import os import socket import sys from session.Process import Process def get_display_number(): """Find a free display number trying to connect to 6000+ ports""" retries = 20 display_number = 1 display_is_free = False while not display_is_free and retries > 0: s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) try: s.connect(('127.0.0.1', 6000 + display_number)) logging.info('Display %d is already in use. Trying next.' % (display_number)) s.close() display_number += 1 retries -= 1 except: display_is_free = True if display_is_free: return display_number else: logging.error('Cannot find a free display.') sys.exit(0) class XephyrProcess(Process): def __init__(self): self._display = get_display_number() cmd = 'Xephyr :%d -ac -screen 640x480' % (self._display) Process.__init__(self, cmd) def get_name(self): return 'Xephyr' def start(self): Process.start(self) os.environ['DISPLAY'] = ":%d" % (self._display) class XnestProcess(Process): def __init__(self): self._display = get_display_number() cmd = 'Xnest :%d -ac -geometry 640x480' % (self._display) Process.__init__(self, cmd) def get_name(self): return 'Xnest' def start(self): Process.start(self) os.environ['DISPLAY'] = ":%d" % (self._display) class Emulator: """The OLPC emulator""" def start(self): try: process = XephyrProcess() process.start() except: try: process = XnestProcess() process.start() except: print('Cannot run the emulator. You need to install\ Xephyr or Xnest.') sys.exit(0)