sudo lock file?

[Todd C. Miller]

The locking is done on the sudoers file itself, not the sudoers
temp file.  The actual locking is done by fileops.c in the current
version of sudo.  The exact method it uses depends on what is
available on the system but basically it will use lockf() if
that is available otherwise it will use flock() or, if all else
fails, it will use fcntl() locking.

Does that answer your question?

 - todd