Tcl Source Code

 */

typedef struct ChannelHandler {
    Channel *chanPtr;		/* The channel structure for this channel. */
    int mask;			/* Mask of desired events. */
    Tcl_ChannelProc *proc;	/* Procedure to call in the type of
				 * Tcl_CreateChannelHandler. */
    ClientData clientData;	/* Argument to pass to procedure. */
    struct ChannelHandler *nextPtr;
				/* Next one in list of registered handlers. */
} ChannelHandler;

/*
 * This structure keeps track of the current ChannelHandler being invoked in
 * the current invocation of Tcl_NotifyChannel. There is a potential

 * nested invocations of Tcl_NotifyChannel and compare the handler being
 * deleted against the NEXT handler to be invoked in that invocation; when it
 * finds such a situation, Tcl_DeleteChannelHandler updates the nextHandlerPtr
 * field of the structure to the next handler.
 */

typedef struct NextChannelHandler {
    ChannelHandler *nextHandlerPtr;	/* The next handler to be invoked in

					 * this invocation. */
    struct NextChannelHandler *nestedHandlerPtr;
					/* Next nested invocation of
					 * Tcl_NotifyChannel. */
} NextChannelHandler;

/*
 * The following structure is used by Tcl_GetsObj() to encapsulates the
 * state for a "gets" operation.
 */

/*
 * Structure to record a close callback. One such record exists for
 * each close callback registered for a channel.
 */

typedef struct CloseCallback {
    Tcl_CloseProc *proc;		/* The procedure to call. */
    ClientData clientData;		/* Arbitrary one-word data to pass
					 * to the callback. */
    struct CloseCallback *nextPtr;	/* For chaining close callbacks. */

} CloseCallback;

/*
 * Static functions in this file:
 */

static ChannelBuffer *	AllocChannelBuffer(int length);
static void		PreserveChannelBuffer(ChannelBuffer *bufPtr);
static void		ReleaseChannelBuffer(ChannelBuffer *bufPtr);
static int		IsShared(ChannelBuffer *bufPtr);
static void		ChannelFree(Channel *chanPtr);
static void		ChannelTimerProc(ClientData clientData);
static int		ChanRead(Channel *chanPtr, char *dst, int dstSize);
static int		CheckChannelErrors(ChannelState *statePtr,
			    int direction);
static int		CheckForDeadChannel(Tcl_Interp *interp,
			    ChannelState *statePtr);
static void		CheckForStdChannelsBeingClosed(Tcl_Channel chan);
static void		CleanupChannelHandlers(Tcl_Interp *interp,
			    Channel *chanPtr);
static int		CloseChannel(Tcl_Interp *interp, Channel *chanPtr,
			    int errorCode);
static int		CloseChannelPart(Tcl_Interp *interp, Channel *chanPtr,
			    int errorCode, int flags);
static int		CloseWrite(Tcl_Interp *interp, Channel *chanPtr);
static void		CommonGetsCleanup(Channel *chanPtr);
static int		CopyData(CopyState *csPtr, int mask);

static int		MoveBytes(CopyState *csPtr);

static void		MBCallback(CopyState *csPtr, Tcl_Obj *errObj);
static void		MBError(CopyState *csPtr, int mask, int errorCode);
static int		MBRead(CopyState *csPtr);
static int		MBWrite(CopyState *csPtr);
static void		MBEvent(ClientData clientData, int mask);

static void		CopyEventProc(ClientData clientData, int mask);
static void		CreateScriptRecord(Tcl_Interp *interp,
			    Channel *chanPtr, int mask, Tcl_Obj *scriptPtr);
static void		DeleteChannelTable(ClientData clientData,
			    Tcl_Interp *interp);
static void		DeleteScriptRecord(Tcl_Interp *interp,
			    Channel *chanPtr, int mask);
static int		DetachChannel(Tcl_Interp *interp, Tcl_Channel chan);
static void		DiscardInputQueued(ChannelState *statePtr,
			    int discardSavedBuffers);
static void		DiscardOutputQueued(ChannelState *chanPtr);
static int		DoRead(Channel *chanPtr, char *dst, int bytesToRead,
			    int allowShortReads);
static int		DoReadChars(Channel *chan, Tcl_Obj *objPtr, int toRead,
			    int appendFlag);
static int		FilterInputBytes(Channel *chanPtr,
			    GetsState *statePtr);
static int		FlushChannel(Tcl_Interp *interp, Channel *chanPtr,
			    int calledFromAsyncFlush);
static int		TclGetsObjBinary(Tcl_Channel chan, Tcl_Obj *objPtr);
static Tcl_Encoding	GetBinaryEncoding(void);
static void		FreeBinaryEncoding(ClientData clientData);
static Tcl_HashTable *	GetChannelTable(Tcl_Interp *interp);
static int		GetInput(Channel *chanPtr);
static void		PeekAhead(Channel *chanPtr, char **dstEndPtr,
			    GetsState *gsPtr);
static int		ReadBytes(ChannelState *statePtr, Tcl_Obj *objPtr,
			    int charsLeft);
static int		ReadChars(ChannelState *statePtr, Tcl_Obj *objPtr,

