JezK

Edit File: dis.py

"""Disassembler of Python byte code into mnemonics.""" import sys import types import collections import io from opcode import * from opcode import ( __all__ as _opcodes_all, _cache_format, _inline_cache_entries, _nb_ops, _specializations, _specialized_instructions, ) __all__ = ["code_info", "dis", "disassemble", "distb", "disco", "findlinestarts", "findlabels", "show_code", "get_instructions", "Instruction", "Bytecode"] + _opcodes_all del _opcodes_all _have_code = (types.MethodType, types.FunctionType, types.CodeType, classmethod, staticmethod, type) FORMAT_VALUE = opmap['FORMAT_VALUE'] FORMAT_VALUE_CONVERTERS = ( (None, ''), (str, 'str'), (repr, 'repr'), (ascii, 'ascii'), ) MAKE_FUNCTION = opmap['MAKE_FUNCTION'] MAKE_FUNCTION_FLAGS = ('defaults', 'kwdefaults', 'annotations', 'closure') LOAD_CONST = opmap['LOAD_CONST'] LOAD_GLOBAL = opmap['LOAD_GLOBAL'] BINARY_OP = opmap['BINARY_OP'] JUMP_BACKWARD = opmap['JUMP_BACKWARD'] CACHE = opmap["CACHE"] _all_opname = list(opname) _all_opmap = dict(opmap) _empty_slot = [slot for slot, name in enumerate(_all_opname) if name.startswith("<")] for spec_op, specialized in zip(_empty_slot, _specialized_instructions): # fill opname and opmap _all_opname[spec_op] = specialized _all_opmap[specialized] = spec_op deoptmap = { specialized: base for base, family in _specializations.items() for specialized in family } def _try_compile(source, name): """Attempts to compile the given source, first as an expression and then as a statement if the first approach fails. Utility function to accept strings in functions that otherwise expect code objects """ try: c = compile(source, name, 'eval') except SyntaxError: c = compile(source, name, 'exec') return c def dis(x=None, *, file=None, depth=None, show_caches=False, adaptive=False): """Disassemble classes, methods, functions, and other compiled objects. With no argument, disassemble the last traceback. Compiled objects currently include generator objects, async generator objects, and coroutine objects, all of which store their code object in a special attribute. """ if x is None: distb(file=file, show_caches=show_caches, adaptive=adaptive) return # Extract functions from methods. if hasattr(x, '__func__'): x = x.__func__ # Extract compiled code objects from... if hasattr(x, '__code__'): # ...a function, or x = x.__code__ elif hasattr(x, 'gi_code'): #...a generator object, or x = x.gi_code elif hasattr(x, 'ag_code'): #...an asynchronous generator object, or x = x.ag_code elif hasattr(x, 'cr_code'): #...a coroutine. x = x.cr_code # Perform the disassembly. if hasattr(x, '__dict__'): # Class or module items = sorted(x.__dict__.items()) for name, x1 in items: if isinstance(x1, _have_code): print("Disassembly of %s:" % name, file=file) try: dis(x1, file=file, depth=depth, show_caches=show_caches, adaptive=adaptive) except TypeError as msg: print("Sorry:", msg, file=file) print(file=file) elif hasattr(x, 'co_code'): # Code object _disassemble_recursive(x, file=file, depth=depth, show_caches=show_caches, adaptive=adaptive) elif isinstance(x, (bytes, bytearray)): # Raw bytecode _disassemble_bytes(x, file=file, show_caches=show_caches) elif isinstance(x, str): # Source code _disassemble_str(x, file=file, depth=depth, show_caches=show_caches, adaptive=adaptive) else: raise TypeError("don't know how to disassemble %s objects" % type(x).