Okay, so newlines in file names are dangerous to a lot of common
idioms...

How much do we lose if we have a filesystem flag to forbid them?

I would think it might be possible to simply silently replace
all non-printing chars with normal spaces.  Now, I doubt the resulting
system is going to win any conformance awards, but there are times when
I'd be willing to give up POSIX conformance for security.

-s