zeroinstall/injector/background.py

   1 """
   2 Check for updates in a background process. If we can start a program immediately, but some of our information
   3 is rather old (longer that the L{policy.Policy.freshness} threshold) then we run it anyway, and check for updates using a new
   4 process that runs quietly in the background.
   5
   6 This avoids the need to annoy people with a 'checking for updates' box when they're trying to run things.
   7 """
   8
   9 import sys, os
  10 from logging import info, warn
  11 from zeroinstall.support import tasks
  12 from zeroinstall.injector.iface_cache import iface_cache
  13 from zeroinstall.injector import handler
  14
  15 # Copyright (C) 2009, Thomas Leonard
  16 # See the README file for details, or visit http://0install.net.
  17
  18 def _escape_xml(s):
  19         return s.replace('&', '&amp;').replace('<', '&lt;')
  20
  21 def _exec_gui(uri, *args):
  22         os.execvp('0launch', ['0launch', '--download-only', '--gui'] + list(args) + [uri])
  23
  24 class _NetworkState:
  25         NM_STATE_UNKNOWN = 0
  26         NM_STATE_ASLEEP = 1
  27         NM_STATE_CONNECTING = 2
  28         NM_STATE_CONNECTED = 3
  29         NM_STATE_DISCONNECTED = 4
  30
  31 class BackgroundHandler(handler.Handler):
  32         """A Handler for non-interactive background updates. Runs the GUI if interaction is required."""
  33         def __init__(self, title):
  34                 handler.Handler.__init__(self)
  35                 self.title = title
  36                 self.notification_service = None
  37                 self.network_manager = None
  38
  39                 try:
  40                         import dbus
  41                         import dbus.glib
  42
  43                         session_bus = dbus.SessionBus()
  44                 except Exception, ex:
  45                         info("Failed to import D-BUS bindings: %s", ex)
  46                         return
  47
  48                 try:
  49                         remote_object = session_bus.get_object('org.freedesktop.Notifications',
  50                                                                 '/org/freedesktop/Notifications')
  51
  52                         self.notification_service = dbus.Interface(remote_object,
  53                                                         'org.freedesktop.Notifications')
  54
  55                         # The Python bindings insist on printing a pointless introspection
  56                         # warning to stderr if the service is missing. Force it to be done
  57                         # now so we can skip it
  58                         old_stderr = sys.stderr
  59                         sys.stderr = None
  60                         try:
  61                                 self.notification_service.GetCapabilities()
  62                         finally:
  63                                 sys.stderr = old_stderr
  64                 except Exception, ex:
  65                         info("No D-BUS notification service available: %s", ex)
  66
  67                 try:
  68                         system_bus = dbus.SystemBus()
  69                         remote_object = system_bus.get_object('org.freedesktop.NetworkManager',
  70                                                                 '/org/freedesktop/NetworkManager')
  71
  72                         self.network_manager = dbus.Interface(remote_object,
  73                                                         'org.freedesktop.NetworkManager')
  74                 except Exception, ex:
  75                         info("No D-BUS network manager service available: %s", ex)
  76
  77         def get_network_state(self):
  78                 if self.network_manager:
  79                         try:
  80                                 return self.network_manager.state()
  81                         except Exception, ex:
  82                                 warn("Error getting network state: %s", ex)
  83                 return _NetworkState.NM_STATE_UNKNOWN
  84
  85         def confirm_trust_keys(self, interface, sigs, iface_xml):
  86                 """Run the GUI if we need to confirm any keys."""
  87                 self.notify("Zero Install", "Can't update interface; signature not yet trusted. Running GUI...", timeout = 2)
  88                 _exec_gui(interface.uri, '--refresh')
  89
  90         def report_error(self, exception, tb = None):
  91                 self.notify("Zero Install", "Error updating %s: %s" % (self.title, str(exception)))
  92
  93         def notify(self, title, message, timeout = 0, actions = []):
  94                 """Send a D-BUS notification message if possible. If there is no notification
  95                 service available, log the message instead."""
  96                 if not self.notification_service:
  97                         info('%s: %s', title, message)
  98                         return None
  99
 100                 LOW = 0
 101                 NORMAL = 1
 102                 CRITICAL = 2
 103
 104                 import dbus.types
 105
 106                 hints = {}
 107                 if actions:
 108                         hints['urgency'] = dbus.types.Byte(NORMAL)
 109                 else:
 110                         hints['urgency'] = dbus.types.Byte(LOW)
 111
 112                 return self.notification_service.Notify('Zero Install',
 113                         0,              # replaces_id,
 114                         '',             # icon
 115                         _escape_xml(title),
 116                         _escape_xml(message),
 117                         actions,
 118                         hints,
 119                         timeout * 1000)
 120
 121 def _detach():
 122         """Fork a detached grandchild.
