Function olm_sys::olm_export_inbound_group_session

pub unsafe extern "C" fn olm_export_inbound_group_session(
    session: *mut OlmInboundGroupSession, 
    key: *mut u8, 
    key_length: usize, 
    message_index: u32
) -> usize

Export the base64-encoded ratchet key for this session, at the given index, in a format which can be used by olm_import_inbound_group_session

Returns the length of the ratchet key on success or olm_error() on failure. On failure last_error will be set with an error code. The last_error will be:

• OUTPUT_BUFFER_TOO_SMALL if the buffer was too small
• OLM_UNKNOWN_MESSAGE_INDEX if we do not have a session key corresponding to the given index (ie, it was sent before the session key was shared with us)