mpd.py

   1 # python-mpd: Python MPD client library
   2 # Copyright (C) 2008-2010  J. Alexander Treuman <jat@spatialrift.net>
   3 #
   4 # python-mpd is free software: you can redistribute it and/or modify
   5 # it under the terms of the GNU Lesser General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # python-mpd is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU Lesser General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU Lesser General Public License
  15 # along with python-mpd.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 import socket
  18
  19
  20 HELLO_PREFIX = "OK MPD "
  21 ERROR_PREFIX = "ACK "
  22 SUCCESS = "OK"
  23 NEXT = "list_OK"
  24
  25
  26 class MPDError(Exception):
  27     pass
  28
  29 class ConnectionError(MPDError):
  30     pass
  31
  32 class ProtocolError(MPDError):
  33     pass
  34
  35 class CommandError(MPDError):
  36     pass
  37
  38 class CommandListError(MPDError):
  39     pass
  40
  41 class PendingCommandError(MPDError):
  42     pass
  43
  44 class IteratingError(MPDError):
  45     pass
  46
  47
  48 class _NotConnected(object):
  49     def __getattr__(self, attr):
  50         return self._dummy
  51
  52     def _dummy(*args):
  53         raise ConnectionError("Not connected")
  54
  55 class MPDClient(object):
  56     def __init__(self):
  57         self.iterate = False
  58         self._reset()
  59         self._commands = {
  60             # Status Commands
  61             "clearerror":       self._fetch_nothing,
  62             "currentsong":      self._fetch_object,
  63             "idle":             self._fetch_list,
  64             "noidle":           None,
  65             "status":           self._fetch_object,
  66             "stats":            self._fetch_object,
  67             # Playback Option Commands
  68             "consume":          self._fetch_nothing,
  69             "crossfade":        self._fetch_nothing,
  70             "random":           self._fetch_nothing,
  71             "repeat":           self._fetch_nothing,
  72             "setvol":           self._fetch_nothing,
  73             "single":           self._fetch_nothing,
  74             "volume":           self._fetch_nothing,
  75             # Playback Control Commands
  76             "next":             self._fetch_nothing,
  77             "pause":            self._fetch_nothing,
  78             "play":             self._fetch_nothing,
  79             "playid":           self._fetch_nothing,
  80             "previous":         self._fetch_nothing,
  81             "seek":             self._fetch_nothing,
  82             "seekid":           self._fetch_nothing,
  83             "stop":             self._fetch_nothing,
  84             # Playlist Commands
  85             "add":              self._fetch_nothing,
  86             "addid":            self._fetch_item,
  87             "clear":            self._fetch_nothing,
  88             "delete":           self._fetch_nothing,
  89             "deleteid":         self._fetch_nothing,
  90             "move":             self._fetch_nothing,
  91             "moveid":           self._fetch_nothing,
  92             "playlist":         self._fetch_playlist,
  93             "playlistfind":     self._fetch_songs,
  94             "playlistid":       self._fetch_songs,
  95             "playlistinfo":     self._fetch_songs,
  96             "playlistsearch":   self._fetch_songs,
  97             "plchanges":        self._fetch_songs,
  98             "plchangesposid":   self._fetch_changes,
  99             "shuffle":          self._fetch_nothing,
 100             "swap":             self._fetch_nothing,
 101             "swapid":           self._fetch_nothing,
 102             # Stored Playlist Commands
 103             "listplaylist":     self._fetch_list,
 104             "listplaylistinfo": self._fetch_songs,
 105             "listplaylists":    self._fetch_playlists,
 106             "load":             self._fetch_nothing,
 107             "playlistadd":      self._fetch_nothing,
 108             "playlistclear":    self._fetch_nothing,
 109             "playlistdelete":   self._fetch_nothing,
 110             "playlistmove":     self._fetch_nothing,
 111             "rename":           self._fetch_nothing,
 112             "rm":               self._fetch_nothing,
 113             "save":             self._fetch_nothing,
 114             # Database Commands
