/usr/lib/language-selector/ls-dbus-backend is in language-selector-common 0.79.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 | #!/usr/bin/python
import dbus
import dbus.mainloop.glib
dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
import dbus.service
import gobject
import logging
import re
import subprocess
import sys
import LanguageSelector.macros
import LanguageSelector.FontConfig
from LanguageSelector.utils import *
DATADIR="/usr/share/language-selector/"
class LanguageSelectorServer(dbus.service.Object):
    def __init__(self, bus=dbus.SystemBus(), datadir=DATADIR):
	    bus_name = dbus.service.BusName('com.ubuntu.LanguageSelector',
					    bus=bus)
	    dbus.service.Object.__init__(self, bus_name, '/')
            self._datadir = "/usr/share/language-selector/"
            self._re_locale = re.compile(r'^[\w.@:-]+$')
    def _authWithPolicyKit(self, sender, connection, priv):
        logging.debug("_authWithPolicyKit")
        system_bus = dbus.SystemBus()
        obj = system_bus.get_object("org.freedesktop.PolicyKit1",
                                    "/org/freedesktop/PolicyKit1/Authority",
                                    "org.freedesktop.PolicyKit1.Authority")
        policykit = dbus.Interface(obj, "org.freedesktop.PolicyKit1.Authority")
        info = dbus.Interface(connection.get_object('org.freedesktop.DBus',
                                              '/org/freedesktop/DBus/Bus',
                                              False),
                              'org.freedesktop.DBus')
        pid = info.GetConnectionUnixProcessID(sender)
        subject = ('unix-process',
                   { 'pid' : dbus.UInt32(pid, variant_level=1),
                     'start-time' : dbus.UInt64(0),
                   }
                  )
        details = { '' : '' }
        flags = dbus.UInt32(1) #   AllowUserInteraction = 0x00000001
        cancel_id = ''
        (ok, notused, details) = policykit.CheckAuthorization(
            subject, priv, details, flags, cancel_id)
        return ok
    @dbus.service.method(dbus_interface='com.ubuntu.LanguageSelector',
			 in_signature="s", 
			 out_signature="b",
                         connection_keyword='connection',
			 sender_keyword='sender')
    def SetSystemDefaultLanguageEnv(self, sysLanguage, sender, connection):
        """ sysLanguage - the default system LANGUAGE and LANG """
        logging.debug("SetSystemDefaultLanguage")
        if not self._re_locale.search(sysLanguage):
            logging.error('SetSystemDefaultLanguage: Invalid locale "%s", rejecting', sysLanguage)
            return False
        if not self._authWithPolicyKit(sender, connection, "com.ubuntu.languageselector.setsystemdefaultlanguage"):
            return False
        conffiles = ["/etc/default/locale", "/etc/environment"]
        findString = "LANGUAGE="
        setString = "LANGUAGE=\"%s\"\n" % sysLanguage
        find_string_and_replace(findString, setString, conffiles)
        defaultLanguageLocale = language2locale(sysLanguage)
        findString = "LANG="
        setString = "LANG=\"%s\"\n" % defaultLanguageLocale
        find_string_and_replace(findString, setString, conffiles)
        # update fontconfig voodoo
        fc = LanguageSelector.FontConfig.FontConfigHack()
        macr = LanguageSelector.macros.LangpackMacros(self._datadir, defaultLanguageLocale)
        defaultLanguageCode = macr["LOCALE"]
        if defaultLanguageCode in fc.getAvailableConfigs():
            subprocess.call(["fontconfig-voodoo", "-f",
                             "--set=%s" % defaultLanguageCode])
        else:
            subprocess.call(["fontconfig-voodoo", "--remove-current"])
        return True
    @dbus.service.method(dbus_interface='com.ubuntu.LanguageSelector',
			 in_signature="s", 
			 out_signature="b",
                         connection_keyword='connection',
			 sender_keyword='sender')
    def SetSystemDefaultFormatsEnv(self, sysFormats, sender, connection):
        """ sysFormats: various LC_* variables (de_DE.UTF-8) """
        logging.debug("SetSystemDefaultFormatsEnv")
        if not self._re_locale.search(sysFormats):
            logging.error('SetSystemDefaultFormatsEnv: Invalid locale "%s", rejecting', sysFormats)
            return False
        if not self._authWithPolicyKit(sender, connection, "com.ubuntu.languageselector.setsystemdefaultlanguage"):
            return False
        conffiles = ["/etc/default/locale", "/etc/environment"]
        macr = LanguageSelector.macros.LangpackMacros(self._datadir, sysFormats)
        for var in 'LC_NUMERIC', 'LC_TIME', 'LC_MONETARY', 'LC_PAPER', 'LC_IDENTIFICATION', \
                   'LC_NAME', 'LC_ADDRESS', 'LC_TELEPHONE', 'LC_MEASUREMENT':
            findString = "%s=" % var
            setString = "%s=\"%s\"\n" % (var, macr["SYSLOCALE"])
            find_string_and_replace(findString, setString, conffiles)
        return True
if __name__ == "__main__":
        # FIXME: use argparse
        if len(sys.argv) > 1 and sys.argv[1] == "--debug":
            logging.basicConfig(level=logging.DEBUG)
	server = LanguageSelectorServer()
	gobject.MainLoop().run()
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