- read-urandom or copy-existing-file are implemented
- fairly chatty on failure
- needs tests (probably the implementation should be moved to
a separate file and unit-tested)
- keep the rootMountPoint and the path-with-random-data separate
instead of concatenating them at the beginning. Then we can
use the "clean" names also within the host system.
- remove existing files for each kind of random-generation
that is enabled. There's a helper function for the case that
Cala is no longer setuid and needs help to remove those files
from the target (e.g. a setuid helper).
