An editor killed with SIGTERM or SIGHUP removes its 9P socket, and a start sweeps the pardes-9p-<pid>.sock files whose pid is gone

The runtime directory had gathered a hundred sockets of dead editors:
only a clean exit removed its own, and a signal or a crash left it. The
terminal's kill handler and, where nothing else handles the signals, a
handler of the listener's own now unlink the socket before the signal's
death. At listen, each pardes-9p-<pid>.sock whose pid kill(pid, 0)
answers ESRCH for, that is a socket of this user's and that nothing
answers on, is removed; a live pid's, a named session's and anything
else are never touched.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 19 insertions, 1 deletions

diff --git a/test/fs.py b/test/fs.py
index ba43c606..2782407d 100644
--- a/test/fs.py
+++ b/test/fs.py
@@ -6,6 +6,7 @@ import os
 import shutil
 import select
 import signal
+import socket
 from pathlib import Path
 import subprocess
 import struct
@@ -1413,13 +1414,25 @@ def test(binary, quic=False):
         # Killed with SIGTERM or SIGHUP, a tty editor puts its terminal
         # back (main screen, cooked mode) before it dies: a nested one
         # killed in a pane leaves that pane usable.
+        # ...and its 9P socket goes with it. One a dead editor left behind
+        # (no process has its pid) is swept at the next start; a live
+        # pid's, here this test's own, never is.
+        def unix_socket_file(path):
+            made = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+            made.bind(str(path))
+            made.close()
         for sig in (signal.SIGTERM, signal.SIGHUP):
+            dead_socket = root / 'pardes-9p-2147483647.sock'
+            live_socket = root / f'pardes-9p-{os.getpid()}.sock'
+            for path in (dead_socket, live_socket):
+                if not path.exists():
+                    unix_socket_file(path)
             master, slave = os.openpty()
             fcntl.ioctl(slave, termios.TIOCSWINSZ, struct.pack('HHHH', 24, 80, 0, 0))
             cooked = termios.tcgetattr(slave)
             env = {k: v for k, v in os.environ.items() if not k.startswith('PARDES_')}
             env.update(HOME=str(root), XDG_RUNTIME_DIR=str(root), TERM='xterm-256color', PARDES_NOTIME='1')
-            killed = subprocess.Popen([binary, '--tty', '--9p=killed', 'x.txt'], cwd=root, env=env,
+            killed = subprocess.Popen([binary, '--tty', 'x.txt'], cwd=root, env=env,
                                       stdin=slave, stdout=slave, stderr=subprocess.DEVNULL,
                                       start_new_session=True,
                                       preexec_fn=lambda: fcntl.ioctl(0, termios.TIOCSCTTY, 0))
@@ -1431,8 +1444,13 @@ def test(binary, quic=False):
                     if select.select([master], [], [], .1)[0]:
                         seen += os.read(master, 65536)
                 time.sleep(.3)
+                own_socket = root / f'pardes-9p-{killed.pid}.sock'
+                assert own_socket.exists()
+                assert not dead_socket.exists()
+                assert live_socket.exists()
                 killed.send_signal(sig)
                 assert killed.wait(timeout=5) == -sig
+                assert not own_socket.exists(), own_socket
                 while select.select([master], [], [], .2)[0]:
                     try:
                         chunk = os.read(master, 65536)