		statePtr != NULL;
		statePtr = statePtr->nextCSPtr) {
	    chanPtr = statePtr->topChanPtr;
            if (GotFlag(statePtr, CHANNEL_DEAD)) {
                continue;
            }
	    if (!GotFlag(statePtr, CHANNEL_INCLOSE | CHANNEL_CLOSED )
                || GotFlag(statePtr, BG_FLUSH_SCHEDULED)) {
                ResetFlag(statePtr, BG_FLUSH_SCHEDULED);
		active = 1;
		break;
	    }
	}

	/*

            if (doflushnb) {
                /*
                 * Set the channel back into blocking mode to ensure that we
                 * wait for all data to flush out.
                 */

                (void) Tcl_SetChannelOption(NULL, (Tcl_Channel) chanPtr,
                                            "-blocking", "on");
            }

	    if ((chanPtr == (Channel *) tsdPtr->stdinChannel) ||
		    (chanPtr == (Channel *) tsdPtr->stdoutChannel) ||
		    (chanPtr == (Channel *) tsdPtr->stderrChannel)) {
		/*
		 * Decrement the refcount which was earlier artificially

void
Tcl_CreateCloseHandler(
    Tcl_Channel chan,		/* The channel for which to create the close
				 * callback. */
    Tcl_CloseProc *proc,	/* The callback routine to call when the
				 * channel will be closed. */
    ClientData clientData)	/* Arbitrary data to pass to the close
				 * callback. */
{
    ChannelState *statePtr = ((Channel *) chan)->state;
    CloseCallback *cbPtr;

    cbPtr = (CloseCallback *)ckalloc(sizeof(CloseCallback));
    cbPtr->proc = proc;

void
Tcl_DeleteCloseHandler(
    Tcl_Channel chan,		/* The channel for which to cancel the close
				 * callback. */
    Tcl_CloseProc *proc,	/* The procedure for the callback to
				 * remove. */
    ClientData clientData)	/* The callback data for the callback to
				 * remove. */
{
    ChannelState *statePtr = ((Channel *) chan)->state;
    CloseCallback *cbPtr, *cbPrevPtr;

    for (cbPtr = statePtr->closeCbPtr, cbPrevPtr = NULL;
	    cbPtr != NULL; cbPtr = cbPtr->nextPtr) {

 *	registered in this interpreter.
 *
 *----------------------------------------------------------------------
 */

static void
DeleteChannelTable(
    ClientData clientData,	/* The per-interpreter data structure. */
    Tcl_Interp *interp)		/* The interpreter being deleted. */
{
    Tcl_HashTable *hTblPtr;	/* The hash table. */
    Tcl_HashSearch hSearch;	/* Search variable. */
    Tcl_HashEntry *hPtr;	/* Search variable. */
    Channel *chanPtr;		/* Channel being deleted. */
    ChannelState *statePtr;	/* State of Channel being deleted. */

    }

    hTblPtr = GetChannelTable(interp);
    hPtr = Tcl_FindHashEntry(hTblPtr, name);
    if (hPtr == NULL) {
	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                "can not find channel named \"%s\"", chanName));
	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "CHANNEL", chanName, (void *)NULL);
	return NULL;
    }

    /*
     * Always return bottom-most channel in the stack. This one lives the
     * longest - other channels may go away unnoticed. The other APIs
     * compensate where necessary to retrieve the topmost channel again.

    }

    if (objPtr->typePtr == &chanObjType) {
	/*
 	 * Confirm validity of saved lookup results.
 	 */

	resPtr = (ResolvedChanName *) objPtr->internalRep.twoPtrValue.ptr1;
	statePtr = resPtr->statePtr;
	if ((resPtr->interp == interp)		/* Same interp context */
			/* No epoch change in channel since lookup */
		&& (resPtr->epoch == statePtr->epoch)) {
	    /*
	     * Have a valid saved lookup. Jump to end to return it.
	     */

	    FreeChannelInternalRep(objPtr);
	}
	return TCL_ERROR;
    }

    if (resPtr && resPtr->refCount == 1) {
	/* Re-use the ResolvedCmdName struct */
	Tcl_Release((ClientData) resPtr->statePtr);

