Unfortunately, fcntl() OFD locks on macOS appear to always return -1 errno=EOPNOTSUPP (45) when the file to be locked in a network (SMB) share. This errno value is not documented on the man page for this use. POSIX (non-OFD) fcntl() locks on network (SMB) shared file "work" (return 0, no error), but then of course, we suffer the POSIX lock semantics. Anyone have a solution?