int sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
The sqlite3_db_readonly(D,N) interface returns 1 if the database N of connection D is read-only, 0 if it is read/write, or -1 if N is not the name of a database on connection D.
See also lists of Objects, Constants, and Functions.
SQLite is in the Public Domain.
https://sqlite.org/c3ref/db_readonly.html