 115             "count":            self._fetch_object,
 116             "find":             self._fetch_songs,
 117             "findadd":          self._fetch_nothing,
 118             "list":             self._fetch_list,
 119             "listall":          self._fetch_database,
 120             "listallinfo":      self._fetch_database,
 121             "lsinfo":           self._fetch_database,
 122             "search":           self._fetch_songs,
 123             "update":           self._fetch_item,
 124             "rescan":           self._fetch_item,
 125             # Sticker Commands
 126             "sticker get":      self._fetch_item,
 127             "sticker set":      self._fetch_nothing,
 128             "sticker delete":   self._fetch_nothing,
 129             "sticker list":     self._fetch_list,
 130             "sticker find":     self._fetch_songs,
 131             # Connection Commands
 132             "close":            None,
 133             "kill":             None,
 134             "password":         self._fetch_nothing,
 135             "ping":             self._fetch_nothing,
 136             # Audio Output Commands
 137             "disableoutput":    self._fetch_nothing,
 138             "enableoutput":     self._fetch_nothing,
 139             "outputs":          self._fetch_outputs,
 140             # Reflection Commands
 141             "commands":         self._fetch_list,
 142             "notcommands":      self._fetch_list,
 143             "tagtypes":         self._fetch_list,
 144             "urlhandlers":      self._fetch_list,
 145             "decoders":         self._fetch_plugins,
 146         }
 147
 148     def __getattr__(self, attr):
 149         if attr.startswith("send_"):
 150             command = attr.replace("send_", "", 1)
 151             wrapper = self._send
 152         elif attr.startswith("fetch_"):
 153             command = attr.replace("fetch_", "", 1)
 154             wrapper = self._fetch
 155         else:
 156             command = attr
 157             wrapper = self._execute
 158         command = command.replace("_", " ")
 159         if command not in self._commands:
 160             raise AttributeError("'%s' object has no attribute '%s'" %
 161                                  (self.__class__.__name__, attr))
 162         return lambda *args: wrapper(command, args)
 163
 164     def _send(self, command, args):
 165         if self._command_list is not None:
 166             raise CommandListError("Cannot use send_%s in a command list" %
 167                                    command.replace(" ", "_"))
 168         self._write_command(command, args)
 169         self._pending.append(command)
 170
 171     def _fetch(self, command, args=None):
 172         if self._command_list is not None:
 173             raise CommandListError("Cannot use fetch_%s in a command list" %
 174                                    command.replace(" ", "_"))
 175         if self._iterating:
 176             raise IteratingError("Cannot use fetch_%s while iterating" %
 177                                  command.replace(" ", "_"))
 178         if not self._pending:
 179             raise PendingCommandError("No pending commands to fetch")
 180         if self._pending[0] != command:
 181             raise PendingCommandError("'%s' is not the currently "
 182                                       "pending command" % command)
 183         del self._pending[0]
 184         retval = self._commands[command]
 185         if callable(retval):
 186             return retval()
 187
 188     def _execute(self, command, args):
 189         if self._iterating:
 190             raise IteratingError("Cannot execute '%s' while iterating" %
 191                                  command)
 192         if self._pending:
 193             raise PendingCommandError("Cannot execute '%s' with "
 194                                       "pending commands" % command)
 195         retval = self._commands[command]
 196         if self._command_list is not None:
 197             if not callable(retval):
 198                 raise CommandListError("'%s' not allowed in command list" %
 199                                         command)
 200             self._write_command(command, args)
 201             self._command_list.append(retval)
 202         else:
 203             self._write_command(command, args)
 204             if callable(retval):
