~azzar1/unity/add-show-desktop-key

# IVLE

# Copyright (C) 2007-2008 The University of Melbourne

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

# Module: Console

# Author: Matt Giuca, Tom Conway, David Coles (refactor)

# Date: 13/8/2008

# Mainly refactored out of consoleservice

import errno

import cPickle

import hashlib

import os

import random

import socket

import StringIO

import uuid

import cjson

from ivle import chat, interpret

class ConsoleError(Exception):

    """ The console failed in some way. This is bad. """

    pass

class ConsoleException(Exception):

    """ The code being exectuted on the console returned an exception. 

    """

    pass

class TruncateStringIO(StringIO.StringIO):

    """ A class that wraps around StringIO and truncates the buffer when the 

    contents are read (except for when using getvalue).

    """

    def __init__(self, buffer=None):

        StringIO.StringIO.__init__(self, buffer)

    def read(self, n=-1):

        """ Read at most size bytes from the file (less if the read hits EOF 

        before obtaining size bytes).

        If the size argument is negative or omitted, read all data until EOF is      

        reached. The bytes are returned as a string object. An empty string is 

        returned when EOF is encountered immediately.

        Truncates the buffer.

        """

        self.seek(0)

        res = StringIO.StringIO.read(self, n)

        self.truncate(0)

        return res

    def readline(self, length=None):

        """ Read one entire line from the file.

        A trailing newline character is kept in the string (but may be absent 

        when a file ends with an incomplete line). If the size argument is   

        present and non-negative, it is a maximum byte count (including the      

        trailing newline) and an incomplete line may be returned.

        An empty string is returned only when EOF is encountered immediately.

        Note: Unlike stdio's fgets(), the returned string contains null   

        characters ('\0') if they occurred in the input.

        Removes the line from the buffer.

        """

        self.seek(0)

        res = StringIO.StringIO.readline(self, length)

        rest = StringIO.StringIO.read(self)

        self.truncate(0)

        self.write(rest)

        return res

    def readlines(self, sizehint=0):

        """ Read until EOF using readline() and return a list containing the        

        lines thus read.

        If the optional sizehint argument is present, instead of reading up to 

        EOF, whole lines totalling approximately sizehint bytes (or more to      

        accommodate a final whole line).

        Truncates the buffer.

        """

        self.seek(0)

        res = StringIO.StringIO.readlines(self, length)

        self.truncate(0)

        return res

class Console(object):

    """ Provides a nice python interface to the console

    """

    def __init__(self, config, user, jail_path, working_dir):

        """Starts up a console service for user uid, inside chroot jail 

        jail_path with work directory of working_dir

        """

        super(Console, self).__init__()

        self.config = config

        self.user = user

        self.jail_path = jail_path

        self.working_dir = working_dir

        # Set up the buffers

        self.stdin = TruncateStringIO()

        self.stdout = TruncateStringIO()

        self.stderr = TruncateStringIO()

        # Fire up the console

        self.restart()

    def restart(self):

        # Empty all the buffers

        self.stdin.truncate(0)

        self.stdout.truncate(0)

        self.stderr.truncate(0)

        # TODO: Check if we are already running a console. If we are shut it 

        # down first.

        # TODO: Figure out the host name the console server is running on.

        self.host = socket.gethostname()

        # Create magic

        # TODO

        self.magic = hashlib.md5(uuid.uuid4().bytes).hexdigest()

        # Try to find a free port on the server.

        # Just try some random ports in the range [3000,8000)

        # until we either succeed, or give up. If you think this

        # sounds risky, it isn't:

        # For N ports (e.g. 5000) with k (e.g. 100) in use, the

        # probability of failing to find a free port in t (e.g. 5) tries

        # is (k / N) ** t (e.g. 3.2*10e-9).

        tries = 0

        error = None

        while tries < 5:

            self.port = int(random.uniform(3000, 8000))

            python_console = os.path.join(self.config['paths']['share'],

                        'services/python-console')

            args = [python_console, str(self.port), str(self.magic)]

            try:

                interpret.execute_raw(self.config, self.user, self.jail_path,

                        self.working_dir, "/usr/bin/python", args)

                # success

                break

            except interpret.ExecutionError, e:

                tries += 1

                error = e.message

        # If we can't start the console after 5 attemps (can't find a free 

        # port during random probing, syntax errors, segfaults) throw an 

        # exception.

        if tries == 5:

            raise ConsoleError('Unable to start console service: %s'%error)

    def __chat(self, cmd, args):

        """ A wrapper around chat.chat to comunicate directly with the 

        console.

