Varlena with recursive data structures?

Hi all,

I've recently started developing an extension for Postgres for which I'll
need to create a new variable-length base type. The type will require a
tree-like structure in order to parse sufficiently, which of course
probably means having some sort of recursive data structure, like a struct
that has members which are pointers to itself for child nodes. After doing
some research, specifically looking at how other variable-length data types
store their data, it seems almost all of them store the data in a binary
representation, using bit masks and offsets etc in order to store/access
the data whilst having an in-memory representation that's used to
manipulate the data.

I presume the purpose for using this approach is because all the data in a
varlena type has to be contiguous, and the moment you start using pointers
this is no longer possible. So my question is, given a structure that looks
something like this,

typedef struct Node
{
char *data;
Node *left;
Node *right;
} Node;

am I right in saying that I wouldn't be able to store that representation
on-disk, but instead I'd have to transform it into some binary
representation and back again when writing/reading respectively, are there
any alternatives?

Regards,

Karl