zeroinstall/helpers.py

   1 """
   2 Convenience routines for performing common operations.
   3 @since: 0.28
   4 """
   5
   6 # Copyright (C) 2009, 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         @return: the selected implementations
  25         @rtype: L{zeroinstall.injector.selections.Selections}
  26         @since: 0.28
  27         """
  28         from zeroinstall.injector import selections, autopolicy, namespaces, model, run, qdom
  29         from StringIO import StringIO
  30
  31         gui_policy = autopolicy.AutoPolicy(namespaces.injector_gui_uri)
  32         if iface_uri != namespaces.injector_gui_uri and (gui_policy.need_download() or gui_policy.stale_feeds):
  33                 # The GUI itself needs updating. Do that first.
  34                 logging.info("The GUI could do with updating first.")
  35                 gui_sel = get_selections_gui(namespaces.injector_gui_uri, ['--refresh'])
  36                 if gui_sel is None:
  37                         logging.info("Aborted at user request")
  38                         return None             # Aborted by user
  39         else:
  40                 # Try to start the GUI without using the network.
  41                 gui_policy.freshness = 0
  42                 gui_policy.network_use = model.network_offline
  43                 gui_policy.recalculate()
  44                 assert gui_policy.ready         # Should always be some version available
  45                 gui_sel = selections.Selections(gui_policy)
  46
  47         import socket
  48         cli, gui = socket.socketpair()
  49
  50         try:
  51                 child = os.fork()
  52                 if child == 0:
  53                         # We are the child (GUI)
  54                         try:
  55                                 try:
  56                                         cli.close()
  57                                         # We used to use pipes to support Python2.3...
  58                                         os.dup2(gui.fileno(), 1)
  59                                         os.dup2(gui.fileno(), 0)
  60                                         run.execute_selections(gui_sel, gui_args + ['--', iface_uri])
  61                                 except:
  62                                         import traceback
  63                                         traceback.print_exc(file = sys.stderr)
  64                         finally:
  65                                 sys.stderr.flush()
  66                                 os._exit(1)
  67                 # We are the parent (CLI)
  68                 gui.close()
  69                 gui = None
  70
  71                 while True:
  72                         logging.info("Waiting for selections from GUI...")
  73
  74                         reply = support.read_bytes(cli.fileno(), len('Length:') + 9, null_ok = True)
  75                         if reply:
  76                                 if not reply.startswith('Length:'):
  77                                         raise Exception("Expected Length:, but got %s" % repr(reply))
  78                                 xml = support.read_bytes(cli.fileno(), int(reply.split(':', 1)[1], 16))
  79
  80                                 dom = qdom.parse(StringIO(xml))
  81                                 sels = selections.Selections(dom)
  82
  83                                 if dom.getAttribute('run-test'):
  84                                         logging.info("Testing program, as requested by GUI...")
  85                                         if test_callback is None:
  86                                                 output = "Can't test: no test_callback was passed to get_selections_gui()\n"
  87                                         else:
  88                                                 output = test_callback(sels)
  89                                         logging.info("Sending results to GUI...")
  90                                         output = ('Length:%8x\n' % len(output)) + output
  91                                         logging.debug("Sending: %s", repr(output))
  92                                         while output:
  93                                                 sent = cli.send(output)
  94                                                 output = output[sent:]
  95                                         continue
  96                         else:
  97                                 sels = None
  98
  99                         pid, status = os.waitpid(child, 0)
 100                         assert pid == child
 101                         if status == 1 << 8:
 102                                 logging.info("User cancelled the GUI; aborting")
 103                                 return None             # Aborted
 104                         if status != 0:
 105                                 raise Exception("Error from GUI: code = %d" % status)
 106                         break
 107         finally:
 108                 for sock in [cli, gui]:
 109                         if sock is not None: sock.close()
 110
 111         return sels
 112
 113 def ensure_cached(uri):
 114         """Ensure that an implementation of uri is cached.
 115         If not, it downloads one. It uses the GUI if a display is
 116         available, or the console otherwise.
 117         @param uri: the required interface
 118         @type uri: str
 119         @return: a new policy for this program, or None if the user cancelled
 120         @rtype: L{zeroinstall.injector.selections.Selections}
 121         """
 122         from zeroinstall.injector import autopolicy, selections
 123
 124         p = autopolicy.AutoPolicy(uri, download_only = True)
 125         p.freshness = 0         # Don't check for updates
 126
 127         if p.need_download() or not p.ready:
 128                 if os.environ.get('DISPLAY', None):
 129                         return get_selections_gui(uri, [])
 130                 else:
 131                         p.recalculate_with_dl()
 132                         p.start_downloading_impls()
 133                         p.handler.wait_for_downloads()
 134
 135         return selections.Selections(p)