"""This module includes tests of the code object representation.
>>> def f(x):
... def g(y):
... return x + y
... return g
...
>>> dump(f.__code__)
name: f
argcount: 1
posonlyargcount: 0
kwonlyargcount: 0
names: ()
varnames: ('x', 'g')
cellvars: ('x',)
freevars: ()
nlocals: 2
flags: 3
consts: ('None', '<code object g>', "'f.<locals>.g'")
>>> dump(f(4).__code__)
name: g
argcount: 1
posonlyargcount: 0
kwonlyargcount: 0
names: ()
varnames: ('y',)
cellvars: ()
freevars: ('x',)
nlocals: 1
flags: 19
consts: ('None',)
>>> def h(x, y):
... a = x + y
... b = x - y
... c = a * b
... return c
...
>>> dump(h.__code__)
name: h
argcount: 2
posonlyargcount: 0
kwonlyargcount: 0
names: ()
varnames: ('x', 'y', 'a', 'b', 'c')
cellvars: ()
freevars: ()
nlocals: 5
flags: 67
consts: ('None',)
>>> def attrs(obj):
... print(obj.attr1)
... print(obj.attr2)
... print(obj.attr3)
>>> dump(attrs.__code__)
name: attrs
argcount: 1
posonlyargcount: 0
kwonlyargcount: 0
names: ('print', 'attr1', 'attr2', 'attr3')
varnames: ('obj',)
cellvars: ()
freevars: ()
nlocals: 1
flags: 67
consts: ('None',)
>>> def optimize_away():
... 'doc string'
... 'not a docstring'
... 53
... 0x53
>>> dump(optimize_away.__code__)
name: optimize_away
argcount: 0
posonlyargcount: 0
kwonlyargcount: 0
names: ()
varnames: ()
cellvars: ()
freevars: ()
nlocals: 0
flags: 67
consts: ("'doc string'", 'None')
>>> def keywordonly_args(a,b,*,k1):
... return a,b,k1
...
>>> dump(keywordonly_args.__code__)
name: keywordonly_args
argcount: 2
posonlyargcount: 0
kwonlyargcount: 1
names: ()
varnames: ('a', 'b', 'k1')
cellvars: ()
freevars: ()
nlocals: 3
flags: 67
consts: ('None',)
>>> def posonly_args(a,b,/,c):
... return a,b,c
...
>>> dump(posonly_args.__code__)
name: posonly_args
argcount: 3
posonlyargcount: 2
kwonlyargcount: 0
names: ()
varnames: ('a', 'b', 'c')
cellvars: ()
freevars: ()
nlocals: 3
flags: 67
consts: ('None',)
"""
import inspect
import sys
import threading
import unittest
import weakref
import opcode
try:
import ctypes
except ImportError:
ctypes = None
from test.support import (run_doctest, run_unittest, cpython_only,
check_impl_detail)
def consts(t):
"""Yield a doctest-safe sequence of object reprs."""
for elt in t:
r = repr(elt)
if r.startswith("<code object"):
yield "<code object %s>" % elt.co_name
else:
yield r
def dump(co):
"""Print out a text representation of a code object."""
