Changeroot for PHP?

[Norbert <norbert_schuetz@bigfoot.com>]

Hi folks!

Although this is not really Debian-specific apart from 
the fact that we run all servers with Debian:

Does anyone know a way to have PHP scripts run
changerooted one namebased virtual servers (Apache)?

More specific: We have set up several domains with
indiviual Apache virtual, namedbased configurations
using the "User/Group" directives. The physical
directory structure is something like
/var/www/domain1/htdocs/
/var/www/domain2/htdocs/
/var/www/domain3/htdocs/

For security and other reasons we would like to have
PHP scripts changerooted to /var/www/domain1/htdocs/.

We know this can be done using PHP-cgi and a sandbox
but that introduces quite some performance penalties
so we would prefer mod_php.

Any hints?


TIA!
Nobbi.