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

#!/usr/bin/python

# usage:

#   python-console <port> <magic> [<working-dir>]

import cjson

import codeop

import md5

import os

import Queue

import signal

import socket

import sys

import traceback

from threading import Thread

import common.chat

class Interrupt(Exception):

    def __init__(self):

        Exception.__init__(self, "Interrupted!")

class ExpiryTimer(object):

    def __init__(self, idle):

        self.idle = idle

        signal.signal(signal.SIGALRM, self.timeout)

    def ping(self):

        signal.alarm(self.idle)

    def start(self, time):

        signal.alarm(time)

    def stop(self):

        self.ping()

    def timeout(self, signum, frame):

        sys.exit(1)

class StdinFromWeb(object):

    def __init__(self, cmdQ, lineQ):

        self.cmdQ = cmdQ

        self.lineQ = lineQ

    def readline(self):

        self.cmdQ.put({"input":None})

        expiry.ping()

        ln = self.lineQ.get()

        if 'chat' in ln:

            return ln['chat']

        if 'interrupt' in ln:

            raise Interrupt()

        if 'terminate' in ln:

            sys.exit(0)

class StdoutToWeb(object):

    def __init__(self, cmdQ, lineQ):

        self.cmdQ = cmdQ

        self.lineQ = lineQ

        self.remainder = ''

    def _trim_incomplete_final(self, stuff):

        '''Trim an incomplete UTF-8 character from the end of a string.

           Returns (trimmed_string, count_of_trimmed_bytes).

        '''

        tokill = incomplete_utf8_sequence(stuff)

        if tokill == 0:

            return (stuff, tokill)

        else:

            return (stuff[:-tokill], tokill)

    def write(self, stuff):

        # print will only give a non-file a unicode or str. There's no way

        # to convince it to encode unicodes, so we have to do it ourselves.

        # Yay for file special-cases (fileobject.c, PyFile_WriteObject).

        # If somebody wants to write some other object to here, they do it

        # at their own peril.

        if isinstance(stuff, unicode):

            stuff = stuff.encode('utf-8')

        self.remainder = self.remainder + stuff

        # if there's less than 128 bytes, buffer

        if len(self.remainder) < 128:

            return

        # if there's lots, then send it in 1/2K blocks

        while len(self.remainder) > 512:

            # We send things as Unicode inside JSON, so we must only send

            # complete UTF-8 characters.

            (blk, count) = self._trim_incomplete_final(self.remainder[:512])

            self.cmdQ.put({"output":blk.decode('utf-8', 'replace')})

            expiry.ping()

            ln = self.lineQ.get()

            self.remainder = self.remainder[512 - count:]

        # Finally, split the remainder up into lines, and ship all the

        # completed lines off to the server.

        lines = self.remainder.split("\n")

        self.remainder = lines[-1]

        del lines[-1]

        if len(lines) > 0:

            lines.append('')

            text = "\n".join(lines)

            self.cmdQ.put({"output":text.decode('utf-8', 'replace')})

            expiry.ping()

            ln = self.lineQ.get()

            if 'interrupt' in ln:

                raise Interrupt()

    def flush(self):

        if len(self.remainder) > 0:

            (out, count) = self._trim_incomplete_final(self.remainder)

            self.cmdQ.put({"output":out.decode('utf-8', 'replace')})

            expiry.ping()

            ln = self.lineQ.get()

            # Leave incomplete characters in the buffer.

            # Yes, this does mean that an incomplete character will be left

            # off the end, but we discussed this and it was deemed best.

            self.remainder = self.remainder[len(self.remainder)-count:]

            if 'interrupt' in ln:

                raise Interrupt()

class WebIO(object):

    """Provides a file like interface to the Web front end of the console.

    You may print text to the console using write(), flush any buffered output 

    using flush(), or request text from the console using readline()"""

    def __init__(self, cmdQ, lineQ):

        self.cmdQ = cmdQ

        self.lineQ = lineQ

        self.stdin = StdinFromWeb(self.cmdQ, self.lineQ)

        self.stdout = StdoutToWeb(self.cmdQ, self.lineQ)

    def write(self, stuff):

        self.stdout.write(stuff)

    def flush(self):

        self.stdout.flush()

    def readline(self):

        self.stdout.flush()

        return self.stdin.readline()

class PythonRunner(Thread):

    def __init__(self, cmdQ, lineQ):

        self.cmdQ = cmdQ

        self.lineQ = lineQ

        self.webio = WebIO(self.cmdQ, self.lineQ)

        Thread.__init__(self)

    def execCmd(self, cmd):

        try:

            sys.stdin = self.webio

            sys.stdout = self.webio

            sys.stderr = self.webio

            # We don't expect a return value - 'single' symbol prints it.

            eval(cmd, self.globs)

            self.webio.flush()

            self.cmdQ.put({"okay": None})

            self.curr_cmd = ''

        except:

            tb = format_exc_start(start=1)

            self.webio.flush()

            self.cmdQ.put({"exc": ''.join(tb).decode('utf-8', 'replace')})

            self.curr_cmd = ''

    def run(self):

        self.globs = {}

        self.globs['__builtins__'] = globals()['__builtins__']

        self.curr_cmd = ''

        while True:

            ln = self.lineQ.get()

            if 'chat' in ln:

                if self.curr_cmd == '':

                    self.curr_cmd = ln['chat']

                else:

                    self.curr_cmd = self.curr_cmd + '\n' + ln['chat']

                try:

                    cmd = codeop.compile_command(self.curr_cmd, '<web session>')

                    if cmd is None:

                        # The command was incomplete,

                        # so send back a None, so the

                        # client can print a '...'

                        self.cmdQ.put({"more":None})

                    else:

                        self.execCmd(cmd)

                except:

                    tb = format_exc_start(start=3)

                    self.cmdQ.put({"exc": ''.join(tb).decode('utf-8', 'replace')})

                    self.webio.flush()

                    self.curr_cmd = ''

            if 'block' in ln:

                # throw away a partial command.

                try:

                    cmd = compile(ln['block'], "<web session>", 'exec');

                    self.execCmd(cmd)

                except:

                    tb = format_exc_start(start=1)

                    self.webio.flush()

                    self.cmdQ.put({"exc": ''.join(tb).decode('utf-8', 'replace')})

                    self.curr_cmd = ''

def daemonize():

    if os.fork():   # launch child and...

        os._exit(0) # kill off parent

    os.setsid()

    if os.fork():   # launch child and...

        os._exit(0) # kill off parent again.

    os.umask(077)

# The global 'magic' is the secret that the client and server share

# which is used to create and md5 digest to authenticate requests.

# It is assigned a real value at startup.

magic = ''

cmdQ = Queue.Queue()

lineQ = Queue.Queue()

interpThread = PythonRunner(cmdQ, lineQ)

terminate = None

# Default expiry time of 15 minutes

expiry = ExpiryTimer(15 * 60)

def initializer():

    interpThread.setDaemon(True)

    interpThread.start()

    signal.signal(signal.SIGXCPU, sig_handler)

    expiry.ping()

def sig_handler(signum, frame):

    """Handles response from signals"""

    global terminate

    if signum == signal.SIGXCPU:

        terminate = "CPU Time Limit Exceeded"

def dispatch_msg(msg):

    expiry.ping()

    lineQ.put({msg['cmd']:msg['text']})

    if terminate:

        raise common.chat.Terminate({"restart":terminate})

    return cmdQ.get()

def format_exc_start(start=0):

    etype, value, tb = sys.exc_info()

    tbbits = traceback.extract_tb(tb)[start:]

    list = ['Traceback (most recent call last):\n']

    list = list + traceback.format_list(tbbits)

    list = list + traceback.format_exception_only(etype, value)

    return ''.join(list)

def incomplete_utf8_sequence(byteseq):

    """

    str -> int

    Given a UTF-8-encoded byte sequence (str), returns the number of bytes at

    the end of the string which comprise an incomplete UTF-8 character

    sequence.

    If the string is empty or ends with a complete character OR INVALID

    sequence, returns 0.

    Otherwise, returns 1-3 indicating the number of bytes in the final

    incomplete (but valid) character sequence.

    Does not check any bytes before the final sequence for correctness.

    >>> incomplete_utf8_sequence("")

    0

    >>> incomplete_utf8_sequence("xy")

    0

    >>> incomplete_utf8_sequence("xy\xc3\xbc")

    0

    >>> incomplete_utf8_sequence("\xc3")

    1

    >>> incomplete_utf8_sequence("\xbc\xc3")

    1

    >>> incomplete_utf8_sequence("xy\xbc\xc3")

    1

    >>> incomplete_utf8_sequence("xy\xe0\xa0")

    2

    >>> incomplete_utf8_sequence("xy\xf4")

    1

    >>> incomplete_utf8_sequence("xy\xf4\x8f")

    2

    >>> incomplete_utf8_sequence("xy\xf4\x8f\xa0")

    3

    """

    count = 0

    expect = None

    for b in byteseq[::-1]:

        b = ord(b)

        count += 1

        if b & 0x80 == 0x0:

            # 0xxxxxxx (single-byte character)

            expect = 1

            break

        elif b & 0xc0 == 0x80:

            # 10xxxxxx (subsequent byte)

            pass

        elif b & 0xe0 == 0xc0:

            # 110xxxxx (start of 2-byte sequence)

            expect = 2

            break

        elif b & 0xf0 == 0xe0:

            # 1110xxxx (start of 3-byte sequence)

            expect = 3

            break

        elif b & 0xf8 == 0xf0:

            # 11110xxx (start of 4-byte sequence)

            expect = 4

            break

        else:

            # Invalid byte

            return 0

        if count >= 4:

            # Seen too many "subsequent bytes", invalid

            return 0

    if expect is None:

        # We never saw a "first byte", invalid

        return 0

    # We now know expect and count

    if count >= expect:

        # Complete, or we saw an invalid sequence

        return 0

    elif count < expect:

        # Incomplete

        return count

if __name__ == "__main__":

    port = int(sys.argv[1])

    magic = sys.argv[2]

    # Sanitise the Enviroment

    os.environ = {}

    os.environ['PATH'] = '/usr/local/bin:/usr/bin:/bin'

    if len(sys.argv) >= 4:

        # working_dir

        os.chdir(sys.argv[3])

        os.environ['HOME'] = sys.argv[3]

    # Make python's search path follow the cwd

    sys.path[0] = ''

    common.chat.start_server(port, magic, True, dispatch_msg, initializer)