Function CGGetEventTapList 

pub unsafe extern "C-unwind" fn CGGetEventTapList(
    max_number_of_taps: u32,
    tap_list: *mut CGEventTapInformation,
    event_tap_count: *mut u32,
) -> CGError

Available on crate features CGError and CGEvent and CGEventTypes and libc only.

Safety

• tap_list must be a valid pointer or null.
• event_tap_count must be a valid pointer or null.