TclFile writeFile;		/* Input from pipe. */
    TclFile errorFile;		/* Error output from pipe. */
    int numPids;		/* Number of processes attached to pipe. */
    Tcl_Pid *pidPtr;		/* Pids of attached processes. */
    Tcl_ThreadId threadId;	/* Thread to which events should be reported.
				 * This value is used by the reader/writer
				 * threads. */
    TclPipeThreadInfo *writeTI;	/* Thread info of writer and reader, this */
    TclPipeThreadInfo *readTI;	/* structure owned by corresponding thread. */
    HANDLE writeThread;		/* Handle to writer thread. */
    HANDLE readThread;		/* Handle to reader thread. */

    HANDLE writable;		/* Manual-reset event to signal when the
				 * writer thread has finished waiting for the
				 * current buffer to be written. */
    HANDLE readable;		/* Manual-reset event to signal when the
				 * reader thread has finished waiting for
				 * input. */
    HANDLE startWriter;		/* Auto-reset event used by the main thread to
				 * signal when the writer thread should
				 * attempt to write to the pipe. */
    HANDLE stopWriter;		/* Manual-reset event used to alert the reader
				 * thread to fall-out and exit */
    HANDLE startReader;		/* Auto-reset event used by the main thread to
				 * signal when the reader thread should
				 * attempt to read from the pipe. */
    HANDLE stopReader;		/* Manual-reset event used to alert the reader
				 * thread to fall-out and exit */
    DWORD writeError;		/* An error caused by the last background
				 * write. Set to 0 if no error has been
				 * detected. This word is shared with the
				 * writer thread so access must be
				 * synchronized with the writable object.
				 */
    char *writeBuf;		/* Current background output buffer. Access is

	if (arg[0] == '\0') {
	    quote = 1;
	} else {
	    int count;
	    Tcl_UniChar ch;

	    for (start = arg; *start != '\0'; start += count) {
		count = Tcl_UtfToUniChar(start, &ch);
		count = TclUtfToUniChar(start, &ch);
		if (Tcl_UniCharIsSpace(ch)) {	/* INTL: ISO space. */
		    quote = 1;
		    break;
		}
	    }
	}
	if (quote) {

    TclFile writeFile,		/* If non-null, gives the file for writing. */
    TclFile errorFile,		/* If non-null, gives the file where errors
				 * can be read. */
    int numPids,		/* The number of pids in the pid array. */
    Tcl_Pid *pidPtr)		/* An array of process identifiers. */
{
    char channelName[16 + TCL_INTEGER_SPACE];
    DWORD id;
    PipeInfo *infoPtr = ckalloc(sizeof(PipeInfo));

    PipeInit();

    infoPtr->watchMask = 0;
    infoPtr->flags = 0;
    infoPtr->readFlags = 0;

    if (readFile != NULL) {
	/*
	 * Start the background reader thread.
	 */

	infoPtr->readable = CreateEvent(NULL, TRUE, TRUE, NULL);
	infoPtr->startReader = CreateEvent(NULL, FALSE, FALSE, NULL);
	infoPtr->stopReader = CreateEvent(NULL, TRUE, FALSE, NULL);
	infoPtr->readThread = CreateThread(NULL, 256, PipeReaderThread,
	    TclPipeThreadCreateTI(&infoPtr->readTI, infoPtr, infoPtr->readable),
		infoPtr, 0, &id);
	    0, NULL);
	SetThreadPriority(infoPtr->readThread, THREAD_PRIORITY_HIGHEST);
	infoPtr->validMask |= TCL_READABLE;
    } else {
    	infoPtr->readTI = NULL;
	infoPtr->readThread = 0;
    }
    if (writeFile != NULL) {
	/*
	 * Start the background writer thread.
	 */

	infoPtr->writable = CreateEvent(NULL, TRUE, TRUE, NULL);
	infoPtr->startWriter = CreateEvent(NULL, FALSE, FALSE, NULL);
	infoPtr->stopWriter = CreateEvent(NULL, TRUE, FALSE, NULL);
	infoPtr->writeThread = CreateThread(NULL, 256, PipeWriterThread,
	    TclPipeThreadCreateTI(&infoPtr->writeTI, infoPtr, infoPtr->writable),
		infoPtr, 0, &id);
	SetThreadPriority(infoPtr->readThread, THREAD_PRIORITY_HIGHEST);
	    0, NULL);
	SetThreadPriority(infoPtr->writeThread, THREAD_PRIORITY_HIGHEST);
	infoPtr->validMask |= TCL_WRITABLE;
    } else {
    	infoPtr->writeTI = NULL;
    	infoPtr->writeThread = 0;
    }

    /*
     * For backward compatibility with previous versions of Tcl, we use
     * "file%d" as the base name for pipes even though it would be more
     * natural to use "pipe%d". Use the pointer to keep the channel names
     * unique, in case channels share handles (stdin/stdout).

    int flags)			/* Flags that indicate which side to close. */
{
    PipeInfo *pipePtr = (PipeInfo *) instanceData;
    Tcl_Channel errChan;
    int errorCode, result;
    PipeInfo *infoPtr, **nextPtrPtr;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
    DWORD exitCode;
    int inExit = (TclInExit() || TclInThreadExit());

    errorCode = 0;
    result = 0;

    if ((!flags || flags == TCL_CLOSE_READ) && (pipePtr->readFile != NULL)) {
    if ((!flags || flags & TCL_CLOSE_READ) && (pipePtr->readFile != NULL)) {
	/*
	 * Clean up the background thread if necessary. Note that this must be
	 * done before we can close the file, since the thread may be blocking
	 * trying to read from the pipe.
	 */

	if (pipePtr->readThread) {
	    /*
	     * The thread may already have closed on its own. Check its exit
	     * code.
	     */

	    GetExitCodeThread(pipePtr->readThread, &exitCode);

	    TclPipeThreadStop(&pipePtr->readTI, pipePtr->readThread);
	    if (exitCode == STILL_ACTIVE) {
		/*
		 * Set the stop event so that if the reader thread is blocked
		 * in PipeReaderThread on WaitForMultipleEvents, it will exit
		 * cleanly.
		 */

		SetEvent(pipePtr->stopReader);

		/*
		 * Wait at most 20 milliseconds for the reader thread to
		 * close.
		 */

		if (WaitForSingleObject(pipePtr->readThread,
			20) == WAIT_TIMEOUT) {
		    /*
		     * The thread must be blocked waiting for the pipe to
		     * become readable in ReadFile(). There isn't a clean way
		     * to exit the thread from this condition. We should
		     * terminate the child process instead to get the reader
		     * thread to fall out of ReadFile with a FALSE. (below) is
		     * not the correct way to do this, but will stay here
		     * until a better solution is found.
		     *
		     * Note that we need to guard against terminating the
		     * thread while it is in the middle of Tcl_ThreadAlert
		     * because it won't be able to release the notifier lock.
		     */

		    Tcl_MutexLock(&pipeMutex);

		    /* BUG: this leaks memory */
		    TerminateThread(pipePtr->readThread, 0);
		    Tcl_MutexUnlock(&pipeMutex);
		}
	    }

	    CloseHandle(pipePtr->readThread);
	    CloseHandle(pipePtr->readable);
	    CloseHandle(pipePtr->startReader);
	    CloseHandle(pipePtr->stopReader);
	    pipePtr->readThread = NULL;
	}
	if (TclpCloseFile(pipePtr->readFile) != 0) {
	    errorCode = errno;
	}
	pipePtr->validMask &= ~TCL_READABLE;
	pipePtr->readFile = NULL;
    }
    if ((!flags || flags & TCL_CLOSE_WRITE)
    if ((!flags || flags & TCL_CLOSE_WRITE) && (pipePtr->writeFile != NULL)) {
	    && (pipePtr->writeFile != NULL)) {
	if (pipePtr->writeThread) {

	    /*
	     * Wait for the  writer thread to finish the  current buffer, then
	     * terminate the thread  and close the handles. If  the channel is
	     * nonblocking but blocked during  exit, bail out since the worker
	     * nonblocking or may block during exit, bail out since the worker
	     * thread is not interruptible and we want TIP#398-fast-exit.
	     */
	    if (TclInExit()
		&& (pipePtr->flags & PIPE_ASYNC)) {
	    if ((pipePtr->flags & PIPE_ASYNC) && inExit) {

		/* give it a chance to leave honorably */
		SetEvent(pipePtr->stopWriter);
		TclPipeThreadStopSignal(&pipePtr->writeTI, pipePtr->writable);

		if (WaitForSingleObject(pipePtr->writable, 0) == WAIT_TIMEOUT) {
		if (WaitForSingleObject(pipePtr->writable, 20) == WAIT_TIMEOUT) {
		    return EWOULDBLOCK;
		}

	    } else {

		WaitForSingleObject(pipePtr->writable, INFINITE);
		WaitForSingleObject(pipePtr->writable, inExit ? 5000 : INFINITE);

	    }

	    /*
	     * The thread may already have closed on it's own. Check its exit
	     * code.
	     */

	    TclPipeThreadStop(&pipePtr->writeTI, pipePtr->writeThread);
	    GetExitCodeThread(pipePtr->writeThread, &exitCode);

	    if (exitCode == STILL_ACTIVE) {
		/*
		 * Set the stop event so that if the reader thread is blocked
		 * in PipeReaderThread on WaitForMultipleEvents, it will exit
		 * cleanly.
		 */

		SetEvent(pipePtr->stopWriter);

		/*
		 * Wait at most 20 milliseconds for the reader thread to
		 * close.
		 */

		if (WaitForSingleObject(pipePtr->writeThread,
			20) == WAIT_TIMEOUT) {
		    /*
		     * The thread must be blocked waiting for the pipe to
		     * consume input in WriteFile(). There isn't a clean way
		     * to exit the thread from this condition. We should
		     * terminate the child process instead to get the writer
		     * thread to fall out of WriteFile with a FALSE. (below)
		     * is not the correct way to do this, but will stay here
		     * until a better solution is found.
		     *
		     * Note that we need to guard against terminating the
		     * thread while it is in the middle of Tcl_ThreadAlert
		     * because it won't be able to release the notifier lock.
		     */

		    Tcl_MutexLock(&pipeMutex);

		    /* BUG: this leaks memory */
		    TerminateThread(pipePtr->writeThread, 0);
		    Tcl_MutexUnlock(&pipeMutex);
		}
	    }

	    CloseHandle(pipePtr->writeThread);
	    CloseHandle(pipePtr->writable);
	    CloseHandle(pipePtr->startWriter);
	    CloseHandle(pipePtr->stopWriter);
	    CloseHandle(pipePtr->writeThread);
	    pipePtr->writeThread = NULL;
	}
	if (TclpCloseFile(pipePtr->writeFile) != 0) {
	    if (errorCode == 0) {
		errorCode = errno;
	    }
	}

	    nextPtrPtr = &infoPtr->nextPtr, infoPtr = *nextPtrPtr) {
	if (infoPtr == (PipeInfo *)pipePtr) {
	    *nextPtrPtr = infoPtr->nextPtr;
	    break;
	}
    }

    if ((pipePtr->flags & PIPE_ASYNC) || TclInExit()) {
    if ((pipePtr->flags & PIPE_ASYNC) || inExit) {
	/*
	 * If the channel is non-blocking or Tcl is being cleaned up, just
	 * detach the children PIDs, reap them (important if we are in a
	 * dynamic load module), and discard the errorFile.
	 */

	Tcl_DetachPids(pipePtr->numPids, pipePtr->pidPtr);

    int *errorCode)		/* Where to store error code. */
{
    PipeInfo *infoPtr = (PipeInfo *) instanceData;
    WinFile *filePtr = (WinFile*) infoPtr->writeFile;
    DWORD bytesWritten, timeout;

    *errorCode = 0;

    /* avoid blocking if pipe-thread exited */
    timeout = (infoPtr->flags & PIPE_ASYNC) ? 0 : INFINITE;
    timeout = ((infoPtr->flags & PIPE_ASYNC) || !TclPipeThreadIsAlive(&infoPtr->writeTI)
	|| TclInExit() || TclInThreadExit()) ? 0 : INFINITE;
    if (WaitForSingleObject(infoPtr->writable, timeout) == WAIT_TIMEOUT) {
	/*
	 * The writer thread is blocked waiting for a write to complete and
	 * the channel is in non-blocking mode.
	 */

	errno = EWOULDBLOCK;

	    }
	    infoPtr->writeBufLen = toWrite;
	    infoPtr->writeBuf = ckalloc(toWrite);
	}
	memcpy(infoPtr->writeBuf, buf, (size_t) toWrite);
	infoPtr->toWrite = toWrite;
	ResetEvent(infoPtr->writable);
	SetEvent(infoPtr->startWriter);
	TclPipeThreadSignal(&infoPtr->writeTI);
	bytesWritten = toWrite;
    } else {
	/*
	 * In the blocking case, just try to write the buffer directly. This
	 * avoids an unnecessary copy.
	 */

    HANDLE *handle = ((WinFile *) infoPtr->readFile)->handle;

    while (1) {
	/*
	 * Synchronize with the reader thread.
	 */

	timeout = blocking ? INFINITE : 0;
	/* avoid blocking if pipe-thread exited */
	timeout = (!blocking || !TclPipeThreadIsAlive(&infoPtr->readTI)
		|| TclInExit() || TclInThreadExit()) ? 0 : INFINITE;
	if (WaitForSingleObject(infoPtr->readable, timeout) == WAIT_TIMEOUT) {
	    /*
	     * The reader thread is blocked waiting for data and the channel
	     * is in non-blocking mode.
	     */

	    errno = EWOULDBLOCK;

	}

	/*
	 * There wasn't any data available, so reset the thread and try again.
	 */

	ResetEvent(infoPtr->readable);
	SetEvent(infoPtr->startReader);
	TclPipeThreadSignal(&infoPtr->readTI);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * PipeReaderThread --

 *----------------------------------------------------------------------
 */

static DWORD WINAPI
PipeReaderThread(
    LPVOID arg)
{
    TclPipeThreadInfo *pipeTI = (TclPipeThreadInfo *)arg;
    PipeInfo *infoPtr = (PipeInfo *)arg;
    HANDLE *handle = ((WinFile *) infoPtr->readFile)->handle;
    PipeInfo *infoPtr = NULL; /* access info only after success init/wait */
    HANDLE handle = NULL;
    DWORD count, err;
    int done = 0;
    HANDLE wEvents[2];
    DWORD waitResult;

    wEvents[0] = infoPtr->stopReader;
    wEvents[1] = infoPtr->startReader;

    while (!done) {
	/*
	 * Wait for the main thread to signal before attempting to wait on the
	 * pipe becoming readable.
	 */
	if (!TclPipeThreadWaitForSignal(&pipeTI)) {
	    /* exit */
	    break;

	}
	waitResult = WaitForMultipleObjects(2, wEvents, FALSE, INFINITE);

	if (waitResult != (WAIT_OBJECT_0 + 1)) {
	if (!infoPtr) {
	    /*
	     * The start event was not signaled. It might be the stop event or
	     * an error, so exit.
	     */

	    break;
	    infoPtr = (PipeInfo *)pipeTI->clientData;
	    handle = ((WinFile *) infoPtr->readFile)->handle;
	}

	/*
	 * Try waiting for 0 bytes. This will block until some data is
	 * available on NT, but will return immediately on Win 95. So, if no
	 * data is available after the first read, we block until we can read
	 * a single byte off of the pipe.
	 */

	if (ReadFile(handle, NULL, 0, &count, NULL) == FALSE ||
		PeekNamedPipe(handle, NULL, 0, NULL, &count, NULL) == FALSE) {
	    /*
	     * The error is a result of an EOF condition, so set the EOF bit
	     * before signalling the main thread.
	     */

	    err = GetLastError();
	    if (err == ERROR_BROKEN_PIPE) {
		infoPtr->readFlags |= PIPE_EOF;
		done = 1;
	    } else if (err == ERROR_INVALID_HANDLE) {
		break;
		done = 1;
	    }
	} else if (count == 0) {
	    if (ReadFile(handle, &(infoPtr->extraByte), 1, &count, NULL)
		    != FALSE) {
		/*
		 * One byte was consumed as a side effect of waiting for the
		 * pipe to become readable.

		     * The error is a result of an EOF condition, so set the
		     * EOF bit before signalling the main thread.
		     */

		    infoPtr->readFlags |= PIPE_EOF;
		    done = 1;
		} else if (err == ERROR_INVALID_HANDLE) {
		    break;
		    done = 1;
		}
	    }
	}


	/*
	 * Signal the main thread by signalling the readable event and then
	 * waking up the notifier thread.
	 */

	SetEvent(infoPtr->readable);

	     */

	    Tcl_ThreadAlert(infoPtr->threadId);
	}
	Tcl_MutexUnlock(&pipeMutex);
    }

    /*
     * If state of thread was set to stop, we can sane free info structure,
     * otherwise it is shared with main thread, so main thread will own it
     */
    TclPipeThreadExit(&pipeTI);

    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * PipeWriterThread --

 *----------------------------------------------------------------------
 */

static DWORD WINAPI
PipeWriterThread(
    LPVOID arg)
{
    TclPipeThreadInfo *pipeTI = (TclPipeThreadInfo *)arg;
    PipeInfo *infoPtr = (PipeInfo *)arg;
    HANDLE *handle = ((WinFile *) infoPtr->writeFile)->handle;
    PipeInfo *infoPtr = NULL; /* access info only after success init/wait */
    HANDLE handle = NULL;
    DWORD count, toWrite;
    char *buf;
    int done = 0;
    HANDLE wEvents[2];
    DWORD waitResult;

    wEvents[0] = infoPtr->stopWriter;
    wEvents[1] = infoPtr->startWriter;

    while (!done) {
	/*
	 * Wait for the main thread to signal before attempting to write.
	 */

	if (!TclPipeThreadWaitForSignal(&pipeTI)) {
	waitResult = WaitForMultipleObjects(2, wEvents, FALSE, INFINITE);

	    /* exit */
	if (waitResult != (WAIT_OBJECT_0 + 1)) {
	    /*
	     * The start event was not signaled. It might be the stop event or
	     * an error, so exit.
	     */

	    break;
	    if (waitResult == WAIT_OBJECT_0) {
		SetEvent(infoPtr->writable);
	    }
	}

	    break;
	if (!infoPtr) {
	    infoPtr = (PipeInfo *)pipeTI->clientData;
	    handle = ((WinFile *) infoPtr->writeFile)->handle;
	}

	buf = infoPtr->writeBuf;
	toWrite = infoPtr->toWrite;

	/*
	 * Loop until all of the bytes are written or an error occurs.
	 */

	     */

	    Tcl_ThreadAlert(infoPtr->threadId);
	}
	Tcl_MutexUnlock(&pipeMutex);
    }

    /*
     * If state of thread was set to stop, we can sane free info structure,
     * otherwise it is shared with main thread, so main thread will own it.
     */
    TclPipeThreadExit(&pipeTI);

    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * PipeThreadActionProc --

    return Tcl_MakeFileChannel((ClientData) handle,
	    TCL_READABLE|TCL_WRITABLE);

  gotError:
    TclWinConvertError(GetLastError());
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * TclPipeThreadCreateTI --
 *
 *	Creates a thread info structure, can be owned by worker.
 *
 * Results:
 *	Pointer to created TI structure.
 *
 *----------------------------------------------------------------------
 */

TclPipeThreadInfo *
TclPipeThreadCreateTI(
    TclPipeThreadInfo **pipeTIPtr,
    ClientData clientData,
    HANDLE wakeEvent)
{
    TclPipeThreadInfo *pipeTI;
#ifndef _PTI_USE_CKALLOC
    pipeTI = malloc(sizeof(TclPipeThreadInfo));
#else
    pipeTI = ckalloc(sizeof(TclPipeThreadInfo));
#endif
    pipeTI->evControl = CreateEvent(NULL, FALSE, FALSE, NULL);
    pipeTI->state = PTI_STATE_IDLE;
    pipeTI->clientData = clientData;
    pipeTI->evWakeUp = wakeEvent;
    return (*pipeTIPtr = pipeTI);
}

/*
 *----------------------------------------------------------------------
 *
 * TclPipeThreadWaitForSignal --
 *
 *	Wait for work/stop signals inside pipe worker.
 *
 * Results:
 *	1 if signaled to work, 0 if signaled to stop.
 *
 * Side effects:
 *	If this function returns 0, TI-structure pointer given via pipeTIPtr
 *	may be NULL, so not accessible (can be owned by main thread).
 *
 *----------------------------------------------------------------------
 */

int
TclPipeThreadWaitForSignal(
    TclPipeThreadInfo **pipeTIPtr)
{
    TclPipeThreadInfo *pipeTI = *pipeTIPtr;
    LONG state;
    DWORD waitResult;
    HANDLE wakeEvent;

    if (!pipeTI) {
	return 0;
    }

    wakeEvent = pipeTI->evWakeUp;
    /*
     * Wait for the main thread to signal before attempting to do the work.
     */

    /* reset work state of thread (idle/waiting) */
    if ((state = InterlockedCompareExchange(&pipeTI->state,
	    PTI_STATE_IDLE, PTI_STATE_WORK)) & (PTI_STATE_STOP|PTI_STATE_END)) {
	/* end of work, check the owner of structure */
	goto end;
    }
    /* entering wait */
    waitResult = WaitForSingleObject(pipeTI->evControl, INFINITE);

    if (waitResult != WAIT_OBJECT_0) {

	/*
	 * The control event was not signaled, so end of work (unexpected
	 * behaviour, main thread can be dead?).
	 */
	goto end;
    }

    /* try to set work state of thread */
    if ((state = InterlockedCompareExchange(&pipeTI->state,
	    PTI_STATE_WORK, PTI_STATE_IDLE)) & (PTI_STATE_STOP|PTI_STATE_END)) {
	/* end of work */
	goto end;
    }

    /* signaled to work */
    return 1;

end:
    /* end of work, check the owner of the TI structure */
    if (state != PTI_STATE_STOP) {
	*pipeTIPtr = NULL;
    } else {
    	pipeTI->evWakeUp = NULL;
    }
    if (wakeEvent) {
    	SetEvent(wakeEvent);
    }
    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * TclPipeThreadStopSignal --
 *
 *	Send stop signal to the pipe worker (without waiting).
 *
 *	After calling of this function, TI-structure pointer given via pipeTIPtr
 *	may be NULL.
 *
 * Results:
 *	1 if signaled (or pipe-thread is down), 0 if pipe thread still working.
 *
 *----------------------------------------------------------------------
 */

int
TclPipeThreadStopSignal(
    TclPipeThreadInfo **pipeTIPtr, HANDLE wakeEvent)
{
    TclPipeThreadInfo *pipeTI = *pipeTIPtr;
    HANDLE evControl;
    int state;

    if (!pipeTI) {
	return 1;
    }
    evControl = pipeTI->evControl;
    pipeTI->evWakeUp = wakeEvent;
    switch (
	(state = InterlockedCompareExchange(&pipeTI->state,
	    PTI_STATE_STOP, PTI_STATE_IDLE))
    ) {

	case PTI_STATE_IDLE:

	    /* Thread was idle/waiting, notify it goes teardown */
	    SetEvent(evControl);

	    *pipeTIPtr = NULL;

	case PTI_STATE_DOWN:

	return 1;

	default:
	    /*
	     * Thread works currently, we should try to end it, own the TI structure
	     * (because of possible sharing the joint structures with thread)
	     */
	    InterlockedExchange(&pipeTI->state, PTI_STATE_END);
	break;
    }

    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * TclPipeThreadStop --
 *
 *	Send stop signal to the pipe worker and wait for thread completion.
 *
 *	May be combined with TclPipeThreadStopSignal.
 *
 *	After calling of this function, TI-structure pointer given via pipeTIPtr
 *	is not accessible (owned by pipe worker or released here).
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Can terminate pipe worker (and / or stop its synchronous operations).
 *
 *----------------------------------------------------------------------
 */

void
TclPipeThreadStop(
    TclPipeThreadInfo **pipeTIPtr,
    HANDLE hThread)
{
    TclPipeThreadInfo *pipeTI = *pipeTIPtr;
    HANDLE evControl;
    int state;

    if (!pipeTI) {
	return;
    }
    pipeTI = *pipeTIPtr;
    evControl = pipeTI->evControl;
    pipeTI->evWakeUp = NULL;
    /*
     * Try to sane stop the pipe worker, corresponding its current state
     */
    switch (
	(state = InterlockedCompareExchange(&pipeTI->state,
	    PTI_STATE_STOP, PTI_STATE_IDLE))
    ) {

	case PTI_STATE_IDLE:

	    /* Thread was idle/waiting, notify it goes teardown */
	    SetEvent(evControl);

	    /* we don't need to wait for it at all, thread frees himself (owns the TI structure) */
	    pipeTI = NULL;
	break;

	case PTI_STATE_STOP:
	    /* already stopped, thread frees himself (owns the TI structure) */
	    pipeTI = NULL;
	break;
	case PTI_STATE_DOWN:
	    /* Thread already down (?), do nothing */

	    /* we don't need to wait for it, but we should free pipeTI */
	    hThread = NULL;
	break;

	/* case PTI_STATE_WORK: */
	default:
	    /*
	     * Thread works currently, we should try to end it, own the TI structure
	     * (because of possible sharing the joint structures with thread)
	     */
	    if ((state = InterlockedCompareExchange(&pipeTI->state,
		    PTI_STATE_END, PTI_STATE_WORK)) == PTI_STATE_DOWN
	    ) {
		/* we don't need to wait for it, but we should free pipeTI */
		hThread = NULL;
	    };
	break;
    }

    if (pipeTI && hThread) {
	DWORD exitCode;

	/*
	 * The thread may already have closed on its own. Check its exit
	 * code.
	 */

	GetExitCodeThread(hThread, &exitCode);

	if (exitCode == STILL_ACTIVE) {

	    int inExit = (TclInExit() || TclInThreadExit());
	    /*
	     * Set the stop event so that if the pipe thread is blocked
	     * somewhere, it may hereafter sane exit cleanly.
	     */

	    SetEvent(evControl);

	    /*
	     * Cancel all sync-IO of this thread (may be blocked there).
	     */
	    if (tclWinProcs.cancelSynchronousIo) {
		tclWinProcs.cancelSynchronousIo(hThread);
	    }

	    /*
	     * Wait at most 20 milliseconds for the reader thread to
	     * close (regarding TIP#398-fast-exit).
	     */

	    /* if we want TIP#398-fast-exit. */
	    if (WaitForSingleObject(hThread, inExit ? 0 : 20) == WAIT_TIMEOUT) {

		/*
		 * The thread must be blocked waiting for the pipe to
		 * become readable in ReadFile(). There isn't a clean way
		 * to exit the thread from this condition. We should
		 * terminate the child process instead to get the reader
		 * thread to fall out of ReadFile with a FALSE. (below) is
		 * not the correct way to do this, but will stay here
		 * until a better solution is found.
		 *
		 * Note that we need to guard against terminating the
		 * thread while it is in the middle of Tcl_ThreadAlert
		 * because it won't be able to release the notifier lock.
		 *
		 * Also note that terminating threads during their initialization or teardown phase
		 * may result in ntdll.dll's LoaderLock to remain locked indefinitely.
		 * This causes ntdll.dll's LdrpInitializeThread() to deadlock trying to acquire LoaderLock.
		 * LdrpInitializeThread() is executed within new threads to perform
		 * initialization and to execute DllMain() of all loaded dlls.
		 * As a result, all new threads are deadlocked in their initialization phase and never execute,
		 * even though CreateThread() reports successful thread creation.
		 * This results in a very weird process-wide behavior, which is extremely hard to debug.
		 *
		 * THREADS SHOULD NEVER BE TERMINATED. Period.
		 *
		 * But for now, check if thread is exiting, and if so, let it die peacefully.
		 *
		 * Also don't terminate if in exit (otherwise deadlocked in ntdll.dll's).
		 */

		if ( pipeTI->state != PTI_STATE_DOWN
		  && WaitForSingleObject(hThread,
			inExit ? 50 : 5000) != WAIT_OBJECT_0
		) {
		    /* BUG: this leaks memory */
		    if (inExit || !TerminateThread(hThread, 0)) {
			/* in exit or terminate fails, just give thread a chance to exit */
			if (InterlockedExchange(&pipeTI->state,
				PTI_STATE_STOP) != PTI_STATE_DOWN) {
			    pipeTI = NULL;
			}
		    };
		}
	    }
	}
    }

    *pipeTIPtr = NULL;
    if (pipeTI) {
	if (pipeTI->evWakeUp) {
	    SetEvent(pipeTI->evWakeUp);
	}
	CloseHandle(pipeTI->evControl);
    #ifndef _PTI_USE_CKALLOC
	free(pipeTI);
    #else
	ckfree(pipeTI);
    #endif
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TclPipeThreadExit --
 *
 *	Clean-up for the pipe thread (removes owned TI-structure in worker).
 *
 *	Should be executed on worker exit, to inform the main thread or
 *	free TI-structure (if owned).
 *
 *	After calling of this function, TI-structure pointer given via pipeTIPtr
 *	is not accessible (owned by main thread or released here).
 *
 * Results:
 *	None.
 *
 *----------------------------------------------------------------------
 */

void
TclPipeThreadExit(
    TclPipeThreadInfo **pipeTIPtr)
{
    LONG state;
    TclPipeThreadInfo *pipeTI = *pipeTIPtr;
    /*
     * If state of thread was set to stop (exactly), we can sane free its info
     * structure, otherwise it is shared with main thread, so main thread will
     * own it.
     */
    if (!pipeTI) {
	return;
    }
    *pipeTIPtr = NULL;
    if ((state = InterlockedExchange(&pipeTI->state,
	    PTI_STATE_DOWN)) == PTI_STATE_STOP) {
	CloseHandle(pipeTI->evControl);
	if (pipeTI->evWakeUp) {
	    SetEvent(pipeTI->evWakeUp);
	}
    #ifndef _PTI_USE_CKALLOC
	free(pipeTI);
    #else
	ckfree(pipeTI);
	/* be sure all subsystems used are finalized */
	Tcl_FinalizeThread();
    #endif
    }
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */