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 from zeroinstall import _
  12
  13 def get_selections_gui(iface_uri, gui_args, test_callback = None):
  14         """Run the GUI to choose and download a set of implementations.
  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, or None to show just the preferences dialog
  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, qdom
  29         from StringIO import StringIO
  30
  31         from os.path import join, dirname
  32         gui_exe = join(dirname(__file__), '0launch-gui', '0launch-gui')
  33
  34         import socket
  35         cli, gui = socket.socketpair()
  36
  37         try:
  38                 child = os.fork()
  39                 if child == 0:
  40                         # We are the child (GUI)
  41                         try:
  42                                 try:
  43                                         cli.close()
  44                                         # We used to use pipes to support Python2.3...
  45                                         os.dup2(gui.fileno(), 1)
  46                                         os.dup2(gui.fileno(), 0)
  47                                         if iface_uri is not None:
  48                                                 gui_args = gui_args + ['--', iface_uri]
  49                                         os.execvp(gui_exe, [gui_exe] + gui_args)
  50                                 except:
  51                                         import traceback
  52                                         traceback.print_exc(file = sys.stderr)
  53                         finally:
  54                                 sys.stderr.flush()
  55                                 os._exit(1)
  56                 # We are the parent (CLI)
  57                 gui.close()
  58                 gui = None
  59
  60                 while True:
  61                         logging.info("Waiting for selections from GUI...")
  62
  63                         reply = support.read_bytes(cli.fileno(), len('Length:') + 9, null_ok = True)
  64                         if reply:
  65                                 if not reply.startswith('Length:'):
  66                                         raise Exception("Expected Length:, but got %s" % repr(reply))
  67                                 xml = support.read_bytes(cli.fileno(), int(reply.split(':', 1)[1], 16))
  68
  69                                 dom = qdom.parse(StringIO(xml))
  70                                 sels = selections.Selections(dom)
  71
  72                                 if dom.getAttribute('run-test'):
  73                                         logging.info("Testing program, as requested by GUI...")
  74                                         if test_callback is None:
  75                                                 output = "Can't test: no test_callback was passed to get_selections_gui()\n"
  76                                         else:
  77                                                 output = test_callback(sels)
  78                                         logging.info("Sending results to GUI...")
  79                                         output = ('Length:%8x\n' % len(output)) + output
  80                                         logging.debug("Sending: %s", repr(output))
  81                                         while output:
  82                                                 sent = cli.send(output)
  83                                                 output = output[sent:]
  84                                         continue
  85                         else:
  86                                 sels = None
  87
  88                         pid, status = os.waitpid(child, 0)
  89                         assert pid == child
  90                         if status == 1 << 8:
  91                                 logging.info("User cancelled the GUI; aborting")
  92                                 return None             # Aborted
  93                         if status != 0:
  94                                 raise Exception("Error from GUI: code = %d" % status)
  95                         break
  96         finally:
  97                 for sock in [cli, gui]:
  98                         if sock is not None: sock.close()
  99
 100         return sels
 101
 102 def ensure_cached(uri):
 103         """Ensure that an implementation of uri is cached.
 104         If not, it downloads one. It uses the GUI if a display is
 105         available, or the console otherwise.
 106         @param uri: the required interface
 107         @type uri: str
 108         @return: a new policy for this program, or None if the user cancelled
 109         @rtype: L{zeroinstall.injector.selections.Selections}
 110         """
 111         from zeroinstall.injector import autopolicy, selections
 112
 113         p = autopolicy.AutoPolicy(uri, download_only = True)
 114         p.freshness = 0         # Don't check for updates
 115
 116         if p.need_download() or not p.ready:
 117                 if os.environ.get('DISPLAY', None):
 118                         return get_selections_gui(uri, [])
 119                 else:
 120                         p.recalculate_with_dl()
 121                         p.start_downloading_impls()
 122                         p.handler.wait_for_downloads()
 123
 124         return selections.Selections(p)