Add safety comments.

    static ref COOKIES: Mutex<HashMap<i32, fn() -> StatsPullResult>> = Mutex::new(HashMap::new());

}

// Safety: We store our callbacks in the global so they are valid.

/// # Safety

///

/// `data` must be a valid pointer with no aliases.

unsafe extern "C" fn callback_wrapper(

    atom_tag: i32,

    data: *mut AStatsEventList,

                let stats = cb();

                let result = stats

                    .iter()

                    .map(|stat| stat.add_astats_event(&mut *data))

                    // Safety: The caller promises that `data` is valid and unaliased.

                    .map(|stat| stat.add_astats_event(unsafe { &mut *data }))

                    .collect::<Result<Vec<()>, StatsError>>();

                match result {

                    Ok(_) => {

        let file = File::options().read(true).write(true).open(device)?;

        let srv_name = CString::new(service).expect("Service name contained null bytes");

        // SAFETY: The file descriptor is valid because it came from a `File`, and the name is a

        // valid C string because it came from a `CString`.

        unsafe {

            tipc_connect(file.as_raw_fd(), srv_name.as_ptr())?;

        }