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  • Committer: William Grant
  • Date: 2009-07-05 12:23:11 UTC
  • mto: (1294.4.2 ui-the-third)
  • mto: This revision was merged to the branch mainline in revision 1353.
  • Revision ID: grantw@unimelb.edu.au-20090705122311-wfyih6snxs4c144p
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ivle/console.py
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import cjson
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from ivle import chat, interpret
 
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from ivle import chat
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class ConsoleError(Exception):
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    """ The console failed in some way. This is bad. """
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    pass
 
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    def __init__(self, value):
 
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        self.value = value
 
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    def __str__(self):
 
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        return repr(self.value)
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class ConsoleException(Exception):
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    """ The code being exectuted on the console returned an exception. 
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    """
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    pass
 
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    def __init__(self, value):
 
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        self.value = value
 
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    def __str__(self):
 
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        return repr(self.value)
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class TruncateStringIO(StringIO.StringIO):
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    """ A class that wraps around StringIO and truncates the buffer when the 
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class Console(object):
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    """ Provides a nice python interface to the console
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    """
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    def __init__(self, config, user, jail_path, working_dir):
 
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    def __init__(self, config, uid, jail_path, working_dir):
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        """Starts up a console service for user uid, inside chroot jail 
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        jail_path with work directory of working_dir
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        """
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        super(Console, self).__init__()
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        self.config = config
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        self.user = user
 
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        self.uid = uid
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        self.jail_path = jail_path
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        self.working_dir = working_dir
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        # is (k / N) ** t (e.g. 3.2*10e-9).
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        tries = 0
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        error = None
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        while tries < 5:
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            self.port = int(random.uniform(3000, 8000))
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            python_console = os.path.join(self.config['paths']['share'],
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                        'services/python-console')
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            args = [python_console, str(self.port), str(self.magic)]
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            try:
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                interpret.execute_raw(self.config, self.user, self.jail_path,
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                        self.working_dir, "/usr/bin/python", args)
 
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            trampoline_path = os.path.join(self.config['paths']['lib'],
 
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                                           "trampoline")
 
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            # Start the console server (port, magic)
 
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            # trampoline usage: tramp uid jail_dir working_dir script_path args
 
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            # console usage:    python-console port magic
 
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            res = os.spawnv(os.P_WAIT, trampoline_path, [
 
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                trampoline_path,
 
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                str(self.uid),
 
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                self.config['paths']['jails']['mounts'],
 
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                self.config['paths']['jails']['src'],
 
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                self.config['paths']['jails']['template'],
 
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                self.jail_path,
 
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                os.path.join(self.config['paths']['share'], 'services'),
 
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                "/usr/bin/python",
 
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                os.path.join(self.config['paths']['share'],
 
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                             'services/python-console'),
 
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                str(self.port),
 
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                str(self.magic),
 
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                self.working_dir
 
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                ])
 
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            if res == 0:
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                # success
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                break
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            except interpret.ExecutionError, e:
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                tries += 1
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                error = e.message
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        # If we can't start the console after 5 attemps (can't find a free 
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        # port during random probing, syntax errors, segfaults) throw an 
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        # exception.
 
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                break;
 
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            tries += 1
 
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        # If we can't start the console after 5 attemps (can't find a free port 
 
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        # during random probing, syntax errors, segfaults) throw an exception.
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        if tries == 5:
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            raise ConsoleError('Unable to start console service: %s'%error)
 
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            raise ConsoleError("Unable to start console service!")
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    def __chat(self, cmd, args):
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        """ A wrapper around chat.chat to comunicate directly with the 
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            # Couldn't decode the JSON
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            raise ConsoleError(
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                "Could not understand the python console response")
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        except chat.ProtocolError, e:
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            raise ConsoleError(*e.args)
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        return response
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        # Unpickle any exceptions
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        if 'exception' in execute:
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            execute['exception'] = cPickle.loads(execute['exception'])
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        return execute
 
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            return cPickle.loads(execute['exception'])
 
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        else:
 
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            return execute
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    def set_vars(self, variables):