 123         @return: True if we are the original."""
 124         child = os.fork()
 125         if child:
 126                 pid, status = os.waitpid(child, 0)
 127                 assert pid == child
 128                 return True
 129
 130         # The calling process might be waiting for EOF from its child.
 131         # Close our stdout so we don't keep it waiting.
 132         # Note: this only fixes the most common case; it could be waiting
 133         # on any other FD as well. We should really use gobject.spawn_async
 134         # to close *all* FDs.
 135         null = os.open('/dev/null', os.O_RDWR)
 136         os.dup2(null, 1)
 137         os.close(null)
 138
 139         grandchild = os.fork()
 140         if grandchild:
 141                 os._exit(0)     # Parent's waitpid returns and grandchild continues
 142
 143         return False
 144
 145 def _check_for_updates(policy, verbose):
 146         root_iface = iface_cache.get_interface(policy.root).get_name()
 147
 148         policy.handler = BackgroundHandler(root_iface)
 149
 150         info("Checking for updates to '%s' in a background process", root_iface)
 151         if verbose:
 152                 policy.handler.notify("Zero Install", "Checking for updates to '%s'..." % root_iface, timeout = 1)
 153
 154         network_state = policy.handler.get_network_state()
 155         if network_state != _NetworkState.NM_STATE_CONNECTED:
 156                 info("Not yet connected to network (status = %d). Sleeping for a bit...", network_state)
 157                 import time
 158                 time.sleep(120)
 159                 if network_state in (_NetworkState.NM_STATE_DISCONNECTED, _NetworkState.NM_STATE_ASLEEP):
 160                         info("Still not connected to network. Giving up.")
 161                         sys.exit(1)
 162         else:
 163                 info("NetworkManager says we're on-line. Good!")
 164
 165         policy.freshness = 0                    # Don't bother trying to refresh when getting the interface
 166         refresh = policy.refresh_all()          # (causes confusing log messages)
 167         policy.handler.wait_for_blocker(refresh)
 168
 169         # We could even download the archives here, but for now just
 170         # update the interfaces.
 171
 172         if not policy.need_download():
 173                 if verbose:
 174                         policy.handler.notify("Zero Install", "No updates to download.", timeout = 1)
 175                 sys.exit(0)
 176
 177         if not policy.handler.notification_service:
 178                 # Can't ask the user to choose, so just notify them
 179                 policy.handler.notify("Zero Install", "Updates ready to download for '%s'." % root_iface)
 180                 sys.exit(0)
 181
 182         notification_closed = tasks.Blocker("wait for notification response")
 183
 184         def _NotificationClosed(nid, *unused):
 185                 if nid != our_question: return
 186                 notification_closed.trigger()
 187
 188         def _ActionInvoked(nid, action):
 189                 if nid != our_question: return
 190                 if action == 'download':
 191                         _exec_gui(policy.root)
 192                 notification_closed.trigger()
 193
 194         policy.handler.notification_service.connect_to_signal('NotificationClosed', _NotificationClosed)
 195         policy.handler.notification_service.connect_to_signal('ActionInvoked', _ActionInvoked)
 196
 197         our_question = policy.handler.notify("Zero Install", "Updates ready to download for '%s'." % root_iface,
 198                                 actions = ['download', 'Download'])
 199
 200         policy.handler.wait_for_blocker(notification_closed)
 201
 202 def spawn_background_update(policy, verbose):
 203         """Spawn a detached child process to check for updates.
 204         @param policy: policy containing interfaces to update
 205         @type policy: L{policy.Policy}
 206         @param verbose: whether to notify the user about minor events
 207         @type verbose: bool"""
 208         # Mark all feeds as being updated. Do this before forking, so that if someone is
 209         # running lots of 0launch commands in series on the same program we don't start
 210         # huge numbers of processes.
 211         for x in policy.implementation:
 212                 iface_cache.mark_as_checking(x.uri)                     # Main feed
 213                 for f in policy.usable_feeds(x):
 214                         iface_cache.mark_as_checking(f.uri)             # Extra feeds
 215
 216         if _detach():
 217                 return
 218
 219         try:
 220                 try:
 221                         _check_for_updates(policy, verbose)
 222                 except SystemExit:
 223                         raise
 224                 except:
 225                         import traceback
 226                         traceback.print_exc()
 227                         sys.stdout.flush()
 228         finally:
 229                 os._exit(1)