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"""Disassembler of Python byte code into mnemonics."""
import sys
import types
from opcode import *
from opcode import __all__ as _opcodes_all
__all__ = ["dis", "disassemble", "distb", "disco",
"findlinestarts", "findlabels"] + _opcodes_all
del _opcodes_all
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__'):
x = x.__func__
if hasattr(x, '__code__'):
x = x.__code__
if hasattr(x, '__dict__'):
items = sorted(x.__dict__.items())
for name, x1 in items:
if isinstance(x1, (types.MethodType, types.FunctionType,
types.CodeType, type)):
print("Disassembly of %s:" % name)
try:
dis(x1)
except TypeError as msg:
print("Sorry:", msg)
print()
elif hasattr(x, 'co_code'):
disassemble(x)
elif isinstance(x, (bytes, bytearray)):
disassemble_string(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)
# XXX This duplicates information from code.h, also duplicated in inspect.py.
# XXX Maybe this ought to be put in a central location, like opcode.py?
flag2name = {
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(flag2name.get(flag, hex(flag)))
flags ^= flag
if not flags:
break
else:
names.append(hex(flags))
return ", ".join(names)
def show_code(co):
"""Show details about a code object."""
print("Name: ", co.co_name)
print("Filename: ", co.co_filename)
print("Argument count: ", co.co_argcount)
print("Kw-only arguments:", co.co_kwonlyargcount)
print("Number of locals: ", co.co_nlocals)
print("Stack size: ", co.co_stacksize)
print("Flags: ", pretty_flags(co.co_flags))
if co.co_consts:
print("Constants:")
for i_c in enumerate(co.co_consts):
print("%4d: %r" % i_c)
if co.co_names:
print("Names:")
for i_n in enumerate(co.co_names):
print("%4d: %s" % i_n)
if co.co_varnames:
print("Variable names:")
for i_n in enumerate(co.co_varnames):
print("%4d: %s" % i_n)
if co.co_freevars:
print("Free variables:")
for i_n in enumerate(co.co_freevars):
print("%4d: %s" % i_n)
if co.co_cellvars:
print("Cell variables:")
for i_n in enumerate(co.co_cellvars):
print("%4d: %s" % i_n)
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=' ')
print()
def disassemble_string(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=' ')
print()
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()
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