Export api from rust for python. How to get correct data from pointer?

help
1

The api function is:

#[no_mangle]
pub extern "C" fn zlgcan_recv(
    device: *const c_void,
    channel: u8,
    timeout: u32,
    buffer: &mut *const CanMessage,
    mut error: &mut *const c_char
) -> u32 {
    match convert(device as *const ZCanDriver, error) {
        Some(v) => {
            let timeout = match timeout {
                0 => None,
                v => Some(v),
            };

            match unify_recv(v, channel, timeout) {
                Ok(v) => {
                    let size = v.len();
                    v.iter().for_each(|f| println!("{:x} {:?}", f.arbitration_id(), f.data()));
                    *buffer = v.as_ptr();
                    std::mem::forget(v);

                    size as u32
                },
                Err(e) => {
                    set_error(e.to_string(), &mut error);
                    0
                }
            }
        },
        None => 0,
    }
}

and the python code is:

error = c_char_p()
buffer = POINTER(CanMessage)()
count = _LIB.zlgcan_recv(self.device, channel, timeout, byref(buffer), byref(error))
if count == 0:
    if error.value is not None:
        LOG.warning(error.value.decode("utf-8"))

for i in range(count):
    raw_msg = buffer[i]
    length = raw_msg.len;
    print(f"{'%02x' % raw_msg.arbitration_id} length of raw message: {length} - {string_at(raw_msg.data, raw_msg.len)}")
    print(f"{[raw_msg.data[j] for j in range(length)]}")
    msg = can.Message(
        timestamp=raw_msg.timestamp / 1000.,
        arbitration_id=raw_msg.arbitration_id,
        is_extended_id=raw_msg.is_extended_id,
        is_remote_frame=raw_msg.is_remote_frame,
        is_error_frame=raw_msg.is_error_frame,
        channel=raw_msg.channel,
        dlc=length,
        data=string_at(raw_msg.data, raw_msg.len), #[raw_msg.data[j] for j in range(length)], # string_at(raw_msg.data, raw_msg.len),
        is_fd=raw_msg.is_fd,
        bitrate_switch=raw_msg.bitrate_switch,
        error_state_indicator=raw_msg.error_state_indicator,
    )

The question is:
[raw_msg.data[j] for j in range(length)] cause Index out of range
and
the data from string_at(raw_msg.data, raw_msg.len) is not correct

2

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