318 lines
9.9 KiB
Python
318 lines
9.9 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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from opcode import *
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from opcode import __all__ as _opcodes_all
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__all__ = ["code_info", "dis", "disassemble", "distb", "disco",
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"findlinestarts", "findlabels", "show_code"] + _opcodes_all
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del _opcodes_all
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_have_code = (types.MethodType, types.FunctionType, types.CodeType, type)
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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):
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"""Disassemble classes, methods, functions, or code.
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With no argument, disassemble the last traceback.
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"""
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if x is None:
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distb()
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return
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if hasattr(x, '__func__'): # Method
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x = x.__func__
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if hasattr(x, '__code__'): # Function
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x = x.__code__
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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)
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try:
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dis(x1)
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except TypeError as msg:
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print("Sorry:", msg)
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print()
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elif hasattr(x, 'co_code'): # Code object
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disassemble(x)
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elif isinstance(x, (bytes, bytearray)): # Raw bytecode
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_disassemble_bytes(x)
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elif isinstance(x, str): # Source code
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_disassemble_str(x)
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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):
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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")
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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)
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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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}
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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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def code_info(x):
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"""Formatted details of methods, functions, or code."""
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if hasattr(x, '__func__'): # Method
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x = x.__func__
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if hasattr(x, '__code__'): # Function
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x = x.__code__
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if isinstance(x, str): # Source code
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x = _try_compile(x, "<code_info>")
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if hasattr(x, 'co_code'): # Code object
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return _format_code_info(x)
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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 _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("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):
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"""Print details of methods, functions, or code to stdout."""
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print(code_info(co))
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def disassemble(co, lasti=-1):
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"""Disassemble a code object."""
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code = co.co_code
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labels = findlabels(code)
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linestarts = dict(findlinestarts(co))
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n = len(code)
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i = 0
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extended_arg = 0
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free = None
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while i < n:
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op = code[i]
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if i in linestarts:
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if i > 0:
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print()
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print("%3d" % linestarts[i], end=' ')
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else:
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print(' ', end=' ')
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if i == lasti: print('-->', end=' ')
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else: print(' ', end=' ')
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if i in labels: print('>>', end=' ')
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else: print(' ', end=' ')
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print(repr(i).rjust(4), end=' ')
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print(opname[op].ljust(20), end=' ')
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i = i+1
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if op >= HAVE_ARGUMENT:
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oparg = code[i] + code[i+1]*256 + extended_arg
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extended_arg = 0
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i = i+2
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if op == EXTENDED_ARG:
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extended_arg = oparg*65536
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print(repr(oparg).rjust(5), end=' ')
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if op in hasconst:
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print('(' + repr(co.co_consts[oparg]) + ')', end=' ')
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elif op in hasname:
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print('(' + co.co_names[oparg] + ')', end=' ')
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elif op in hasjrel:
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print('(to ' + repr(i + oparg) + ')', end=' ')
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elif op in haslocal:
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print('(' + co.co_varnames[oparg] + ')', end=' ')
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elif op in hascompare:
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print('(' + cmp_op[oparg] + ')', end=' ')
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elif op in hasfree:
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if free is None:
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free = co.co_cellvars + co.co_freevars
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print('(' + free[oparg] + ')', end=' ')
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elif op in hasnargs:
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print('(%d positional, %d keyword pair)'
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% (code[i-2], code[i-1]), end=' ')
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print()
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def _disassemble_bytes(code, lasti=-1, varnames=None, names=None,
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constants=None):
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labels = findlabels(code)
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n = len(code)
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i = 0
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while i < n:
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op = code[i]
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if i == lasti: print('-->', end=' ')
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else: print(' ', end=' ')
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if i in labels: print('>>', end=' ')
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else: print(' ', end=' ')
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print(repr(i).rjust(4), end=' ')
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print(opname[op].ljust(15), end=' ')
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i = i+1
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if op >= HAVE_ARGUMENT:
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oparg = code[i] + code[i+1]*256
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i = i+2
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print(repr(oparg).rjust(5), end=' ')
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if op in hasconst:
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if constants:
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print('(' + repr(constants[oparg]) + ')', end=' ')
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else:
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print('(%d)'%oparg, end=' ')
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elif op in hasname:
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if names is not None:
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print('(' + names[oparg] + ')', end=' ')
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else:
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print('(%d)'%oparg, end=' ')
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elif op in hasjrel:
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print('(to ' + repr(i + oparg) + ')', end=' ')
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elif op in haslocal:
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if varnames:
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print('(' + varnames[oparg] + ')', end=' ')
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else:
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print('(%d)' % oparg, end=' ')
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elif op in hascompare:
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print('(' + cmp_op[oparg] + ')', end=' ')
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elif op in hasnargs:
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print('(%d positional, %d keyword pair)'
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% (code[i-2], code[i-1]), end=' ')
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print()
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def _disassemble_str(source):
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"""Compile the source string, then disassemble the code object."""
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disassemble(_try_compile(source, '<dis>'))
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disco = disassemble # XXX For backwards compatibility
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def findlabels(code):
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"""Detect all offsets in a byte code which are jump targets.
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Return the list of offsets.
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"""
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labels = []
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n = len(code)
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i = 0
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while i < n:
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op = code[i]
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i = i+1
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if op >= HAVE_ARGUMENT:
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oparg = code[i] + code[i+1]*256
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i = i+2
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label = -1
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if op in hasjrel:
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label = i+oparg
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elif op in hasjabs:
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label = oparg
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if label >= 0:
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if label not in labels:
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labels.append(label)
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return labels
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def findlinestarts(code):
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"""Find the offsets in a byte code which are start of lines in the source.
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Generate pairs (offset, lineno) as described in Python/compile.c.
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"""
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byte_increments = list(code.co_lnotab[0::2])
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line_increments = list(code.co_lnotab[1::2])
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lastlineno = None
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lineno = code.co_firstlineno
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addr = 0
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for byte_incr, line_incr in zip(byte_increments, line_increments):
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if byte_incr:
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if lineno != lastlineno:
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yield (addr, lineno)
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lastlineno = lineno
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addr += byte_incr
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lineno += line_incr
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if lineno != lastlineno:
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yield (addr, lineno)
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def _test():
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"""Simple test program to disassemble a file."""
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if sys.argv[1:]:
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if sys.argv[2:]:
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sys.stderr.write("usage: python dis.py [-|file]\n")
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sys.exit(2)
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fn = sys.argv[1]
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if not fn or fn == "-":
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fn = None
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else:
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fn = None
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if fn is None:
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f = sys.stdin
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else:
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f = open(fn)
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source = f.read()
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if fn is not None:
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f.close()
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else:
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fn = "<stdin>"
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code = compile(source, fn, "exec")
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dis(code)
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if __name__ == "__main__":
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_test()
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