# -*- Mode: Python; tab-width: 4 -*-

# set the global SO_OPENTYPE parameter

import struct
import windll
import winerror

wsock32 = windll.module ('wsock32')

option = windll.membuf (4)
option_len = windll.membuf (4)

option_len.write (struct.pack ('l', 4))

INVALID_SOCKET		= -1
SOCKET_SOL			= 0xffff

#
# Option for opening sockets for synchronous access.
#

SO_OPENTYPE     		= 0x7008

SO_SYNCHRONOUS_ALERT   	= 0x10
SO_SYNCHRONOUS_NONALERT	= 0x20

def set_sync_option (on=1):
    result = wsock32.getsockopt (
            INVALID_SOCKET,
            SOCKET_SOL,
            SO_OPENTYPE,
            option,
            option_len
            )
    if result:
        raise SystemError, "getsockopt: (%d)" % (
                wsock32.WSAGetLastError()
                )
    else:
        old = struct.unpack ('l', option.read())[0]
    if on:
        new = old | SO_SYNCHRONOUS_ALERT
    else:
        new = old & (~SO_SYNCHRONOUS_ALERT)
    option.write (struct.pack ('l', new))
    result = wsock32.setsockopt (
            INVALID_SOCKET,
            SOCKET_SOL,
            SO_OPENTYPE,
            option,
            option_len
            )
    if result:
        raise SystemError, "getsockopt: (%d)" % (
                wsock32.WSAGetLastError()
                )
    return old
    
def sync_on():
    return set_sync_option (1)
    
def sync_off():
    return set_sync_option (0)