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