    } else {
	TclFreeIntRep(objPtr);

	resPtr = (ResolvedChanName *) ckalloc(sizeof(ResolvedChanName));
	resPtr->refCount = 1;
	objPtr->internalRep.twoPtrValue.ptr1 = (ClientData) resPtr;
	objPtr->typePtr = &chanObjType;
    }
    statePtr = ((Channel *)chan)->state;
    resPtr->statePtr = statePtr;
    Tcl_Preserve((ClientData) statePtr);
    resPtr->interp = interp;
    resPtr->epoch = statePtr->epoch;

  valid:
    *channelPtr = (Tcl_Channel) statePtr->bottomChanPtr;

    if (modePtr != NULL) {

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

Tcl_Channel
Tcl_CreateChannel(
    const Tcl_ChannelType *typePtr, /* The channel type record. */
    const char *chanName,	/* Name of channel to record. */
    ClientData instanceData,	/* Instance specific data. */
    int mask)			/* TCL_READABLE & TCL_WRITABLE to indicate if
				 * the channel is readable, writable. */
{
    Channel *chanPtr;		/* The channel structure newly created. */
    ChannelState *statePtr;	/* The stack-level independent state info for
				 * the channel. */
    const char *name;

    }
    if ((TCL_WRITABLE & mask) &&  (NULL == typePtr->outputProc)) {
	Tcl_Panic("channel type %s must define outputProc when used for writer channel", typePtr->typeName);
    }
    if (NULL == typePtr->watchProc) {
	Tcl_Panic("channel type %s must define watchProc", typePtr->typeName);
    }
    if ((NULL!=typePtr->wideSeekProc) && (NULL == typePtr->seekProc)) {
	Tcl_Panic("channel type %s must define seekProc if defining wideSeekProc", typePtr->typeName);
    }

    /*
     * JH: We could subsequently memset these to 0 to avoid the numerous
     * assignments to 0/NULL below.
     */

Tcl_Channel
Tcl_StackChannel(
    Tcl_Interp *interp,		/* The interpreter we are working in */
    const Tcl_ChannelType *typePtr,
				/* The channel type record for the new
				 * channel. */
    ClientData instanceData,	/* Instance specific data for the new
				 * channel. */
    int mask,			/* TCL_READABLE & TCL_WRITABLE to indicate if
				 * the channel is readable, writable. */
    Tcl_Channel prevChan)	/* The channel structure to replace */
{
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
    Channel *chanPtr, *prevChanPtr;

 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

ClientData
Tcl_GetChannelInstanceData(
    Tcl_Channel chan)		/* Channel for which to return client data. */
{
    Channel *chanPtr = (Channel *) chan;
				/* The actual channel. */

    return chanPtr->instanceData;

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

int
Tcl_GetChannelHandle(
    Tcl_Channel chan,		/* The channel to get file from. */
    int direction,		/* TCL_WRITABLE or TCL_READABLE. */
    ClientData *handlePtr)	/* Where to store handle */
{
    Channel *chanPtr;		/* The actual channel. */
    ClientData handle;
    int result;

    chanPtr = ((Channel *) chan)->state->bottomChanPtr;
    if (!chanPtr->typePtr->getHandleProc) {
        Tcl_SetChannelError(chan, Tcl_ObjPrintf(
                "channel \"%s\" does not support OS handles",
                Tcl_GetChannelName(chan)));

    return bufPtr;
}

static void
PreserveChannelBuffer(
    ChannelBuffer *bufPtr)
{
    if (bufPtr->refCount == 0) {
	Tcl_Panic("Reuse of ChannelBuffer! %p", bufPtr);
    }
    bufPtr->refCount++;
}

static void
ReleaseChannelBuffer(

	}
    }

    /*
     * Cancel any outstanding timer.
     */

    if (statePtr->timer != NULL) {
	Tcl_DeleteTimerHandler(statePtr->timer);
	statePtr->timer = NULL;
	TclChannelRelease((Tcl_Channel)statePtr->timerChanPtr);
	statePtr->timerChanPtr = NULL;
    }


    /*
     * Mark the channel as deleted by clearing the type structure.
     */

    if (chanPtr->downChanPtr != NULL) {
	Channel *downChanPtr = chanPtr->downChanPtr;

	result = EINVAL;
    }

    if (stickyError != 0) {
	Tcl_SetErrno(stickyError);
	if (interp != NULL) {
	    Tcl_SetObjResult(interp,
			     Tcl_NewStringObj(Tcl_PosixError(interp), -1));
	}
	return TCL_ERROR;
    }

    /*
     * Bug 97069ea11a: set error message if a flush code is set and no error
     * message set up to now.

    statePtr = chanPtr->state;
    chanPtr = statePtr->topChanPtr;

