"""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

__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, type)

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):

"""Disassemble classes, methods, functions, or code.

With no argument, disassemble the last traceback.

"""

if x is None:

distb(file=file)

return

if hasattr(x, '__func__'): # Method

x = x.__func__

if hasattr(x, '__code__'): # Function

x = x.__code__

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)

except TypeError as msg:

print("Sorry:", msg, file=file)

print(file=file)

elif hasattr(x, 'co_code'): # Code object

disassemble(x, file=file)

elif isinstance(x, (bytes, bytearray)): # Raw bytecode

_disassemble_bytes(x, file=file)

elif isinstance(x, str): # Source code

_disassemble_str(x, file=file)

else:

raise TypeError("don't know how to disassemble %s objects" %

type(x).__name__)

def distb(tb=None, *, file=None):

"""Disassemble a traceback (default: last traceback)."""

if tb is None:

try:

tb = sys.last_traceback

except AttributeError:

raise RuntimeError("no last traceback to disassemble")

while tb.tb_next: tb = tb.tb_next

disassemble(tb.tb_frame.f_code, tb.tb_lasti, file=file)

# 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",

}

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)

def _get_code_object(x):

"""Helper to handle methods, functions, strings and raw code objects"""

if hasattr(x, '__func__'): # Method

x = x.__func__

if hasattr(x, '__code__'): # Function

x = x.__code__

if isinstance(x, str): # Source code

x = _try_compile(x, "<disassembly>")

if hasattr(x, 'co_code'): # Code object

return x

raise TypeError("don't know how to disassemble %s objects" %

type(x).__name__)

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("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)

_Instruction = collections.namedtuple("_Instruction",

"opname opcode arg argval argrepr offset starts_line is_jump_target")

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

"""

def _disassemble(self, lineno_width=3, mark_as_current=False):

"""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

"""

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(4))

# Column: Opcode name

fields.append(self.opname.ljust(20))

# Column: Opcode argument

if self.arg is not None:

fields.append(repr(self.arg).rjust(5))

# Column: Opcode argument details

if self.argrepr:

fields.append('(' + self.argrepr + ')')

return ' '.join(fields).rstrip()

def get_instructions(x, *, first_line=None):

"""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)

cell_names = co.co_cellvars + co.co_freevars

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(co.co_code, co.co_varnames, co.co_names,

co.co_consts, cell_names, linestarts,

line_offset)

def _get_const_info(const_index, const_list):

"""Helper to get optional details about const references

Returns the dereferenced constant and its repr if the constant

list is defined.

Otherwise returns the constant index and its repr().

"""

argval = const_index

if const_list is not None:

argval = const_list[const_index]

return argval, repr(argval)

def _get_name_info(name_index, name_list):

"""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 name index and its repr().

"""

argval = name_index

if name_list is not None:

argval = name_list[name_index]

argrepr = argval

else:

argrepr = repr(argval)

return argval, argrepr

def _get_instructions_bytes(code, varnames=None, names=None, constants=None,

cells=None, linestarts=None, line_offset=0):

"""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, constants) can be specified using optional

arguments.

"""

labels = findlabels(code)

extended_arg = 0

starts_line = None

free = None

# enumerate() is not an option, since we sometimes process

# multiple elements on a single pass through the loop

n = len(code)

i = 0

while i < n:

op = code[i]

offset = i

if linestarts is not None:

starts_line = linestarts.get(i, None)

if starts_line is not None:

starts_line += line_offset

is_jump_target = i in labels

i = i+1

arg = None

argval = None

argrepr = ''

if op >= HAVE_ARGUMENT:

arg = code[i] + code[i+1]*256 + extended_arg

extended_arg = 0

i = i+2

if op == EXTENDED_ARG:

extended_arg = arg*65536

# Set argval to the dereferenced value of the argument when

# availabe, 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 op in hasconst:

argval, argrepr = _get_const_info(arg, constants)

elif op in hasname:

argval, argrepr = _get_name_info(arg, names)

elif op in hasjrel:

argval = i + arg

argrepr = "to " + repr(argval)

elif op in haslocal:

argval, argrepr = _get_name_info(arg, varnames)

elif op in hascompare:

argval = cmp_op[arg]

argrepr = argval

elif op in hasfree:

argval, argrepr = _get_name_info(arg, cells)

elif op in hasnargs:

argrepr = "%d positional, %d keyword pair" % (code[i-2], code[i-1])

yield Instruction(opname[op], op,

arg, argval, argrepr,

offset, starts_line, is_jump_target)

def disassemble(co, lasti=-1, *, file=None):

"""Disassemble a code object."""

cell_names = co.co_cellvars + co.co_freevars

linestarts = dict(findlinestarts(co))

_disassemble_bytes(co.co_code, lasti, co.co_varnames, co.co_names,

co.co_consts, cell_names, linestarts, file=file)

def _disassemble_bytes(code, lasti=-1, varnames=None, names=None,

constants=None, cells=None, linestarts=None,

*, file=None, line_offset=0):

# Omit the line number column entirely if we have no line number info

show_lineno = linestarts is not None

# TODO?: Adjust width upwards if max(linestarts.values()) >= 1000?

lineno_width = 3 if show_lineno else 0

for instr in _get_instructions_bytes(code, varnames, names,

constants, cells, linestarts,

line_offset=line_offset):

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), file=file)

def _disassemble_str(source, *, file=None):

"""Compile the source string, then disassemble the code object."""

disassemble(_try_compile(source, '<dis>'), file=file)

disco = disassemble # XXX For backwards compatibility

def findlabels(code):

"""Detect all offsets in a byte code which are jump targets.

Return the list of offsets.

"""

labels = []

# enumerate() is not an option, since we sometimes process

# multiple elements on a single pass through the loop

n = len(code)

i = 0

while i < n:

op = code[i]

i = i+1

if op >= HAVE_ARGUMENT:

arg = code[i] + code[i+1]*256

i = i+2

label = -1

if op in hasjrel:

label = i+arg

elif op in hasjabs:

label = arg

if label >= 0:

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) as described in Python/compile.c.

"""

byte_increments = list(code.co_lnotab[0::2])

line_increments = list(code.co_lnotab[1::2])

lastlineno = None

lineno = code.co_firstlineno

addr = 0

for byte_incr, line_incr in zip(byte_increments, line_increments):

if byte_incr:

if lineno != lastlineno:

yield (addr, lineno)

lastlineno = lineno

addr += byte_incr

lineno += line_incr

if lineno != lastlineno:

yield (addr, lineno)

class Bytecode:

"""The bytecode operations of a piece of code

Instantiate this with a function, method, 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._cell_names = co.co_cellvars + co.co_freevars

self._linestarts = dict(findlinestarts(co))

self._original_object = x

self.current_offset = current_offset

def __iter__(self):

co = self.codeobj

return _get_instructions_bytes(co.co_code, co.co_varnames, co.co_names,

co.co_consts, self._cell_names,

self._linestarts,

line_offset=self._line_offset)

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, varnames=co.co_varnames,

names=co.co_names, constants=co.co_consts,

cells=self._cell_names,

linestarts=self._linestarts,

line_offset=self._line_offset,

file=output,

lasti=offset)

return output.getvalue()

def _test():

"""Simple test program to disassemble a file."""

import argparse

parser = argparse.ArgumentParser()

parser.add_argument('infile', type=argparse.FileType(), 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()