machine-readable pg_controldata?

All,

Currently, the only way for admin scripts to get individual data items
out of pg_controldata (such as the next XID or the catalog version) is
via grep and regex. Given that people are going to be relying on some of
this data for replication admin in the future, it seems past time to
have a form of pg_controldata which either outputs machine-readable text
(XML or JSON), or (my preference) takes options to output just the
invididual items, e.g.

pg_controldata --catalog_version

Even better would be the ability to get everything which is in
pg_controldata currently as part of a system view in a running
PostgreSQL; I can get most of them, but certainly not all.

Thoughts?

--Josh Berkus