def check_dirs_and_files(self):
        if not os.path.isdir(self.config["local"]["media_dir"]):
            logger.warning("Local media dir %s does not exist." % self.config["local"]["media_dir"])

        try:
            path.get_or_create_dir(self.config["local"]["data_dir"])
        except EnvironmentError as error:
            logger.warning("Could not create local data dir: %s", encoding.locale_decode(error))

        # TODO: replace with data dir?
        try:
            path.get_or_create_dir(self.config["local"]["playlists_dir"])
        except EnvironmentError as error:
            logger.warning("Could not create local playlists dir: %s", encoding.locale_decode(error))

def _process(pipeline, timeout_ms):
    clock = pipeline.get_clock()
    bus = pipeline.get_bus()
    timeout = timeout_ms * gst.MSECOND
    tags, mime, have_audio, missing_description = {}, None, False, None

    types = (
        gst.MESSAGE_ELEMENT
        | gst.MESSAGE_APPLICATION
        | gst.MESSAGE_ERROR
        | gst.MESSAGE_EOS
        | gst.MESSAGE_ASYNC_DONE
        | gst.MESSAGE_TAG
    )

    start = clock.get_time()
    while timeout > 0:
        message = bus.timed_pop_filtered(timeout, types)

        if message is None:
            break
        elif message.type == gst.MESSAGE_ELEMENT:
            if gst.pbutils.is_missing_plugin_message(message):
                missing_description = encoding.locale_decode(_missing_plugin_desc(message))
        elif message.type == gst.MESSAGE_APPLICATION:
            if message.structure.get_name() == "have-type":
                mime = message.structure["caps"].get_name()
                if mime.startswith("text/") or mime == "application/xml":
                    return tags, mime, have_audio
            elif message.structure.get_name() == "have-audio":
                have_audio = True
        elif message.type == gst.MESSAGE_ERROR:
            error = encoding.locale_decode(message.parse_error()[0])
            if missing_description:
                error = "%s (%s)" % (missing_description, error)
            raise exceptions.ScannerError(error)
        elif message.type == gst.MESSAGE_EOS:
            return tags, mime, have_audio
        elif message.type == gst.MESSAGE_ASYNC_DONE:
            if message.src == pipeline:
                return tags, mime, have_audio
        elif message.type == gst.MESSAGE_TAG:
            taglist = message.parse_tag()
            # Note that this will only keep the last tag.
            tags.update(utils.convert_taglist(taglist))

        timeout -= clock.get_time() - start

    raise exceptions.ScannerError("Timeout after %dms" % timeout_ms)

    def test_can_decode_utf8_strings_with_french_content(self, mock):
        mock.return_value = 'UTF-8'

        result = locale_decode(
            b'[Errno 98] Adresse d\xc3\xa9j\xc3\xa0 utilis\xc3\xa9e')

        self.assertEqual('[Errno 98] Adresse d\xe9j\xe0 utilis\xe9e', result)

    def __init__(self, config, core):
        super(MpdFrontend, self).__init__()

        hostname = network.format_hostname(config['mpd']['hostname'])
        self.hostname = hostname
        self.port = config['mpd']['port']
        self.zeroconf_name = config['mpd']['zeroconf']
        self.zeroconf_service = None

        try:
            network.Server(
                self.hostname, self.port,
                protocol=session.MpdSession,
                protocol_kwargs={
                    'config': config,
                    'core': core,
                },
                max_connections=config['mpd']['max_connections'],
                timeout=config['mpd']['connection_timeout'])
        except IOError as error:
            logger.error(
                'MPD server startup failed: %s',
                encoding.locale_decode(error))
            sys.exit(1)

        logger.info('MPD server running at [%s]:%s', self.hostname, self.port)

    def _collect(self):
        """Polls for messages to collect data."""
        start = time.time()
        timeout_s = self._timeout_ms / float(1000)
        tags = {}

        while time.time() - start < timeout_s:
            if not self._bus.have_pending():
                continue
            message = self._bus.pop()

            if message.type == gst.MESSAGE_ERROR:
                raise exceptions.ScannerError(
                    encoding.locale_decode(message.parse_error()[0]))
            elif message.type == gst.MESSAGE_EOS:
                return tags
            elif message.type == gst.MESSAGE_ASYNC_DONE:
                if message.src == self._pipe:
                    return tags
            elif message.type == gst.MESSAGE_TAG:
                # Taglists are not really dicts, hence the lack of .items() and
                # explicit .keys. We only keep the last tag for each key, as we
                # assume this is the best, some formats will produce multiple
                # taglists. Lastly we force everything to lists for conformity.
                taglist = message.parse_tag()
                for key in taglist.keys():
                    value = taglist[key]
                    if not isinstance(value, list):
                        value = [value]
                    tags[key] = value

        raise exceptions.ScannerError('Timeout after %dms' % self._timeout_ms)

    def check_dirs_and_files(self):
        if not os.path.isdir(self.config['local']['media_dir']):
            logger.warning('Local media dir %s does not exist.' %
                           self.config['local']['media_dir'])

