mirror of
https://github.com/CPunch/LuaDecompy.git
synced 2024-11-14 20:00:04 +00:00
240 lines
9.0 KiB
Python
240 lines
9.0 KiB
Python
'''
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lparser.py
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Depends on lundump.py for lua dump deserialization.
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An experimental bytecode decompiler.
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'''
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from operator import concat
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from subprocess import call
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from lundump import Chunk, Constant, Instruction, Opcodes, whichRK, readRKasK
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class _Scope:
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def __init__(self, startPC: int, endPC: int):
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self.startPC = startPC
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self.endPC = endPC
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class LuaDecomp:
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def __init__(self, chunk: Chunk):
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self.chunk = chunk
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self.pc = 0
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self.scope = []
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self.top = {}
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self.locals = {}
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self.unknownLocalCount = 0
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self.src: str = ""
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# configurations!
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self.aggressiveLocals = False # should *EVERY* accessed register be considered a local?
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self.indexWidth = 4 # how many spaces for indentions?
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# parse instructions
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while self.pc < len(self.chunk.instructions):
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self.parseInstr()
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self.pc += 1
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# end the scope (if we're supposed too)
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self.__checkScope()
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print("\n==== [[" + str(self.chunk.name) + "'s decompiled source]] ====\n")
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print(self.src)
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# =======================================[[ Helpers ]]=========================================
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def __getInstrAtPC(self, pc: int) -> Instruction:
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if pc < len(self.chunk.instructions):
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return self.chunk.instructions[pc]
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raise Exception("Decompilation failed!")
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def __getNextInstr(self) -> Instruction:
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return self.__getInstrAtPC(self.pc + 1)
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def __getCurrInstr(self) -> Instruction:
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return self.__getInstrAtPC(self.pc)
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def __addExpr(self, code: str) -> None:
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self.src += code
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def __startStatement(self):
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self.src += '\n' + (' ' * self.indexWidth * len(self.scope))
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def __getReg(self, indx: int) -> str:
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# if the top indx is a local, get it
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return self.locals[indx] if indx in self.locals else self.top[indx]
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def __setReg(self, indx: int, code: str) -> None:
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# if the top indx is a local, set it
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if indx in self.locals:
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self.__startStatement()
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self.__addExpr(self.locals[indx] + " = " + code)
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elif self.aggressiveLocals: # 'every register is a local!!'
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self.__newLocal(indx, code)
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self.top[indx] = code
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# ========================================[[ Locals ]]=========================================
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def __makeLocalIdentifier(self, indx: int) -> str:
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self.locals[indx] = "__unknLocal%d" % self.unknownLocalCount
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self.unknownLocalCount += 1
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return self.locals[indx]
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def __newLocal(self, indx: int, expr: str) -> None:
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# TODO: grab identifier from chunk(?)
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self.__makeLocalIdentifier(indx)
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self.__startStatement()
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self.__addExpr("local " + self.locals[indx] + " = " + expr)
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# ========================================[[ Scopes ]]=========================================
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def __startScope(self, scopeType: str, size: int) -> None:
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self.__addExpr(scopeType)
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self.scope.append(_Scope(self.pc, self.pc + size))
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# checks if we need to end a scope
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def __checkScope(self) -> None:
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if len(self.scope) == 0:
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return
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if self.pc > self.scope[len(self.scope) - 1].endPC:
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self.__endScope()
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def __endScope(self) -> None:
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self.scope.pop()
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self.__startStatement()
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self.__addExpr("end")
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# =====================================[[ Instructions ]]======================================
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def __emitOperand(self, a: int, b: str, c: str, op: str) -> None:
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self.__setReg(a, "(" + b + op + c + ")")
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def __compJmp(self, op: str):
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instr = self.__getCurrInstr()
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jmpType = "if"
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scopeStart = "then"
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# we need to check if the jmp location has a jump back (if so, it's a while loop)
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jmp = self.__getNextInstr().B + 1
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jmpToInstr = self.__getInstrAtPC(self.pc + jmp)
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if jmpToInstr.opcode == Opcodes.JMP:
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# if this jump jumps back to this compJmp, it's a loop!
