# Copyright (c) 2016, 2017 by Rocky Bernstein """ Python 3.0 bytecode scanner/deparser This sets up opcodes Python's 3.0 and calls a generalized scanner routine for Python 3. """ from __future__ import print_function # bytecode verification, verify(), uses JUMP_OPs from here from xdis.opcodes import opcode_30 as opc from xdis.bytecode import op_size JUMP_OPS = opc.JUMP_OPS JUMP_TF = frozenset([opc.JUMP_IF_FALSE, opc.JUMP_IF_TRUE]) from uncompyle6.scanners.scanner3 import Scanner3 class Scanner30(Scanner3): def __init__(self, show_asm=None, is_pypy=False): Scanner3.__init__(self, 3.0, show_asm, is_pypy) return pass def detect_control_flow(self, offset, targets): """ Detect structures and their boundaries to fix optimized jumps Python 3.0 is more like Python 2.6 than it is Python 3.x. So we have a special routine here. """ code = self.code op = code[offset] # Detect parent structure parent = self.structs[0] start = parent['start'] end = parent['end'] # Pick inner-most parent for our offset for struct in self.structs: current_start = struct['start'] current_end = struct['end'] if ((current_start <= offset < current_end) and (current_start >= start and current_end <= end)): start = current_start end = current_end parent = struct if op == self.opc.SETUP_LOOP: # We categorize loop types: 'for', 'while', 'while 1' with # possibly suffixes '-loop' and '-else' # Try to find the jump_back instruction of the loop. # It could be a return instruction. start = offset+3 target = self.get_target(offset) end = self.restrict_to_parent(target, parent) self.setup_loop_targets[offset] = target self.setup_loops[target] = offset if target != end: self.fixed_jumps[offset] = end (line_no, next_line_byte) = self.lines[offset] jump_back = self.last_instr(start, end, self.opc.JUMP_ABSOLUTE, next_line_byte, False) if jump_back: jump_forward_offset = jump_back+3 else: jump_forward_offset = None return_val_offset1 = self.prev[self.prev[end]] if (jump_back and jump_back != self.prev_op[end] and self.is_jump_forward(jump_forward_offset)): if (code[self.prev_op[end]] == self.opc.RETURN_VALUE or (code[self.prev_op[end]] == self.opc.POP_BLOCK and code[return_val_offset1] == self.opc.RETURN_VALUE)): jump_back = None if not jump_back: # loop suite ends in return jump_back = self.last_instr(start, end, self.opc.RETURN_VALUE) if not jump_back: return jump_back += 2 if_offset = None if code[self.prev_op[next_line_byte]] not in JUMP_TF: if_offset = self.prev[next_line_byte] if if_offset: loop_type = 'while' self.ignore_if.add(if_offset) else: loop_type = 'for' target = next_line_byte end = jump_back + 3 else: if self.get_target(jump_back) >= next_line_byte: jump_back = self.last_instr(start, end, self.opc.JUMP_ABSOLUTE, start, False) if end > jump_back+4 and self.is_jump_forward(end): if self.is_jump_forward(jump_back+4): if self.get_target(jump_back+4) == self.get_target(end): self.fixed_jumps[offset] = jump_back+4 end = jump_back+4 elif target < offset: self.fixed_jumps[offset] = jump_back+4 end = jump_back+4 target = self.get_target(jump_back) if code[target] in (self.opc.FOR_ITER, self.opc.GET_ITER): loop_type = 'for' else: loop_type = 'while' test = self.prev_op[next_line_byte] if test == offset: loop_type = 'while 1' elif self.code[test] in opc.JUMP_OPs: self.ignore_if.add(test) test_target = self.get_target(test) if test_target > (jump_back+3): jump_back = test_target self.not_continue.add(jump_back) self.loops.append(target) self.structs.append({'type': loop_type + '-loop', 'start': target, 'end': jump_back}) if jump_back+3 != end: self.structs.append({'type': loop_type + '-else', 'start': jump_back+3, 'end': end}) elif op in JUMP_TF: start = offset + op_size(op, self.opc) target = self.get_target(offset) rtarget = self.restrict_to_parent(target, parent) prev_op = self.prev_op # Do not let jump to go out of parent struct bounds if target != rtarget and parent['type'] == 'and/or': self.fixed_jumps[offset] = rtarget return # Does this jump to right after another conditional jump that is # not myself? If so, it's part of a larger conditional. # rocky: if we have a conditional jump to the next instruction, then # possibly I am "skipping over" a "pass" or null statement. if ((code[prev_op[target]] in self.pop_jump_if_pop) and (target > offset) and prev_op[target] != offset): self.fixed_jumps[offset] = prev_op[target] self.structs.append({'type': 'and/or', 'start': start, 'end': prev_op[target]}) return # The op offset just before the target jump offset is important # in making a determination of what we have. Save that. pre_rtarget = prev_op[rtarget] # Is it an "and" inside an "if" or "while" block if op == opc.JUMP_IF_FALSE: # Search for another JUMP_IF_FALSE targetting the same op, # in current statement, starting from current offset, and filter # everything inside inner 'or' jumps and midline ifs match = self.rem_or(start, self.next_stmt[offset], opc.JUMP_IF_FALSE, target) # If we still have any offsets in set, start working on it if match: is_jump_forward = self.is_jump_forward(pre_rtarget) if (is_jump_forward and pre_rtarget not in self.stmts and self.restrict_to_parent(self.get_target(pre_rtarget), parent) == rtarget): if (code[prev_op[pre_rtarget]] == self.opc.JUMP_ABSOLUTE and self.remove_mid_line_ifs([offset]) and target == self.get_target(prev_op[pre_rtarget]) and (prev_op[pre_rtarget] not in self.stmts or self.get_target(prev_op[pre_rtarget]) > prev_op[pre_rtarget]) and 1 == len(self.remove_mid_line_ifs(self.rem_or(start, prev_op[pre_rtarget], JUMP_TF, target)))): pass elif (code[prev_op[pre_rtarget]] == self.opc.RETURN_VALUE and self.remove_mid_line_ifs([offset]) and 1 == (len(set(self.remove_mid_line_ifs(self.rem_or(start, prev_op[pre_rtarget], JUMP_TF, target))) | set(self.remove_mid_line_ifs(self.rem_or(start, prev_op[pre_rtarget], (opc.JUMP_IF_FALSE, opc.JUMP_IF_TRUE, opc.JUMP_ABSOLUTE), pre_rtarget, True)))))): pass else: fix = None jump_ifs = self.all_instr(start, self.next_stmt[offset], opc.JUMP_IF_FALSE) last_jump_good = True for j in jump_ifs: if target == self.get_target(j): if self.lines[j].next == j + 3 and last_jump_good: fix = j break else: last_jump_good = False self.fixed_jumps[offset] = fix or match[-1] return else: self.fixed_jumps[offset] = match[-1] return # op == JUMP_IF_TRUE else: next = self.next_stmt[offset] if prev_op[next] == offset: pass elif self.is_jump_forward(next) and target == self.get_target(next): if code[prev_op[next]] == opc.JUMP_IF_FALSE: if (code[next] == self.opc.JUMP_FORWARD or target != rtarget or code[prev_op[pre_rtarget]] not in (self.opc.JUMP_ABSOLUTE, self.opc.RETURN_VALUE)): self.fixed_jumps[offset] = prev_op[next] return elif (code[next] == self.opc.JUMP_ABSOLUTE and self.is_jump_forward(target) and self.get_target(target) == self.get_target(next)): self.fixed_jumps[offset] = prev_op[next] return # Don't add a struct for a while test, it's already taken care of if offset in self.ignore_if: return if (code[pre_rtarget] == self.opc.JUMP_ABSOLUTE and pre_rtarget in self.stmts and pre_rtarget != offset and prev_op[pre_rtarget] != offset and not (code[rtarget] == self.opc.JUMP_ABSOLUTE and code[rtarget+3] == self.opc.POP_BLOCK and code[prev_op[pre_rtarget]] != self.opc.JUMP_ABSOLUTE)): rtarget = pre_rtarget # Does the "jump if" jump beyond a jump op? # That is, we have something like: # JUMP_IF_FALSE HERE # ... # JUMP_FORWARD # HERE: # # If so, this can be block inside an "if" statement # or a conditional assignment like: # x = 1 if x else 2 # # There are other contexts we may need to consider # like whether the target is "END_FINALLY" # or if the condition jump is to a forward location if self.is_jump_forward(pre_rtarget): if_end = self.get_target(pre_rtarget) # If the jump target is back, we are looping if (if_end < pre_rtarget and (code[prev_op[if_end]] == self.opc.SETUP_LOOP)): if (if_end > start): return end = self.restrict_to_parent(if_end, parent) self.structs.append({'type': 'if-then', 'start': start, 'end': pre_rtarget}) self.not_continue.add(pre_rtarget) # if rtarget < end and ( # code[rtarget] not in (self.opc.END_FINALLY, # self.opc.JUMP_ABSOLUTE) and # code[prev_op[pre_rtarget]] not in (self.opc.POP_EXCEPT, # self.opc.END_FINALLY)): # self.structs.append({'type': 'else', # 'start': rtarget, # 'end': end}) # self.else_start[rtarget] = end elif self.is_jump_back(pre_rtarget): if_end = rtarget self.structs.append({'type': 'if-then', 'start': start, 'end': pre_rtarget}) self.not_continue.add(pre_rtarget) elif code[pre_rtarget] in (self.opc.RETURN_VALUE, self.opc.BREAK_LOOP): self.structs.append({'type': 'if-then', 'start': start, 'end': rtarget}) # It is important to distingish if this return is inside some sort # except block return jump_prev = prev_op[offset] if self.is_pypy and code[jump_prev] == self.opc.COMPARE_OP: if self.opc.cmp_op[code[jump_prev+1]] == 'exception-match': return if self.version >= 3.5: # Python 3.5 may remove as dead code a JUMP # instruction after a RETURN_VALUE. So we check # based on seeing SETUP_EXCEPT various places. if code[rtarget] == self.opc.SETUP_EXCEPT: return # Check that next instruction after pops and jump is # not from SETUP_EXCEPT next_op = rtarget if code[next_op] == self.opc.POP_BLOCK: next_op += op_size(self.code[next_op], self.opc) if code[next_op] == self.opc.JUMP_ABSOLUTE: next_op += op_size(self.code[next_op], self.opc) if next_op in targets: for try_op in targets[next_op]: come_from_op = code[try_op] if come_from_op == self.opc.SETUP_EXCEPT: return pass pass if code[pre_rtarget] == self.opc.RETURN_VALUE: self.return_end_ifs.add(pre_rtarget) else: self.fixed_jumps[offset] = rtarget self.not_continue.add(pre_rtarget) elif op == self.opc.SETUP_EXCEPT: target = self.get_target(offset) end = self.restrict_to_parent(target, parent) self.fixed_jumps[offset] = end elif op == self.opc.SETUP_FINALLY: target = self.get_target(offset) end = self.restrict_to_parent(target, parent) self.fixed_jumps[offset] = end elif op in self.jump_if_pop: target = self.get_target(offset) if target > offset: unop_target = self.last_instr(offset, target, self.opc.JUMP_FORWARD, target) if unop_target and code[unop_target+3] != self.opc.ROT_TWO: self.fixed_jumps[offset] = unop_target else: self.fixed_jumps[offset] = self.restrict_to_parent(target, parent) pass pass elif self.version >= 3.5: # 3.5+ has Jump optimization which too often causes RETURN_VALUE to get # misclassified as RETURN_END_IF. Handle that here. # In RETURN_VALUE, JUMP_ABSOLUTE, RETURN_VALUE is never RETURN_END_IF if op == self.opc.RETURN_VALUE: if (offset+1 < len(code) and code[offset+1] == self.opc.JUMP_ABSOLUTE and offset in self.return_end_ifs): self.return_end_ifs.remove(offset) pass pass elif op == self.opc.JUMP_FORWARD: # If we have: # JUMP_FORWARD x, [non-jump, insns], RETURN_VALUE, x: # then RETURN_VALUE is not RETURN_END_IF rtarget = self.get_target(offset) rtarget_prev = self.prev[rtarget] if (code[rtarget_prev] == self.opc.RETURN_VALUE and rtarget_prev in self.return_end_ifs): i = rtarget_prev while i != offset: if code[i] in [opc.JUMP_FORWARD, opc.JUMP_ABSOLUTE]: return i = self.prev[i] self.return_end_ifs.remove(rtarget_prev) pass return def rem_or(self, start, end, instr, target=None, include_beyond_target=False): """ Find offsets of all requested between and , optionally ing specified offset, and return list found offsets which are not within any POP_JUMP_IF_TRUE jumps. """ assert(start>=0 and end<=len(self.code) and start <= end) # Find all offsets of requested instructions instr_offsets = self.all_instr(start, end, instr, target, include_beyond_target) # Get all JUMP_IF_TRUE (or) offsets pjit_offsets = self.all_instr(start, end, opc.JUMP_IF_TRUE) filtered = [] for pjit_offset in pjit_offsets: pjit_tgt = self.get_target(pjit_offset) - 3 for instr_offset in instr_offsets: if instr_offset <= pjit_offset or instr_offset >= pjit_tgt: filtered.append(instr_offset) instr_offsets = filtered filtered = [] return instr_offsets if __name__ == "__main__": from uncompyle6 import PYTHON_VERSION if PYTHON_VERSION == 3.0: import inspect co = inspect.currentframe().f_code tokens, customize = Scanner30().ingest(co) for t in tokens: print(t) pass else: print("Need to be Python 3.0 to demo; I am %s." % PYTHON_VERSION)