for attr in ["name", "argcount", "posonlyargcount",
"kwonlyargcount", "names", "varnames",
"cellvars", "freevars", "nlocals", "flags"]:
print("%s: %s" % (attr, getattr(co, "co_" + attr)))
print("consts:", tuple(consts(co.co_consts)))
# Needed for test_closure_injection below
# Defined at global scope to avoid implicitly closing over __class__
def external_getitem(self, i):
return f"Foreign getitem: {super().__getitem__(i)}"
class CodeTest(unittest.TestCase):
@cpython_only
def test_newempty(self):
import _testcapi
co = _testcapi.code_newempty("filename", "funcname", 15)
self.assertEqual(co.co_filename, "filename")
self.assertEqual(co.co_name, "funcname")
self.assertEqual(co.co_firstlineno, 15)
@cpython_only
def test_closure_injection(self):
# From https://bugs.python.org/issue32176
from types import FunctionType
def create_closure(__class__):
return (lambda: __class__).__closure__
def new_code(c):
'''A new code object with a __class__ cell added to freevars'''
return c.replace(co_freevars=c.co_freevars + ('__class__',))
def add_foreign_method(cls, name, f):
code = new_code(f.__code__)
assert not f.__closure__
closure = create_closure(cls)
defaults = f.__defaults__
setattr(cls, name, FunctionType(code, globals(), name, defaults, closure))
class List(list):
pass
add_foreign_method(List, "__getitem__", external_getitem)
# Ensure the closure injection actually worked
function = List.__getitem__
class_ref = function.__closure__[0].cell_contents
self.assertIs(class_ref, List)
# Ensure the code correctly indicates it accesses a free variable
self.assertFalse(function.__code__.co_flags & inspect.CO_NOFREE,
hex(function.__code__.co_flags))
# Ensure the zero-arg super() call in the injected method works
obj = List([1, 2, 3])
self.assertEqual(obj[0], "Foreign getitem: 1")
def test_constructor(self):
def func(): pass
co = func.__code__
CodeType = type(co)
# test code constructor
return CodeType(co.co_argcount,
co.co_posonlyargcount,
co.co_kwonlyargcount,
co.co_nlocals,
co.co_stacksize,
co.co_flags,
co.co_code,
co.co_consts,
co.co_names,
co.co_varnames,
co.co_filename,
co.co_name,
co.co_firstlineno,
co.co_lnotab,
co.co_freevars,
co.co_cellvars)
def test_replace(self):
def func():
x = 1
return x
code = func.__code__
# different co_name, co_varnames, co_consts
def func2():
y = 2
return y
code2 = func.__code__
for attr, value in (
("co_argcount", 0),
("co_posonlyargcount", 0),
("co_kwonlyargcount", 0),
("co_nlocals", 0),
("co_stacksize", 0),
("co_flags", code.co_flags | inspect.CO_COROUTINE),
("co_firstlineno", 100),
("co_code", code2.co_code),
("co_consts", code2.co_consts),
("co_names", ("myname",)),
("co_varnames", code2.co_varnames),
("co_freevars", ("freevar",)),
("co_cellvars", ("cellvar",)),
("co_filename", "newfilename"),
("co_name", "newname"),
("co_lnotab", code2.co_lnotab),
):
with self.subTest(attr=attr, value=value):
new_code = code.replace(**{attr: value})
self.assertEqual(getattr(new_code, attr), value)
def isinterned(s):
return s is sys.intern(('_' + s + '_')[1:-1])
class CodeConstsTest(unittest.TestCase):
def find_const(self, consts, value):
for v in consts:
if v == value:
return v
self.assertIn(value, consts) # raises an exception
self.fail('Should never be reached')
def assertIsInterned(self, s):
if not isinterned(s):
self.fail('String %r is not interned' % (s,))
def assertIsNotInterned(self, s):
if isinterned(s):
self.fail('String %r is interned' % (s,))
@cpython_only
def test_interned_string(self):
co = compile('res = "str_value"', '?', 'exec')
v = self.find_const(co.co_consts, 'str_value')
self.assertIsInterned(v)
@cpython_only
def test_interned_string_in_tuple(self):
co = compile('res = ("str_value",)', '?', 'exec')
v = self.find_const(co.co_consts, ('str_value',))
self.assertIsInterned(v[0])
@cpython_only
def test_interned_string_in_frozenset(self):
co = compile('res = a in {"str_value"}', '?', 'exec')
v = self.find_const(co.co_consts, frozenset(('str_value',)))
self.assertIsInterned(tuple(v)[0])
@cpython_only
def test_interned_string_default(self):
def f(a='str_value'):
return a
self.assertIsInterned(f())
@cpython_only
def test_interned_string_with_null(self):
co = compile(r'res = "str\0value!"', '?', 'exec')
v = self.find_const(co.co_consts, 'str\0value!')
self.assertIsNotInterned(v)
class CodeWeakRefTest(unittest.TestCase):
def test_basic(self):
# Create a code object in a clean environment so that we know we have
# the only reference to it left.
namespace = {}
exec("def f(): pass", globals(), namespace)
f = namespace["f"]
del namespace
self.called = False
def callback(code):
