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
  10 from zeroinstall import support, SafeException, logger
  11 from zeroinstall.support import tasks
  12
  13 DontUseGUI = object()
  14
  15 def get_selections_gui(iface_uri, gui_args, test_callback = None, use_gui = True):
  16         """Run the GUI to choose and download a set of implementations.
  17         The user may ask the GUI to submit a bug report about the program. In that case,
  18         the GUI may ask us to test it. test_callback is called in that case with the implementations
  19         to be tested; the callback will typically call L{zeroinstall.injector.run.test_selections} and return the result of that.
  20         @param iface_uri: the required program, or None to show just the preferences dialog
  21         @type iface_uri: str
  22         @param gui_args: any additional arguments for the GUI itself
  23         @type gui_args: [str]
  24         @param test_callback: function to use to try running the program
  25         @type test_callback: L{zeroinstall.injector.selections.Selections} -> str
  26         @param use_gui: if True, raise a SafeException if the GUI is not available. If None, returns DontUseGUI if the GUI cannot be started. If False, returns DontUseGUI always. (since 1.11)
  27         @param use_gui: bool | None
  28         @return: the selected implementations
  29         @rtype: L{zeroinstall.injector.selections.Selections}
  30         @since: 0.28
  31         """
  32         if use_gui is False:
  33                 return DontUseGUI
  34
  35         if 'DISPLAY' not in os.environ:
  36                 if use_gui is None:
  37                         return DontUseGUI
  38                 else:
  39                         raise SafeException("Can't use GUI because $DISPLAY is not set")
  40
  41         from zeroinstall.injector import selections, qdom
  42         from io import BytesIO
  43
  44         from os.path import join, dirname
  45         gui_exe = join(dirname(__file__), '0launch-gui', '0launch-gui')
  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                                         if use_gui is True:
  61                                                 gui_args = ['-g'] + gui_args
  62                                         if iface_uri is not None:
  63                                                 gui_args = gui_args + ['--', iface_uri]
  64                                         os.execvp(sys.executable, [sys.executable, gui_exe] + gui_args)
  65                                 except:
  66                                         import traceback
  67                                         traceback.print_exc(file = sys.stderr)
  68                         finally:
  69                                 sys.stderr.flush()
  70                                 os._exit(1)
  71                 # We are the parent (CLI)
  72                 gui.close()
  73                 gui = None
  74
  75                 while True:
  76                         logger.info("Waiting for selections from GUI...")
  77
  78                         reply = support.read_bytes(cli.fileno(), len('Length:') + 9, null_ok = True)
  79                         if reply:
  80                                 if not reply.startswith(b'Length:'):
  81                                         raise Exception("Expected Length:, but got %s" % repr(reply))
  82                                 reply = reply.decode('ascii')
  83                                 xml = support.read_bytes(cli.fileno(), int(reply.split(':', 1)[1], 16))
  84
  85                                 dom = qdom.parse(BytesIO(xml))
  86                                 sels = selections.Selections(dom)
  87
  88                                 if dom.getAttribute('run-test'):
  89                                         logger.info("Testing program, as requested by GUI...")
  90                                         if test_callback is None:
  91                                                 output = b"Can't test: no test_callback was passed to get_selections_gui()\n"
  92                                         else:
  93                                                 output = test_callback(sels)
  94                                         logger.info("Sending results to GUI...")
  95                                         output = ('Length:%8x\n' % len(output)).encode('utf-8') + output
  96                                         logger.debug("Sending: %s", repr(output))
  97                                         while output:
  98                                                 sent = cli.send(output)
  99                                                 output = output[sent:]
 100                                         continue
 101                         else:
 102                                 sels = None
 103
 104                         pid, status = os.waitpid(child, 0)
 105                         assert pid == child
 106                         if status == 1 << 8:
 107                                 logger.info("User cancelled the GUI; aborting")
 108                                 return None             # Aborted
 109                         elif status == 100 << 8:
 110                                 if use_gui is None:
 111                                         return DontUseGUI
 112                                 else:
 113                                         raise SafeException("No GUI available")
 114                         if status != 0:
 115                                 raise Exception("Error from GUI: code = %d" % status)
 116                         break
 117         finally:
 118                 for sock in [cli, gui]:
 119                         if sock is not None: sock.close()
 120
 121         return sels
 122
 123 def ensure_cached(uri, command = 'run', config = None):
 124         """Ensure that an implementation of uri is cached.
 125         If not, it downloads one. It uses the GUI if a display is
 126         available, or the console otherwise.
 127         @param uri: the required interface
 128         @type uri: str
 129         @return: the selected implementations, or None if the user cancelled
 130         @rtype: L{zeroinstall.injector.selections.Selections}
 131         """
 132         from zeroinstall.injector.driver import Driver
 133
 134         if config is None:
 135                 from zeroinstall.injector.config import load_config
 136                 config = load_config()
 137
 138         from zeroinstall.injector.requirements import Requirements
 139         requirements = Requirements(uri)
 140         requirements.command = command
 141
 142         d = Driver(config, requirements)
 143
 144         if d.need_download() or not d.solver.ready:
 145                 sels = get_selections_gui(uri, ['--command', command], use_gui = None)
 146                 if sels != DontUseGUI:
 147                         return sels
 148                 done = d.solve_and_download_impls()
 149                 tasks.wait_for_blocker(done)
 150
 151         return d.solver.selections