Bundled KDE Connect: close the races the second review found

- The need-packages retry only runs if no start() has taken over, so two
  agents can't end up running for one session.
- Each copy goes to its own incoming folder; the agent removes its own once
  connected (and any a cancelled start left over an hour ago), so a stopped
  start can't delete files another is copying or still needs.
- A missing package folder means need-packages, not an error.
- Tests keep fake agents running, so they check ready and which agent owns
  the session, plus a bounded retry and the tidy rule.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/test_input.py

@@ -173,9 +173,11 @@ class Bundled(unittest.TestCase):
             self.deliver(frame_has=False, damaged=True)
 
     def lifecycle(self, agent_lines, deliver=None):
-        """An InputAgent whose ssh and agent are fakes; returns it and the folders each launch used."""
+        """An InputAgent whose ssh and agent are fakes. Returns it, the folders each launch
-        launches = []
+        used, and the fake agents. A fake agent reports its lines, then keeps running
-        test = self
+        (unless its lines end with need-packages) until the test ends."""
+        launches, procs, done = [], [], threading.Event()
+        self.addCleanup(done.set)
 
         class Agent(self.server.InputAgent):
             def deliver(self, report, force=False):
@@ -191,34 +193,60 @@ class Bundled(unittest.TestCase):
             stdin = None
 
             def __init__(self, lines):
-                self.stdout = iter(lines)
+                self.lines, self.ended = lines, threading.Event()
+                procs.append(self)
+
+            @property
+            def stdout(self):
+                yield from self.lines
+                if b"need-packages" not in self.lines[-1]:
+                    while not (done.is_set() or self.ended.is_set()):
+                        self.ended.wait(0.02)
+                self.ended.set()
 
             def wait(self):
+                self.ended.wait(5)
                 return 0
 
             def poll(self):
-                return None
+                return 0 if self.ended.is_set() else None
 
             def terminate(self):
-                pass
+                self.ended.set()
 
         def popen(*a, **k):
             return Proc(agent_lines.pop(0) if agent_lines else [b'{"state": "ready"}\n'])
         old = self.server.ensure_master, self.server.subprocess.Popen
         self.server.ensure_master, self.server.subprocess.Popen = lambda: None, popen
-        test.addCleanup(lambda: (setattr(self.server, "ensure_master", old[0]),
+        self.addCleanup(lambda: (setattr(self.server, "ensure_master", old[0]),
                                  setattr(self.server.subprocess, "Popen", old[1])))
-        return Agent(packages=[("a.pkg.tar.zst", "0" * 64)]), launches
+        return Agent(packages=[("a.pkg.tar.zst", "0" * 64)]), launches, procs
+
+    def wait_for(self, check):
+        for _ in range(250):
+            if check():
+                return
+            time.sleep(0.02)
+        self.fail("timed out")
 
     def test_agent_asking_for_packages_gets_them_and_starts_again(self):
-        agent, launches = self.lifecycle([[b'{"state": "need-packages"}\n'], [b'{"state": "ready"}\n']])
+        agent, launches, procs = self.lifecycle([[b'{"state": "need-packages"}\n'], [b'{"state": "ready"}\n']])
-        agent._launch(agent.generation)
+        agent.start()
+        self.wait_for(lambda: agent.status == {"state": "ready"})
         self.assertEqual(launches, ["", "~/copied"])
-        self.assertNotIn("reach", agent.status.get("message", ""))
+        self.assertIs(agent.proc, procs[1])
+
+    def test_asking_twice_is_an_error_not_a_loop(self):
+        need = [b'{"state": "need-packages"}\n']
+        agent, launches, _ = self.lifecycle([need, list(need)])
+        agent.start()
+        self.wait_for(lambda: agent.status.get("state") == "error")
+        self.assertEqual(launches, ["", "~/copied"])
+        self.assertIn("didn't reach", agent.status["message"])
 
     def test_start_after_stop_during_the_copy_still_starts(self):
         gate, entered = threading.Event(), threading.Event()
-        agent, launches = self.lifecycle([], deliver=lambda: (entered.set(), gate.wait(5)))
+        agent, launches, procs = self.lifecycle([], deliver=lambda: (entered.set(), gate.wait(5)))
         agent.start()
         self.assertTrue(entered.wait(5))
         agent.stop()
@@ -226,11 +254,17 @@ class Bundled(unittest.TestCase):
         agent.start()  # while the first launch is still copying
         self.assertTrue(entered.wait(5), "the second start didn't launch")
         gate.set()
-        for _ in range(100):
+        self.wait_for(lambda: len(procs) == 2 and agent.status == {"state": "ready"})
-            if len(launches) == 2:
+        # The stopped launch's agent was ended; the new one is the one in use.
-                break
+        self.wait_for(lambda: sum(p.ended.is_set() for p in procs) == 1)
-            time.sleep(0.02)
+        self.assertFalse(agent.proc.ended.is_set())
-        self.assertEqual(len(launches), 2)  # the stopped launch ran its agent too, then ended it
+        agent.stop()
+        self.wait_for(lambda: all(p.ended.is_set() for p in procs))
+
+    def test_copies_go_to_a_folder_of_their_own(self):
+        first, _, _ = self.deliver(frame_has=False)
+        second, _, _ = self.deliver(frame_has=False)
+        self.assertNotEqual(first, second)
 
