Some clients list the albums belonging to an artist by issuing the
command `list album <ARTIST NAME>`. This change inserts the tag `artist`
before the artist name so that this succeeds. Fixes#3007
A new `ControlConnection` is created each time a client connects over
a new control socket. This is used to forward events from the player,
and also for debugging utilities that are not part of the real MPD
protocol.
This new feature reuses as much infrastructure from the normal protocol
handling as possible (e.g. `Command` for parsing messages). While the
normal connection delegates to server `cmd_*` methods which are string
generators, the control connections delegate to `ctrl_*` methods defined
on the connection itself that are full coroutines.
Getting this command puts the connection into a special mode where it
awaits MPD events (like the player changing state or the playlist
changing due to other clients interacting with the server.
The MPD specification states that events should queue while a client is
connected, and when it issues the `idle` command any matching events
should be sent immediately if there are any, or as soon as they happen
otherwise.
Keep track of a list of currently-connected clients.
Use `socket.getpeername()` to get an identifier for each connection and
include this in each log message. This function is documented as not
being available on all systems, but it's unclear which systems this
involves.
Also log a message on client connect and disconnect events. If the
disconnection reason is because the client sent a blank line, match MPD
by returning a protocol error then hanging up. Escape curly braces.
Improved the method to get the path of the current song. Before, the complete playlist was fetched from the server. Now, the command "currentsong" is used for this purpose. This improves performance when a huge playlist is active.
Check function signature instead of using TypeError to crudely guess
that the wrong number of arguments were provided.
Prevent bpd from crashing when trying to log a traceback. The
`traceback.format_exc` function takes an optional argument which is
supposed to be an integer restricting the length of the backtrace to
show. Instead we were passing the exception object to this function and
causing a new exception to be raised.
Previously issuing the 'previous' command when at position 0 on the
playlist would cause bpd to stop playing. MPD instead just restarts the
currently playing song instead, so we now match this behaviour.
The songs are indexed starting from zero for the play command, however
the bound check was off by one. An index matching the length of the
playlist would crash the server instead of responding with an error
message over the protocol.
