(ITS#7361) alock is broken on Windows

Full_Name: Howard Chu Version: 2.4.32 OS: URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (76.94.188.8) Submitted by: hyc

alock assumes (wrongly) that it can always read from a locked region. That's true for POSIX advisory locks, but Windows locks are mandatory. I.e., attempting to read from a region with a write lock returns EACCES.

Because alock doesn't detect this situation correctly, it will end up waiting forever to acquire a lock on a region that's already locked. (E.g., if slapd is already running and slapcat is started, slapcat will hang trying to get the region lock.)

A fix is coming shortly.