From 3bb03bc5d095cf51c8605521fcc2ce8cad36995f Mon Sep 17 00:00:00 2001
From: Fiona Klute <fiona.klute@gmx.de>
Date: Tue, 25 Mar 2025 13:29:04 +0100
Subject: [PATCH] gi.events._Selector.get_map(): look up file objects by file
 descriptor

File objects and their underlying file descriptors must be treated as
equivalent for lookup, or one may incorrectly be treated as not
registered when the other was used for the registration, leading to
bugs.

Signed-off-by: Fiona Klute <fiona.klute@gmx.de>
Upstream: https://gitlab.gnome.org/GNOME/pygobject/-/commit/3bb03bc5d095cf51c8605521fcc2ce8cad36995f
---
 gi/events.py         | 36 +++++++++++++++++++++-----
 tests/test_events.py | 61 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+), 7 deletions(-)

diff --git a/gi/events.py b/gi/events.py
index 9f00059ec..980cae0fe 100644
--- a/gi/events.py
+++ b/gi/events.py
@@ -28,6 +28,7 @@ import threading
 import selectors
 import weakref
 import warnings
+from collections.abc import Mapping
 from contextlib import contextmanager
 from . import _ossighelper
 
@@ -381,9 +382,33 @@ if sys.platform != 'win32':
         # Subclass to attach _tag
         pass
 
+    class _FileObjectMapping(Mapping):
+        def __init__(self, fd_dict):
+            self.fd_dict = fd_dict
+
+        def __len__(self):
+            return len(self.fd_dict)
+
+        def get(self, fileobj, default=None):
+            fd = _fileobj_to_fd(fileobj)
+            return self.fd_dict.get(fd, default)
+
+        def __getitem__(self, fileobj):
+            value = self.get(fileobj)
+            if value is None:
+                raise KeyError("{!r} is not registered".format(fileobj))
+            return value
+
+        def __iter__(self):
+            return iter(self.fd_dict)
+
     class _Selector(_SelectorMixin, selectors.BaseSelector):
         """A Selector for gi.events.GLibEventLoop registering python IO with GLib."""
 
+        def __init__(self, context, loop):
+            super().__init__(context, loop)
+            self._map = _FileObjectMapping(self._fd_to_key)
+
         def attach(self):
             self._source.attach(self._loop._context)
 
@@ -432,15 +457,12 @@ if sys.platform != 'win32':
         # We could override modify, but it is only slightly when the "events" change.
 
         def get_key(self, fileobj):
-            fd = _fileobj_to_fd(fileobj)
-            return self._fd_to_key[fd]
+            return self._map[fileobj]
 
         def get_map(self):
-            """Return a mapping of file objects to selector keys."""
-            # Horribly inefficient
-            # It should never be called and exists just to prevent issues if e.g.
-            # python decides to use it for debug purposes.
-            return {k.fileobj: k for k in self._fd_to_key.values()}
+            """Return a mapping of file objects or file descriptors to
+            selector keys."""
+            return self._map
 
 
 else:
diff --git a/tests/test_events.py b/tests/test_events.py
index 81409abae..c075af095 100644
--- a/tests/test_events.py
+++ b/tests/test_events.py
@@ -45,6 +45,7 @@ import sys
 import gi
 import gi.events
 import asyncio
+import socket
 import threading
 from gi.repository import GLib
 
@@ -262,3 +263,63 @@ class GLibEventLoopPolicyTests(unittest.TestCase):
         GLib.MainLoop().run()
 
         loop.close()
+
+    @unittest.skipIf(sys.platform == 'win32', 'add reader/writer not implemented')
+    def test_source_fileobj_fd(self):
+        """Regression test for
+        https://gitlab.gnome.org/GNOME/pygobject/-/issues/689
+        """
+        class Echo:
+            def __init__(self, sock, expect_bytes):
+                self.sock = sock
+                self.sent_bytes = 0
+                self.expect_bytes = expect_bytes
+                self.done = asyncio.Future()
+                self.data = bytes()
+
+            def send(self):
+                if self.done.done():
+                    return
+                if self.sent_bytes < len(self.data):
+                    self.sent_bytes += self.sock.send(
+                        self.data[self.sent_bytes:])
+                    print('sent', self.data)
+                if self.sent_bytes >= self.expect_bytes:
+                    self.done.set_result(None)
+                    self.sock.shutdown(socket.SHUT_WR)
+
+            def recv(self):
+                if self.done.done():
+                    return
+                self.data += self.sock.recv(self.expect_bytes)
+                print('received', self.data)
+                if len(self.data) >= self.expect_bytes:
+                    self.sock.shutdown(socket.SHUT_RD)
+
+        async def run():
+            loop = asyncio.get_running_loop()
+            s1, s2 = socket.socketpair()
+            sample = b'Hello!'
+            e = Echo(s1, len(sample))
+            # register using file object and file descriptor
+            loop.add_reader(s1, e.recv)
+            loop.add_writer(s1.fileno(), e.send)
+            s2.sendall(sample)
+            await asyncio.wait_for(e.done, timeout=2.0)
+            echo = bytes()
+            for _ in range(len(sample)):
+                echo += s2.recv(len(sample))
+                if len(echo) == len(sample):
+                    break
+            # remove using file object and file descriptor
+            loop.remove_reader(s1)
+            loop.remove_writer(s1.fileno())
+            s1.close()
+            s2.close()
+            # check if the data was echoed correctly
+            self.assertEqual(sample, echo)
+
+        policy = self.create_policy()
+        loop = policy.get_event_loop()
+        loop.run_until_complete(run())
+        loop.close()
-- 
GitLab