def open_serial(device, baud=9600, logfile=None, flags=None):
"""Return a SerialPort object wrapping a serial port device. Call with
devicename, baudrate, logfile is optional, and flags should be a tuple of
strings in stty flag format.
"""
if not lockdev.dev_testlock(device):
raise IOError, (EACCES, "device %r is locked." % (device,))
lockdev.dev_lock(device)
fd = os.open(device, os.O_RDWR)
termtools.setraw(fd)
termtools.set_baud(fd, baud)
if flags:
termtools.stty(fd, *flags)
fo = os.fdopen(fd, "w+", 0)
return fo