gh-81441: shutil.rmtree() FileNotFoundError race condition (GH-14064)

Ignore missing files and directories while enumerating
directory entries in shutil.rmtree().

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Lib/test/test_shutil.py

@@ -633,6 +633,63 @@ class TestRmTree(BaseTest, unittest.TestCase):
         finally:
             shutil.rmtree(TESTFN, ignore_errors=True)
 
+    @unittest.skipIf(sys.platform[:6] == 'cygwin',
+                     "This test can't be run on Cygwin (issue #1071513).")
+    @os_helper.skip_if_dac_override
+    @os_helper.skip_unless_working_chmod
+    def test_rmtree_deleted_race_condition(self):
+        # bpo-37260
+        #
+        # Test that a file or a directory deleted after it is enumerated
+        # by scandir() but before unlink() or rmdr() is called doesn't
+        # generate any errors.
+        def _onexc(fn, path, exc):
+            assert fn in (os.rmdir, os.unlink)
+            if not isinstance(exc, PermissionError):
+                raise
+            # Make the parent and the children writeable.
+            for p, mode in zip(paths, old_modes):
+                os.chmod(p, mode)
+            # Remove other dirs except one.
+            keep = next(p for p in dirs if p != path)
+            for p in dirs:
+                if p != keep:
+                    os.rmdir(p)
+            # Remove other files except one.
+            keep = next(p for p in files if p != path)
+            for p in files:
+                if p != keep:
+                    os.unlink(p)
+
+        os.mkdir(TESTFN)
+        paths = [TESTFN] + [os.path.join(TESTFN, f'child{i}')
+                            for i in range(6)]
+        dirs = paths[1::2]
+        files = paths[2::2]
+        for path in dirs:
+            os.mkdir(path)
+        for path in files:
+            write_file(path, '')
+
+        old_modes = [os.stat(path).st_mode for path in paths]
+
+        # Make the parent and the children non-writeable.
+        new_mode = stat.S_IREAD|stat.S_IEXEC
+        for path in reversed(paths):
+            os.chmod(path, new_mode)
+
+        try:
+            shutil.rmtree(TESTFN, onexc=_onexc)
+        except:
+            # Test failed, so cleanup artifacts.
+            for path, mode in zip(paths, old_modes):
+                try:
+                    os.chmod(path, mode)
+                except OSError:
+                    pass
+            shutil.rmtree(TESTFN)
+            raise
+
 
 class TestCopyTree(BaseTest, unittest.TestCase):