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690 lines
24 KiB
Python
690 lines
24 KiB
Python
"""Disassembler of Python byte code into mnemonics."""
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import sys
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import types
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import collections
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import io
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from opcode import *
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from opcode import __all__ as _opcodes_all
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from opcode import _nb_ops
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__all__ = ["code_info", "dis", "disassemble", "distb", "disco",
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"findlinestarts", "findlabels", "show_code",
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"get_instructions", "Instruction", "Bytecode"] + _opcodes_all
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del _opcodes_all
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_have_code = (types.MethodType, types.FunctionType, types.CodeType,
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classmethod, staticmethod, type)
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FORMAT_VALUE = opmap['FORMAT_VALUE']
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FORMAT_VALUE_CONVERTERS = (
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(None, ''),
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(str, 'str'),
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(repr, 'repr'),
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(ascii, 'ascii'),
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)
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MAKE_FUNCTION = opmap['MAKE_FUNCTION']
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MAKE_FUNCTION_FLAGS = ('defaults', 'kwdefaults', 'annotations', 'closure')
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LOAD_CONST = opmap['LOAD_CONST']
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BINARY_OP = opmap['BINARY_OP']
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def _try_compile(source, name):
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"""Attempts to compile the given source, first as an expression and
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then as a statement if the first approach fails.
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Utility function to accept strings in functions that otherwise
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expect code objects
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"""
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try:
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c = compile(source, name, 'eval')
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except SyntaxError:
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c = compile(source, name, 'exec')
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return c
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def dis(x=None, *, file=None, depth=None):
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"""Disassemble classes, methods, functions, and other compiled objects.
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With no argument, disassemble the last traceback.
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Compiled objects currently include generator objects, async generator
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objects, and coroutine objects, all of which store their code object
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in a special attribute.
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"""
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if x is None:
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distb(file=file)
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return
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# Extract functions from methods.
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if hasattr(x, '__func__'):
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x = x.__func__
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# Extract compiled code objects from...
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if hasattr(x, '__code__'): # ...a function, or
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x = x.__code__
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elif hasattr(x, 'gi_code'): #...a generator object, or
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x = x.gi_code
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elif hasattr(x, 'ag_code'): #...an asynchronous generator object, or
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x = x.ag_code
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elif hasattr(x, 'cr_code'): #...a coroutine.
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x = x.cr_code
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# Perform the disassembly.
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if hasattr(x, '__dict__'): # Class or module
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items = sorted(x.__dict__.items())
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for name, x1 in items:
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if isinstance(x1, _have_code):
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print("Disassembly of %s:" % name, file=file)
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try:
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dis(x1, file=file, depth=depth)
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except TypeError as msg:
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print("Sorry:", msg, file=file)
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print(file=file)
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elif hasattr(x, 'co_code'): # Code object
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_disassemble_recursive(x, file=file, depth=depth)
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elif isinstance(x, (bytes, bytearray)): # Raw bytecode
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_disassemble_bytes(x, file=file)
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elif isinstance(x, str): # Source code
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_disassemble_str(x, file=file, depth=depth)
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else:
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raise TypeError("don't know how to disassemble %s objects" %
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type(x).__name__)
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def distb(tb=None, *, file=None):
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"""Disassemble a traceback (default: last traceback)."""
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if tb is None:
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try:
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tb = sys.last_traceback
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except AttributeError:
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raise RuntimeError("no last traceback to disassemble") from None
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while tb.tb_next: tb = tb.tb_next
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disassemble(tb.tb_frame.f_code, tb.tb_lasti, file=file)
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# The inspect module interrogates this dictionary to build its
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# list of CO_* constants. It is also used by pretty_flags to
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# turn the co_flags field into a human readable list.
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COMPILER_FLAG_NAMES = {
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1: "OPTIMIZED",
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2: "NEWLOCALS",
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4: "VARARGS",
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8: "VARKEYWORDS",
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16: "NESTED",
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32: "GENERATOR",
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64: "NOFREE",
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128: "COROUTINE",
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256: "ITERABLE_COROUTINE",
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512: "ASYNC_GENERATOR",
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}
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def pretty_flags(flags):
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"""Return pretty representation of code flags."""
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names = []
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for i in range(32):
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flag = 1<<i
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if flags & flag:
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names.append(COMPILER_FLAG_NAMES.get(flag, hex(flag)))
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flags ^= flag
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if not flags:
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break
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else:
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names.append(hex(flags))
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return ", ".join(names)
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class _Unknown:
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def __repr__(self):
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return "<unknown>"
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# Sentinel to represent values that cannot be calculated
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UNKNOWN = _Unknown()
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def _get_code_object(x):
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"""Helper to handle methods, compiled or raw code objects, and strings."""