    /*
     * Cancel any outstanding timer.
     */

    if (statePtr->timer != NULL) {
	Tcl_DeleteTimerHandler(statePtr->timer);
	statePtr->timer = NULL;
	TclChannelRelease((Tcl_Channel)statePtr->timerChanPtr);
	statePtr->timerChanPtr = NULL;
    }

    /*
     * Remove any references to channel handlers for this channel that may be
     * about to be invoked.
     */

    for (nhPtr = tsdPtr->nestedHandlerPtr; nhPtr != NULL;

 *	buffer is ready e.g. if it contains a newline and we are in line
 *	buffering mode. Compensates stacking, i.e. will redirect the data from
 *	the specified channel to the topmost channel in a stack.
 *
 *	No encoding conversions are applied to the bytes being read.
 *
 * Results:
 *	The number of bytes written or -1 in case of error. If -1,
 *	Tcl_GetErrno will return the error code.
 *
 * Side effects:
 *	May buffer up output and may cause output to be produced on the
 *	channel.
 *
 *----------------------------------------------------------------------
 */

 *	buffer is ready e.g. if it contains a newline and we are in line
 *	buffering mode. Writes directly to the driver of the channel, does not
 *	compensate for stacking.
 *
 *	No encoding conversions are applied to the bytes being read.
 *
 * Results:
 *	The number of bytes written or -1 in case of error. If -1,
 *	Tcl_GetErrno will return the error code.
 *
 * Side effects:
 *	May buffer up output and may cause output to be produced on the
 *	channel.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_WriteRaw(
    Tcl_Channel chan,		/* The channel to buffer output for. */
    const char *src,		/* Data to queue in output buffer. */
    int srcLen)			/* Length of data in bytes, or < 0 for
				 * strlen(). */
{
    Channel *chanPtr = ((Channel *) chan);
    ChannelState *statePtr = chanPtr->state;
				/* State info for channel */
    int errorCode;
    int written;

 *	using the channel's current encoding, may queue the buffer for output
 *	if it gets full, and also remembers whether the current buffer is
 *	ready e.g. if it contains a newline and we are in line buffering
 *	mode. Compensates stacking, i.e. will redirect the data from the
 *	specified channel to the topmost channel in a stack.
 *
 * Results:
 *	The number of bytes written or -1 in case of error. If -1,
 *	Tcl_GetErrno will return the error code.
 *
 * Side effects:
 *	May buffer up output and may cause output to be produced on the
 *	channel.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_WriteChars(
    Tcl_Channel chan,		/* The channel to buffer output for. */
    const char *src,		/* UTF-8 characters to queue in output
				 * buffer. */
    int len)			/* Length of string in bytes, or < 0 for
				 * strlen(). */
{
    Channel *chanPtr = (Channel *) chan;
    ChannelState *statePtr = chanPtr->state;	/* State info for channel */
    int result;
    Tcl_Obj *objPtr;

 *	characters in the UTF-8 (string) representation of the object and
 *	converts them for output using the channel's current encoding. May
 *	flush internal buffers to output if one becomes full or is ready for
 *	some other reason, e.g. if it contains a newline and the channel is in
 *	line buffering mode.
 *
 * Results:
 *	The number of bytes written or -1 in case of error. If -1,
 *	Tcl_GetErrno() will return the error code.
 *
 * Side effects:
 *	May buffer up output and may cause output to be produced on the
 *	channel.
 *
 *----------------------------------------------------------------------
 */

	 * bg flushing.  Channels we know that can do that - sockets, pipes -
	 * are not seekable. If the assumption is wrong, more drastic measures
	 * may be required here like temporarily setting the channel into
	 * blocking mode.
	 */

	if (FlushChannel(NULL, chanPtr, 0) != 0) {
	return -1;
	}
    }
    return 0;
}

/*
 *----------------------------------------------------------------------

    encoding = statePtr->encoding;

    /*
     * Preserved so we can restore the channel's state in case we don't find a
     * newline in the available input.
     */

    TclGetStringFromObj(objPtr, &oldLength);
    oldFlags = statePtr->inputEncodingFlags;
    oldState = statePtr->inputEncodingState;
    oldRemoved = BUFFER_PADDING;
    if (bufPtr != NULL) {
	oldRemoved = bufPtr->nextRemoved;
    }

    Tcl_Obj *objPtr)		/* The line read will be appended to this
				 * object as UTF-8 characters. */
{
    Channel *chanPtr = (Channel *) chan;
    ChannelState *statePtr = chanPtr->state;
				/* State info for channel */
    ChannelBuffer *bufPtr;
    int inEofChar, skip, copiedTotal, oldLength, oldFlags, oldRemoved;
    int rawLen, byteLen, eolChar;

    unsigned char *dst, *dstEnd, *eol, *eof, *byteArray;