 
 @unittest.skipIf(sys.platform == "win32", "the agent runs on the Frame (Linux)")
@@ -296,11 +330,21 @@ class AgentInstall(unittest.TestCase):
     def test_asks_for_packages_it_was_not_sent(self):
         self.agent.listening, old = (lambda: False), self.agent.listening
         try:
-            with self.assertRaises(self.agent.NeedPackages):
+            for folder in ("", str(self.dir / "gone")):  # none sent, or already tidied away
-                self.agent.ensure_daemon("", [("new.pkg.tar.zst", "1" * 64)])
+                with self.assertRaises(self.agent.NeedPackages):
+                    self.agent.ensure_daemon(folder, [("new.pkg.tar.zst", "1" * 64)])
         finally:
             self.agent.listening = old
 
+    def test_tidy_keeps_other_starts_copies(self):
+        incoming = self.agent.BASE / "incoming"
+        mine, theirs, stale = incoming / "mine", incoming / "theirs", incoming / "stale"
+        for d in (mine, theirs, stale):
+            d.mkdir(parents=True)
+        os.utime(stale, (time.time() - 7200,) * 2)
+        self.agent.tidy_incoming(str(mine))
+        self.assertEqual(sorted(p.name for p in incoming.iterdir()), ["theirs"])
+
     def test_server_and_agent_agree_on_the_stamp(self):
         import server
         packages = [("a.pkg.tar.zst", "1" * 64), ("b.pkg.tar.zst", "2" * 64)]

ui/frame_input_agent.py

@@ -166,7 +166,7 @@ def ensure_daemon(folder, packages):
     """
     system = SYSTEM_DAEMON.exists()
     if not system and not installed(packages) and not (listening() and our_daemons()):
-        if not folder:
+        if not folder or not Path(folder).is_dir():
             raise NeedPackages()
         install(folder, packages)
     if listening():
@@ -346,6 +346,20 @@ def main():
                 stop_daemon()
 
 
+def tidy_incoming(folder):
+    """Remove this start's copy of the packages, and any a cancelled start left over an hour ago."""
+    incoming = BASE / "incoming"
+    if folder.startswith(str(incoming) + "/"):
+        shutil.rmtree(folder, ignore_errors=True)
+    try:
+        for old in incoming.iterdir():
+            if time.time() - old.stat().st_mtime > 3600:
+                shutil.rmtree(old, ignore_errors=True)
+        incoming.rmdir()
+    except OSError:
+        pass  # none, or another start's copy is still there
+
+
 class daemon_lock:
     """Installing, starting and restarting KDE Connect happen one agent at a time."""
 
@@ -361,12 +375,6 @@ def run(client, name, folder, packages):
     try:
         with daemon_lock():
             ensure_daemon(folder, packages)
-        if folder.startswith(str(BASE / "incoming") + "/"):
-            shutil.rmtree(folder, ignore_errors=True)  # unpacked; the copy isn't needed again
-            try:
-                (BASE / "incoming").rmdir()
-            except OSError:
-                pass  # another device's copy is still there
         device, cert, key = identity(client)
         say("pairing")
         seen = our_daemons()
@@ -390,6 +398,7 @@ def run(client, name, folder, packages):
     except (OSError, RuntimeError, subprocess.SubprocessError) as e:
         say("error", message=str(e))
         return 1
+    tidy_incoming(folder)  # unpacked or not needed: the copy has done its job
     say("ready", keyboard=link.keyboard is not False)
     stdin, pending = sys.stdin.fileno(), b""
     sel = selectors.DefaultSelector()

ui/server.py

@@ -635,8 +635,8 @@ class InputAgent:
                        " && echo yes || true", stdin=kdeconnect_stamp(self.packages).encode(), text=False, timeout=20)
             if have.strip() == b"yes":
                 return ""
-        client = "".join(c for c in input_client() if c.isalnum() or c in "-_")[:64] or "default"
+        # A folder of its own: a cancelled start's agent may still be cleaning up another.
-        folder = f"{KDECONNECT_HOME}/incoming/{client}"
+        folder = f"{KDECONNECT_HOME}/incoming/{secrets.token_hex(8)}"
         ssh(f"mkdir -p {folder}", timeout=20)
         for name, sha in self.packages:
             path = KDECONNECT / "packages" / name
@@ -645,8 +645,7 @@ class InputAgent:
                               " (a build runs app/build/fetch-deps.js to add it)", 500)
             report(f"Copying KDE Connect to the Frame ({name.rsplit('-', 3)[0]})")
             quoted = shlex.quote(name)
-            # Its own temporary name: two starts can be copying at once.
+            ssh(f"cd {folder} && cat > {quoted}.part && mv {quoted}.part {quoted}",
-            ssh(f"cd {folder} && cat > {quoted}.part$$ && mv {quoted}.part$$ {quoted}",
                 stdin=path.read_bytes(), text=False, timeout=600)
         return f"~/{folder}"
 
@@ -693,7 +692,8 @@ class InputAgent:
             # It needed the packages after all (another device changed what's
             # installed after we looked): copy them and start once more.
             with self.lock:
-                if self.proc is not proc or self.generation != generation:
+                # Unless a start() already took over (it launches, and copies if still needed).
+                if self.proc is not proc or self.generation != generation or self.launching is not None:
                     return
                 self.proc, self.launching, self.status = None, generation, {"state": "starting"}
             self._launch(generation, force=True)