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{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{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         cli_from_gui, gui_to_cli = os.pipe()            # socket.socketpair() not in Python 2.3 :-(
  46         gui_from_cli, cli_to_gui = os.pipe()
  47         try:
  48                 child = os.fork()
  49                 if child == 0:
  50                         # We are the child
  51                         try:
  52                                 try:
  53                                         os.close(cli_from_gui)
  54                                         os.close(cli_to_gui)
  55                                         os.dup2(gui_to_cli, 1)
  56                                         os.dup2(gui_from_cli, 0)
  57                                         run.execute_selections(gui_sel, gui_args + ['--', iface_uri])
  58                                 except:
  59                                         import traceback
  60                                         traceback.print_exc(file = sys.stderr)
  61                         finally:
  62                                 sys.stderr.flush()
  63                                 os._exit(1)
  64                 os.close(gui_from_cli)
  65                 gui_from_cli = None
  66                 os.close(gui_to_cli)
  67                 gui_to_cli = None
  68
  69                 while True:
  70                         logging.info("Waiting for selections from GUI...")
  71
  72                         reply = support.read_bytes(cli_from_gui, 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_from_gui, 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 = os.write(cli_to_gui, 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 fd in [cli_to_gui, cli_from_gui, gui_to_cli, gui_from_cli]:
 107                         if fd is not None: os.close(fd)
 108
 109         return sels