    /*
     * This operation should occur at the top of a channel stack.
     */

    chanPtr = statePtr->topChanPtr;

 *	None.
 *
 *---------------------------------------------------------------------------
 */

static void
FreeBinaryEncoding(
    ClientData dummy)	/* Not used */
{
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
    (void)dummy;

    if (tsdPtr->binaryEncoding != NULL) {
	Tcl_FreeEncoding(tsdPtr->binaryEncoding);
	tsdPtr->binaryEncoding = NULL;

     */

    if (GotFlag(statePtr, CHANNEL_EOF)) {
	statePtr->inputEncodingFlags |= TCL_ENCODING_START;
    }
    ResetFlag(statePtr, CHANNEL_BLOCKED|CHANNEL_EOF);
    statePtr->inputEncodingFlags &= ~TCL_ENCODING_END;
    for (copied = 0; (unsigned) toRead > 0; ) {
	int copiedNow = -1;
	if (statePtr->inQueueHead != NULL) {
	    if (binaryMode) {
		copiedNow = ReadBytes(statePtr, objPtr, toRead);
	    } else {
		copiedNow = ReadChars(statePtr, objPtr, toRead, &factor);
	    }

    assert(!GotFlag(statePtr, CHANNEL_EOF)
	    || GotFlag(statePtr, CHANNEL_STICKY_EOF)
	    || Tcl_InputBuffered((Tcl_Channel)chanPtr) == 0);
    assert(!(GotFlag(statePtr, CHANNEL_EOF|CHANNEL_BLOCKED)
            == (CHANNEL_EOF|CHANNEL_BLOCKED)));
    UpdateInterest(chanPtr);

    TclChannelRelease((Tcl_Channel)chanPtr);
    return copied;
}

/*
 *---------------------------------------------------------------------------
 *

ReadBytes(
    ChannelState *statePtr,	/* State of the channel to read. */
    Tcl_Obj *objPtr,		/* Input data is appended to this ByteArray
				 * object. Its length is how much space has
				 * been allocated to hold data, not how many
				 * bytes of data have been stored in the
				 * object. */
    int bytesToRead)		/* Maximum number of bytes to store, or < 0 to
				 * get all available bytes. Bytes are obtained
				 * from the first buffer in the queue - even
				 * if this number is larger than the number of
				 * bytes available in the first buffer, only
				 * the bytes from the first buffer are
				 * returned. */
{

    Tcl_Encoding encoding = statePtr->encoding? statePtr->encoding
	    : GetBinaryEncoding();
    Tcl_EncodingState savedState = statePtr->inputEncodingState;
    ChannelBuffer *bufPtr = statePtr->inQueueHead;
    int savedIEFlags = statePtr->inputEncodingFlags;
    int savedFlags = statePtr->flags;
    char *dst, *src = RemovePoint(bufPtr);

    int numBytes, srcLen = BytesLeft(bufPtr);

    /*
     * One src byte can yield at most one character.  So when the number of
     * src bytes we plan to read is less than the limit on character count to
     * be read, clearly we will remain within that limit, and we can use the
     * value of "srcLen" as a tighter limit for sizing receiving buffers.
     */

	char *dst = dstStart;
	int lesser = (dstLen < srcLen) ? dstLen : srcLen;

	while ((crFound = (const char *)memchr(src, '\r', lesser))) {
	    int numBytes = crFound - src;
	    memmove(dst, src, numBytes);

	    dst += numBytes; dstLen -= numBytes;

	    src += numBytes; srcLen -= numBytes;

	    if (srcLen == 1) {
		/* valid src bytes end in \r */
		if (eof) {
		    *dst++ = '\r';
		    src++; srcLen--;

		} else {
		    lesser = 0;
		    break;
		}
	    } else if (src[1] == '\n') {
		*dst++ = '\n';
		src += 2; srcLen -= 2;

	    } else {
		*dst++ = '\r';
		src++; srcLen--;

	    }
	    dstLen--;
	    lesser = (dstLen < srcLen) ? dstLen : srcLen;
	}
	memmove(dst, src, lesser);
	srcLen = src + lesser - srcStart;
	dstLen = dst + lesser - dstStart;
	break;
    }
    case TCL_TRANSLATE_AUTO: {
	const char *crFound, *src = srcStart;
	char *dst = dstStart;
	int lesser;

	if (GotFlag(statePtr, INPUT_SAW_CR) && srcLen) {
	    if (*src == '\n') { src++; srcLen--; }



