layout of metadata information

[Guido Guenther <agx@debian.org>]

Hi,
I've written a small tool that calculates how much space a package uses
on different mount points (can be used as an apt-get 'hook' to make sure
one has enough free space to install packages). To do this properly it
also needs to take the package's {preinst,postinst,debconf templates}
into account. Now I could easily look up how much space the
package needs in /var/lib/dpkg/info but I'd prefer to ask dpkg where it
stores these kinds of 'metadata'. Is there a proper way to do this? If
not, is /var/lib/dpkg/info going to stay the only place where dpkg puts
all the stuff from a package's control.tar.gz?
Regards,
 -- Guido