# Initialize
#
# Douglas Thrift
#
# $Id$

import os
import socket
import sys

path = os.path.abspath(os.path.join(os.path.dirname(__file__), '..'))

if path not in sys.path:
	sys.path.insert(0, path)

path = os.path.abspath(os.path.join(os.path.dirname(__file__), '..', 'lib'))

if path not in sys.path:
	sys.path.insert(0, path)

del path

os.environ['DJANGO_SETTINGS_MODULE'] = 'ccscslab.settings' if socket.gethostname() != 'wireless.ccs.ucsb.edu' else 'ccscslab.settings.wireless'

def lock(debug, file = sys.argv[0]):
	import atexit
	import tempfile

	dir = os.path.join(tempfile.gettempdir(), '.ccscslab')
	root = os.getuid() == 0

	if root:
		os.seteuid(1001)

	if not os.path.exists(dir):
		os.mkdir(dir, 0700)

	file = os.path.join(dir, os.path.basename(file))

	try:
		fd = os.open(file, os.O_WRONLY | os.O_NONBLOCK | os.O_CREAT | os.O_EXLOCK, 0600)
	except OSError, error:
		import errno

		if error.errno == errno.EWOULDBLOCK:
			if debug:
				print 'lock:\n   %s\n   locked' % file

			sys.exit(1)
		else:
			raise

	if debug:
		print 'lock:\n   %s\n   locking' % file

	@atexit.register
	def unlock():
		os.close(fd)

		if debug:
			print 'lock:\n   %s\n   unlocked' % file

	if root:
		os.seteuid(0)