	    ResetFlag(statePtr, INPUT_SAW_CR);
	}
	lesser = (dstLen < srcLen) ? dstLen : srcLen;
	while ((crFound = (const char *)memchr(src, '\r', lesser))) {
	    int numBytes = crFound - src;
	    memmove(dst, src, numBytes);

	    dst[numBytes] = '\n';
	    dst += numBytes + 1; dstLen -= numBytes + 1;

	    src += numBytes + 1; srcLen -= numBytes + 1;

	    if (srcLen == 0) {
		SetFlag(statePtr, INPUT_SAW_CR);
	    } else if (*src == '\n') {
		src++; srcLen--;

	    }
	    lesser = (dstLen < srcLen) ? dstLen : srcLen;
	}
	memmove(dst, src, lesser);
	srcLen = src + lesser - srcStart;
	dstLen = dst + lesser - dstStart;
	break;

     */

    if (CheckForDeadChannel(NULL, statePtr)) {
	return EINVAL;
    }

    /*
     * WARNING: There was once a comment here claiming that it was
     * a bad idea to make another call to the inputproc of a channel
     * driver when EOF has already been detected on the channel.  Through
     * much of Tcl's history, this warning was then completely negated
     * by having all (most?) read paths clear the EOF setting before
     * reaching here.  So we had a guard that was never triggered.
     *
     * Don't be tempted to restore the guard.  Even if EOF is set on
     * the channel, continue through and call the inputproc again.  This
     * is the way to enable the ability to [read] again beyond the EOF,
     * which seems a strange thing to do, but for which use cases exist
     * [Tcl Bug 5adc350683] and which may even be essential for channels
     * representing things like ttys or other devices where the stream
     * might take the logical form of a series of 'files' separated by
     * an EOF condition.
     */

    /*
     * First check for more buffers in the pushback area of the topmost
     * channel in the stack and use them. They can be the result of a
     * transformation which went away without reading all the information
     * placed in the area when it was stacked.
     */

    if (chanPtr->inQueueHead != NULL) {

	    mask &= ~TCL_EXCEPTION;

	    if (!statePtr->timer) {
		TclChannelPreserve((Tcl_Channel)chanPtr);
		statePtr->timerChanPtr = chanPtr;
		statePtr->timer = Tcl_CreateTimerHandler(SYNTHETIC_EVENT_TIME,
		    ChannelTimerProc, chanPtr);
	    }
	}
    }
    ChanWatch(chanPtr, mask);
}

/*

 *	May invoke channel handlers.
 *
 *----------------------------------------------------------------------
 */

static void
ChannelTimerProc(
    ClientData clientData)
{
    Channel *chanPtr = (Channel *)clientData;
    /* State info for channel */
    ChannelState *statePtr = chanPtr->state;

    if (chanPtr->typePtr == NULL) {
	statePtr->timer = NULL;

	    statePtr->timer = NULL;
	    UpdateInterest(chanPtr);
	    TclChannelRelease((Tcl_Channel)statePtr->timerChanPtr);
	    statePtr->timerChanPtr = NULL;
	}
    }
}














/*
 *----------------------------------------------------------------------
 *
 * Tcl_CreateChannelHandler --
 *
 *	Arrange for a given procedure to be invoked whenever the channel

    int mask,			/* OR'ed combination of TCL_READABLE,
				 * TCL_WRITABLE, and TCL_EXCEPTION: indicates
				 * conditions under which proc should be
				 * called. Use 0 to disable a registered
				 * handler. */
    Tcl_ChannelProc *proc,	/* Procedure to call for each selected
				 * event. */
    ClientData clientData)	/* Arbitrary data to pass to proc. */
{
    ChannelHandler *chPtr;
    Channel *chanPtr = (Channel *) chan;
    ChannelState *statePtr = chanPtr->state;
				/* State info for channel */

    /*

 */

void
Tcl_DeleteChannelHandler(
    Tcl_Channel chan,		/* The channel for which to remove the
				 * callback. */
    Tcl_ChannelProc *proc,	/* The procedure in the callback to delete. */
    ClientData clientData)	/* The client data in the callback to
				 * delete. */
{
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
    ChannelHandler *chPtr, *prevChPtr;
    Channel *chanPtr = (Channel *) chan;
    ChannelState *statePtr = chanPtr->state;
				/* State info for channel */

 *	Whatever the script does.
 *
 *----------------------------------------------------------------------
 */

void
TclChannelEventScriptInvoker(
    ClientData clientData,	/* The script+interp record. */
    int mask)			/* Not used. */
{
    Tcl_Interp *interp;		/* Interpreter in which to eval the script. */
    Channel *chanPtr;		/* The channel for which this handler is
				 * registered. */
    EventScriptRecord *esPtr;	/* The event script + interpreter to eval it
				 * in. */

 *	May create a channel handler for the specified channel.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_FileEventObjCmd(
    ClientData dummy,	/* Not used. */
    Tcl_Interp *interp,		/* Interpreter in which the channel for which
				 * to create the handler is found. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *const objv[])	/* Argument objects. */
{
    Channel *chanPtr;		/* The channel to create the handler for. */
    ChannelState *statePtr;	/* State info for channel */

