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 from zeroinstall.support import tasks
  13
  14 def get_selections_gui(iface_uri, gui_args, test_callback = None):
  15         """Run the GUI to choose and download a set of implementations.
  16         The user may ask the GUI to submit a bug report about the program. In that case,
  17         the GUI may ask us to test it. test_callback is called in that case with the implementations
  18         to be tested; the callback will typically call L{zeroinstall.injector.run.test_selections} and return the result of that.
  19         @param iface_uri: the required program, or None to show just the preferences dialog
  20         @type iface_uri: str
  21         @param gui_args: any additional arguments for the GUI itself
  22         @type gui_args: [str]
  23         @param test_callback: function to use to try running the program
  24         @type test_callback: L{zeroinstall.injector.selections.Selections} -> str
  25         @return: the selected implementations
  26         @rtype: L{zeroinstall.injector.selections.Selections}
  27         @since: 0.28
  28         """
  29         from zeroinstall.injector import selections, qdom
  30         from StringIO import StringIO
  31
  32         from os.path import join, dirname
  33         gui_exe = join(dirname(__file__), '0launch-gui', '0launch-gui')
  34
  35         import socket
  36         cli, gui = socket.socketpair()
  37
  38         try:
  39                 child = os.fork()
  40                 if child == 0:
  41                         # We are the child (GUI)
  42                         try:
  43                                 try:
  44                                         cli.close()
  45                                         # We used to use pipes to support Python2.3...
  46                                         os.dup2(gui.fileno(), 1)
  47                                         os.dup2(gui.fileno(), 0)
  48                                         if iface_uri is not None:
  49                                                 gui_args = gui_args + ['--', iface_uri]
  50                                         os.execvp(gui_exe, [gui_exe] + gui_args)
  51                                 except:
  52                                         import traceback
  53                                         traceback.print_exc(file = sys.stderr)
  54                         finally:
  55                                 sys.stderr.flush()
  56                                 os._exit(1)
  57                 # We are the parent (CLI)
  58                 gui.close()
  59                 gui = None
  60
  61                 while True:
  62                         logging.info("Waiting for selections from GUI...")
  63
  64                         reply = support.read_bytes(cli.fileno(), len('Length:') + 9, null_ok = True)
  65                         if reply:
  66                                 if not reply.startswith('Length:'):
  67                                         raise Exception("Expected Length:, but got %s" % repr(reply))
  68                                 xml = support.read_bytes(cli.fileno(), int(reply.split(':', 1)[1], 16))
  69
  70                                 dom = qdom.parse(StringIO(xml))
  71                                 sels = selections.Selections(dom)
  72
  73                                 if dom.getAttribute('run-test'):
  74                                         logging.info("Testing program, as requested by GUI...")
  75                                         if test_callback is None:
  76                                                 output = "Can't test: no test_callback was passed to get_selections_gui()\n"
  77                                         else:
  78                                                 output = test_callback(sels)
  79                                         logging.info("Sending results to GUI...")
  80                                         output = ('Length:%8x\n' % len(output)) + output
  81                                         logging.debug("Sending: %s", repr(output))
  82                                         while output:
  83                                                 sent = cli.send(output)
  84                                                 output = output[sent:]
  85                                         continue
  86                         else:
  87                                 sels = None
  88
  89                         pid, status = os.waitpid(child, 0)
  90                         assert pid == child
  91                         if status == 1 << 8:
  92                                 logging.info("User cancelled the GUI; aborting")
  93                                 return None             # Aborted
  94                         if status != 0:
  95                                 raise Exception("Error from GUI: code = %d" % status)
  96                         break
  97         finally:
  98                 for sock in [cli, gui]:
  99                         if sock is not None: sock.close()
 100
 101         return sels
 102
 103 def ensure_cached(uri, command = 'run'):
 104         """Ensure that an implementation of uri is cached.
 105         If not, it downloads one. It uses the GUI if a display is
 106         available, or the console otherwise.
 107         @param uri: the required interface
 108         @type uri: str
 109         @return: the selected implementations, or None if the user cancelled
 110         @rtype: L{zeroinstall.injector.selections.Selections}
 111         """
 112         from zeroinstall.injector import policy, selections
 113         from zeroinstall.injector.config import load_config
 114
 115         config = load_config()
 116         p = policy.Policy(uri, command = command, config = config)
 117         p.freshness = 0         # Don't check for updates
 118
 119         if p.need_download() or not p.ready:
 120                 if os.environ.get('DISPLAY', None):
 121                         return get_selections_gui(uri, ['--command', command])
 122                 else:
 123                         done = p.solve_and_download_impls()
 124                         tasks.wait_for_blocker(done)
 125
 126         return selections.Selections(p)