Function iio_device_buffer_attr_read_longlong 

pub unsafe extern "C" fn iio_device_buffer_attr_read_longlong(
    dev: *const iio_device,
    attr: *const c_char,
    val: *mut c_longlong,
) -> c_int

@brief Read the content of the given buffer-specific attribute @param dev A pointer to an iio_device structure @param attr A NULL-terminated string corresponding to the name of the attribute @param val A pointer to a long long variable where the value should be stored @return On success, 0 is returned @return On error, a negative errno code is returned