 *	Calls CopyData for -command invocation.
 *
 *----------------------------------------------------------------------
 */

static void
ZeroTransferTimerProc(
    ClientData clientData)
{
    /* calling CopyData with mask==0 still implies immediate invocation of the
     *  -command callback, and completion of the fcopy.
     */
    CopyData((CopyState *)clientData, 0);
}


	return TCL_ERROR;
    }

    /*
     * Make sure the output side is unbuffered.
     */

    outStatePtr->flags = (outStatePtr->flags & ~CHANNEL_LINEBUFFERED)
	    | CHANNEL_UNBUFFERED;

    /*
     * Test for conditions where we know we can just move bytes from input
     * channel to output channel with no transformation or even examination
     * of the bytes themselves.
     */

	Tcl_SetObjResult(csPtr->interp, errObj);
	StopCopy(csPtr);
    }
}

static void
MBEvent(
    ClientData clientData,
    int mask)
{
    CopyState *csPtr = (CopyState *) clientData;
    Tcl_Channel inChan = (Tcl_Channel) csPtr->readPtr;
    Tcl_Channel outChan = (Tcl_Channel) csPtr->writePtr;
    ChannelState *inStatePtr = csPtr->readPtr->state;

	}

	if (size < 0) {
	readError:
	    if (interp) {
		TclNewObj(errObj);
		Tcl_AppendStringsToObj(errObj, "error reading \"",
			Tcl_GetChannelName(inChan), "\": ", (void *)NULL);
		if (msg != NULL) {
		    Tcl_AppendObjToObj(errObj, msg);
		} else {
		    Tcl_AppendStringsToObj(errObj, Tcl_PosixError(interp),
			    (void *)NULL);
		}
	    }
	    if (msg != NULL) {
		Tcl_DecrRefCount(msg);
	    }
	    break;
	} else if (underflow) {
	    /*
	     * We had an underflow on the read side. If we are at EOF, and not
	     * in the synchronous part of an asynchronous fcopy, then the
	     * copying is done, otherwise set up a channel handler to detect
	     * when the channel becomes readable again.
	     */

	    if ((size == 0) && Tcl_Eof(inChan) && !(cmdPtr && (mask == 0))) {
		break;
	    }
	    if (cmdPtr && (!Tcl_Eof(inChan) || (mask == 0)) &&
                !(mask & TCL_READABLE)) {
		if (mask & TCL_WRITABLE) {
		    Tcl_DeleteChannelHandler(outChan, CopyEventProc, csPtr);
		}
		Tcl_CreateChannelHandler(inChan, TCL_READABLE, CopyEventProc,
			csPtr);
	    }
	    if (size == 0) {

	 */

	if (sizeb < 0) {
	writeError:
	    if (interp) {
		TclNewObj(errObj);
		Tcl_AppendStringsToObj(errObj, "error writing \"",
			Tcl_GetChannelName(outChan), "\": ", (void *)NULL);
		if (msg != NULL) {
		    Tcl_AppendObjToObj(errObj, msg);
		} else {
		    Tcl_AppendStringsToObj(errObj, Tcl_PosixError(interp),
			    (void *)NULL);
		}
	    }
	    if (msg != NULL) {
		Tcl_DecrRefCount(msg);
	    }
	    break;
	}

 *	None.
 *
 *----------------------------------------------------------------------
 */

static void
CopyEventProc(
    ClientData clientData,
    int mask)
{
    (void) CopyData((CopyState *)clientData, mask);
}

/*
 *----------------------------------------------------------------------

static void
FreeChannelInternalRep(
    Tcl_Obj *objPtr)		/* Object with internal rep to free. */
{
    ResolvedChanName *resPtr = (ResolvedChanName *)objPtr->internalRep.twoPtrValue.ptr1;

    objPtr->typePtr = NULL;
    if (--resPtr->refCount) {
	return;
    }
    Tcl_Release(resPtr->statePtr);
    ckfree(resPtr);
}