        try:
            path.get_or_create_dir(self.config['local']['playlists_dir'])
        except EnvironmentError as error:
            logger.warning(
                'Could not create local playlists dir: %s',
                encoding.locale_decode(error))

        try:
            path.get_or_create_file(self.config['local']['tag_cache_file'])
        except EnvironmentError as error:
            logger.warning(
                'Could not create empty tag cache file: %s',
                encoding.locale_decode(error))

def _send_broadcast(client, msg):
    # We could check for client.ws_connection, but we don't really
    # care why the broadcast failed, we just want the rest of them
    # to succeed, so catch everything.
    try:
        client.write_message(msg)
    except Exception as e:
        error_msg = encoding.locale_decode(e)
        logger.debug('Broadcast of WebSocket message to %s failed: %s',
                     client.request.remote_ip, error_msg)

    def __init__(self, frontend, serial_port, serial_bps):
        super(SerialMonoboxController, self).__init__()
        try:
            self.s = serial.Serial(serial_port, serial_bps, timeout=0.5)
        except Exception as error:
            raise exceptions.FrontendError('SMC serial connection failed: %s' %
                    encoding.locale_decode(error))

        self.frontend = frontend
        self.buffer = ''

 def send(self, data):
     """Send data to client, return any unsent data."""
     try:
         sent = self.sock.send(data)
         return data[sent:]
     except socket.error as e:
         if e.errno in (errno.EWOULDBLOCK, errno.EINTR):
             return data
         self.stop(
             'Unexpected client error: %s' % encoding.locale_decode(e))
         return b''

def check_dirs_and_files(config):
    if not os.path.isdir(config['local']['media_dir']):
        logger.warning(
            'Local media dir %s does not exist.' %
            config['local']['media_dir'])

    try:
        path.get_or_create_dir(config['local']['data_dir'])
    except EnvironmentError as error:
        logger.warning(
            'Could not create local data dir: %s',
            encoding.locale_decode(error))

    # TODO: replace with data dir?
    try:
        path.get_or_create_dir(config['local']['playlists_dir'])
    except EnvironmentError as error:
        logger.warning(
            'Could not create local playlists dir: %s',
            encoding.locale_decode(error))

    def test_can_decode_an_ioerror_with_french_content(self, mock):
        mock.return_value = 'UTF-8'

        error = IOError(98, b'Adresse d\xc3\xa9j\xc3\xa0 utilis\xc3\xa9e')
        result = locale_decode(error)
        expected = '[Errno 98] Adresse d\xe9j\xe0 utilis\xe9e'

        self.assertEqual(
            expected, result,
            '%r decoded to %r does not match expected %r' % (
                error, result, expected))

def try_ipv6_socket():
    """Determine if system really supports IPv6"""
    if not socket.has_ipv6:
        return False
    try:
        socket.socket(socket.AF_INET6).close()
        return True
    except IOError as error:
        logger.debug(
            "Platform supports IPv6, but socket creation failed, " "disabling: %s", encoding.locale_decode(error)
        )
    return False

    def __init__(self, config, audio):
        super(M3UBackend, self).__init__()

        self._config = config

        try:
            path.get_or_create_dir(config['m3u']['playlists_dir'])
        except EnvironmentError as error:
            logger.warning(
                'Could not create M3U playlists dir: %s',
                encoding.locale_decode(error))

        self.playlists = M3UPlaylistsProvider(backend=self)
        self.library = M3ULibraryProvider(backend=self)

def _find_worker(relative, follow, done, work, results, errors):
    """Worker thread for collecting stat() results.

    :param str relative: directory to make results relative to
    :param bool follow: if symlinks should be followed
    :param threading.Event done: event indicating that all work has been done
    :param queue.Queue work: queue of paths to process
    :param dict results: shared dictionary for storing all the stat() results
    :param dict errors: shared dictionary for storing any per path errors
    """
    while not done.is_set():
        try:
            entry, parents = work.get(block=False)
        except queue.Empty:
            continue

        if relative:
            path = os.path.relpath(entry, relative)
        else:
            path = entry

        try:
            if follow:
                st = os.stat(entry)
            else:
                st = os.lstat(entry)

            if (st.st_dev, st.st_ino) in parents:
                errors[path] = exceptions.FindError('Sym/hardlink loop found.')
                continue

            parents = parents + [(st.st_dev, st.st_ino)]
            if stat.S_ISDIR(st.st_mode):
                for e in os.listdir(entry):
                    work.put((os.path.join(entry, e), parents))
            elif stat.S_ISREG(st.st_mode):
                results[path] = st
            elif stat.S_ISLNK(st.st_mode):
                errors[path] = exceptions.FindError('Not following symlinks.')
            else:
                errors[path] = exceptions.FindError('Not a file or directory.')

