Function zxio_readv_at 

pub unsafe extern "C" fn zxio_readv_at(
    io: *mut zxio_t,
    offset: zx_off_t,
    vector: *const zx_iovec_t,
    vector_count: usize,
    flags: zxio_flags_t,
    out_actual: *mut usize,
) -> zx_status_t