I am no expert on file locking but I don't think that's possible.
$ touch lock $ perl -M5.010 -MFcntl=LOCK_EX -e' open(my $fh, "<", "lock") or die $!; flock($fh, LOCK_EX) or die $!; say "ok"; ' ok
flock locks have nothing to do with reading and writing, and they prevent neither. They merely prevent locks from being obtained.
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