This is a newbie question.

If I were to set up lighttpd in a chrooted environment, does the
barrier go both ways?  Will I be able to access files within the
chrooted directory from outside that environment?

Section 6.3.6 of the pkgsrc guide mentions null mounts:

http://netbsd.org/docs/pkgsrc/binary.html#setting-up-a-sandbox

...yet I haven't been able to find this defined?  Can someone elaborate?

Thanks.