"""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', '', "'f..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("" % 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 = func2.__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()