__name__) def distb(tb=None, *, file=None, show_caches=False, adaptive=False): """Disassemble a traceback (default: last traceback).""" if tb is None: try: tb = sys.last_traceback except AttributeError: raise RuntimeError("no last traceback to disassemble") from None while tb.tb_next: tb = tb.tb_next disassemble(tb.tb_frame.f_code, tb.tb_lasti, file=file, show_caches=show_caches, adaptive=adaptive) # The inspect module interrogates this dictionary to build its # list of CO_* constants. It is also used by pretty_flags to # turn the co_flags field into a human readable list. COMPILER_FLAG_NAMES = { 1: "OPTIMIZED", 2: "NEWLOCALS", 4: "VARARGS", 8: "VARKEYWORDS", 16: "NESTED", 32: "GENERATOR", 64: "NOFREE", 128: "COROUTINE", 256: "ITERABLE_COROUTINE", 512: "ASYNC_GENERATOR", } def pretty_flags(flags): """Return pretty representation of code flags.""" names = [] for i in range(32): flag = 1<<i if flags & flag: names.append(COMPILER_FLAG_NAMES.get(flag, hex(flag))) flags ^= flag if not flags: break else: names.append(hex(flags)) return ", ".join(names) class _Unknown: def __repr__(self): return "<unknown>" # Sentinel to represent values that cannot be calculated UNKNOWN = _Unknown() def _get_code_object(x): """Helper to handle methods, compiled or raw code objects, and strings.""" # Extract functions from methods. if hasattr(x, '__func__'): x = x.__func__ # Extract compiled code objects from... if hasattr(x, '__code__'): # ...a function, or x = x.__code__ elif hasattr(x, 'gi_code'): #...a generator object, or x = x.gi_code elif hasattr(x, 'ag_code'): #...an asynchronous generator object, or x = x.ag_code elif hasattr(x, 'cr_code'): #...a coroutine. x = x.cr_code # Handle source code. if isinstance(x, str): x = _try_compile(x, "<disassembly>") # By now, if we don't have a code object, we can't disassemble x. if hasattr(x, 'co_code'): return x raise TypeError("don't know how to disassemble %s objects" % type(x).__name__) def _deoptop(op): name = _all_opname[op] return _all_opmap[deoptmap[name]] if name in deoptmap else op def _get_code_array(co, adaptive): return co._co_code_adaptive if adaptive else co.co_code def code_info(x): """Formatted details of methods, functions, or code.""" return _format_code_info(_get_code_object(x)) def _format_code_info(co): lines = [] lines.append("Name: %s" % co.co_name) lines.append("Filename: %s" % co.co_filename) lines.append("Argument count: %s" % co.co_argcount) lines.append("Positional-only arguments: %s" % co.co_posonlyargcount) lines.append("Kw-only arguments: %s" % co.co_kwonlyargcount) lines.append("Number of locals: %s" % co.co_nlocals) lines.append("Stack size: %s" % co.co_stacksize) lines.append("Flags: %s" % pretty_flags(co.co_flags)) if co.co_consts: lines.append("Constants:") for i_c in enumerate(co.co_consts): lines.append("%4d: %r" % i_c) if co.co_names: lines.append("Names:") for i_n in enumerate(co.co_names): lines.append("%4d: %s" % i_n) if co.co_varnames: lines.append("Variable names:") for i_n in enumerate(co.co_varnames): lines.append("%4d: %s" % i_n) if co.co_freevars: lines.append("Free variables:") for i_n in enumerate(co.co_freevars): lines.append("%4d: %s" % i_n) if co.co_cellvars: lines.append("Cell variables:") for i_n in enumerate(co.co_cellvars): lines.append("%4d: %s" % i_n) return "\n".join(lines) def show_code(co, *, file=None): """Print details of methods, functions, or code to *file*. If *file* is not provided, the output is printed on stdout. """ print(code_info(co), file=file) Positions = collections.namedtuple( 'Positions', [ 'lineno', 'end_lineno', 'col_offset', 'end_col_offset', ], defaults=[None] * 4 ) _Instruction = collections.namedtuple( "_Instruction", [ 'opname', 'opcode', 'arg', 'argval', 'argrepr', 'offset', 'starts_line', 'is_jump_target', 'positions' ], defaults=[None] ) _Instruction.opname.__doc__ = "Human readable name for operation" _Instruction.opcode.__doc__ = "Numeric code for operation" _Instruction.arg.__doc__ = "Numeric argument to operation (if any), otherwise None" _Instruction.argval.__doc__ = "Resolved arg value (if known), otherwise same as arg" _Instruction.argrepr.__doc__ = "Human readable description of operation argument" _Instruction.offset.__doc__ = "Start index of operation within bytecode sequence" _Instruction.starts_line.__doc__ = "Line started by this opcode (if any), otherwise None" _Instruction.is_jump_target.__doc__ = "True if other code jumps to here, otherwise False" _Instruction.positions.__doc__ = "dis.Positions object holding the span of source code covered by this instruction" _ExceptionTableEntry = collections.namedtuple("_ExceptionTableEntry", "start end target depth lasti") _OPNAME_WIDTH = 20 _OPARG_WIDTH = 5 class Instruction(_Instruction): """Details for a bytecode operation Defined fields: opname - human readable name for operation opcode - numeric code for operation arg - numeric argument to operation (if any), otherwise None argval - resolved arg value (if known), otherwise same as arg argrepr - human readable description of operation argument offset - start index of operation within bytecode sequence starts_line - line started by this opcode (if any), otherwise None is_jump_target - True if other code jumps to here, otherwise False positions - Optional dis.Positions object holding the span of source code covered by this instruction """ def _disassemble(self, lineno_width=3, mark_as_current=False, offset_width=4): """Format instruction details for inclusion in disassembly output *lineno_width* sets the width of the line number field (0 omits it) *mark_as_current* inserts a '-->' marker arrow as part of the line *offset_width* sets the width of the instruction offset field """ fields = [] # Column: Source code line number if lineno_width: if self.starts_line is not None: lineno_fmt = "%%%dd" % lineno_width fields.append(lineno_fmt % self.starts_line) else: fields.append(' ' * lineno_width) # Column: Current instruction indicator if mark_as_current: fields.append('-->') else: fields.append(' ') # Column: Jump target marker if self.is_jump_target: fields.append('>>') else: fields.append(' ') # Column: Instruction offset from start of code sequence fields.append(repr(self.offset).rjust(offset_width)) # Column: Opcode name fields.append(self.opname.ljust(_OPNAME_WIDTH)) # Column: Opcode argument if self.arg is not None: fields.append(repr(self.arg).rjust(_OPARG_WIDTH)) # Column: Opcode argument details if self.argrepr: fields.append('(' + self.argrepr + ')') return ' '.join(fields).rstrip() def get_instructions(x, *, first_line=None, show_caches=False, adaptive=False): """Iterator for the opcodes in methods, functions or code Generates a series of Instruction named tuples giving the details of each operations in the supplied code. If *first_line* is not None, it indicates the line number that should be reported for the first source line in the disassembled code. Otherwise, the source line information (if any) is taken directly from the disassembled code object. """ co = _get_code_object(x) linestarts = dict(findlinestarts(co)) if first_line is not None: line_offset = first_line - co.co_firstlineno else: line_offset = 0 return _get_instructions_bytes(_get_code_array(co, adaptive), co._varname_from_oparg, co.co_names, co.co_consts, linestarts, line_offset, co_positions=co.co_positions(), show_caches=show_caches) def _get_const_value(op, arg, co_consts): """Helper to get the value of the const in a hasconst op. Returns the dereferenced constant if this is possible. Otherwise (if it is a LOAD_CONST and co_consts is not provided) returns the dis.UNKNOWN sentinel. """ assert op in hasconst argval = UNKNOWN if op == LOAD_CONST: if co_consts is not None: argval = co_consts[arg] return argval def _get_const_info(op, arg, co_consts): """Helper to get optional details about const references Returns the dereferenced constant and its repr if the value can be calculated. Otherwise returns the sentinel value dis.UNKNOWN for the value and an empty string for its repr. """ argval = _get_const_value(op, arg, co_consts) argrepr = repr(argval) if argval is not UNKNOWN else '' return argval, argrepr def _get_name_info(name_index, get_name, **extrainfo): """Helper to get optional details about named references Returns the dereferenced name as both value and repr if the name list is defined. Otherwise returns the sentinel value dis.UNKNOWN for the value and an empty string for its repr. """ if get_name is not None: argval = get_name(name_index, **extrainfo) return argval, argval else: return UNKNOWN, '' def _parse_varint(iterator): b = next(iterator) val = b & 63 while b&64: val <<= 6 b = next(iterator) val |= b&63 return val def _parse_exception_table(code): iterator = iter(code.co_exceptiontable) entries = [] try: while True: start = _parse_varint(iterator)*2 length = _parse_varint(iterator)*2 end = start + length target = _parse_varint(iterator)*2 dl = _parse_varint(iterator) depth = dl >> 1 lasti = bool(dl&1) entries.append(_ExceptionTableEntry(start, end, target, depth, lasti)) except StopIteration: return entries def _is_backward_jump(op): return 'JUMP_BACKWARD' in opname[op] def _get_instructions_bytes(code, varname_from_oparg=None, names=None, co_consts=None, linestarts=None, line_offset=0, exception_entries=(), co_positions=None, show_caches=False): """Iterate over the instructions in a bytecode string. Generates a sequence of Instruction namedtuples giving the details of each opcode. Additional information about the code's runtime environment (e.g. variable names, co_consts) can be specified using optional arguments. """ co_positions = co_positions or iter(()) get_name = None if names is None else names.__getitem__ labels = set(findlabels(code)) for start, end, target, _, _ in exception_entries: for i in range(start, end): labels.add(target) starts_line = None for offset, op, arg in _unpack_opargs(code): if linestarts is not None: starts_line = linestarts.get(offset, None) if starts_line is not None: starts_line += line_offset is_jump_target = offset in labels argval = None argrepr = '' positions = Positions(*next(co_positions, ())) deop = _deoptop(op) if arg is not None: # Set argval to the dereferenced value of the argument when # available, and argrepr to the string representation of argval. # _disassemble_bytes needs the string repr of the # raw name index for LOAD_GLOBAL, LOAD_CONST, etc. argval = arg if deop in hasconst: argval, argrepr = _get_const_info(deop, arg, co_consts) elif deop in hasname: if deop == LOAD_GLOBAL: argval, argrepr = _get_name_info(arg//2, get_name) if (arg & 1) and argrepr: argrepr = "NULL + " + argrepr else: argval, argrepr = _get_name_info(arg, get_name) elif deop in hasjabs: argval = arg*2 argrepr = "to " + repr(argval) elif deop in hasjrel: signed_arg = -arg if _is_backward_jump(deop) else arg argval = offset + 2 + signed_arg*2 argrepr = "to " + repr(argval) elif deop in haslocal or deop in hasfree: argval, argrepr = _get_name_info(arg, varname_from_oparg) elif deop in hascompare: argval = cmp_op[arg] argrepr = argval elif deop == FORMAT_VALUE: argval, argrepr = FORMAT_VALUE_CONVERTERS[arg & 0x3] argval = (argval, bool(arg & 0x4)) if argval[1]: if argrepr: argrepr += ', ' argrepr += 'with format' elif deop == MAKE_FUNCTION: argrepr = ', '.join(s for i, s in enumerate(MAKE_FUNCTION_FLAGS) if arg & (1<<i)) elif deop == BINARY_OP: _, argrepr = _nb_ops[arg] yield Instruction(_all_opname[op], op, arg, argval, argrepr, offset, starts_line, is_jump_target, positions) caches = _inline_cache_entries[deop] if not caches: continue if not show_caches: # We still need to advance the co_positions iterator: for _ in range(caches): next(co_positions, ()) continue for name, size in _cache_format[opname[deop]].items(): for i in range(size): offset += 2 # Only show the fancy