        """

        try:

            response = chat.chat(self.host, self.port,

                {'cmd': cmd, 'text': args}, self.magic)

        except socket.error, (enumber, estring):

            if enumber == errno.ECONNREFUSED:

                # Timeout

                raise ConsoleError(

                    "Could not establish a connection to the python console")

            else:

                # Some other error - probably serious

                raise socket.error, (enumber, estring)

        except cjson.DecodeError:

            # Couldn't decode the JSON

            raise ConsoleError(

                "Could not understand the python console response")

        except chat.ProtocolError, e:

            raise ConsoleError(*e.args)

        return response

    def __handle_chat(self, cmd, args):

        """ A wrapper around self.__chat that handles all the messy responses 

        of chat for higher level interfaces such as inspect

        """

        # Do the request

        response = self.__chat(cmd, args)

        # Process I/O requests

        while 'output' in response or 'input' in response:

            if 'output' in response:

                self.stdout.write(response['output'])

                response = self.chat()

            elif 'input' in response:

                response = self.chat(self.stdin.readline())

        # Process user exceptions

        if 'exc' in response:

            raise ConsoleException(response['exc'])

        return response

    def chat(self, code=''):

        """ Executes a partial block of code """

        return self.__chat('chat', code)

    def block(self, code):

        """ Executes a block of code and returns the output """

        block = self.__handle_chat('block', code)

        if 'output' in block:

            return block['output']

        elif 'okay' in block:

            return

        else:

            raise ConsoleException("Bad response from console: %s"%str(block))

    def globals(self, globs=None):

        """ Returns a dictionary of the console's globals and optionally set 

        them to a new value

        """

        # Pickle the globals

        pickled_globs = None

        if globs is not None:

            pickled_globs = {}

            for g in globs:

                pickled_globs[g] = cPickle.dumps(globs[g])

        globals = self.__handle_chat('globals', pickled_globs)

        # Unpickle the globals

        for g in globals['globals']:

            globals['globals'][g] = cPickle.loads(globals['globals'][g])

        return globals['globals']

    def call(self, function, *args, **kwargs):

        """ Calls a function in the python console. Can take in a list of 

        repr() args and dictionary of repr() values kwargs. These will be 

        evaluated on the server side.

        """

        call_args = {

            'function': function,

            'args': args,

            'kwargs': kwargs}

        call = self.__handle_chat('call', call_args)

        # Unpickle any exceptions

        if 'exception' in call:

            call['exception']['except'] = \

                cPickle.loads(call['exception']['except'])

        return call

    def execute(self, code=''):

        """ Runs a block of code in the python console.

        If an exception was thrown then returns an exception object.

        """

        execute = self.__handle_chat('execute', code)

        # Unpickle any exceptions

        if 'exception' in execute:

            execute['exception'] = cPickle.loads(execute['exception'])

        return execute

    def set_vars(self, variables):

        """ Takes a dictionary of varibles to add to the console's global 

        space. These are evaluated in the local space so you can't use this to 

        set a varible to a value to be calculated on the console side.

        """

        vars = {}

        for v in variables:

            vars[v] = repr(variables[v])

        set_vars = self.__handle_chat('set_vars', vars)

        if set_vars.get('response') != 'okay':

            raise ConsoleError("Could not set variables")

    def close(self):

        """ Causes the console process to terminate """

        return self.__chat('terminate', None)

class ExistingConsole(Console):

    """ Provides a nice python interface to an existing console.

    Note: You can't restart an existing console since there is no way to infer 

    all the starting parameters. Just start a new Console instead.

    """

    def __init__(self, host, port, magic):

        self.host = host

        self.port = port

        self.magic = magic

        # Set up the buffers

        self.stdin = TruncateStringIO()

        self.stdout = TruncateStringIO()

        self.stderr = TruncateStringIO()

    def restart():

        raise NotImplementedError('You can not restart an existing console')