/usr/lib/python2.7/dist-packages/xvfbwrapper.py is in python-xvfbwrapper 0.2.9-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 | #!/usr/bin/env python
#
# * Corey Goldberg, 2012, 2013, 2015, 2016
#
# * inspired by: PyVirtualDisplay
"""wrapper for running display inside X virtual framebuffer (Xvfb)"""
import os
import subprocess
import tempfile
import time
import fcntl
from random import randint
try:
BlockingIOError
except NameError:
# python 2
BlockingIOError = IOError
class Xvfb(object):
# Maximum value to use for a display. 32-bit maxint is the
# highest Xvfb currently supports
MAX_DISPLAY = 2147483647
SLEEP_TIME_BEFORE_START = 0.1
def __init__(self, width=800, height=680, colordepth=24, tempdir=None,
**kwargs):
self.width = width
self.height = height
self.colordepth = colordepth
self._tempdir = tempdir or tempfile.gettempdir()
if not self.xvfb_exists():
msg = 'Can not find Xvfb. Please install it and try again.'
raise EnvironmentError(msg)
self.extra_xvfb_args = ['-screen', '0', '{}x{}x{}'.format(
self.width, self.height, self.colordepth)]
for key, value in kwargs.items():
self.extra_xvfb_args += ['-{}'.format(key), value]
if 'DISPLAY' in os.environ:
self.orig_display = os.environ['DISPLAY'].split(':')[1]
else:
self.orig_display = None
self.proc = None
def __enter__(self):
self.start()
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.stop()
def start(self):
self.new_display = self._get_next_unused_display()
display_var = ':{}'.format(self.new_display)
self.xvfb_cmd = ['Xvfb', display_var] + self.extra_xvfb_args
with open(os.devnull, 'w') as fnull:
self.proc = subprocess.Popen(self.xvfb_cmd,
stdout=fnull,
stderr=fnull,
close_fds=True)
# give Xvfb time to start
time.sleep(self.__class__.SLEEP_TIME_BEFORE_START)
ret_code = self.proc.poll()
if ret_code is None:
self._set_display_var(self.new_display)
else:
self._cleanup_lock_file()
raise RuntimeError('Xvfb did not start')
def stop(self):
try:
if self.orig_display is None:
del os.environ['DISPLAY']
else:
self._set_display_var(self.orig_display)
if self.proc is not None:
try:
self.proc.terminate()
self.proc.wait()
except OSError:
pass
self.proc = None
finally:
self._cleanup_lock_file()
def _cleanup_lock_file(self):
'''
This should always get called if the process exits safely
with Xvfb.stop() (whether called explicitly, or by __exit__).
If you are ending up with /tmp/X123-lock files when Xvfb is not
running, then Xvfb is not exiting cleanly. Always either call
Xvfb.stop() in a finally block, or use Xvfb as a context manager
to ensure lock files are purged.
'''
self._lock_display_file.close()
try:
os.remove(self._lock_display_file.name)
except OSError:
pass
def _get_next_unused_display(self):
'''
In order to ensure multi-process safety, this method attempts
to acquire an exclusive lock on a temporary file whose name
contains the display number for Xvfb.
'''
tempfile_path = os.path.join(self._tempdir, '.X{0}-lock')
while True:
rand = randint(1, self.__class__.MAX_DISPLAY)
self._lock_display_file = open(tempfile_path.format(rand), 'w')
try:
fcntl.flock(self._lock_display_file,
fcntl.LOCK_EX | fcntl.LOCK_NB)
except BlockingIOError:
continue
else:
return rand
def _set_display_var(self, display):
os.environ['DISPLAY'] = ':{}'.format(display)
def xvfb_exists(self):
"""Check that Xvfb is available on PATH and is executable."""
paths = os.environ['PATH'].split(os.pathsep)
return any(os.access(os.path.join(path, 'Xvfb'), os.X_OK)
for path in paths)
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