Issue #12981: rewrite multiprocessing_{sendfd,recvfd} in Python.

1 files changed, 18 insertions, 3 deletions

diff --git a/Lib/multiprocessing/reduction.py b/Lib/multiprocessing/reduction.py
index b32c725..042a136 100644
--- a/Lib/multiprocessing/reduction.py
+++ b/Lib/multiprocessing/reduction.py
@@ -39,6 +39,7 @@ import os
 import sys
 import socket
 import threading
+import struct
 
 import _multiprocessing
 from multiprocessing import current_process
@@ -51,7 +52,8 @@ from multiprocessing.connection import Client, Listener, Connection
 #
 #
 
-if not(sys.platform == 'win32' or hasattr(_multiprocessing, 'recvfd')):
+if not(sys.platform == 'win32' or (hasattr(socket, 'CMSG_LEN') and
+                                   hasattr(socket, 'SCM_RIGHTS'))):
     raise ImportError('pickling of connections not supported')
 
 #
@@ -77,10 +79,23 @@ if sys.platform == 'win32':
 
 else:
     def send_handle(conn, handle, destination_pid):
-        _multiprocessing.sendfd(conn.fileno(), handle)
+        with socket.fromfd(conn.fileno(), socket.AF_UNIX, socket.SOCK_STREAM) as s:
+            s.sendmsg([b'x'], [(socket.SOL_SOCKET, socket.SCM_RIGHTS,
+                                struct.pack("@i", handle))])
 
     def recv_handle(conn):
-        return _multiprocessing.recvfd(conn.fileno())
+        size = struct.calcsize("@i")
+        with socket.fromfd(conn.fileno(), socket.AF_UNIX, socket.SOCK_STREAM) as s:
+            msg, ancdata, flags, addr = s.recvmsg(1, socket.CMSG_LEN(size))
+            try:
+                cmsg_level, cmsg_type, cmsg_data = ancdata[0]
+                if (cmsg_level == socket.SOL_SOCKET and
+                    cmsg_type == socket.SCM_RIGHTS):
+                    return struct.unpack("@i", cmsg_data[:size])[0]
+            except (ValueError, IndexError, struct.error):
+                pass
+            raise RuntimeError('Invalid data received')
+
 
 #
 # Support for a per-process server thread which caches pickled handles