zeroinstall/helpers.py

   1 """
   2 Convenience routines for performing common operations.
   3 @since: 0.28
   4 """
   5
   6 # Copyright (C) 2007, Thomas Leonard
   7 # See the README file for details, or visit http://0install.net.
   8
   9 import os, sys, logging
  10 from zeroinstall import support
  11
  12 def get_selections_gui(iface_uri, gui_args, test_callback = None):
  13         """Run the GUI to choose and download a set of implementations.
  14         If the GUI itself is due for a check, refresh it first.
  15         The user may ask the GUI to submit a bug report about the program. In that case,
  16         the GUI may ask us to test it. test_callback is called in that case with the implementations
  17         to be tested; the callback will typically call L{zeroinstall.injector.run.test_selections} and return the result of that.
  18         @param iface_uri: the required program
  19         @type iface_uri: str
  20         @param gui_args: any additional arguments for the GUI itself
  21         @type gui_args: [str]
  22         @param test_callback: function to use to try running the program
  23         @type test_callback: L{zeroinstall.injector.selections.Selections} -> str
  24         @since: 0.28
  25         """
  26         from zeroinstall.injector import selections, autopolicy, namespaces, model, run, qdom
  27         from StringIO import StringIO
  28
  29         gui_policy = autopolicy.AutoPolicy(namespaces.injector_gui_uri)
  30         if iface_uri != namespaces.injector_gui_uri and (gui_policy.need_download() or gui_policy.stale_feeds):
  31                 # The GUI itself needs updating. Do that first.
  32                 logging.info("The GUI could do with updating first.")
  33                 gui_sel = get_selections_gui(namespaces.injector_gui_uri, ['--refresh'])
  34                 if gui_sel is None:
  35                         logging.info("Aborted at user request")
  36                         return None             # Aborted by user
  37         else:
  38                 # Try to start the GUI without using the network.
  39                 gui_policy.freshness = 0
  40                 gui_policy.network_use = model.network_offline
  41                 gui_policy.recalculate()
  42                 assert gui_policy.ready         # Should always be some version available
  43                 gui_sel = selections.Selections(gui_policy)
  44
  45         import socket
  46         cli, gui = socket.socketpair()
  47
  48         try:
  49                 child = os.fork()
  50                 if child == 0:
  51                         # We are the child (GUI)
  52                         try:
  53                                 try:
  54                                         cli.close()
  55                                         # We used to use pipes to support Python2.3...
  56                                         os.dup2(gui.fileno(), 1)
  57                                         os.dup2(gui.fileno(), 0)
  58                                         run.execute_selections(gui_sel, gui_args + ['--', iface_uri])
  59                                 except:
  60                                         import traceback
  61                                         traceback.print_exc(file = sys.stderr)
  62                         finally:
  63                                 sys.stderr.flush()
  64                                 os._exit(1)
  65                 # We are the parent (CLI)
  66                 gui.close()
  67                 gui = None
  68
  69                 while True:
  70                         logging.info("Waiting for selections from GUI...")
  71
  72                         reply = support.read_bytes(cli.fileno(), len('Length:') + 9, null_ok = True)
  73                         if reply:
  74                                 if not reply.startswith('Length:'):
  75                                         raise Exception("Expected Length:, but got %s" % repr(reply))
  76                                 xml = support.read_bytes(cli.fileno(), int(reply.split(':', 1)[1], 16))
  77
  78                                 dom = qdom.parse(StringIO(xml))
  79                                 sels = selections.Selections(dom)
  80
  81                                 if dom.getAttribute('run-test'):
  82                                         logging.info("Testing program, as requested by GUI...")
  83                                         if test_callback is None:
  84                                                 output = "Can't test: no test_callback was passed to get_selections_gui()\n"
  85                                         else:
  86                                                 output = test_callback(sels)
  87                                         logging.info("Sending results to GUI...")
  88                                         output = ('Length:%8x\n' % len(output)) + output
  89                                         logging.debug("Sending: %s" % `output`)
  90                                         while output:
  91                                                 sent = cli.send(output)
  92                                                 output = output[sent:]
  93                                         continue
  94                         else:
  95                                 sels = None
  96
  97                         pid, status = os.waitpid(child, 0)
  98                         assert pid == child
  99                         if status == 1 << 8:
 100                                 logging.info("User cancelled the GUI; aborting")
 101                                 return None             # Aborted
 102                         if status != 0:
 103                                 raise Exception("Error from GUI: code = %d" % status)
 104                         break
 105         finally:
 106                 for sock in [cli, gui]:
 107                         if sock is not None: sock.close()
 108
 109         return sels
 110
 111 def ensure_cached(uri):
 112         """Ensure that an implementation of uri is cached.
 113         If not, it downloads one. It uses the GUI if a display is
 114         available, or the console otherwise.
 115         @param uri: the required interface
 116         @type uri: str
 117         @return: a new policy for this program, or None if the user cancelled
 118         @rtype: L{zeroinstall.injector.selections.Selections}
 119         """
 120         from zeroinstall.injector import autopolicy, selections
 121
 122         p = autopolicy.AutoPolicy(uri, download_only = True)
 123         p.freshness = 0         # Don't check for updates
 124
 125         if p.need_download() or not p.ready:
 126                 if os.environ.get('DISPLAY', None):
 127                         return get_selections_gui(uri, [])
 128                 else:
 129                         p.recalculate_with_dl()
 130                         p.start_downloading_impls()
 131                         p.handler.wait_for_downloads()
 132
 133         return selections.Selections(p)