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# Extract functions from methods.
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if hasattr(x, '__func__'):
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x = x.__func__
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# Extract compiled code objects from...
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if hasattr(x, '__code__'): # ...a function, or
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x = x.__code__
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elif hasattr(x, 'gi_code'): #...a generator object, or
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x = x.gi_code
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elif hasattr(x, 'ag_code'): #...an asynchronous generator object, or
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x = x.ag_code
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elif hasattr(x, 'cr_code'): #...a coroutine.
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x = x.cr_code
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# Handle source code.
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if isinstance(x, str):
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x = _try_compile(x, "<disassembly>")
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# By now, if we don't have a code object, we can't disassemble x.
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if hasattr(x, 'co_code'):
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return x
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raise TypeError("don't know how to disassemble %s objects" %
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type(x).__name__)
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def code_info(x):
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"""Formatted details of methods, functions, or code."""
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return _format_code_info(_get_code_object(x))
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def _format_code_info(co):
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lines = []
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lines.append("Name: %s" % co.co_name)
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lines.append("Filename: %s" % co.co_filename)
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lines.append("Argument count: %s" % co.co_argcount)
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lines.append("Positional-only arguments: %s" % co.co_posonlyargcount)
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lines.append("Kw-only arguments: %s" % co.co_kwonlyargcount)
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lines.append("Number of locals: %s" % co.co_nlocals)
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lines.append("Stack size: %s" % co.co_stacksize)
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lines.append("Flags: %s" % pretty_flags(co.co_flags))
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if co.co_consts:
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lines.append("Constants:")
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for i_c in enumerate(co.co_consts):
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lines.append("%4d: %r" % i_c)
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if co.co_names:
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lines.append("Names:")
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for i_n in enumerate(co.co_names):
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lines.append("%4d: %s" % i_n)
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if co.co_varnames:
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lines.append("Variable names:")
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for i_n in enumerate(co.co_varnames):
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lines.append("%4d: %s" % i_n)
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if co.co_freevars:
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lines.append("Free variables:")
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for i_n in enumerate(co.co_freevars):
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lines.append("%4d: %s" % i_n)
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if co.co_cellvars:
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lines.append("Cell variables:")
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for i_n in enumerate(co.co_cellvars):
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lines.append("%4d: %s" % i_n)
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return "\n".join(lines)
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def show_code(co, *, file=None):
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"""Print details of methods, functions, or code to *file*.
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If *file* is not provided, the output is printed on stdout.
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"""
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print(code_info(co), file=file)
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Positions = collections.namedtuple(
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'Positions',
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[
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'lineno',
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'end_lineno',
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'col_offset',
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'end_col_offset',
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],
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defaults=[None] * 4
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)
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_Instruction = collections.namedtuple(
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"_Instruction",
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[
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'opname',
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'opcode',
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'arg',
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'argval',
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'argrepr',
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'offset',
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'starts_line',
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'is_jump_target',
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'positions'
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],
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defaults=[None]
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)
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_Instruction.opname.__doc__ = "Human readable name for operation"
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_Instruction.opcode.__doc__ = "Numeric code for operation"
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_Instruction.arg.__doc__ = "Numeric argument to operation (if any), otherwise None"
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_Instruction.argval.__doc__ = "Resolved arg value (if known), otherwise same as arg"
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_Instruction.argrepr.__doc__ = "Human readable description of operation argument"
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_Instruction.offset.__doc__ = "Start index of operation within bytecode sequence"
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_Instruction.starts_line.__doc__ = "Line started by this opcode (if any), otherwise None"
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_Instruction.is_jump_target.__doc__ = "True if other code jumps to here, otherwise False"
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_Instruction.positions.__doc__ = "dis.Positions object holding the span of source code covered by this instruction"
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_ExceptionTableEntry = collections.namedtuple("_ExceptionTableEntry",
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"start end target depth lasti")
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_OPNAME_WIDTH = 20
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_OPARG_WIDTH = 5
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class Instruction(_Instruction):
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"""Details for a bytecode operation
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Defined fields:
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opname - human readable name for operation
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opcode - numeric code for operation
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arg - numeric argument to operation (if any), otherwise None
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argval - resolved arg value (if known), otherwise same as arg
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argrepr - human readable description of operation argument
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offset - start index of operation within bytecode sequence
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starts_line - line started by this opcode (if any), otherwise None
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is_jump_target - True if other code jumps to here, otherwise False
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positions - Optional dis.Positions object holding the span of source code
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covered by this instruction
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"""
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def _disassemble(self, lineno_width=3, mark_as_current=False, offset_width=4):
