/* 
 * tclWinSock.c --
 *
 *	This file contains Windows-specific socket related code.
 *
 * Copyright (c) 1995-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclWinSock.c,v 1.36.2.10 2009/04/27 22:10:28 ferrieux Exp $
 * RCS: @(#) $Id: tclWinSock.c,v 1.36.2.11 2010/09/24 17:53:14 andreas_kupries Exp $
 *
 * -----------------------------------------------------------------------
 *
 * General information on how this module works.
 *
 * - Each Tcl-thread with its sockets maintains an internal window to receive
 *   socket messages from the OS.
 *
 * - To ensure that message reception is always running this window is
 *   actually owned and handled by an internal thread. This we call the
 *   co-thread of Tcl's thread.
 *
 * - The whole structure is set up by InitSockets() which is called for each
 *   Tcl thread. The implementation of the co-thread is in SocketThread(),
 *   and the messages are handled by SocketProc(). The connection between
 *   both is not directly visible, it is done through a Win32 window class.
 *   This class is initialized by InitSockets() as well, and used in the
 *   creation of the message receiver windows.
 *
 * - An important thing to note is that *both* thread and co-thread have
 *   access to the list of sockets maintained in the private TSD data of the
 *   thread. The co-thread was given access to it upon creation through the
 *   new thread's client-data.
 *
 *   Because of this dual access the TSD data contains an OS mutex, the
 *   "socketListLock", to mediate exclusion between thread and co-thread.
 *
 *   The co-thread's access is all in SocketProc(). The thread's access is
 *   through SocketEventProc() (1) and the functions called by it.
 *
 *   (Ad 1) This is the handler function for all queued socket events, which
 *          all the OS messages are translated to through the EventSource (2)
 *          driven by the OS messages.
 *
 *   (Ad 2) The main functions for this are SocketSetupProc() and
 *          SocketCheckProc().
 */

#include "tclWinInt.h"

/*
 * Make sure to remove the redirection defines set in tclWinPort.h
 * that is in use in other sections of the core, except for us.

     */

    len = sizeof(SOCKADDR_IN);

    newSocket = winSock.accept(infoPtr->socket, (SOCKADDR *)&addr,
	    &len);

    /*
     * Protect access to sockets (acceptEventCount, readyEvents) in socketList
     * by the lock.  Fix for SF Tcl Bug 3056775.
     */
    WaitForSingleObject(tsdPtr->socketListLock, INFINITE);

    /*
     * Clear the ready mask so we can detect the next connection request.
     * Note that connection requests are level triggered, so if there is
     * a request already pending, a new event will be generated.
     */

    if (newSocket == INVALID_SOCKET) {
	infoPtr->acceptEventCount = 0;
	infoPtr->readyEvents &= ~(FD_ACCEPT);

	SetEvent(tsdPtr->socketListLock);
	return;
    }

    /*
     * It is possible that more than one FD_ACCEPT has been sent, so an extra
     * count must be kept.  Decrement the count, and reset the readyEvent bit
     * if the count is no longer > 0.
     */

    infoPtr->acceptEventCount--;

    if (infoPtr->acceptEventCount <= 0) {
	infoPtr->readyEvents &= ~(FD_ACCEPT);
    }

    SetEvent(tsdPtr->socketListLock);

    /*
     * Win-NT has a misfeature that sockets are inherited in child
     * processes by default.  Turn off the inherit bit.
     */

    SetHandleInformation( (HANDLE) newSocket, HANDLE_FLAG_INHERIT, 0 );