argrepr for a CACHE instruction when it's # the first entry for a particular cache value and the # instruction using it is actually quickened: if i == 0 and op != deop: data = code[offset: offset + 2 * size] argrepr = f"{name}: {int.from_bytes(data, sys.byteorder)}" else: argrepr = "" yield Instruction( "CACHE", CACHE, 0, None, argrepr, offset, None, False, Positions(*next(co_positions, ())) ) def disassemble(co, lasti=-1, *, file=None, show_caches=False, adaptive=False): """Disassemble a code object.""" linestarts = dict(findlinestarts(co)) exception_entries = _parse_exception_table(co) _disassemble_bytes(_get_code_array(co, adaptive), lasti, co._varname_from_oparg, co.co_names, co.co_consts, linestarts, file=file, exception_entries=exception_entries, co_positions=co.co_positions(), show_caches=show_caches) def _disassemble_recursive(co, *, file=None, depth=None, show_caches=False, adaptive=False): disassemble(co, file=file, show_caches=show_caches, adaptive=adaptive) if depth is None or depth > 0: if depth is not None: depth = depth - 1 for x in co.co_consts: if hasattr(x, 'co_code'): print(file=file) print("Disassembly of %r:" % (x,), file=file) _disassemble_recursive( x, file=file, depth=depth, show_caches=show_caches, adaptive=adaptive ) def _disassemble_bytes(code, lasti=-1, varname_from_oparg=None, names=None, co_consts=None, linestarts=None, *, file=None, line_offset=0, exception_entries=(), co_positions=None, show_caches=False): # Omit the line number column entirely if we have no line number info show_lineno = bool(linestarts) if show_lineno: maxlineno = max(linestarts.values()) + line_offset if maxlineno >= 1000: lineno_width = len(str(maxlineno)) else: lineno_width = 3 else: lineno_width = 0 maxoffset = len(code) - 2 if maxoffset >= 10000: offset_width = len(str(maxoffset)) else: offset_width = 4 for instr in _get_instructions_bytes(code, varname_from_oparg, names, co_consts, linestarts, line_offset=line_offset, exception_entries=exception_entries, co_positions=co_positions, show_caches=show_caches): new_source_line = (show_lineno and instr.starts_line is not None and instr.offset > 0) if new_source_line: print(file=file) is_current_instr = instr.offset == lasti print(instr._disassemble(lineno_width, is_current_instr, offset_width), file=file) if exception_entries: print("ExceptionTable:", file=file) for entry in exception_entries: lasti = " lasti" if entry.lasti else "" end = entry.end-2 print(f" {entry.start} to {end} -> {entry.target} [{entry.depth}]{lasti}", file=file) def _disassemble_str(source, **kwargs): """Compile the source string, then disassemble the code object.""" _disassemble_recursive(_try_compile(source, '<dis>'), **kwargs) disco = disassemble # XXX For backwards compatibility # Rely on C `int` being 32 bits for oparg _INT_BITS = 32 # Value for c int when it overflows _INT_OVERFLOW = 2 ** (_INT_BITS - 1) def _unpack_opargs(code): extended_arg = 0 caches = 0 for i in range(0, len(code), 2): # Skip inline CACHE entries: if caches: caches -= 1 continue op = code[i] deop = _deoptop(op) caches = _inline_cache_entries[deop] if deop >= HAVE_ARGUMENT: arg = code[i+1] | extended_arg extended_arg = (arg << 8) if deop == EXTENDED_ARG else 0 # The oparg is stored as a signed integer # If the value exceeds its upper limit, it will overflow and wrap # to a negative integer if extended_arg >= _INT_OVERFLOW: extended_arg -= 2 * _INT_OVERFLOW else: arg = None extended_arg = 0 yield (i, op, arg) def findlabels(code): """Detect all offsets in a byte code which are jump targets. Return the list of offsets. """ labels = [] for offset, op, arg in _unpack_opargs(code): if arg is not None: if op in hasjrel: if _is_backward_jump(op): arg = -arg label = offset + 2 + arg*2 elif op in hasjabs: label = arg*2 else: continue if