Restricting Direct Access to a C Function in PostgreSQL

Hi PostgreSQL Community,

I have a scenario where I am working with two functions: one in SQL and another in C, where the SQL function is a wrapper around C function. Here’s an example:

CREATE OR REPLACE FUNCTION my_func(IN input text)
RETURNS BIGINT AS $$
DECLARE    result BIGINT;
BEGIN    SELECT col2 INTO result FROM my_func_extended(input);    RETURN result;
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION my_func_extended(    IN  input text,    OUT col1 text,    OUT col2 BIGINT
)
RETURNS SETOF record
AS 'MODULE_PATHNAME', 'my_func_extended'
LANGUAGE C STRICT PARALLEL SAFE;

I need to prevent direct execution of my_func_extended from psql while still allowing it to be called from within the wrapper function my_func.

I’m considering the following options:

1. Using GRANT/REVOKE in SQL to manage permissions.
2. Adding a check in the C function to allow execution only if my_func is in the call stack (previous parent or something), and otherwise throwing an error.

Is there an existing approach to achieve this, or would you recommend a specific solution?

Best regards,
Ayush Vatsa
AWS