 205                 return retval()
 206             return retval
 207
 208     def _write_line(self, line):
 209         self._wfile.write("%s\n" % line)
 210         self._wfile.flush()
 211
 212     def _write_command(self, command, args=[]):
 213         parts = [command]
 214         for arg in args:
 215             parts.append('"%s"' % escape(str(arg)))
 216         self._write_line(" ".join(parts))
 217
 218     def _read_line(self):
 219         line = self._rfile.readline()
 220         if not line.endswith("\n"):
 221             raise ConnectionError("Connection lost while reading line")
 222         line = line.rstrip("\n")
 223         if line.startswith(ERROR_PREFIX):
 224             error = line[len(ERROR_PREFIX):].strip()
 225             raise CommandError(error)
 226         if self._command_list is not None:
 227             if line == NEXT:
 228                 return
 229             if line == SUCCESS:
 230                 raise ProtocolError("Got unexpected '%s'" % SUCCESS)
 231         elif line == SUCCESS:
 232             return
 233         return line
 234
 235     def _read_pair(self, separator):
 236         line = self._read_line()
 237         if line is None:
 238             return
 239         pair = line.split(separator, 1)
 240         if len(pair) < 2:
 241             raise ProtocolError("Could not parse pair: '%s'" % line)
 242         return pair
 243
 244     def _read_pairs(self, separator=": "):
 245         pair = self._read_pair(separator)
 246         while pair:
 247             yield pair
 248             pair = self._read_pair(separator)
 249
 250     def _read_list(self):
 251         seen = None
 252         for key, value in self._read_pairs():
 253             if key != seen:
 254                 if seen is not None:
 255                     raise ProtocolError("Expected key '%s', got '%s'" %
 256                                         (seen, key))
 257                 seen = key
 258             yield value
 259
 260     def _read_playlist(self):
 261         for key, value in self._read_pairs(":"):
 262             yield value
 263
 264     def _read_objects(self, delimiters=[]):
 265         obj = {}
 266         for key, value in self._read_pairs():
 267             key = key.lower()
 268             if obj:
 269                 if key in delimiters:
 270                     yield obj
 271                     obj = {}
 272                 elif key in obj:
 273                     if not isinstance(obj[key], list):
 274                         obj[key] = [obj[key], value]
 275                     else:
 276                         obj[key].append(value)
 277                     continue
 278             obj[key] = value
 279         if obj:
 280             yield obj
 281
 282     def _read_command_list(self):
 283         try:
 284             for retval in self._command_list:
 285                 yield retval()
 286         finally:
 287             self._command_list = None
 288         self._fetch_nothing()
 289
 290     def _iterator_wrapper(self, iterator):
 291         try:
 292             for item in iterator:
 293                 yield item
 294         finally:
 295             self._iterating = False
 296
 297     def _wrap_iterator(self, iterator):
 298         if not self.iterate:
 299             return list(iterator)
 300         self._iterating = True
 301         return self._iterator_wrapper(iterator)
 302
 303     def _fetch_nothing(self):
 304         line = self._read_line()
 305         if line is not None:
 306             raise ProtocolError("Got unexpected return value: '%s'" % line)
 307
 308     def _fetch_item(self):
 309         pairs = list(self._read_pairs())
 310         if len(pairs) != 1:
 311             return
 312         return pairs[0][1]
 313
 314     def _fetch_list(self):
 315         return self._wrap_iterator(self._read_list())
 316
 317     def _fetch_playlist(self):
 318         return self._wrap_iterator(self._read_playlist())
 319
 320     def _fetch_object(self):
 321         objs = list(self._read_objects())
 322         if not objs:
 323             return {}
 324         return objs[0]
 325
 326     def _fetch_objects(self, delimiters):
 327         return self._wrap_iterator(self._read_objects(delimiters))
 328
 329     def _fetch_changes(self):
 330         return self._fetch_objects(["cpos"])
 331
 332     def _fetch_songs(self):
 333         return self._fetch_objects(["file"])