label not in labels: labels.append(label) return labels def findlinestarts(code): """Find the offsets in a byte code which are start of lines in the source. Generate pairs (offset, lineno) """ lastline = None for start, end, line in code.co_lines(): if line is not None and line != lastline: lastline = line yield start, line return def _find_imports(co): """Find import statements in the code Generate triplets (name, level, fromlist) where name is the imported module and level, fromlist are the corresponding args to __import__. """ IMPORT_NAME = opmap['IMPORT_NAME'] LOAD_CONST = opmap['LOAD_CONST'] consts = co.co_consts names = co.co_names opargs = [(op, arg) for _, op, arg in _unpack_opargs(co.co_code) if op != EXTENDED_ARG] for i, (op, oparg) in enumerate(opargs): if op == IMPORT_NAME and i >= 2: from_op = opargs[i-1] level_op = opargs[i-2] if (from_op[0] in hasconst and level_op[0] in hasconst): level = _get_const_value(level_op[0], level_op[1], consts) fromlist = _get_const_value(from_op[0], from_op[1], consts) yield (names[oparg], level, fromlist) def _find_store_names(co): """Find names of variables which are written in the code Generate sequence of strings """ STORE_OPS = { opmap['STORE_NAME'], opmap['STORE_GLOBAL'] } names = co.co_names for _, op, arg in _unpack_opargs(co.co_code): if op in STORE_OPS: yield names[arg] class Bytecode: """The bytecode operations of a piece of code Instantiate this with a function, method, other compiled object, string of code, or a code object (as returned by compile()). Iterating over this yields the bytecode operations as Instruction instances. """ def __init__(self, x, *, first_line=None, current_offset=None, show_caches=False, adaptive=False): self.codeobj = co = _get_code_object(x) if first_line is None: self.first_line = co.co_firstlineno self._line_offset = 0 else: self.first_line = first_line self._line_offset = first_line - co.co_firstlineno self._linestarts = dict(findlinestarts(co)) self._original_object = x self.current_offset = current_offset self.exception_entries = _parse_exception_table(co) self.show_caches = show_caches self.adaptive = adaptive def __iter__(self): co = self.codeobj return _get_instructions_bytes(_get_code_array(co, self.adaptive), co._varname_from_oparg, co.co_names, co.co_consts, self._linestarts, line_offset=self._line_offset, exception_entries=self.exception_entries, co_positions=co.co_positions(), show_caches=self.show_caches) def __repr__(self): return "{}({!r})".format(self.__class__.__name__, self._original_object) @classmethod def from_traceback(cls, tb, *, show_caches=False, adaptive=False): """ Construct a Bytecode from the given traceback """ while tb.tb_next: tb = tb.tb_next return cls( tb.tb_frame.f_code, current_offset=tb.tb_lasti, show_caches=show_caches, adaptive=adaptive ) def info(self): """Return formatted information about the code object.""" return _format_code_info(self.codeobj) def dis(self): """Return a formatted view of the bytecode operations.""" co = self.codeobj if self.current_offset is not None: offset = self.current_offset else: offset = -1 with io.StringIO() as output: _disassemble_bytes(_get_code_array(co, self.adaptive), varname_from_oparg=co._varname_from_oparg, names=co.co_names, co_consts=co.co_consts, linestarts=self._linestarts, line_offset=self._line_offset, file=output, lasti=offset, exception_entries=self.exception_entries, co_positions=co.co_positions(), show_caches=self.show_caches) return output.getvalue() def main(): import argparse parser = argparse.ArgumentParser() parser.add_argument('infile', type=argparse.FileType('rb'), nargs='?', default='-') args = parser.parse_args() with args.infile as infile: source = infile.read() code = compile(source, args.infile.name, "exec") dis(code) if __name__ == "__main__": main()