programmatically retrieve details of a custom Postgres type

Hello,

I was unable to find how to get column names, sizes and types for a given composite type.

Example. For a type defines as:

  CREATE TYPE inventory_item AS (

  name text,

  supplier_id integer,

  price numeric

);

I have a plpgsql stored proc that returns SETOF inventory_item (i.e. there is no table with a column of this type).

I looked into the pg_type table but it only contains oid and typrelid for the inventory_item type. I need a query that returns information about structure of the composite type, i.e.:

  ColumnName  |  ColumnType  |  ColumnSize

  name             | text                | -1

  supplier_id      | integer           | 4

  price              | numeric          | 16

Is this possible? I'm executing queries via libpq...

Thank you!