From e34c1203500451e65f0439435df55a2fa4c0f4ab Mon Sep 17 00:00:00 2001 From: Agando Date: Fri, 23 Oct 2026 20:30:20 +0200 Subject: fix(chat): three concurrency holes found reviewing my own patch (v4.6.77) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 1. chat.py renamed the temp file AFTER releasing the flock, so two writers could each read the pre-replace snapshot and the later rename silently dropped the earlier message. os.replace now happens inside the lock. 2. The agent cursor was global. After hermes-reset it pointed past the end of the new empty thread, so every read returned nothing — the agent would think it had been ignored. Key is now per thread and reset clears every chat cursor. 3. chat-relay.sh had no overlap guard: a slow agent run (up to 5 min) could collide with the next tick and answer the same thread twice. flock -n on /tmp/chat-relay.lock. Verified: stale cursor 'webx11_chat_agent_cursor_oldthread00000' set to 9999999999999, hermes-reset -> zero cursor keys remain, read returns {messages:[], note:'no new messages...'}. --- scripts/chat.py | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'scripts/chat.py') diff --git a/scripts/chat.py b/scripts/chat.py index e19fb6b..5b44b64 100755 --- a/scripts/chat.py +++ b/scripts/chat.py @@ -78,9 +78,11 @@ def reply(thread, text): with open(tmp, 'w') as fh: json.dump(msgs, fh, ensure_ascii=False) os.chmod(tmp, 0o664) + # replace INSIDE the lock: doing it after unlock lets a second writer read + # the pre-replace snapshot and rename over this message (lost update). + os.replace(tmp, path) finally: fcntl.flock(lock, fcntl.LOCK_UN) - os.replace(tmp, path) # atomic: a poll never sees a half-written file return msg -- cgit v1.2.3