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"""Format instruction details for inclusion in disassembly output
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*lineno_width* sets the width of the line number field (0 omits it)
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*mark_as_current* inserts a '-->' marker arrow as part of the line
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*offset_width* sets the width of the instruction offset field
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"""
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fields = []
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# Column: Source code line number
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if lineno_width:
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if self.starts_line is not None:
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lineno_fmt = "%%%dd" % lineno_width
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fields.append(lineno_fmt % self.starts_line)
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else:
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fields.append(' ' * lineno_width)
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# Column: Current instruction indicator
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if mark_as_current:
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fields.append('-->')
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else:
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fields.append(' ')
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# Column: Jump target marker
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if self.is_jump_target:
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fields.append('>>')
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else:
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fields.append(' ')
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# Column: Instruction offset from start of code sequence
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fields.append(repr(self.offset).rjust(offset_width))
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# Column: Opcode name
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fields.append(self.opname.ljust(_OPNAME_WIDTH))
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# Column: Opcode argument
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if self.arg is not None:
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fields.append(repr(self.arg).rjust(_OPARG_WIDTH))
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# Column: Opcode argument details
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if self.argrepr:
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fields.append('(' + self.argrepr + ')')
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return ' '.join(fields).rstrip()
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def get_instructions(x, *, first_line=None):
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"""Iterator for the opcodes in methods, functions or code
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Generates a series of Instruction named tuples giving the details of
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each operations in the supplied code.
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If *first_line* is not None, it indicates the line number that should
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be reported for the first source line in the disassembled code.
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Otherwise, the source line information (if any) is taken directly from
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the disassembled code object.
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"""
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co = _get_code_object(x)
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linestarts = dict(findlinestarts(co))
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if first_line is not None:
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line_offset = first_line - co.co_firstlineno
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else:
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line_offset = 0
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return _get_instructions_bytes(co.co_code,
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co._varname_from_oparg,
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co.co_names, co.co_consts,
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linestarts, line_offset, co_positions=co.co_positions())
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def _get_const_value(op, arg, co_consts):
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"""Helper to get the value of the const in a hasconst op.
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Returns the dereferenced constant if this is possible.
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Otherwise (if it is a LOAD_CONST and co_consts is not
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provided) returns the dis.UNKNOWN sentinel.
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"""
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assert op in hasconst
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argval = UNKNOWN
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if op == LOAD_CONST:
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if co_consts is not None:
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argval = co_consts[arg]
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return argval
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def _get_const_info(op, arg, co_consts):
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"""Helper to get optional details about const references
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Returns the dereferenced constant and its repr if the value
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can be calculated.
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Otherwise returns the sentinel value dis.UNKNOWN for the value
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and an empty string for its repr.
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"""
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argval = _get_const_value(op, arg, co_consts)
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argrepr = repr(argval) if argval is not UNKNOWN else ''
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return argval, argrepr
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def _get_name_info(name_index, get_name, **extrainfo):
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"""Helper to get optional details about named references
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Returns the dereferenced name as both value and repr if the name
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list is defined.
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Otherwise returns the sentinel value dis.UNKNOWN for the value
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and an empty string for its repr.
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"""
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if get_name is not None:
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argval = get_name(name_index, **extrainfo)
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return argval, argval
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else:
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return UNKNOWN, ''
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def parse_varint(iterator):
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b = next(iterator)
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val = b & 63
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while b&64:
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val <<= 6
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b = next(iterator)
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val |= b&63
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return val
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def parse_exception_table(code):
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iterator = iter(code.co_exceptiontable)
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entries = []
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try:
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while True:
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start = parse_varint(iterator)*2
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length = parse_varint(iterator)*2
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end = start + length
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target = parse_varint(iterator)*2
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dl = parse_varint(iterator)
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depth = dl >> 1
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lasti = bool(dl&1)
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entries.append(_ExceptionTableEntry(start, end, target, depth, lasti))
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except StopIteration:
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return entries
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def _get_instructions_bytes(code, varname_from_oparg=None,
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names=None, co_consts=None,
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linestarts=None, line_offset=0,
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exception_entries=(), co_positions=None):
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"""Iterate over the instructions in a bytecode string.