self.called = True
# f is now the last reference to the function, and through it, the code
# object. While we hold it, check that we can create a weakref and
# deref it. Then delete it, and check that the callback gets called and
# the reference dies.
coderef = weakref.ref(f.__code__, callback)
self.assertTrue(bool(coderef()))
del f
self.assertFalse(bool(coderef()))
self.assertTrue(self.called)
if check_impl_detail(cpython=True) and ctypes is not None:
py = ctypes.pythonapi
freefunc = ctypes.CFUNCTYPE(None,ctypes.c_voidp)
RequestCodeExtraIndex = py._PyEval_RequestCodeExtraIndex
RequestCodeExtraIndex.argtypes = (freefunc,)
RequestCodeExtraIndex.restype = ctypes.c_ssize_t
SetExtra = py._PyCode_SetExtra
SetExtra.argtypes = (ctypes.py_object, ctypes.c_ssize_t, ctypes.c_voidp)
SetExtra.restype = ctypes.c_int
GetExtra = py._PyCode_GetExtra
GetExtra.argtypes = (ctypes.py_object, ctypes.c_ssize_t,
ctypes.POINTER(ctypes.c_voidp))
GetExtra.restype = ctypes.c_int
LAST_FREED = None
def myfree(ptr):
global LAST_FREED
LAST_FREED = ptr
FREE_FUNC = freefunc(myfree)
FREE_INDEX = RequestCodeExtraIndex(FREE_FUNC)
class CoExtra(unittest.TestCase):
def get_func(self):
# Defining a function causes the containing function to have a
# reference to the code object. We need the code objects to go
# away, so we eval a lambda.
return eval('lambda:42')
def test_get_non_code(self):
f = self.get_func()
self.assertRaises(SystemError, SetExtra, 42, FREE_INDEX,
ctypes.c_voidp(100))
self.assertRaises(SystemError, GetExtra, 42, FREE_INDEX,
ctypes.c_voidp(100))
def test_bad_index(self):
f = self.get_func()
self.assertRaises(SystemError, SetExtra, f.__code__,
FREE_INDEX+100, ctypes.c_voidp(100))
self.assertEqual(GetExtra(f.__code__, FREE_INDEX+100,
ctypes.c_voidp(100)), 0)
def test_free_called(self):
# Verify that the provided free function gets invoked
# when the code object is cleaned up.
f = self.get_func()
SetExtra(f.__code__, FREE_INDEX, ctypes.c_voidp(100))
del f
self.assertEqual(LAST_FREED, 100)
def test_get_set(self):
# Test basic get/set round tripping.
f = self.get_func()
extra = ctypes.c_voidp()
SetExtra(f.__code__, FREE_INDEX, ctypes.c_voidp(200))
# reset should free...
SetExtra(f.__code__, FREE_INDEX, ctypes.c_voidp(300))
self.assertEqual(LAST_FREED, 200)
extra = ctypes.c_voidp()
GetExtra(f.__code__, FREE_INDEX, extra)
self.assertEqual(extra.value, 300)
del f
def test_free_different_thread(self):
# Freeing a code object on a different thread then
# where the co_extra was set should be safe.
f = self.get_func()
class ThreadTest(threading.Thread):
def __init__(self, f, test):
super().__init__()
self.f = f
self.test = test
def run(self):
del self.f
self.test.assertEqual(LAST_FREED, 500)
SetExtra(f.__code__, FREE_INDEX, ctypes.c_voidp(500))
tt = ThreadTest(f, self)
del f
tt.start()
tt.join()
self.assertEqual(LAST_FREED, 500)
@cpython_only
def test_clean_stack_on_return(self):
def f(x):
return x
code = f.__code__
ct = type(f.__code__)
# Insert an extra LOAD_FAST, this duplicates the value of
# 'x' in the stack, leaking it if the frame is not properly
# cleaned up upon exit.
bytecode = list(code.co_code)
bytecode.insert(-2, opcode.opmap['LOAD_FAST'])
bytecode.insert(-2, 0)
c = ct(code.co_argcount, code.co_posonlyargcount,
code.co_kwonlyargcount, code.co_nlocals, code.co_stacksize+1,
code.co_flags, bytes(bytecode),
code.co_consts, code.co_names, code.co_varnames,
code.co_filename, code.co_name, code.co_firstlineno,
code.co_lnotab, code.co_freevars, code.co_cellvars)
new_function = type(f)(c, f.__globals__, 'nf', f.__defaults__, f.__closure__)
class Var:
pass
the_object = Var()
var = weakref.ref(the_object)
new_function(the_object)
# Check if the_object is leaked
del the_object
assert var() is None
def test_main(verbose=None):
from test import test_code
run_doctest(test_code, verbose)
tests = [CodeTest, CodeConstsTest, CodeWeakRefTest]
if check_impl_detail(cpython=True) and ctypes is not None:
tests.append(CoExtra)
run_unittest(*tests)
if __name__ == "__main__":
test_main()