Shutting the Barn Door [File Locking]

Problem: The open call erases the file before the process has the lock

        open F, "> somefile"; # DERP you already erased all the data in somefile by opening it
        flock F, LOCK_EX;     # before obtaining this lock
        # Now write F
        close F;

Now you have two problems: +< still erases the file before the process has the lock

        open F, "+< somefile";
        flock F, LOCK_EX;
        truncate F, 0;
        # Now write F
        close F;

Dear /prog/, what am I missing?

>>7
man stat