https://gitlab.synchro.net/main/sbbs/-/commit/9021d114d289bcf7e191e525
Modified Files:
src/sbbs3/nopen.c nopen.h qwkjob.cpp
Log Message:
fmutex_close(): retry an unlink another host blocks; read QWK lock text shared

When two hosts' event threads act on the same QWK pack semaphore (both glob data/pack*.now), the one that finds the user's lock busy opens the lock file briefly: to stat it, to try creating it, and to read the holder's text for
the log. On Windows those opens don't permit deletion, so the holder's unlink over SMB/CIFS fails with EBUSY if it lands inside one. This happened on 2026-10-26 between VERT and a Linux host: the Linux host's older build (from before 251c99b699 (camera-37-lies, 2026-10-25)) returned from fmutex_close() without closing the lock file, and that user's QWK packets
stayed blocked on every host until the process was restarted.

The current fmutex_close() already closes the descriptor when the unlink
fails, but leaves a lock file nobody holds, so the user waits for it to age
out (an hour for a QWK user lock).

- fmutex_close() now retries an unlink that fails with EBUSY, up to
FMUTEX_UNLINK_RETRIES (10) times, LOCK_RETRY_DELAY (100 ms) apart, and
treats the file vanishing meanwhile as removed.
- qwkjob_lock_busy() on Windows reads the holder's text through a handle
that permits FILE_SHARE_DELETE (the read added by 4365e08932
(fuel-0-know, 2026-10-25)), so reading the text no longer blocks the
holder's removal. Its stat and create attempts still can, which the retry
covers.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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