sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
The sqlite3_context_db_handle() interface returns a copy of the pointer to the database connection (the 1st parameter) of the sqlite3_create_function() and sqlite3_create_function16() routines that originally registered the application defined function.
See also lists of Objects, Constants, and Functions.
SQLite is in the Public Domain.
https://sqlite.org/c3ref/context_db_handle.html