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if self.pc + jmp + jmpToInstr.B <= self.pc + 1:
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jmpType = "while"
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scopeStart = "do"
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self.__startStatement()
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if instr.A > 0:
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self.__addExpr("%s not " % jmpType)
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else:
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self.__addExpr("%s " % jmpType)
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self.__addExpr(self.__readRK(instr.B) + op + self.__readRK(instr.C) + " ")
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self.__startScope("%s " % scopeStart, jmp)
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self.pc += 1 # skip next instr
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# 'RK's are special in because can be a register or a konstant. a bitflag is read to determine which
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def __readRK(self, rk: int) -> str:
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if (whichRK(rk)) > 0:
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return self.chunk.getConstant(readRKasK(rk)).toCode()
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else:
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return self.__getReg(rk)
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def parseInstr(self):
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instr = self.__getCurrInstr()
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# python, add switch statements *please*
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if instr.opcode == Opcodes.MOVE: # move is a fake ABC instr, C is ignored
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# move registers
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self.__setReg(instr.A, self.__getReg(instr.B))
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elif instr.opcode == Opcodes.LOADK:
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self.__setReg(instr.A, self.chunk.getConstant(instr.B).toCode())
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elif instr.opcode == Opcodes.LOADBOOL:
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if instr.B == 0:
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self.__setReg(instr.A, "false")
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else:
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self.__setReg(instr.A, "true")
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elif instr.opcode == Opcodes.GETGLOBAL:
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self.__setReg(instr.A, self.chunk.getConstant(instr.B).data)
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elif instr.opcode == Opcodes.GETTABLE:
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self.__setReg(instr.A, self.__getReg(instr.B) + "[" + self.__readRK(instr.C) + "]")
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elif instr.opcode == Opcodes.SETGLOBAL:
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self.__startStatement()
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self.__addExpr(self.chunk.getConstant(instr.B).data + " = " + self.__getReg(instr.A))
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elif instr.opcode == Opcodes.SETTABLE:
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self.__startStatement()
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self.__addExpr(self.__getReg(instr.A) + "[" + self.__readRK(instr.B) + "] = " + self.__readRK(instr.C))
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elif instr.opcode == Opcodes.ADD:
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self.__emitOperand(instr.A, self.__readRK(instr.B), self.__readRK(instr.C), " + ")
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elif instr.opcode == Opcodes.SUB:
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self.__emitOperand(instr.A, self.__readRK(instr.B), self.__readRK(instr.C), " - ")
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elif instr.opcode == Opcodes.MUL:
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self.__emitOperand(instr.A, self.__readRK(instr.B), self.__readRK(instr.C), " * ")
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elif instr.opcode == Opcodes.DIV:
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self.__emitOperand(instr.A, self.__readRK(instr.B), self.__readRK(instr.C), " / ")
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elif instr.opcode == Opcodes.MOD:
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self.__emitOperand(instr.A, self.__readRK(instr.B), self.__readRK(instr.C), " % ")
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elif instr.opcode == Opcodes.POW:
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self.__emitOperand(instr.A, self.__readRK(instr.B), self.__readRK(instr.C), " ^ ")
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elif instr.opcode == Opcodes.UNM:
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self.__setReg(instr.A, "-" + self.__getReg(instr.B))
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elif instr.opcode == Opcodes.NOT:
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self.__setReg(instr.A, "!" + self.__getReg(instr.B))
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elif instr.opcode == Opcodes.LEN:
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self.__setReg(instr.A, "#" + self.__getCurrInstr(instr.B))
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elif instr.opcode == Opcodes.CONCAT:
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count = instr.C-instr.B+1
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concatStr = ""
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# concat all items on stack from RC to RB
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for i in range(count):
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concatStr += self.__getReg(instr.B + i) + (" .. " if not i == count - 1 else "")
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self.__setReg(instr.A, concatStr)
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elif instr.opcode == Opcodes.JMP:
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pass
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elif instr.opcode == Opcodes.EQ:
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self.__compJmp(" == ")
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elif instr.opcode == Opcodes.LT:
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self.__compJmp(" < ")
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elif instr.opcode == Opcodes.LE:
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self.__compJmp(" <= ")
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elif instr.opcode == Opcodes.CALL:
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preStr = ""
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callStr = ""
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ident = ""
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# parse arguments
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callStr += self.__getReg(instr.A) + "("
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for i in range(instr.A + 1, instr.A + instr.B):
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callStr += self.__getReg(i) + (", " if not i + 1 == instr.A + instr.B else "")
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callStr += ")"
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# parse return values
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if instr.C > 1:
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preStr = "local "
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for indx in range(instr.A, instr.A + instr.C - 1):
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if indx in self.locals:
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ident = self.locals[indx]
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else:
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ident = self.__makeLocalIdentifier(indx)
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preStr += ident
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# normally setReg() does this
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self.top[indx] = ident
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# just so we don't have a trailing ', '
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preStr += ", " if not indx == instr.A + instr.C - 2 else ""
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preStr += " = "
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self.__startStatement()
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self.__addExpr(preStr + callStr)
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elif instr.opcode == Opcodes.RETURN:
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self.__startStatement()
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pass # no-op for now
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else:
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raise Exception("unsupported instruction: %s" % instr.toString()) |