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             "list":             self._fetch_list,
 118             "listall":          self._fetch_database,
 119             "listallinfo":      self._fetch_database,
 120             "lsinfo":           self._fetch_database,
 121             "search":           self._fetch_songs,
 122             "update":           self._fetch_item,
 123             # Sticker Commands
 124             "sticker get":      self._fetch_item,
 125             "sticker set":      self._fetch_nothing,
 126             "sticker delete":   self._fetch_nothing,
 127             "sticker list":     self._fetch_list,
 128             "sticker find":     self._fetch_songs,
 129             # Connection Commands
 130             "close":            None,
 131             "kill":             None,
 132             "password":         self._fetch_nothing,
 133             "ping":             self._fetch_nothing,
 134             # Audio Output Commands
 135             "disableoutput":    self._fetch_nothing,
 136             "enableoutput":     self._fetch_nothing,
 137             "outputs":          self._fetch_outputs,
 138             # Reflection Commands
 139             "commands":         self._fetch_list,
 140             "notcommands":      self._fetch_list,
 141             "tagtypes":         self._fetch_list,
 142             "urlhandlers":      self._fetch_list,
 143             "decoders":         self._fetch_plugins,
 144         }
 145
 146     def __getattr__(self, attr):
 147         if attr.startswith("send_"):
 148             command = attr.replace("send_", "", 1)
 149             wrapper = self._send
 150         elif attr.startswith("fetch_"):
 151             command = attr.replace("fetch_", "", 1)
 152             wrapper = self._fetch
 153         else:
 154             command = attr
 155             wrapper = self._execute
 156         command = command.replace("_", " ")
 157         if command not in self._commands:
 158             raise AttributeError("'%s' object has no attribute '%s'" %
 159                                  (self.__class__.__name__, attr))
 160         return lambda *args: wrapper(command, args)
 161
 162     def _send(self, command, args):
 163         if self._command_list is not None:
 164             raise CommandListError("Cannot use send_%s in a command list" %
 165                                    command.replace(" ", "_"))
 166         self._write_command(command, args)
 167         self._pending.append(command)
 168
 169     def _fetch(self, command, args=None):
 170         if self._command_list is not None:
 171             raise CommandListError("Cannot use fetch_%s in a command list" %
 172                                    command.replace(" ", "_"))
 173         if self._iterating:
 174             raise IteratingError("Cannot use fetch_%s while iterating" %
 175                                  command.replace(" ", "_"))
 176         if not self._pending:
 177             raise PendingCommandError("No pending commands to fetch")
 178         if self._pending[0] != command:
 179             raise PendingCommandError("'%s' is not the currently "
 180                                       "pending command" % command)
 181         del self._pending[0]
 182         retval = self._commands[command]
 183         if callable(retval):
 184             return retval()
 185
 186     def _execute(self, command, args):
 187         if self._iterating:
 188             raise IteratingError("Cannot execute '%s' while iterating" %
 189                                  command)
 190         if self._pending:
 191             raise PendingCommandError("Cannot execute '%s' with "
 192                                       "pending commands" % command)
 193         retval = self._commands[command]
 194         if self._command_list is not None:
 195             if not callable(retval):
 196                 raise CommandListError("'%s' not allowed in command list" %
 197                                         command)
 198             self._write_command(command, args)
 199             self._command_list.append(retval)
 200         else:
 201             self._write_command(command, args)
 202             if callable(retval):
 203                 return retval()
 204             return retval
 205
 206     def _write_line(self, line):
 207         self._wfile.write("%s\n" % line)
 208         self._wfile.flush()
 209
 210     def _write_command(self, command, args=[]):
 211         parts = [command]
 212         for arg in args:
 213             parts.append('"%s"' % escape(str(arg)))
 214         self._write_line(" ".join(parts))
 215
 216     def _read_line(self):
 217         line = self._rfile.readline()
 218         if not line.endswith("\n"):
 219             raise ConnectionError("Connection lost while reading line")
 220         line = line.rstrip("\n")
 221         if line.startswith(ERROR_PREFIX):
 222             error = line[len(ERROR_PREFIX):].strip()
 223             raise CommandError(error)
 224         if self._command_list is not None:
 225             if line == NEXT:
 226                 return
 227             if line == SUCCESS:
 228                 raise ProtocolError("Got unexpected '%s'" % SUCCESS)
 229         elif line == SUCCESS:
 230             return
 231         return line
 232
 233     def _read_pair(self, separator):
 234         line = self._read_line()
 235         if line is None:
 236             return
 237         pair = line.split(separator, 1)
 238         if len(pair) < 2:
 239             raise ProtocolError("Could not parse pair: '%s'" % line)
 240         return pair
 241
 242     def _read_pairs(self, separator=": "):
 243         pair = self._read_pair(separator)
 244         while pair:
 245             yield pair
 246             pair = self._read_pair(separator)
 247
 248     def _read_list(self):
 249         seen = None
 250         for key, value in self._read_pairs():
 251             if key != seen:
 252                 if seen is not None:
 253                     raise ProtocolError("Expected key '%s', got '%s'" %
 254                                         (seen, key))
 255                 seen = key
 256             yield value
 257
 258     def _read_playlist(self):
 259         for key, value in self._read_pairs(":"):
 260             yield value
 261
 262     def _read_objects(self, delimiters=[]):
 263         obj = {}
 264         for key, value in self._read_pairs():
 265             key = key.lower()
 266             if obj:
 267                 if key in delimiters:
 268                     yield obj
 269                     obj = {}
 270                 elif key in obj:
 271                     if not isinstance(obj[key], list):
 272                         obj[key] = [obj[key], value]
 273                     else:
 274                         obj[key].append(value)
 275                     continue
 276             obj[key] = value
 277         if obj:
 278             yield obj
 279
 280     def _read_command_list(self):
 281         try:
 282             for retval in self._command_list:
 283                 yield retval()
 284         finally:
 285             self._command_list = None
 286         self._fetch_nothing()
 287
 288     def _iterator_wrapper(self, iterator):
 289         try:
 290             for item in iterator:
 291                 yield item
 292         finally:
 293             self._iterating = False
 294
 295     def _wrap_iterator(self, iterator):
 296         if not self.iterate:
 297             return list(iterator)
 298         self._iterating = True
 299         return self._iterator_wrapper(iterator)
 300
 301     def _fetch_nothing(self):
 302         line = self._read_line()
 303         if line is not None:
 304             raise ProtocolError("Got unexpected return value: '%s'" % line)
 305
 306     def _fetch_item(self):
 307         pairs = list(self._read_pairs())
 308         if len(pairs) != 1:
 309             return
 310         return pairs[0][1]
 311
 312     def _fetch_list(self):
 313         return self._wrap_iterator(self._read_list())
 314
 315     def _fetch_playlist(self):
 316         return self._wrap_iterator(self._read_playlist())
 317
 318     def _fetch_object(self):
 319         objs = list(self._read_objects())
 320         if not objs:
 321             return {}
 322         return objs[0]
 323
 324     def _fetch_objects(self, delimiters):
 325         return self._wrap_iterator(self._read_objects(delimiters))
 326
 327     def _fetch_changes(self):
 328         return self._fetch_objects(["cpos"])
 329
 330     def _fetch_songs(self):
 331         return self._fetch_objects(["file"])
 332
 333     def _fetch_playlists(self):
 334         return self._fetch_objects(["playlist"])
 335
 336     def _fetch_database(self):
 337         return self._fetch_objects(["file", "directory", "playlist"])
 338
 339     def _fetch_outputs(self):
 340         return self._fetch_objects(["outputid"])
 341
 342     def _fetch_plugins(self):
 343         return self._fetch_objects(["plugin"])
 344
 345     def _fetch_command_list(self):
 346         return self._wrap_iterator(self._read_command_list())
 347
 348     def _hello(self):
 349         line = self._rfile.readline()
 350         if not line.endswith("\n"):
 351             raise ConnectionError("Connection lost while reading MPD hello")
 352         line = line.rstrip("\n")
 353         if not line.startswith(HELLO_PREFIX):
 354             raise ProtocolError("Got invalid MPD hello: '%s'" % line)
 355         self.mpd_version = line[len(HELLO_PREFIX):].strip()
 356
 357     def _reset(self):
 358         self.mpd_version = None
 359         self._iterating = False
 360         self._pending = []
 361         self._command_list = None
 362         self._sock = None
 363         self._rfile = _NotConnected()
 364         self._wfile = _NotConnected()
 365
 366     def _connect_unix(self, path):
 367         if not hasattr(socket, "AF_UNIX"):
 368             raise ConnectionError("Unix domain sockets not supported "
 369                                   "on this platform")
 370         sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
 371         sock.connect(path)
 372         return sock
 373
 374     def _connect_tcp(self, host, port):
 375         try:
 376             flags = socket.AI_ADDRCONFIG
 377         except AttributeError:
 378             flags = 0
 379         err = None
 380         for res in socket.getaddrinfo(host, port, socket.AF_UNSPEC,
 381                                       socket.SOCK_STREAM, socket.IPPROTO_TCP,
 382                                       flags):
 383             af, socktype, proto, canonname, sa = res
 384             sock = None
 385             try:
 386                 sock = socket.socket(af, socktype, proto)
 387                 sock.connect(sa)
 388                 return sock
 389             except socket.error, err:
 390                 if sock is not None:
 391                     sock.close()
 392         if err is not None:
 393             raise err
 394         else:
 395             raise ConnectionError("getaddrinfo returns an empty list")
 396
 397     def connect(self, host, port):
 398         if self._sock is not None:
 399             raise ConnectionError("Already connected")
 400         if host.startswith("/"):
 401             self._sock = self._connect_unix(host)
 402         else:
 403             self._sock = self._connect_tcp(host, port)
 404         self._rfile = self._sock.makefile("rb")
 405         self._wfile = self._sock.makefile("wb")
 406         try:
 407             self._hello()
 408         except:
 409             self.disconnect()
 410             raise
 411
 412     def disconnect(self):
 413         self._rfile.close()
 414         self._wfile.close()
 415         self._sock.close()
 416         self._reset()
 417
 418     def fileno(self):
 419         if self._sock is None:
 420             raise ConnectionError("Not connected")
 421         return self._sock.fileno()
 422
 423     def command_list_ok_begin(self):
 424         if self._command_list is not None:
 425             raise CommandListError("Already in command list")
 426         if self._iterating:
 427             raise IteratingError("Cannot begin command list while iterating")
 428         if self._pending:
 429             raise PendingCommandError("Cannot begin command list "
 430                                       "with pending commands")
 431         self._write_command("command_list_ok_begin")
 432         self._command_list = []
 433
 434     def command_list_end(self):
 435         if self._command_list is None:
 436             raise CommandListError("Not in command list")
 437         if self._iterating:
 438             raise IteratingError("Already iterating over a command list")
 439         self._write_command("command_list_end")
 440         return self._fetch_command_list()
 441
 442
 443 def escape(text):
 444     return text.replace("\\", "\\\\").replace('"', '\\"')
 445
 446
 447 # vim: set expandtab shiftwidth=4 softtabstop=4 textwidth=79: