mpd.py

   1 # Python MPD client library
   2 # Copyright (C) 2008-2010  J. Alexander Treuman <jat@spatialrift.net>
   3 #
   4 # This program is free software: you can redistribute it and/or modify
   5 # it under the terms of the GNU 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 # This program 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 General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU General Public License
  15 # along with this program.  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         }
 144
 145     def __getattr__(self, attr):
 146         if attr.startswith("send_"):
 147             command = attr.replace("send_", "", 1)
 148             wrapper = self._send
 149         elif attr.startswith("fetch_"):
 150             command = attr.replace("fetch_", "", 1)
 151             wrapper = self._fetch
 152         else:
 153             command = attr
 154             wrapper = self._execute
 155         command = command.replace("_", " ")
 156         if command not in self._commands:
 157             raise AttributeError("'%s' object has no attribute '%s'" %
 158                                  (self.__class__.__name__, attr))
 159         return lambda *args: wrapper(command, args)
 160
 161     def _send(self, command, args):
 162         if self._command_list is not None:
 163             raise CommandListError("Cannot use send_%s in a command list" %
 164                                    command.replace(" ", "_"))
 165         self._write_command(command, args)
 166         self._pending.append(command)
 167
 168     def _fetch(self, command, args=None):
 169         if self._command_list is not None:
 170             raise CommandListError("Cannot use fetch_%s in a command list" %
 171                                    command.replace(" ", "_"))
 172         if self._iterating:
 173             raise IteratingError("Cannot use fetch_%s while iterating" %
 174                                  command.replace(" ", "_"))
 175         if not self._pending:
 176             raise PendingCommandError("No pending commands to fetch")
 177         if self._pending[0] != command:
 178             raise PendingCommandError("'%s' is not the currently "
 179                                       "pending command" % command)
 180         del self._pending[0]
 181         retval = self._commands[command]
 182         if callable(retval):
 183             return retval()
 184
 185     def _execute(self, command, args):
 186         if self._iterating:
 187             raise IteratingError("Cannot execute '%s' while iterating" %
 188                                  command)
 189         if self._pending:
 190             raise PendingCommandError("Cannot execute '%s' with "
 191                                       "pending commands" % command)
 192         retval = self._commands[command]
 193         if self._command_list is not None:
 194             if not callable(retval):
 195                 raise CommandListError("'%s' not allowed in command list" %
 196                                         command)
 197             self._write_command(command, args)
 198             self._command_list.append(retval)
 199         else:
 200             self._write_command(command, args)
 201             if callable(retval):
 202                 return retval()
 203             return retval
 204
 205     def _write_line(self, line):
 206         self._wfile.write("%s\n" % line)
 207         self._wfile.flush()
 208
 209     def _write_command(self, command, args=[]):
 210         parts = [command]
 211         for arg in args:
 212             parts.append('"%s"' % escape(str(arg)))
 213         self._write_line(" ".join(parts))
 214
 215     def _read_line(self):
 216         line = self._rfile.readline()
 217         if not line.endswith("\n"):
 218             raise ConnectionError("Connection lost while reading line")
 219         line = line.rstrip("\n")
 220         if line.startswith(ERROR_PREFIX):
 221             error = line[len(ERROR_PREFIX):].strip()
 222             raise CommandError(error)
 223         if self._command_list is not None:
 224             if line == NEXT:
 225                 return
 226             if line == SUCCESS:
 227                 raise ProtocolError("Got unexpected '%s'" % SUCCESS)
 228         elif line == SUCCESS:
 229             return
 230         return line
 231
 232     def _read_pair(self, separator):
 233         line = self._read_line()
 234         if line is None:
 235             return
 236         pair = line.split(separator, 1)
 237         if len(pair) < 2:
 238             raise ProtocolError("Could not parse pair: '%s'" % line)
 239         return pair
 240
 241     def _read_pairs(self, separator=": "):
 242         pair = self._read_pair(separator)
 243         while pair:
 244             yield pair
 245             pair = self._read_pair(separator)
 246
 247     def _read_list(self):
 248         seen = None
 249         for key, value in self._read_pairs():
 250             if key != seen:
 251                 if seen is not None:
 252                     raise ProtocolError("Expected key '%s', got '%s'" %
 253                                         (seen, key))
 254                 seen = key
 255             yield value
 256
 257     def _read_playlist(self):
 258         for key, value in self._read_pairs(":"):
 259             yield value
 260
 261     def _read_objects(self, delimiters=[]):
 262         obj = {}
 263         for key, value in self._read_pairs():
 264             key = key.lower()
 265             if obj:
 266                 if key in delimiters:
 267                     yield obj
 268                     obj = {}
 269                 elif key in obj:
 270                     if not isinstance(obj[key], list):
 271                         obj[key] = [obj[key], value]
 272                     else:
 273                         obj[key].append(value)
 274                     continue
 275             obj[key] = value
 276         if obj:
