Close #13022: _multiprocessing.recvfd() doesn't check that file descriptor was actually received

1 files changed, 17 insertions, 0 deletions

diff --git a/Lib/test/test_multiprocessing.py b/Lib/test/test_multiprocessing.py
index c33fa7b..b211861 100644
--- a/Lib/test/test_multiprocessing.py
+++ b/Lib/test/test_multiprocessing.py
@@ -1689,6 +1689,23 @@ class _TestConnection(BaseTestCase):
         with open(test.support.TESTFN, "rb") as f:
             self.assertEqual(f.read(), b"bar")
 
+    @classmethod
+    def _send_data_without_fd(self, conn):
+        os.write(conn.fileno(), b"\0")
+
+    @unittest.skipIf(sys.platform == "win32", "doesn't make sense on Windows")
+    def test_missing_fd_transfer(self):
+        # Check that exception is raised when received data is not
+        # accompanied by a file descriptor in ancillary data.
+        if self.TYPE != 'processes':
+            self.skipTest("only makes sense with processes")
+        conn, child_conn = self.Pipe(duplex=True)
+
+        p = self.Process(target=self._send_data_without_fd, args=(child_conn,))
+        p.daemon = True
+        p.start()
+        self.assertRaises(RuntimeError, reduction.recv_handle, conn)
+        p.join()
 
 class _TestListenerClient(BaseTestCase):