From 56065d4c8ac03042cb7e29ffda9b1ac544a37b4d Mon Sep 17 00:00:00 2001
From: Quentin Dawans <github@ovv.wtf>
Date: Tue, 9 Apr 2019 15:40:59 +0200
Subject: [PATCH] bpo-34139: Remove unix datagram socket from FS before binding
 (GH-8323)

https://bugs.python.org/issue34139
---
 Lib/asyncio/base_events.py                         | 14 ++++++++++++++
 Lib/test/test_asyncio/test_base_events.py          | 14 ++++++++++++++
 .../2018-07-18-11-25-34.bpo-34139.tKbmW7.rst       |  1 +
 3 files changed, 29 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2018-07-18-11-25-34.bpo-34139.tKbmW7.rst

diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index 36fe7e0076c..9b4b846131d 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -20,6 +20,7 @@ import heapq
 import itertools
 import os
 import socket
+import stat
 import subprocess
 import threading
 import time
@@ -1183,6 +1184,19 @@ class BaseEventLoop(events.AbstractEventLoop):
                 for addr in (local_addr, remote_addr):
                     if addr is not None and not isinstance(addr, str):
                         raise TypeError('string is expected')
+
+                if local_addr and local_addr[0] not in (0, '\x00'):
+                    try:
+                        if stat.S_ISSOCK(os.stat(local_addr).st_mode):
+                            os.remove(local_addr)
+                    except FileNotFoundError:
+                        pass
+                    except OSError as err:
+                        # Directory may have permissions only to create socket.
+                        logger.error('Unable to check or remove stale UNIX '
+                                     'socket %r: %r',
+                                     local_addr, err)
+
                 addr_pairs_info = (((family, proto),
                                     (local_addr, remote_addr)), )
             else:
diff --git a/Lib/test/test_asyncio/test_base_events.py b/Lib/test/test_asyncio/test_base_events.py
index 53854758a27..c245c472996 100644
--- a/Lib/test/test_asyncio/test_base_events.py
+++ b/Lib/test/test_asyncio/test_base_events.py
@@ -1662,6 +1662,20 @@ class BaseEventLoopWithSelectorTests(test_utils.TestCase):
         self.loop.run_until_complete(protocol.done)
         self.assertEqual('CLOSED', protocol.state)
 
+    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
+    def test_create_datagram_endpoint_existing_sock_unix(self):
+        with test_utils.unix_socket_path() as path:
+            sock = socket.socket(socket.AF_UNIX, type=socket.SOCK_DGRAM)
+            sock.bind(path)
+            sock.close()
+
+            coro = self.loop.create_datagram_endpoint(
+                lambda: MyDatagramProto(create_future=True, loop=self.loop),
+                path, family=socket.AF_UNIX)
+            transport, protocol = self.loop.run_until_complete(coro)
+            transport.close()
+            self.loop.run_until_complete(protocol.done)
+
     def test_create_datagram_endpoint_sock_sockopts(self):
         class FakeSock:
             type = socket.SOCK_DGRAM
diff --git a/Misc/NEWS.d/next/Library/2018-07-18-11-25-34.bpo-34139.tKbmW7.rst b/Misc/NEWS.d/next/Library/2018-07-18-11-25-34.bpo-34139.tKbmW7.rst
new file mode 100644
index 00000000000..44284a72ad8
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-07-18-11-25-34.bpo-34139.tKbmW7.rst
@@ -0,0 +1 @@
+Remove stale unix datagram socket before binding