Function module_config 

pub unsafe extern "C" fn module_config(
    configfile: *const c_char,
) -> c_int

Read the module configuration from the given optional/nullable path, called at startup

Returning a non-zero code from the function will abort module startup.

Your module implementation must export it’s own version of this function as:

#[unsafe(no_mangle)]
unsafe extern "C" fn module_config(configfile: *const raw::c_char) -> raw::c_int {
    0  // Stub implementation
}