 334
 335     def _fetch_playlists(self):
 336         return self._fetch_objects(["playlist"])
 337
 338     def _fetch_database(self):
 339         return self._fetch_objects(["file", "directory", "playlist"])
 340
 341     def _fetch_outputs(self):
 342         return self._fetch_objects(["outputid"])
 343
 344     def _fetch_plugins(self):
 345         return self._fetch_objects(["plugin"])
 346
 347     def _fetch_command_list(self):
 348         return self._wrap_iterator(self._read_command_list())
 349
 350     def _hello(self):
 351         line = self._rfile.readline()
 352         if not line.endswith("\n"):
 353             raise ConnectionError("Connection lost while reading MPD hello")
 354         line = line.rstrip("\n")
 355         if not line.startswith(HELLO_PREFIX):
 356             raise ProtocolError("Got invalid MPD hello: '%s'" % line)
 357         self.mpd_version = line[len(HELLO_PREFIX):].strip()
 358
 359     def _reset(self):
 360         self.mpd_version = None
 361         self._iterating = False
 362         self._pending = []
 363         self._command_list = None
 364         self._sock = None
 365         self._rfile = _NotConnected()
 366         self._wfile = _NotConnected()
 367
 368     def _connect_unix(self, path):
 369         if not hasattr(socket, "AF_UNIX"):
 370             raise ConnectionError("Unix domain sockets not supported "
 371                                   "on this platform")
 372         sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
 373         sock.connect(path)
 374         return sock
 375
 376     def _connect_tcp(self, host, port):
 377         try:
 378             flags = socket.AI_ADDRCONFIG
 379         except AttributeError:
 380             flags = 0
 381         err = None
 382         for res in socket.getaddrinfo(host, port, socket.AF_UNSPEC,
 383                                       socket.SOCK_STREAM, socket.IPPROTO_TCP,
 384                                       flags):
 385             af, socktype, proto, canonname, sa = res
 386             sock = None
 387             try:
 388                 sock = socket.socket(af, socktype, proto)
 389                 sock.connect(sa)
 390                 return sock
 391             except socket.error, err:
 392                 if sock is not None:
 393                     sock.close()
 394         if err is not None:
 395             raise err
 396         else:
 397             raise ConnectionError("getaddrinfo returns an empty list")
 398
 399     def connect(self, host, port):
 400         if self._sock is not None:
 401             raise ConnectionError("Already connected")
 402         if host.startswith("/"):
 403             self._sock = self._connect_unix(host)
 404         else:
 405             self._sock = self._connect_tcp(host, port)
 406         self._rfile = self._sock.makefile("rb")
 407         self._wfile = self._sock.makefile("wb")
 408         try:
 409             self._hello()
 410         except:
 411             self.disconnect()
 412             raise
 413
 414     def disconnect(self):
 415         self._rfile.close()
 416         self._wfile.close()
 417         self._sock.close()
 418         self._reset()
 419
 420     def fileno(self):
 421         if self._sock is None:
 422             raise ConnectionError("Not connected")
 423         return self._sock.fileno()
 424
 425     def command_list_ok_begin(self):
 426         if self._command_list is not None:
 427             raise CommandListError("Already in command list")
 428         if self._iterating:
 429             raise IteratingError("Cannot begin command list while iterating")
 430         if self._pending:
 431             raise PendingCommandError("Cannot begin command list "
 432                                       "with pending commands")
 433         self._write_command("command_list_ok_begin")
 434         self._command_list = []
 435
 436     def command_list_end(self):
 437         if self._command_list is None:
 438             raise CommandListError("Not in command list")
 439         if self._iterating:
 440             raise IteratingError("Already iterating over a command list")
 441         self._write_command("command_list_end")
 442         return self._fetch_command_list()
 443
 444
 445 def escape(text):
 446     return text.replace("\\", "\\\\").replace('"', '\\"')
 447
 448
 449 # vim: set expandtab shiftwidth=4 softtabstop=4 textwidth=79: