + "'s protos]] ====\n")
for z in self.protos:
z.print()
instr_lookup_tbl = [
Instruction(InstructionType.ABC, "MOVE"), Instruction(InstructionType.ABx, "LOADK"), Instruction(InstructionType.ABC, "LOADBOOL"),
Instruction(InstructionType.ABC, "LOADNIL"), Instruction(InstructionType.ABC, "GETUPVAL"), Instruction(InstructionType.ABx, "GETGLOBAL"),
Instruction(InstructionType.ABC, "GETTABLE"), Instruction(InstructionType.ABx, "SETGLOBAL"), Instruction(InstructionType.ABC, "SETUPVAL"),
Instruction(InstructionType.ABC, "SETTABLE"), Instruction(InstructionType.ABC, "NEWTABLE"), Instruction(InstructionType.ABC, "SELF"),
Instruction(InstructionType.ABC, "ADD"), Instruction(InstructionType.ABC, "SUB"), Instruction(InstructionType.ABC, "MUL"),
Instruction(InstructionType.ABC, "DIV"), Instruction(InstructionType.ABC, "MOD"), Instruction(InstructionType.ABC, "POW"),
Instruction(InstructionType.ABC, "UNM"), Instruction(InstructionType.ABC, "NOT"), Instruction(InstructionType.ABC, "LEN"),
Instruction(InstructionType.ABC, "CONCAT"), Instruction(InstructionType.AsBx, "JMP"), Instruction(InstructionType.ABC, "EQ"),
Instruction(InstructionType.ABC, "LT"), Instruction(InstructionType.ABC, "LE"), Instruction(InstructionType.ABC, "TEST"),
Instruction(InstructionType.ABC, "TESTSET"), Instruction(InstructionType.ABC, "CALL"), Instruction(InstructionType.ABC, "TAILCALL"),
Instruction(InstructionType.ABC, "RETURN"), Instruction(InstructionType.AsBx, "FORLOOP"), Instruction(InstructionType.AsBx, "FORPREP"),
Instruction(InstructionType.ABC, "TFORLOOP"), Instruction(InstructionType.ABC, "SETLIST"), Instruction(InstructionType.ABC, "CLOSE"),
Instruction(InstructionType.ABx, "CLOSURE"), Instruction(InstructionType.ABC, "VARARG")
]
# at [p]osition, with [s]ize of bits
def get_bits(num: int, p: int, s: int):
return (num>>p) & (~((~0)<<s))
# set bits from data to num at [p]osition, with [s]ize of bits
def set_bits(num, data, p, s) -> int:
return (num & (~((~((~0)<<s))<<p))) | ((data << p) & ((~((~0)<<s))<<p))
def _decode_instr(data: int) -> Instruction:
opcode = get_bits(data, 0, 6)
template = instr_lookup_tbl[opcode]
instr = Instruction(template.type, template.name)
# i read the lopcodes.h file to get these bit position and sizes.
instr.opcode = opcode
instr.A = get_bits(data, 6, 8) # starts after POS_OP + SIZE_OP (6), with a size of 8
if instr.type == InstructionType.ABC:
instr.B = get_bits(data, 23, 9) # starts after POS_C + SIZE_C (23), with a size of 9
instr.C = get_bits(data, 14, 9) # starts after POS_A + SIZE_A (14), with a size of 9
elif instr.type == InstructionType.ABx:
instr.B = get_bits(data, 14, 18) # starts after POS_A + SIZE_A (14), with a size of 18
elif instr.type == InstructionType.AsBx:
instr.B = get_bits(data, 14, 18) - 131071 # Bx is now signed, so just sub half of the MAX_UINT for 18 bits
return instr
# returns a u32 instruction
def _encode_instr(instr: Instruction) -> int:
data = 0
# encode instruction (basically, do the inverse of _decode_instr)
data = set_bits(data, instr.opcode, 0, 6)
data = set_bits(data, instr.A, 6, 8)
if instr.type == InstructionType.ABC:
data = set_bits(data, instr.B, 23, 9)
data = set_bits(data, instr.C, 14, 9)
elif instr.type == InstructionType.ABx:
data = set_bits(data, instr.B, 14, 18)
elif instr.type == InstructionType.AsBx:
data = set_bits(data, instr.B + 131071, 14, 18)
return data
class LuaUndump:
def __init__(self):
self.rootChunk: Chunk = None
self.index = 0
def _loadBlock(self, sz) -> bytearray:
if self.index + sz > len(self.bytecode):
raise Exception("Malformed bytecode!")
