HANDLE readable;		/* Manual-reset event to signal when the
				 * reader thread has finished waiting for
				 * input. */
    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
				 * synchronized with the writable object. */
    int writeBufLen;		/* Size of write buffer. Access is
				 * synchronized with the writable object. */
    int toWrite;		/* Current amount to be written. Access is
				 * synchronized with the writable object. */
    int readFlags;		/* Flags that are shared with the reader

    PipeGetHandleProc,		/* Get an OS handle from channel. */
    PipeClose2Proc,		/* close2proc */
    PipeBlockModeProc,		/* Set blocking or non-blocking mode.*/
    NULL,			/* flush proc. */
    NULL,			/* handler proc. */
    NULL,			/* wide seek proc */
    PipeThreadActionProc,	/* thread action proc */
    NULL			/* truncate */
};

/*
 *----------------------------------------------------------------------
 *
 * PipeInit --
 *

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

static const char *
BuildCmdLineBypassBS(
    const char *current,
    const char **bspos)

{
    /*
     * Mark first backslash position.
     */

    if (!*bspos) {
	*bspos = current;
    }
    do {
	current++;
    } while (*current == '\\');
    return current;
}

static void
QuoteCmdLineBackslash(
    Tcl_DString *dsPtr,
    const char *start,
    const char *current,
    const char *bspos)

{
    if (!bspos) {
	if (current > start) {	/* part before current (special) */
	    Tcl_DStringAppend(dsPtr, start, (int) (current - start));
	}
    } else {
    	if (bspos > start) {	/* part before first backslash */
	    Tcl_DStringAppend(dsPtr, start, (int) (bspos - start));
	}
	while (bspos++ < current) { /* each backslash twice */
	    TclDStringAppendLiteral(dsPtr, "\\\\");
	}
    }
}

static const char *
QuoteCmdLinePart(
    Tcl_DString *dsPtr,
    const char *start,
    const char *special,
    const char *specMetaChars,
    const char **bspos)

{
    if (!*bspos) {
	/*
	 * Rest before special (before quote).
	 */

	QuoteCmdLineBackslash(dsPtr, start, special, NULL);
	start = special;
    } else {
	/*
	 * Rest before first backslash and backslashes into new quoted block.
	 */

	QuoteCmdLineBackslash(dsPtr, start, *bspos, NULL);
	start = *bspos;
    }

    /*
     * escape all special chars enclosed in quotes like `"..."`, note that
     * here we don't must escape `\` (with `\`), because it's outside of the
     * main quotes, so `\` remains `\`, but important - not at end of part,
     * because results as before the quote, so `%\%\` should be escaped as
     * `"%\%"\\`).
     */

    TclDStringAppendLiteral(dsPtr, "\""); /* opening escape quote-char */
    do {
    	*bspos = NULL;
	special++;
	if (*special == '\\') {
	    /*
	     * Bypass backslashes (and mark first backslash position).
	     */

	    special = BuildCmdLineBypassBS(special, bspos);
	    if (*special == '\0') {
		break;
	    }
	}
    } while (*special && strchr(specMetaChars, *special));
    if (!*bspos) {
	/*
	 * Unescaped rest before quote.
	 */

	QuoteCmdLineBackslash(dsPtr, start, special, NULL);
    } else {
	/*
	 * Unescaped rest before first backslash (rather belongs to the main
	 * block).
	 */

	QuoteCmdLineBackslash(dsPtr, start, *bspos, NULL);
    }
    TclDStringAppendLiteral(dsPtr, "\""); /* closing escape quote-char */
    return special;
}

static void
BuildCommandLine(
    const char *executable,	/* Full path of executable (including
				 * extension). Replacement for argv[0]. */
    int argc,			/* Number of arguments. */
    const char **argv,		/* Argument strings in UTF. */
    Tcl_DString *linePtr)	/* Initialized Tcl_DString that receives the
				 * command line (WCHAR). */
{
    const char *arg, *start, *special, *bspos;
    int quote = 0, i;
    Tcl_DString ds;
    static const char specMetaChars[] = "&|^<>!()%";
				/* Characters to enclose in quotes if unpaired
				 * quote flag set. */
    static const char specMetaChars2[] = "%";
				/* Character to enclose in quotes in any case

				 * (regardless of unpaired-flag). */
    /*
     * Quote flags:
     *   CL_ESCAPE   - escape argument;
     *   CL_QUOTE    - enclose in quotes;
     *   CL_UNPAIRED - previous arguments chain contains unpaired quote-char;
     */
    enum {CL_ESCAPE = 1, CL_QUOTE = 2, CL_UNPAIRED = 4};

    Tcl_DStringInit(&ds);

	quote &= ~(CL_ESCAPE|CL_QUOTE); /* reset escape flags */
	bspos = NULL;
	if (arg[0] == '\0') {
	    quote = CL_QUOTE;
	} else {
	    for (start = arg;
		    *start != '\0' &&
			(quote & (CL_ESCAPE|CL_QUOTE)) != (CL_ESCAPE|CL_QUOTE);
		    start++) {

		if (*start & 0x80) {
		    continue;
		}
		if (TclIsSpaceProc(*start)) {
		    quote |= CL_QUOTE;	/* quote only */
		    if (bspos) {	/* if backslash found, escape & quote */
			quote |= CL_ESCAPE;
			break;
		    }
		    continue;
		}
		if (strchr(specMetaChars, *start)) {
		    quote |= (CL_ESCAPE|CL_QUOTE); /* escape & quote */
		    break;
		}
		if (*start == '"') {
		    quote |= CL_ESCAPE;		/* escape only */
		    continue;
		}
		if (*start == '\\') {
		    bspos = start;
		    if (quote & CL_QUOTE) {	/* if quote, escape & quote */
			quote |= CL_ESCAPE;
			break;
		    }
		    continue;
		}
	    }
	    bspos = NULL;
	}
	if (quote & CL_QUOTE) {
	    /*
	     * Start of argument (main opening quote-char).
	     */

	    TclDStringAppendLiteral(&ds, "\"");
	}
	if (!(quote & CL_ESCAPE)) {
	    /*
	     * Nothing to escape.
	     */

	    Tcl_DStringAppend(&ds, arg, -1);
	} else {
	    start = arg;
	    for (special = arg; *special != '\0'; ) {
		/*
		 * Position of `\` is important before quote or at end (equal
		 * `\"` because quoted).
		 */

		if (*special == '\\') {
		    /*
		     * Bypass backslashes (and mark first backslash position)
		     */

		    special = BuildCmdLineBypassBS(special, &bspos);
		    if (*special == '\0') {
			break;
		    }
		}
		/* ["] */
		if (*special == '"') {
		    /*
		     * Invert the unpaired flag - observe unpaired quotes
		     */

		    quote ^= CL_UNPAIRED;

		    /*
		     * Add part before (and escape backslashes before quote).
		     */

		    QuoteCmdLineBackslash(&ds, start, special, bspos);
		    bspos = NULL;

		    /*
		     * Escape using backslash
		     */

		    TclDStringAppendLiteral(&ds, "\\\"");
		    start = ++special;
		    continue;
		}

		/*
		 * Unpaired (escaped) quote causes special handling on
		 * meta-chars
		 */

		if ((quote & CL_UNPAIRED) && strchr(specMetaChars, *special)) {
		    special = QuoteCmdLinePart(&ds, start, special,
			    specMetaChars, &bspos);

		    /*
		     * Start to current or first backslash
		     */

		    start = !bspos ? special : bspos;
		    continue;
		}

		/*
		 * Special case for % - should be enclosed always (paired
		 * also)
		 */

		if (strchr(specMetaChars2, *special)) {
		    special = QuoteCmdLinePart(&ds, start, special,
			    specMetaChars2, &bspos);

		    /*
		     * Start to current or first backslash.
		     */

		    start = !bspos ? special : bspos;
		    continue;
		}

		/*
		 * Other not special (and not meta) character
		 */

		bspos = NULL;		/* reset last backslash position (not
					 * interesting) */
		special++;
	    }

	    /*
	     * Rest of argument (and escape backslashes before closing main
	     * quote)
	     */

	    QuoteCmdLineBackslash(&ds, start, special,
		    (quote & CL_QUOTE) ? bspos : NULL);
	}
	if (quote & CL_QUOTE) {
	    /*
	     * End of argument (main closing quote-char)
	     */

	    TclDStringAppendLiteral(&ds, "\"");
	}
    }
    Tcl_DStringFree(linePtr);
    Tcl_WinUtfToTChar(Tcl_DStringValue(&ds), Tcl_DStringLength(&ds), linePtr);
    Tcl_DStringFree(&ds);
}

    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)
	    || !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;

     * Since most of the work is handled by the background threads, we just
     * need to update the watchMask and then force the notifier to poll once.
     */

    infoPtr->watchMask = mask & infoPtr->validMask;
    if (infoPtr->watchMask) {
	Tcl_Time blockTime = { 0, 0 };

	if (!oldMask) {
	    infoPtr->nextPtr = tsdPtr->firstPipePtr;
	    tsdPtr->firstPipePtr = infoPtr;
	}
	Tcl_SetMaxBlockTime(&blockTime);
    } else {
	if (oldMask) {

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

static DWORD WINAPI
PipeReaderThread(
    LPVOID arg)
{
    TclPipeThreadInfo *pipeTI = (TclPipeThreadInfo *) arg;
    PipeInfo *infoPtr = NULL; /* access info only after success init/wait */
    HANDLE handle = NULL;
    DWORD count, err;
    int done = 0;

    while (!done) {
	/*
	 * Wait for the main thread to signal before attempting to wait on the
	 * pipe becoming readable.
	 */

	if (!TclPipeThreadWaitForSignal(&pipeTI)) {
	    /* exit */
	    break;
	}

	if (!infoPtr) {
	    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

    HANDLE wakeEvent)
{
    TclPipeThreadInfo *pipeTI;
#ifndef _PTI_USE_CKALLOC
    pipeTI = malloc(sizeof(TclPipeThreadInfo));
#else
    pipeTI = Tcl_Alloc(sizeof(TclPipeThreadInfo));
#endif /* !_PTI_USE_CKALLOC */
    pipeTI->evControl = CreateEvent(NULL, FALSE, FALSE, NULL);
    pipeTI->state = PTI_STATE_IDLE;
    pipeTI->clientData = clientData;
    pipeTI->evWakeUp = wakeEvent;
    return (*pipeTIPtr = pipeTI);
}


    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)
     */

    state = InterlockedCompareExchange(&pipeTI->state, PTI_STATE_IDLE,
	    PTI_STATE_WORK);
    if (state & (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
     */

    state = InterlockedCompareExchange(&pipeTI->state, PTI_STATE_WORK,
	    PTI_STATE_IDLE);
    if (state & (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);

 *	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;

    state = InterlockedCompareExchange(&pipeTI->state, PTI_STATE_STOP,
	    PTI_STATE_IDLE);
    switch (state) {

    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;
}

/*

    if (!pipeTI) {
	return;
    }
    pipeTI = *pipeTIPtr;
    evControl = pipeTI->evControl;
    pipeTI->evWakeUp = NULL;

    /*
     * Try to sane stop the pipe worker, corresponding its current state
     */

    state = InterlockedCompareExchange(&pipeTI->state, PTI_STATE_STOP,
	    PTI_STATE_IDLE);
    switch (state) {

    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)
	 */

	state = InterlockedCompareExchange(&pipeTI->state, PTI_STATE_END,
		PTI_STATE_WORK);
	if (state == 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).
	     */

	    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
	Tcl_Free(pipeTI);
#endif /* !_PTI_USE_CKALLOC */
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TclPipeThreadExit --

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;
    state = InterlockedExchange(&pipeTI->state, PTI_STATE_DOWN);
    if (state == PTI_STATE_STOP) {
	CloseHandle(pipeTI->evControl);
	if (pipeTI->evWakeUp) {
	    SetEvent(pipeTI->evWakeUp);
	}
#ifndef _PTI_USE_CKALLOC
	free(pipeTI);
#else
	Tcl_Free(pipeTI);
	/* be sure all subsystems used are finalized */
	Tcl_FinalizeThread();
#endif /* !_PTI_USE_CKALLOC */
    }
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */