Add a new simple object "brei_result" that maps to the protocol-type
reason + explanation. That object is now returned instead of the errno,
giving us better debugging options.
This changes the dispatcher functions from returning an int to returning
a brei_result instead (default NULL for success). A helper function for
converting a neg errno to a result is provided for convenience for now,
eventually all these paths should deal with things correctly.
This is currently the only interface that requires client-created
objects, so the client needs to know which version it can use. Let's
send it to them before the connection object.
For most interfaces, the client announcing its supported version is
sufficient - the objects are all created server-side. For some
interfaces (ei_connection_setup and ei_callback right now) the client
needs to know the server-supported version.
So let's switch the current ei_connection_setup.version event (used to
negotiate ei_connection_setup's version) to a generic
`interface_version` event. This way our EIS implementation can
eventually send a version for ei_callback as well.
A client that skips on announcing those will get connected and
immediately disconnected again. There's no point to libei if you support
neither of those (at least for now).
Leave the ei_callback as-is and instead add ei_pingpong for the same
thing initiated by the server. The interface is otherwise identical but
for the direction it is supposed to flow.
This reduces the possibility of a client accidentally sending a
request when it is supposed to handle an event or vice versa.
This is effectively the same as connection.sync, but goes the other way.
This adds the ei_callback.done request.
In libeis this is (currently) enforced immediately after sending the
connection object. Not required there and makes the code a bit messier
but this way we can ensure that any client library handles that part of
the code.
This event is to notify the client that an object used in a request was
unknown. This allows the client to work around race conditions like
binding to a seat that was removed.
This is currently the server-side only which is probably enough for now.
The only client-side created objects we have are the callbacks.
This changes the initial connection negotiation to have the
ei_connection_setup as the pre-existing object id 0. Once the client has
sent all the data to set up the connection, the EIS implementation
replies with a new object ID that is the ei_connection protocol object,
i.e. the main object.
This allows for version negotiation of our main protocol object.
This allows us to have a device support multiple interfaces and evolve
those interfaces individually, e.g. add things to the keyboard interface
without having to bump the touchscreen interface.
Note that due to a name clash with the existing struct ei_touch public
API the protocol interface is named touchscreen.
The idea here is that the client announces the interfaces it can support
and their version (including the core ei_connection). The server can
then send the various bits based on those versions, where applicable.
This replaces the connect/connect_done and version/get_version requests.
Immediately after connecting, the server sends an ei_protocol_setup
event to the client with the ID of the object and the server's highest
supported version number (of this object).
This is a one-shot object that the client can use to configure its name
and whether it is a sender or receiver context. Once .done is sent, the
object is discarded.
The server version is sent along to the client to allow for requests to
be added to this object in the future.
As a fixme left: the client now assumes to be connected as soon as the
.done request is sent and the following sync event is received. The
EIS implementation will not have actually eis_client_connect()ed the
client yet, but it's good enough for now.
Arguably, the CONNECTED event is superfluous anyway since *any* event
other than DISCONNECTED indicates connected status. CONNECTED is a
leftover from when the client created devices and needed to know if it's
worth doing so.