        except OSError as e:
            errors[path] = exceptions.FindError(
                encoding.locale_decode(e.strerror), e.errno)
        finally:
            work.task_done()

def create_file_structures_and_config(args, extensions):
    path.get_or_create_dir(b'$XDG_DATA_DIR/mopidy')
    path.get_or_create_dir(b'$XDG_CONFIG_DIR/mopidy')

    # Initialize whatever the last config file is with defaults
    config_file = args.config_files[-1]
    if os.path.exists(path.expand_path(config_file)):
        return

    try:
        default = config_lib.format_initial(extensions)
        path.get_or_create_file(config_file, mkdir=False, content=default)
        logger.info('Initialized %s with default config', config_file)
    except IOError as error:
        logger.warning(
            'Unable to initialize %s with default config: %s',
            config_file, encoding.locale_decode(error))

    def __init__(self, core):
        super(MpdFrontend, self).__init__()
        hostname = network.format_hostname(settings.MPD_SERVER_HOSTNAME)
        port = settings.MPD_SERVER_PORT

        try:
            network.Server(
                hostname, port,
                protocol=session.MpdSession, protocol_kwargs={'core': core},
                max_connections=settings.MPD_SERVER_MAX_CONNECTIONS)
        except IOError as error:
            logger.error(
                'MPD server startup failed: %s',
                encoding.locale_decode(error))
            sys.exit(1)

        logger.info('MPD server running at [%s]:%s', hostname, port)

def load_library(json_file):
    if not os.path.isfile(json_file):
        logger.info(
            'No local library metadata cache found at %s. Please run '
            '`mopidy local scan` to index your local music library. '
            'If you do not have a local music collection, you can disable the '
            'local backend to hide this message.',
            json_file)
        return {}
    try:
        with gzip.open(json_file, 'rb') as fp:
            return json.load(fp, object_hook=models.model_json_decoder)
    except (IOError, ValueError) as error:
        logger.warning(
            'Loading JSON local library failed: %s',
            encoding.locale_decode(error))
        return {}

def parse_m3u(file_path, media_dir):
    r"""
    Convert M3U file list of uris

    Example M3U data::

        # This is a comment
        Alternative\Band - Song.mp3
        Classical\Other Band - New Song.mp3
        Stuff.mp3
        D:\More Music\Foo.mp3
        http://www.example.com:8000/Listen.pls
        http://www.example.com/~user/Mine.mp3

    - Relative paths of songs should be with respect to location of M3U.
    - Paths are normaly platform specific.
    - Lines starting with # should be ignored.
    - m3u files are latin-1.
    - This function does not bother with Extended M3U directives.
    """
    # TODO: uris as bytes
    uris = []
    try:
        with open(file_path) as m3u:
            contents = m3u.readlines()
    except IOError as error:
        logger.warning('Couldn\'t open m3u: %s', locale_decode(error))
        return uris

    for line in contents:
        line = line.strip().decode('latin1')

        if line.startswith('#'):
            continue

        if urlparse.urlsplit(line).scheme:
            uris.append(line)
        elif os.path.normpath(line) == os.path.abspath(line):
            path = path_to_uri(line)
            uris.append(path)
        else:
            path = path_to_uri(os.path.join(media_dir, line))
            uris.append(path)

    return uris

    def __init__(self, config, core):
        super(HttpFrontend, self).__init__()

        self.hostname = network.format_hostname(config["http"]["hostname"])
        self.port = config["http"]["port"]
        tornado_hostname = config["http"]["hostname"]
        if tornado_hostname == "::":
            tornado_hostname = None

        try:
            logger.debug("Starting HTTP server")
            sockets = tornado.netutil.bind_sockets(self.port, tornado_hostname)
            self.server = HttpServer(config=config, core=core, sockets=sockets, apps=self.apps, statics=self.statics)
        except IOError as error:
            raise exceptions.FrontendError("HTTP server startup failed: %s" % encoding.locale_decode(error))

        self.zeroconf_name = config["http"]["zeroconf"]
        self.zeroconf_http = None
        self.zeroconf_mopidy_http = None

def parse_m3u(file_path, music_folder):
    r"""
    Convert M3U file list of uris

    Example M3U data::

        # This is a comment
        Alternative\Band - Song.mp3
        Classical\Other Band - New Song.mp3
        Stuff.mp3
        D:\More Music\Foo.mp3
        http://www.example.com:8000/Listen.pls
        http://www.example.com/~user/Mine.mp3

    - Relative paths of songs should be with respect to location of M3U.
    - Paths are normaly platform specific.
    - Lines starting with # should be ignored.
    - m3u files are latin-1.
    - This function does not bother with Extended M3U directives.
    """

    uris = []
    try:
        with open(file_path) as m3u:
            contents = m3u.readlines()
    except IOError as error:
        logger.error("Couldn't open m3u: %s", locale_decode(error))
        return uris

    for line in contents:
        line = line.strip().decode("latin1")

        if line.startswith("#"):
            continue

        # FIXME what about other URI types?
        if line.startswith("file://"):
            uris.append(line)
        else:
            path = path_to_uri(music_folder, line)
            uris.append(path)

    return uris