Function safe_app::ffi::mutable_data::entries::mdata_entries_len

#[no_mangle]
pub unsafe extern "C" fn mdata_entries_len(
    app: *const App, 
    entries_h: MDataEntriesHandle, 
    user_data: *mut c_void, 
    o_cb: extern "C" fn(_: *mut c_void, _: FfiResult, _: usize)
)

Returns the number of entries.

Callback parameters: user data, error code, length