"""Disassembler of Python byte code into mnemonics."""
import sys
import types
from opcode import *
from opcode import __all__ as _opcodes_all
__all__ = ["code_info", "dis", "disassemble", "distb", "disco",
"findlinestarts", "findlabels", "show_code"] + _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):
"""Disassemble classes, methods, functions, or code.
With no argument, disassemble the last traceback.
"""
if x is None:
distb()
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)
try:
dis(x1)
except TypeError as msg:
print("Sorry:", msg)
print()
elif hasattr(x, 'co_code'): # Code object
disassemble(x)
elif isinstance(x, (bytes, bytearray)): # Raw bytecode
_disassemble_bytes(x)
elif isinstance(x, str): # Source code
_disassemble_str(x)
else:
raise TypeError("don't know how to disassemble %s objects" %
type(x).__name__)
def distb(tb=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)
# 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 code_info(x):
"""Formatted details of methods, functions, or code."""
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, "<code_info>")
if hasattr(x, 'co_code'): # Code object
return _format_code_info(x)
else:
raise TypeError("don't know how to disassemble %s objects" %
type(x).__name__)
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):
"""Print details of methods, functions, or code to stdout."""
print(code_info(co))
def disassemble(co, lasti=-1):
"""Disassemble a code object."""
code = co.co_code
labels = findlabels(code)
linestarts = dict(findlinestarts(co))
n = len(code)
i = 0
extended_arg = 0
free = None
while i < n:
op = code[i]
if i in linestarts:
if i > 0:
print()
print("%3d" % linestarts[i], end=' ')
else:
print(' ', end=' ')
if i == lasti: print('-->', end=' ')
else: print(' ', end=' ')
if i in labels: print('>>', end=' ')
else: print(' ', end=' ')
print(repr(i).rjust(4), end=' ')
print(opname[op].ljust(20), end=' ')
i = i+1
if op >= HAVE_ARGUMENT:
oparg = code[i] + code[i+1]*256 + extended_arg
extended_arg = 0
i = i+2
if op == EXTENDED_ARG:
extended_arg = oparg*65536
print(repr(oparg).rjust(5), end=' ')
if op in hasconst:
print('(' + repr(co.co_consts[oparg]) + ')', end=' ')
elif op in hasname:
print('(' + co.co_names[oparg] + ')', end=' ')
elif op in hasjrel:
print('(to ' + repr(i + oparg) + ')', end=' ')
elif op in haslocal:
print('(' + co.co_varnames[oparg] + ')', end=' ')
elif op in hascompare:
print('(' + cmp_op[oparg] + ')', end=' ')
elif op in hasfree:
if free is None:
free = co.co_cellvars + co.co_freevars
print('(' + free[oparg] + ')', end=' ')
elif op in hasnargs:
print('(%d positional, %d keyword pair)'
% (code[i-2], code[i-1]), end=' ')
print()
def _disassemble_bytes(code, lasti=-1, varnames=None, names=None,
constants=None):
labels = findlabels(code)
n = len(code)
i = 0
while i < n:
op = code[i]
if i == lasti: print('-->', end=' ')
else: print(' ', end=' ')
if i in labels: print('>>', end=' ')
else: print(' ', end=' ')
print(repr(i).rjust(4), end=' ')
print(opname[op].ljust(15), end=' ')
i = i+1
if op >= HAVE_ARGUMENT:
oparg = code[i] + code[i+1]*256
i = i+2
print(repr(oparg).rjust(5), end=' ')
if op in hasconst:
if constants:
print('(' + repr(constants[oparg]) + ')', end=' ')
else:
print('(%d)'%oparg, end=' ')
elif op in hasname:
if names is not None:
print('(' + names[oparg] + ')', end=' ')
else:
print('(%d)'%oparg, end=' ')
elif op in hasjrel:
print('(to ' + repr(i + oparg) + ')', end=' ')
elif op in haslocal:
if varnames:
print('(' + varnames[oparg] + ')', end=' ')
else:
print('(%d)' % oparg, end=' ')
elif op in hascompare:
print('(' + cmp_op[oparg] + ')', end=' ')
elif op in hasnargs:
print('(%d positional, %d keyword pair)'
% (code[i-2], code[i-1]), end=' ')
print()
def _disassemble_str(source):
"""Compile the source string, then disassemble the code object."""
disassemble(_try_compile(source, '<dis>'))
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 = []
n = len(code)
i = 0
while i < n:
op = code[i]
i = i+1
if op >= HAVE_ARGUMENT:
oparg = code[i] + code[i+1]*256
i = i+2
label = -1
if op in hasjrel:
label = i+oparg
elif op in hasjabs:
label = oparg
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)
def _test():
"""Simple test program to disassemble a file."""
if sys.argv[1:]:
if sys.argv[2:]:
sys.stderr.write("usage: python dis.py [-|file]\n")
sys.exit(2)
fn = sys.argv[1]
if not fn or fn == "-":
fn = None
else:
fn = None
if fn is None:
f = sys.stdin
else:
f = open(fn)
source = f.read()
if fn is not None:
f.close()
else:
fn = "<stdin>"
code = compile(source, fn, "exec")
dis(code)
if __name__ == "__main__":
_test()
