Question

Is it possible to test if extension loading is enabled in SQLite 3 from C interface or using SQL without actually trying to load an extension?

Answer 1

You can use this query to check if extension loading is enabled by default:

SELECT sqlite_compileoption_used('ENABLE_LOAD_EXTENSION');

But this works for you only if you know that sqlite3_enable_load_extension is never called.

The internal SQLITE_LoadExtension flag is not accessible; it is read only when SQLite actually tries to load an extension.

What you could do is to try to load a known-invalid extension, such as load_extension('/dev/null'). If extension loading is disabled, the error message will be not authorized instead of something like file too short.