temp = bytearray(self.bytecode[self.index:self.index+sz])
self.index = self.index + sz
return temp
def _get_byte(self) -> int:
return self._loadBlock(1)[0]
def _get_uint32(self) -> int:
order = 'big' if self.big_endian else 'little'
return int.from_bytes(self._loadBlock(4), byteorder=order, signed=False)
def _get_uint(self) -> int:
order = 'big' if self.big_endian else 'little'
return int.from_bytes(self._loadBlock(self.int_size), byteorder=order, signed=False)
def _get_size_t(self) -> int:
order = 'big' if self.big_endian else 'little'
return int.from_bytes(self._loadBlock(self.size_t), byteorder=order, signed=False)
def _get_double(self) -> int:
order = '>d' if self.big_endian else '<d'
return struct.unpack(order, self._loadBlock(self.l_number_size))[0]
def _get_string(self) -> str:
size = self._get_size_t()
if (size == 0):
return ""
# [:-1] to remove the NULL terminator
return ("".join(chr(x) for x in self._loadBlock(size)))[:-1]
def decode_chunk(self) -> Chunk:
chunk = Chunk()
# chunk meta info
chunk.name = self._get_string()
chunk.frst_line = self._get_uint()
chunk.last_line = self._get_uint()
chunk.numUpvals = self._get_byte()
chunk.numParams = self._get_byte()
chunk.isVarg = (self._get_byte() != 0)
chunk.maxStack = self._get_byte()
# parse instructions
num = self._get_uint()
for i in range(num):
chunk.appendInstruction(_decode_instr(self._get_uint32()))
# get constants
num = self._get_uint()
for i in range(num):
constant: Constant = None
type = self._get_byte()
if type == 0: # nil
constant = Constant(ConstType.NIL, None)
elif type == 1: # bool
constant = Constant(ConstType.BOOL, (self._get_byte() != 0))
elif type == 3: # number
constant = Constant(ConstType.NUMBER, self._get_double())
elif type == 4: # string
constant = Constant(ConstType.STRING, self._get_string())
else:
raise Exception("Unknown Datatype! [%d]" % type)
chunk.appendConstant(constant)
# parse protos
num = self._get_uint()
for i in range(num):
chunk.appendProto(self.decode_chunk())
# debug stuff, maybe i'll add this to chunks to have better disassembly annotation in the future?
# eh, for now just consume the bytes.
# line numbers
num = self._get_uint()
for i in range(num):
self._get_uint()
# locals
num = self._get_uint()
for i in range(num):
name = self._get_string() # local name
start = self._get_uint() # local start PC
end = self._get_uint() # local end PC
chunk.appendLocal(Local(name, start, end))
# upvalues
num = self._get_uint()
for i in range(num):
chunk.appendUpval(self._get_string()) # upvalue name
return chunk
def decode_rawbytecode(self, rawbytecode):
# bytecode sanity checks
if not rawbytecode[0:4] == _LUAMAGIC:
raise Exception("Lua Bytecode expected!")
bytecode = array.array('b', rawbytecode)
return self.decode_bytecode(bytecode)
def decode_bytecode(self, bytecode):
self.bytecode = bytecode
# aligns index, skips header
self.index = 4
self.vm_version = self._get_byte()
self.bytecode_format = self._get_byte()
self.big_endian = (self._get_byte() == 0)
self.int_size = self._get_byte()
self.size_t = self._get_byte()
self.instr_size = self._get_byte() # gets size of instructions
self.l_number_size = self._get_byte() # size of lua_Number
self.integral_flag = self._get_byte() # is lua_Number defined as an int? false = float/double, true = int/long/short/etc.