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Generates a sequence of Instruction namedtuples giving the details of each
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opcode. Additional information about the code's runtime environment
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(e.g. variable names, co_consts) can be specified using optional
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arguments.
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"""
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co_positions = co_positions or iter(())
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get_name = None if names is None else names.__getitem__
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labels = set(findlabels(code))
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for start, end, target, _, _ in exception_entries:
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for i in range(start, end):
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labels.add(target)
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starts_line = None
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for offset, op, arg in _unpack_opargs(code):
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if linestarts is not None:
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starts_line = linestarts.get(offset, None)
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if starts_line is not None:
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starts_line += line_offset
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is_jump_target = offset in labels
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argval = None
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argrepr = ''
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positions = Positions(*next(co_positions, ()))
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if arg is not None:
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# Set argval to the dereferenced value of the argument when
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# available, and argrepr to the string representation of argval.
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# _disassemble_bytes needs the string repr of the
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# raw name index for LOAD_GLOBAL, LOAD_CONST, etc.
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argval = arg
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if op in hasconst:
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argval, argrepr = _get_const_info(op, arg, co_consts)
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elif op in hasname:
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argval, argrepr = _get_name_info(arg, get_name)
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elif op in hasjabs:
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argval = arg*2
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argrepr = "to " + repr(argval)
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elif op in hasjrel:
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argval = offset + 2 + arg*2
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argrepr = "to " + repr(argval)
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elif op in haslocal or op in hasfree:
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argval, argrepr = _get_name_info(arg, varname_from_oparg)
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elif op in hascompare:
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argval = cmp_op[arg]
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argrepr = argval
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elif op == FORMAT_VALUE:
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argval, argrepr = FORMAT_VALUE_CONVERTERS[arg & 0x3]
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argval = (argval, bool(arg & 0x4))
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if argval[1]:
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if argrepr:
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argrepr += ', '
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argrepr += 'with format'
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elif op == MAKE_FUNCTION:
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argrepr = ', '.join(s for i, s in enumerate(MAKE_FUNCTION_FLAGS)
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if arg & (1<<i))
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elif op == BINARY_OP:
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_, argrepr = _nb_ops[arg]
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yield Instruction(opname[op], op,
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arg, argval, argrepr,
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offset, starts_line, is_jump_target, positions)
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def disassemble(co, lasti=-1, *, file=None):
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"""Disassemble a code object."""
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linestarts = dict(findlinestarts(co))
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exception_entries = parse_exception_table(co)
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_disassemble_bytes(co.co_code, lasti,
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co._varname_from_oparg,
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co.co_names, co.co_consts, linestarts, file=file,
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exception_entries=exception_entries, co_positions=co.co_positions())
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def _disassemble_recursive(co, *, file=None, depth=None):
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disassemble(co, file=file)
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if depth is None or depth > 0:
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if depth is not None:
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depth = depth - 1
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for x in co.co_consts:
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if hasattr(x, 'co_code'):
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print(file=file)
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print("Disassembly of %r:" % (x,), file=file)
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_disassemble_recursive(x, file=file, depth=depth)
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def _disassemble_bytes(code, lasti=-1, varname_from_oparg=None,
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names=None, co_consts=None, linestarts=None,
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*, file=None, line_offset=0, exception_entries=(),
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co_positions=None):
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# Omit the line number column entirely if we have no line number info
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show_lineno = bool(linestarts)
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if show_lineno:
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maxlineno = max(linestarts.values()) + line_offset
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if maxlineno >= 1000:
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lineno_width = len(str(maxlineno))
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else:
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lineno_width = 3
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else:
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|
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):
|
|
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
|
|
for i in range(0, len(code), 2):
|
|
op = code[i]
|
|
if op >= HAVE_ARGUMENT:
|
|
arg = code[i+1] | extended_arg
|
|
extended_arg = (arg << 8) if op == 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:
|
|
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):
|
|
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)
|
|
|
|
def __iter__(self):
|
|
co = self.codeobj
|
|
return _get_instructions_bytes(co.co_code,
|
|
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())
|
|
|
|
def __repr__(self):
|
|
return "{}({!r})".format(self.__class__.__name__,
|
|
self._original_object)
|
|
|
|
@classmethod
|
|
def from_traceback(cls, tb):
|
|
""" 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)
|
|
|
|
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(co.co_code,
|
|
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())
|
|
return output.getvalue()
|
|
|
|
|
|
def _test():
|
|
"""Simple test program to disassemble a file."""
|
|
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__":
|
|
_test()
|