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