Revert "testing: fix find_display() to speak the real protocol"

This reverts commit aae8463.

This does not seem to actually fix the problem, viz the race from:

https://github.com/tych0/xcffib/actions/runs/18052535989/job/51377039923

    _____________________ TestConnection.test_build_atom_cache _____________________
    [gw1] linux -- Python 3.10.18 /home/runner/work/xcffib/xcffib/xcffib_venv/bin/python3

    args = (<xcffib.Connection object at 0x7f8d997db8e0>, 4527)
    self = <xcffib.Connection object at 0x7f8d997db8e0>

        @functools.wraps(f)
        def wrapper(*args):
            self = args[0]
            self.invalid()
            try:
    >           return f(*args)

    xcffib/__init__.py:598:
    _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
    xcffib/__init__.py:686: in wait_for_reply
        self._process_error(error_p[0])
    xcffib/__init__.py:673: in _process_error
        self.invalid()
    _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

    self = <xcffib.Connection object at 0x7f8d997db8e0>

        def invalid(self):
            if self._conn is None:
                raise XcffibException("Invalid connection.")
            err = lib.xcb_connection_has_error(self._conn)
            if err > 0:
    >           raise ConnectionException(err)
    E           xcffib.ConnectionException: xcb connection errors because of socket, pipe and other stream errors.

    xcffib/__init__.py:585: ConnectionException

    During handling of the above exception, another exception occurred:

    self = <test.test_connection.TestConnection object at 0x7f8d99a0ead0>
    xproto_test = <test.conftest.XcffibTest object at 0x7f8d997db880>

        def test_build_atom_cache(self, xproto_test):
            # This will hold the forward *and* reverse lookups for any given atom
            atoms = {}
            cookies = []
            # Batch the replies by creating a list of cookies first:
            for i in range(1, 10000):
                c = xproto_test.conn.core.GetAtomName(i)
                cookies.append((i, c))
            for i, c in cookies:
                try:
    >               name = c.reply().name.to_string()

    test/test_connection.py:306:
    _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
    xcffib/__init__.py:341: in reply
        data = self.conn.wait_for_reply(self.sequence)
    xcffib/__init__.py:600: in wrapper
        self.invalid()
    _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

    self = <xcffib.Connection object at 0x7f8d997db8e0>

        def invalid(self):
            if self._conn is None:
                raise XcffibException("Invalid connection.")
            err = lib.xcb_connection_has_error(self._conn)
            if err > 0:
    >           raise ConnectionException(err)
    E           xcffib.ConnectionException: xcb connection errors because of socket, pipe and other stream errors.

    xcffib/__init__.py:585: ConnectionException
    ----------------------------- Captured stderr call -----------------------------
    _XSERVTransSocketUNIXCreateListener: ...SocketCreateListener() failed
    _XSERVTransMakeAllCOTSServerListeners: server already running
    (EE)
    Fatal server error:
    (EE) Cannot establish any listening sockets - Make sure an X server isn't already running(EE)
    --------------------------- Captured stderr teardown --------------------------

so let's revert for now since it's an API break.

Signed-off-by: Tycho Andersen <[email protected]>

Author: tych0

module/testing.py

@@ -16,6 +16,7 @@
 # others who want to test things using xcffib.
 
 import errno
+import fcntl
 import os
 import subprocess
 import time
@@ -30,32 +31,17 @@ def lock_path(display):
 def find_display():
     display = 10
     while True:
-        lock_file = lock_path(display)
-
         try:
-            with open(lock_file, 'r') as f:
-                pid = int(f.read().strip())
-
+            f = open(lock_path(display), "w+")
             try:
-                os.kill(pid, 0)
-                display += 1
-                continue
-            except (OSError, ProcessLookupError):
-                try:
-                    os.remove(lock_file)
-                except FileNotFoundError:
-                    pass
-
-        except (FileNotFoundError, ValueError, OSError):
-            pass
-
-        try:
-            fd = os.open(lock_file, os.O_CREAT | os.O_EXCL | os.O_WRONLY, 0o644)
-            os.write(fd, str(os.getpid()).encode())
-            return display, fd
-        except FileExistsError:
+                fcntl.flock(f.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
+            except OSError:
+                f.close()
+                raise
+        except OSError:
             display += 1
             continue
+        return display, f
 
 
 class XvfbTest:
@@ -117,7 +103,7 @@ def tearDown(self):
         # clean up after itself.
         try:
             os.remove(lock_path(self._display))
-            os.close(self._display_lock)
+            self._display_lock.close()
         except OSError as e:
             # we don't care if it doesn't exist, maybe something crashed and
             # cleaned it up during a test.

pyproject.toml

@@ -38,5 +38,4 @@ xcffib = ["py.typed"]
 [project.optional-dependencies]
 dev = [
     "pytest>=8.4",
-    "pytest-xdist",
 ]