Subj : src/xpdev/filewrap.c
To   : Git commit to main/sbbs/master
From : Rob Swindell (on Windows 11)
Date : Wed Jun 03 2026 09:44:35

https://gitlab.synchro.net/main/sbbs/-/commit/e3fd4e7cf195c14e9e12c577
Modified Files:
	src/xpdev/filewrap.c
Log Message:
xpdev/filewrap: flock path of xp_lockfile() honors fd open mode too (#1153)

The non-Linux POSIX (flock) path of xp_lockfile() always took LOCK_EX,
even for a read-only descriptor, unlike the Linux/fcntl path which
derives the lock type from the fd's open mode. So on FreeBSD/macOS/etc.
(USE_FCNTL_LOCKS is Linux-only) a read-only lock() serialized concurrent
readers - the same exclusive-lock-on-reads issue fixed for Windows in the
previous commit. flock() (unlike fcntl()) isn't forced to a lock type by
the access mode, so the LOCK_EX was a choice; mirror the fcntl path and
take LOCK_SH for an O_RDONLY fd.

The user.tab read path is already covered on these platforms (rdlock()'s
flock branch uses LOCK_SH); this brings the lock() primitive itself to
parity, so any read-only-fd caller benefits. flock remains whole-file
(pos/len ignored) - a pre-existing coarseness, unchanged here.

Not compiled in this environment (the flock branch builds only on
non-Linux POSIX); mirrors the existing fcntl-branch idiom.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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