mirror of https://github.com/python/cpython
444 lines
14 KiB
Python
444 lines
14 KiB
Python
import gc
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import operator
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import re
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import sys
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import textwrap
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import threading
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import types
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import unittest
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import weakref
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try:
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import _testcapi
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except ImportError:
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_testcapi = None
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from test import support
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from test.support import threading_helper
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from test.support.script_helper import assert_python_ok
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class ClearTest(unittest.TestCase):
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"""
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Tests for frame.clear().
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"""
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def inner(self, x=5, **kwargs):
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1/0
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def outer(self, **kwargs):
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try:
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self.inner(**kwargs)
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except ZeroDivisionError as e:
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exc = e
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return exc
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def clear_traceback_frames(self, tb):
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"""
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Clear all frames in a traceback.
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"""
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while tb is not None:
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tb.tb_frame.clear()
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tb = tb.tb_next
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def test_clear_locals(self):
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class C:
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pass
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c = C()
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wr = weakref.ref(c)
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exc = self.outer(c=c)
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del c
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support.gc_collect()
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# A reference to c is held through the frames
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self.assertIsNot(None, wr())
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self.clear_traceback_frames(exc.__traceback__)
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support.gc_collect()
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# The reference was released by .clear()
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self.assertIs(None, wr())
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def test_clear_does_not_clear_specials(self):
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class C:
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pass
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c = C()
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exc = self.outer(c=c)
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del c
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f = exc.__traceback__.tb_frame
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f.clear()
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self.assertIsNot(f.f_code, None)
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self.assertIsNot(f.f_locals, None)
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self.assertIsNot(f.f_builtins, None)
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self.assertIsNot(f.f_globals, None)
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def test_clear_generator(self):
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endly = False
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def g():
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nonlocal endly
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try:
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yield
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self.inner()
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finally:
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endly = True
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gen = g()
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next(gen)
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self.assertFalse(endly)
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# Clearing the frame closes the generator
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gen.gi_frame.clear()
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self.assertTrue(endly)
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def test_clear_executing(self):
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# Attempting to clear an executing frame is forbidden.
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try:
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1/0
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except ZeroDivisionError as e:
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f = e.__traceback__.tb_frame
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with self.assertRaises(RuntimeError):
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f.clear()
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with self.assertRaises(RuntimeError):
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f.f_back.clear()
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def test_clear_executing_generator(self):
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# Attempting to clear an executing generator frame is forbidden.
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endly = False
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def g():
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nonlocal endly
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try:
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1/0
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except ZeroDivisionError as e:
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f = e.__traceback__.tb_frame
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with self.assertRaises(RuntimeError):
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f.clear()
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with self.assertRaises(RuntimeError):
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f.f_back.clear()
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yield f
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finally:
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endly = True
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gen = g()
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f = next(gen)
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self.assertFalse(endly)
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# Clearing the frame closes the generator
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f.clear()
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self.assertTrue(endly)
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def test_lineno_with_tracing(self):
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def record_line():
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f = sys._getframe(1)
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lines.append(f.f_lineno-f.f_code.co_firstlineno)
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def test(trace):
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record_line()
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if trace:
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sys._getframe(0).f_trace = True
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record_line()
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record_line()
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expected_lines = [1, 4, 5]
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lines = []
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test(False)
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self.assertEqual(lines, expected_lines)
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lines = []
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test(True)
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self.assertEqual(lines, expected_lines)
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@support.cpython_only
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def test_clear_refcycles(self):
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# .clear() doesn't leave any refcycle behind
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with support.disable_gc():
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class C:
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pass
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c = C()
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wr = weakref.ref(c)
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exc = self.outer(c=c)
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del c
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self.assertIsNot(None, wr())
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self.clear_traceback_frames(exc.__traceback__)
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self.assertIs(None, wr())
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class FrameAttrsTest(unittest.TestCase):
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def make_frames(self):
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def outer():
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x = 5
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y = 6
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def inner():
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z = x + 2
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1/0
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t = 9
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return inner()
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try:
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outer()
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except ZeroDivisionError as e:
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tb = e.__traceback__
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frames = []
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while tb:
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frames.append(tb.tb_frame)
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tb = tb.tb_next
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return frames
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def test_locals(self):
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f, outer, inner = self.make_frames()
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outer_locals = outer.f_locals
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self.assertIsInstance(outer_locals.pop('inner'), types.FunctionType)
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self.assertEqual(outer_locals, {'x': 5, 'y': 6})
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inner_locals = inner.f_locals
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self.assertEqual(inner_locals, {'x': 5, 'z': 7})
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def test_clear_locals(self):
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# Test f_locals after clear() (issue #21897)
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f, outer, inner = self.make_frames()
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outer.clear()
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inner.clear()
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self.assertEqual(outer.f_locals, {})
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self.assertEqual(inner.f_locals, {})
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def test_locals_clear_locals(self):
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# Test f_locals before and after clear() (to exercise caching)
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f, outer, inner = self.make_frames()
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outer.f_locals
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inner.f_locals
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outer.clear()
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inner.clear()
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self.assertEqual(outer.f_locals, {})
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self.assertEqual(inner.f_locals, {})
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def test_f_lineno_del_segfault(self):
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f, _, _ = self.make_frames()
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with self.assertRaises(AttributeError):
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del f.f_lineno
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class ReprTest(unittest.TestCase):
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"""
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Tests for repr(frame).
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"""
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def test_repr(self):
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def outer():
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x = 5
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y = 6
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def inner():
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z = x + 2
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1/0
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t = 9
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return inner()
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offset = outer.__code__.co_firstlineno
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try:
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outer()
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except ZeroDivisionError as e:
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tb = e.__traceback__
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frames = []
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while tb:
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frames.append(tb.tb_frame)
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tb = tb.tb_next
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else:
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self.fail("should have raised")
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f_this, f_outer, f_inner = frames
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file_repr = re.escape(repr(__file__))
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self.assertRegex(repr(f_this),
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r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code test_repr>$"
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% (file_repr, offset + 23))
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self.assertRegex(repr(f_outer),
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r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code outer>$"
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% (file_repr, offset + 7))
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self.assertRegex(repr(f_inner),
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r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code inner>$"
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% (file_repr, offset + 5))
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class TestIncompleteFrameAreInvisible(unittest.TestCase):
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def test_issue95818(self):
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# See GH-95818 for details
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code = textwrap.dedent(f"""
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import gc
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gc.set_threshold(1,1,1)
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class GCHello:
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def __del__(self):
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print("Destroyed from gc")
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def gen():
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yield
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fd = open({__file__!r})
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l = [fd, GCHello()]
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l.append(l)
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del fd
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del l
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gen()
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""")
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assert_python_ok("-c", code)
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@support.cpython_only
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def test_sneaky_frame_object(self):
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def trace(frame, event, arg):
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"""
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Don't actually do anything, just force a frame object to be created.
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"""
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def callback(phase, info):
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"""
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Yo dawg, I heard you like frames, so I'm allocating a frame while
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you're allocating a frame, so you can have a frame while you have a
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frame!
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"""
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nonlocal sneaky_frame_object
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sneaky_frame_object = sys._getframe().f_back.f_back
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# We're done here:
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gc.callbacks.remove(callback)
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def f():
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while True:
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yield
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old_threshold = gc.get_threshold()
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old_callbacks = gc.callbacks[:]
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old_enabled = gc.isenabled()
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old_trace = sys.gettrace()
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try:
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# Stop the GC for a second while we set things up:
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gc.disable()
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# Create a paused generator:
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g = f()
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next(g)
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# Move all objects to the oldest generation, and tell the GC to run
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# on the *very next* allocation:
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gc.collect()
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gc.set_threshold(1, 0, 0)
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# Okay, so here's the nightmare scenario:
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# - We're tracing the resumption of a generator, which creates a new
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# frame object.
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# - The allocation of this frame object triggers a collection
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# *before* the frame object is actually created.
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# - During the collection, we request the exact same frame object.
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# This test does it with a GC callback, but in real code it would
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# likely be a trace function, weakref callback, or finalizer.
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# - The collection finishes, and the original frame object is
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# created. We now have two frame objects fighting over ownership
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# of the same interpreter frame!
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sys.settrace(trace)
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gc.callbacks.append(callback)
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sneaky_frame_object = None
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gc.enable()
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next(g)
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# g.gi_frame should be the the frame object from the callback (the
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# one that was *requested* second, but *created* first):
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self.assertIs(g.gi_frame, sneaky_frame_object)
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finally:
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gc.set_threshold(*old_threshold)
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gc.callbacks[:] = old_callbacks
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sys.settrace(old_trace)
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if old_enabled:
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gc.enable()
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@support.cpython_only
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@threading_helper.requires_working_threading()
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def test_sneaky_frame_object_teardown(self):
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class SneakyDel:
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def __del__(self):
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"""
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Stash a reference to the entire stack for walking later.
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It may look crazy, but you'd be surprised how common this is
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when using a test runner (like pytest). The typical recipe is:
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ResourceWarning + -Werror + a custom sys.unraisablehook.
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"""
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nonlocal sneaky_frame_object
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sneaky_frame_object = sys._getframe()
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class SneakyThread(threading.Thread):
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"""
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A separate thread isn't needed to make this code crash, but it does
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make crashes more consistent, since it means sneaky_frame_object is
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backed by freed memory after the thread completes!
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"""
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def run(self):
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"""Run SneakyDel.__del__ as this frame is popped."""
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ref = SneakyDel()
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sneaky_frame_object = None
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t = SneakyThread()
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t.start()
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t.join()
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# sneaky_frame_object can be anything, really, but it's crucial that
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# SneakyThread.run's frame isn't anywhere on the stack while it's being
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# torn down:
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self.assertIsNotNone(sneaky_frame_object)
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while sneaky_frame_object is not None:
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self.assertIsNot(
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sneaky_frame_object.f_code, SneakyThread.run.__code__
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)
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sneaky_frame_object = sneaky_frame_object.f_back
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def test_entry_frames_are_invisible_during_teardown(self):
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class C:
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"""A weakref'able class."""
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def f():
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"""Try to find globals and locals as this frame is being cleared."""
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ref = C()
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# Ignore the fact that exec(C()) is a nonsense callback. We're only
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# using exec here because it tries to access the current frame's
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# globals and locals. If it's trying to get those from a shim frame,
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# we'll crash before raising:
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return weakref.ref(ref, exec)
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with support.catch_unraisable_exception() as catcher:
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# Call from C, so there is a shim frame directly above f:
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weak = operator.call(f) # BOOM!
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# Cool, we didn't crash. Check that the callback actually happened:
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self.assertIs(catcher.unraisable.exc_type, TypeError)
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self.assertIsNone(weak())
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@unittest.skipIf(_testcapi is None, 'need _testcapi')
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class TestCAPI(unittest.TestCase):
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def getframe(self):
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return sys._getframe()
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def test_frame_getters(self):
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frame = self.getframe()
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self.assertEqual(frame.f_locals, _testcapi.frame_getlocals(frame))
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self.assertIs(frame.f_globals, _testcapi.frame_getglobals(frame))
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self.assertIs(frame.f_builtins, _testcapi.frame_getbuiltins(frame))
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self.assertEqual(frame.f_lasti, _testcapi.frame_getlasti(frame))
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def test_getvar(self):
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current_frame = sys._getframe()
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x = 1
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self.assertEqual(_testcapi.frame_getvar(current_frame, "x"), 1)
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self.assertEqual(_testcapi.frame_getvarstring(current_frame, b"x"), 1)
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with self.assertRaises(NameError):
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_testcapi.frame_getvar(current_frame, "y")
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with self.assertRaises(NameError):
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_testcapi.frame_getvarstring(current_frame, b"y")
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# wrong name type
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with self.assertRaises(TypeError):
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_testcapi.frame_getvar(current_frame, b'x')
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with self.assertRaises(TypeError):
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_testcapi.frame_getvar(current_frame, 123)
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def getgenframe(self):
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yield sys._getframe()
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def test_frame_get_generator(self):
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gen = self.getgenframe()
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frame = next(gen)
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self.assertIs(gen, _testcapi.frame_getgenerator(frame))
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def test_frame_fback_api(self):
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"""Test that accessing `f_back` does not cause a segmentation fault on
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a frame created with `PyFrame_New` (GH-99110)."""
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def dummy():
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pass
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frame = _testcapi.frame_new(dummy.__code__, globals(), locals())
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# The following line should not cause a segmentation fault.
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self.assertIsNone(frame.f_back)
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if __name__ == "__main__":
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unittest.main()
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