 277             yield obj
 278
 279     def _read_command_list(self):
 280         try:
 281             for retval in self._command_list:
 282                 yield retval()
 283         finally:
 284             self._command_list = None
 285         self._fetch_nothing()
 286
 287     def _iterator_wrapper(self, iterator):
 288         try:
 289             for item in iterator:
 290                 yield item
 291         finally:
 292             self._iterating = False
 293
 294     def _wrap_iterator(self, iterator):
 295         if not self.iterate:
 296             return list(iterator)
 297         self._iterating = True
 298         return self._iterator_wrapper(iterator)
 299
 300     def _fetch_nothing(self):
 301         line = self._read_line()
 302         if line is not None:
 303             raise ProtocolError("Got unexpected return value: '%s'" % line)
 304
 305     def _fetch_item(self):
 306         pairs = list(self._read_pairs())
 307         if len(pairs) != 1:
 308             return
 309         return pairs[0][1]
 310
 311     def _fetch_list(self):
 312         return self._wrap_iterator(self._read_list())
 313
 314     def _fetch_playlist(self):
 315         return self._wrap_iterator(self._read_playlist())
 316
 317     def _fetch_object(self):
 318         objs = list(self._read_objects())
 319         if not objs:
 320             return {}
 321         return objs[0]
 322
 323     def _fetch_objects(self, delimiters):
 324         return self._wrap_iterator(self._read_objects(delimiters))
 325
 326     def _fetch_songs(self):
 327         return self._fetch_objects(["file"])
 328
 329     def _fetch_playlists(self):
 330         return self._fetch_objects(["playlist"])
 331
 332     def _fetch_database(self):
 333         return self._fetch_objects(["file", "directory", "playlist"])
 334
 335     def _fetch_outputs(self):
 336         return self._fetch_objects(["outputid"])
 337
 338     def _fetch_changes(self):
 339         return self._fetch_objects(["cpos"])
 340
 341     def _fetch_command_list(self):
 342         return self._wrap_iterator(self._read_command_list())
 343
 344     def _hello(self):
 345         line = self._rfile.readline()
 346         if not line.endswith("\n"):
 347             raise ConnectionError("Connection lost while reading MPD hello")
 348         line = line.rstrip("\n")
 349         if not line.startswith(HELLO_PREFIX):
 350             raise ProtocolError("Got invalid MPD hello: '%s'" % line)
 351         self.mpd_version = line[len(HELLO_PREFIX):].strip()
 352
 353     def _reset(self):
 354         self.mpd_version = None
 355         self._iterating = False
 356         self._pending = []
 357         self._command_list = None
 358         self._sock = None
 359         self._rfile = _NotConnected()
 360         self._wfile = _NotConnected()
 361
 362     def _connect_unix(self, path):
 363         if not hasattr(socket, "AF_UNIX"):
 364             raise ConnectionError("Unix domain sockets not supported "
 365                                   "on this platform")
 366         sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
 367         sock.connect(path)
 368         return sock
 369
 370     def _connect_tcp(self, host, port):
 371         try:
 372             flags = socket.AI_ADDRCONFIG
 373         except AttributeError:
 374             flags = 0
 375         err = None
 376         for res in socket.getaddrinfo(host, port, socket.AF_UNSPEC,
 377                                       socket.SOCK_STREAM, socket.IPPROTO_TCP,
 378                                       flags):
 379             af, socktype, proto, canonname, sa = res
 380             sock = None
 381             try:
 382                 sock = socket.socket(af, socktype, proto)
 383                 sock.connect(sa)
 384                 return sock
 385             except socket.error, err:
 386                 if sock is not None:
 387                     sock.close()
 388         if err is not None:
 389             raise err
 390         else:
 391             raise ConnectionError("getaddrinfo returns an empty list")
 392
 393     def connect(self, host, port):
 394         if self._sock is not None:
 395             raise ConnectionError("Already connected")
 396         if host.startswith("/"):
 397             self._sock = self._connect_unix(host)
 398         else:
 399             self._sock = self._connect_tcp(host, port)
 400         self._rfile = self._sock.makefile("rb")
 401         self._wfile = self._sock.makefile("wb")
 402         try:
 403             self._hello()
 404         except:
 405             self.disconnect()
 406             raise
 407
 408     def disconnect(self):
 409         self._rfile.close()
 410         self._wfile.close()
 411         self._sock.close()
 412         self._reset()
 413
 414     def fileno(self):
 415         if self._sock is None:
 416             raise ConnectionError("Not connected")
 417         return self._sock.fileno()
 418
 419     def command_list_ok_begin(self):
 420         if self._command_list is not None:
 421             raise CommandListError("Already in command list")
 422         if self._iterating:
 423             raise IteratingError("Cannot begin command list while iterating")
 424         if self._pending:
 425             raise PendingCommandError("Cannot begin command list "
 426                                       "with pending commands")
 427         self._write_command("command_list_ok_begin")
 428         self._command_list = []
 429
 430     def command_list_end(self):
 431         if self._command_list is None:
 432             raise CommandListError("Not in command list")
 433         if self._iterating:
 434             raise IteratingError("Already iterating over a command list")
 435         self._write_command("command_list_end")
 436         return self._fetch_command_list()
 437
 438
 439 def escape(text):
 440     return text.replace("\\", "\\\\").replace('"', '\\"')
 441
 442
 443 # vim: set expandtab shiftwidth=4 softtabstop=4 textwidth=79: