/* 
 * tclWinPipe.c --
 *
 *	This file implements the Windows-specific exec pipeline functions,
 *	the "pipe" channel driver, and the "pid" Tcl command.
 *
 * Copyright (c) 1996-1997 by 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: tclWinPipe.c,v 1.11.2.1 2000/07/27 01:39:25 hobbs Exp $
 * RCS: @(#) $Id: tclWinPipe.c,v 1.11.2.2 2001/04/03 22:54:39 hobbs Exp $
 */

#include "tclWinInt.h"

#include <dos.h>
#include <fcntl.h>
#include <io.h>

				 * 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 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.

	     * stdio of another.
	     */

	    if (!TclInExit() 
		    || ((GetStdHandle(STD_INPUT_HANDLE) != filePtr->handle)
			    && (GetStdHandle(STD_OUTPUT_HANDLE) != filePtr->handle)
			    && (GetStdHandle(STD_ERROR_HANDLE) != filePtr->handle))) {
		if (filePtr->handle != NULL &&
		if (CloseHandle(filePtr->handle) == FALSE) {
			CloseHandle(filePtr->handle) == FALSE) {
		    TclWinConvertError(GetLastError());
		    ckfree((char *) filePtr);
		    return -1;
		}
	    }
	    break;

     * using ab~1.def instead of "a b.default").  
     */

    BuildCommandLine(execPath, argc, argv, &cmdLine);

    if ((*tclWinProcs->createProcessProc)(NULL, 
	    (TCHAR *) Tcl_DStringValue(&cmdLine), NULL, NULL, TRUE, 
	    createFlags, NULL, NULL, &startInfo, &procInfo) == 0) {
	    (DWORD) createFlags, NULL, NULL, &startInfo, &procInfo) == 0) {
	TclWinConvertError(GetLastError());
	Tcl_AppendResult(interp, "couldn't execute \"", argv[0],
		"\": ", Tcl_PosixError(interp), (char *) NULL);
	goto end;
    }

    /*

	    special++;
	}
	Tcl_DStringAppend(&ds, start, special - start);
	if (quote) {
	    Tcl_DStringAppend(&ds, "\"", 1);
	}
    }
    Tcl_DStringFree(linePtr);
    Tcl_WinUtfToTChar(Tcl_DStringValue(&ds), Tcl_DStringLength(&ds), linePtr);
    Tcl_DStringFree(&ds);
}

/*
 *----------------------------------------------------------------------
 *

    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, 8000, PipeReaderThread,
	infoPtr->readThread = CreateThread(NULL, 512, PipeReaderThread,
		infoPtr, 0, &id);
	SetThreadPriority(infoPtr->readThread, THREAD_PRIORITY_HIGHEST); 
        infoPtr->validMask |= TCL_READABLE;
    } else {
	infoPtr->readThread = 0;
    }
    if (writeFile != NULL) {
	/*
	 * Start the background writeer thwrite.
	 * Start the background writer thread.
	 */

	infoPtr->writable = CreateEvent(NULL, TRUE, TRUE, NULL);
	infoPtr->startWriter = CreateEvent(NULL, FALSE, FALSE, NULL);
	infoPtr->writeThread = CreateThread(NULL, 8000, PipeWriterThread,
	infoPtr->writeThread = CreateThread(NULL, 512, PipeWriterThread,
		infoPtr, 0, &id);
	SetThreadPriority(infoPtr->readThread, THREAD_PRIORITY_HIGHEST); 
        infoPtr->validMask |= TCL_WRITABLE;
    }

    /*
     * For backward compatibility with previous versions of Tcl, we

    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;

    errorCode = 0;
    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) {
	    /*
	     * Forcibly terminate the background thread.  We cannot rely on the
	     * thread to cleanly terminate itself because we have no way of
	     * closing the pipe handle without blocking in the case where the
	     * thread is in the middle of an I/O operation.  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.
	     * 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);

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

	    TerminateThread(pipePtr->readThread, 0);
	    GetExitCodeThread(pipePtr->readThread, &exitCode);

	    if (exitCode == STILL_ACTIVE) {
	    /*
	     * Wait for the thread to terminate.  This ensures that we are
	     * completely cleaned up before we leave this function. 
	     */
		/*
		 * 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 10 milliseconds for the reader thread to close.
		 */

		WaitForSingleObject(pipePtr->readThread, 10);
		GetExitCodeThread(pipePtr->readThread, &exitCode);

		if (exitCode == STILL_ACTIVE) {
		    /*
		     * 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.
		     */

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

		    /* Wait for the thread to terminate. */
	    WaitForSingleObject(pipePtr->readThread, INFINITE);
		    WaitForSingleObject(pipePtr->readThread, INFINITE);
		}
	    }

	    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;

	     * Reallocate the buffer to be large enough to hold the data.
	     */

	    if (infoPtr->writeBuf) {
		ckfree(infoPtr->writeBuf);
	    }
	    infoPtr->writeBufLen = toWrite;
	    infoPtr->writeBuf = ckalloc(toWrite);
	    infoPtr->writeBuf = ckalloc((unsigned int) toWrite);
	}
	memcpy(infoPtr->writeBuf, buf, toWrite);
	memcpy(infoPtr->writeBuf, buf, (size_t) toWrite);
	infoPtr->toWrite = toWrite;
	ResetEvent(infoPtr->writable);
	SetEvent(infoPtr->startWriter);
	bytesWritten = toWrite;
    } else {
	/*
	 * In the blocking case, just try to write the buffer directly.

Tcl_Pid
Tcl_WaitPid(
    Tcl_Pid pid,
    int *statPtr,
    int options)
{
    ProcInfo *infoPtr, **prevPtrPtr;
    int flags;
    DWORD flags;
    Tcl_Pid result;
    DWORD ret;

    PipeInit();

    /*
     * If no pid is specified, do nothing.

 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Signals the main thread when input become available.  May
 *	cause the main thread to wake up by posting a message.  May
 *	consume one byte from the pipe for each wait operation.
 *	consume one byte from the pipe for each wait operation.  Will
 *	cause a memory leak of ~4k, if forcefully terminated with
 *	TerminateThread().
 *
 *----------------------------------------------------------------------
 */

static DWORD WINAPI
PipeReaderThread(LPVOID arg)
{
    PipeInfo *infoPtr = (PipeInfo *)arg;
    HANDLE *handle = ((WinFile *) infoPtr->readFile)->handle;
    DWORD count, err;
    int done = 0;
    HANDLE wEvents[2] = {infoPtr->stopReader, infoPtr->startReader};
    DWORD dwWait;

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

	dwWait = WaitForMultipleObjects(2, wEvents, FALSE, INFINITE);
	WaitForSingleObject(infoPtr->startReader, INFINITE);

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

	    return 0;
	}

	/*
	 * 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.
	 */