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