Obtaining information on the schema of tables which I do not own

Dear list,

I am currently developing an application which needs to know information
about table schema in order to display them correctly (specificly
foreign keys, default values and not null characteristics).

For security reasons I would prefer for it not to run as superuser.

I may often wish to display tables which I do not own and potentially
not even have anything other than SELECT permissions to. I will need the
schema information for these tables.

It is desirable since the app needs to also work with other DB's
besides postgres, to implement the requirements using as standard a
technique as possible, and consequently the views inside
information_schema look to me to be the best option. The problem is
that as best as I can tell from experimentation and reading the
documentation, I am only given information on tables owned by the
current user.

Is there any way to achieve I want without being forced to use the
postgres-specific system tables ?

Your assistance is much appreciated,

Daniel