Function dump_doc 

pub unsafe fn dump_doc() -> *mut _xmlDoc

Build the catalog document for dumping/saving: XML declaration, the OASIS catalog DOCTYPE, and a <catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> root with the current entries.

The DOCTYPE node is prepended as the first child of the document (the serializer emits <!DOCTYPE catalog PUBLIC ...> from child DTD nodes); doc->intSubset is left NULL so free_doc frees the DTD exactly once via the children list.

Returns a newly allocated document, or NULL on allocation failure.