self.rootChunk = self.decode_chunk()
return self.rootChunk
def loadFile(self, luaCFile):
with open(luaCFile, 'rb') as luac_file:
bytecode = luac_file.read()
return self.decode_rawbytecode(bytecode)
def print_dissassembly(self):
self.rootChunk.print()
class LuaDump:
def __init__(self, rootChunk: Chunk):
self.rootChunk = rootChunk
self.bytecode = bytearray()
# header info
self.vm_version = 0x51
self.bytecode_format = 0x00
self.big_endian = False
# data sizes
self.int_size = 4
self.size_t = 8
self.instr_size = 4
self.l_number_size = 8
self.integral_flag = False # lua_Number is a double
def _writeBlock(self, data: bytes):
self.bytecode += bytearray(data)
def _set_byte(self, b: int):
self.bytecode.append(b)
def _set_uint32(self, i: int):
order = 'big' if self.big_endian else 'little'
self._writeBlock(i.to_bytes(4, order, signed=False))
def _set_uint(self, i: int):
order = 'big' if self.big_endian else 'little'
self._writeBlock(i.to_bytes(self.int_size, order, signed=False))
def _set_size_t(self, i: int):
order = 'big' if self.big_endian else 'little'
self._writeBlock(i.to_bytes(self.size_t, order, signed=False))
def _set_double(self, f: float):
order = '>d' if self.big_endian else '<d'
self._writeBlock(struct.pack(order, f))
def _set_string(self, string: str):
self._set_size_t(len(string)+1)
self._writeBlock(string.encode('utf-8'))
self._set_byte(0x00) # write null terminator
def _dumpChunk(self, chunk: Chunk):
# write meta info
self._set_string(chunk.name)
self._set_uint(chunk.frst_line)
self._set_uint(chunk.last_line)
self._set_byte(chunk.numUpvals)
self._set_byte(chunk.numParams)
self._set_byte(1 if chunk.isVarg else 1)
self._set_byte(chunk.maxStack)
# write instructions
self._set_uint(len(chunk.instructions))
for l in chunk.instructions:
self._set_uint32(_encode_instr(l))
# write constants
self._set_uint(len(chunk.constants))
for constant in chunk.constants:
# write constant data
if constant.type == ConstType.NIL:
self._set_byte(0)
elif constant.type == ConstType.BOOL:
self._set_byte(1)
self._set_byte(1 if constant.data else 0)
elif constant.type == ConstType.NUMBER: # number
self._set_byte(3)
self._set_double(constant.data)
elif constant.type == ConstType.STRING: # string
self._set_byte(4)
self._set_string(constant.data)
else:
raise Exception("Unknown Datatype! [%s]" % str(constant.type))
# write child protos
self._set_uint(len(chunk.protos))
for p in chunk.protos:
self._dumpChunk(p)
# write line numbers
self._set_uint(len(chunk.lineNums))
for l in chunk.lineNums:
self._set_uint(l)
# write locals
self._set_uint(len(chunk.locals))
for l in chunk.locals:
self._set_string(l.name)
self._set_uint(l.start)
self._set_uint(l.end)
# write upvals
self._set_uint(len(chunk.upvalues))
for u in chunk.upvalues:
self._set_string(u)
def _dumpHeader(self):
self._writeBlock(_LUAMAGIC)
# write header info
self._set_byte(self.vm_version)
self._set_byte(self.bytecode_format)
self._set_byte(0 if self.big_endian else 1)
self._set_byte(self.int_size)
self._set_byte(self.size_t)
self._set_byte(self.instr_size)
self._set_byte(self.l_number_size)
self._set_byte(self.integral_flag)
def dump(self) -> bytearray:
self._dumpHeader()
self._dumpChunk(self.rootChunk)
return self.bytecode