GH-88968: Reject socket that is already used as a transport (#98010)

Author: gvanrossum

Lib/asyncio/selector_events.py

@@ -58,6 +58,7 @@ def __init__(self, selector=None):
 
     def _make_socket_transport(self, sock, protocol, waiter=None, *,
                                extra=None, server=None):
+        self._ensure_fd_no_transport(sock)
         return _SelectorSocketTransport(self, sock, protocol, waiter,
                                         extra, server)
 
@@ -68,6 +69,7 @@ def _make_ssl_transport(
             ssl_handshake_timeout=constants.SSL_HANDSHAKE_TIMEOUT,
             ssl_shutdown_timeout=constants.SSL_SHUTDOWN_TIMEOUT,
     ):
+        self._ensure_fd_no_transport(rawsock)
         ssl_protocol = sslproto.SSLProtocol(
             self, protocol, sslcontext, waiter,
             server_side, server_hostname,
@@ -80,6 +82,7 @@ def _make_ssl_transport(
 
     def _make_datagram_transport(self, sock, protocol,
                                  address=None, waiter=None, extra=None):
+        self._ensure_fd_no_transport(sock)
         return _SelectorDatagramTransport(self, sock, protocol,
                                           address, waiter, extra)
 

Lib/test/test_asyncio/test_selector_events.py

@@ -61,8 +61,10 @@ def setUp(self):
     def test_make_socket_transport(self):
         m = mock.Mock()
         self.loop.add_reader = mock.Mock()
+        self.loop._ensure_fd_no_transport = mock.Mock()
         transport = self.loop._make_socket_transport(m, asyncio.Protocol())
         self.assertIsInstance(transport, _SelectorSocketTransport)
+        self.assertEqual(self.loop._ensure_fd_no_transport.call_count, 1)
 
         # Calling repr() must not fail when the event loop is closed
         self.loop.close()
@@ -78,8 +80,10 @@ def test_make_ssl_transport_without_ssl_error(self):
         self.loop.add_writer = mock.Mock()
         self.loop.remove_reader = mock.Mock()
         self.loop.remove_writer = mock.Mock()
+        self.loop._ensure_fd_no_transport = mock.Mock()
         with self.assertRaises(RuntimeError):
             self.loop._make_ssl_transport(m, m, m, m)
+        self.assertEqual(self.loop._ensure_fd_no_transport.call_count, 1)
 
     def test_close(self):
         class EventLoop(BaseSelectorEventLoop):