build/android/pylib/utils/xvfb.py

   1 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 # pylint: disable=W0702
   6
   7 import os
   8 import signal
   9 import subprocess
  10 import sys
  11 import time
  12
  13
  14 def _IsLinux():
  15   """Return True if on Linux; else False."""
  16   return sys.platform.startswith('linux')
  17
  18
  19 class Xvfb(object):
  20   """Class to start and stop Xvfb if relevant.  Nop if not Linux."""
  21
  22   def __init__(self):
  23     self._pid = 0
  24
  25   def Start(self):
  26     """Start Xvfb and set an appropriate DISPLAY environment.  Linux only.
  27
  28     Copied from tools/code_coverage/coverage_posix.py
  29     """
  30     if not _IsLinux():
  31       return
  32     proc = subprocess.Popen(['Xvfb', ':9', '-screen', '0', '1024x768x24',
  33                              '-ac'],
  34                             stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
  35     self._pid = proc.pid
  36     if not self._pid:
  37       raise Exception('Could not start Xvfb')
  38     os.environ['DISPLAY'] = ':9'
  39
  40     # Now confirm, giving a chance for it to start if needed.
  41     for _ in range(10):
  42       proc = subprocess.Popen('xdpyinfo >/dev/null', shell=True)
  43       _, retcode = os.waitpid(proc.pid, 0)
  44       if retcode == 0:
  45         break
  46       time.sleep(0.25)
  47     if retcode != 0:
  48       raise Exception('Could not confirm Xvfb happiness')
  49
  50   def Stop(self):
  51     """Stop Xvfb if needed.  Linux only."""
  52     if self._pid:
  53       try:
  54         os.kill(self._pid, signal.SIGKILL)
  55       except:
  56         pass
  57       del os.environ['DISPLAY']
  58       self._pid = 0