#if 0

#define EOK	0
#endif

/*
 * Signatures of all functions used in the C layer of the reflection.
 */

static int		ReflectClose(ClientData clientData,
			    Tcl_Interp *interp);
static int		ReflectClose2(ClientData clientData,
			    Tcl_Interp *interp, int flags);
static int		ReflectInput(ClientData clientData, char *buf,
			    int toRead, int *errorCodePtr);
static int		ReflectOutput(ClientData clientData, const char *buf,
			    int toWrite, int *errorCodePtr);
static void		ReflectWatch(ClientData clientData, int mask);
static int		ReflectBlock(ClientData clientData, int mode);
#ifdef TCL_THREADS
static void		ReflectThread(ClientData clientData, int action);
static int		ReflectEventRun(Tcl_Event *ev, int flags);
static int		ReflectEventDelete(Tcl_Event *ev, ClientData cd);
#endif
static Tcl_WideInt	ReflectSeekWide(ClientData clientData,
			    Tcl_WideInt offset, int mode, int *errorCodePtr);
static int		ReflectSeek(ClientData clientData, long offset,
			    int mode, int *errorCodePtr);
static int		ReflectGetOption(ClientData clientData,
			    Tcl_Interp *interp, const char *optionName,
			    Tcl_DString *dsPtr);
static int		ReflectSetOption(ClientData clientData,
			    Tcl_Interp *interp, const char *optionName,
			    const char *newValue);

/*
 * The C layer channel type/driver definition used by the reflection.
 */

 * involved in the forwarding exits. It also clean things up so that we don't
 * leak resources when threads go away.
 */

static void		ForwardOpToHandlerThread(ReflectedChannel *rcPtr,
			    ForwardedOperation op, const void *param);
static int		ForwardProc(Tcl_Event *evPtr, int mask);
static void		SrcExitProc(ClientData clientData);

#define FreeReceivedError(p) \
	if ((p)->base.mustFree) {                               \
	    ckfree((p)->base.msgStr);                           \
	}
#define PassReceivedErrorInterp(i,p) \
	if ((i) != NULL) {                                      \

	(p)->base.code = TCL_ERROR;                             \
	(p)->base.mustFree = 1;                                 \
	(p)->base.msgStr = (char *) (emsg)

static void		ForwardSetObjError(ForwardParam *p, Tcl_Obj *objPtr);

static ReflectedChannelMap *	GetThreadReflectedChannelMap(void);
static void		DeleteThreadReflectedChannelMap(ClientData clientData);

#endif /* TCL_THREADS */

#define SetChannelErrorStr(c,msgStr) \
	Tcl_SetChannelError((c), Tcl_NewStringObj((msgStr), -1))

static Tcl_Obj *	MarshallError(Tcl_Interp *interp);

static Tcl_Obj *	NextHandle(void);
static Tcl_FreeProc	FreeReflectedChannel;
static int		InvokeTclMethod(ReflectedChannel *rcPtr,
			    MethodName method, Tcl_Obj *argOneObj,
			    Tcl_Obj *argTwoObj, Tcl_Obj **resultObjPtr);

static ReflectedChannelMap *	GetReflectedChannelMap(Tcl_Interp *interp);
static void		DeleteReflectedChannelMap(ClientData clientData,
			    Tcl_Interp *interp);
static int		ErrnoReturn(ReflectedChannel *rcPtr, Tcl_Obj *resObj);
static void		MarkDead(ReflectedChannel *rcPtr);

/*
 * Global constant strings (messages). ==================
 * These string are used directly as bypass errors, thus they have to be valid

 *	Creates a new channel.
 *
 *----------------------------------------------------------------------
 */

int
TclChanCreateObjCmd(
    ClientData dummy,
    Tcl_Interp *interp,
    int objc,
    Tcl_Obj *const *objv)
{
    ReflectedChannel *rcPtr;	/* Instance data of the new channel */
    Tcl_Obj *rcId;		/* Handle of the new channel */
    int mode;			/* R/W mode of new channel. Has to match

    Tcl_NotifyChannel(e->rcPtr->chan, e->events);
    return 1;
}

static int
ReflectEventDelete(
    Tcl_Event *ev,
    ClientData cd)
{
    /* OWNER thread
     *
     * Invoked by DeleteThreadReflectedChannelMap() and ReflectClose(). The
     * latter ensures that no pending events of this type are run on an
     * invalid channel.
     */

    ReflectEvent *e = (ReflectEvent *) ev;

    if ((ev->proc != ReflectEventRun) || ((cd != NULL) && (cd != e->rcPtr))) {
        return 0;
    }
    return 1;
}
#endif

int
TclChanPostEventObjCmd(
    ClientData dummy,
    Tcl_Interp *interp,
    int objc,
    Tcl_Obj *const *objv)
{
    /*
     * Ensure -> HANDLER thread
     *

    rcmPtr = GetReflectedChannelMap(interp);
    hPtr = Tcl_FindHashEntry(&rcmPtr->map, chanId);

    if (hPtr == NULL) {
	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                "can not find reflected channel named \"%s\"", chanId));
	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "CHANNEL", chanId, NULL);
	return TCL_ERROR;
    }

    /*
     * Note that the search above subsumes several of the older checks,
     * namely:
     *

 *	Releases memory. Arbitrary, as it calls upon a script.
 *
 *----------------------------------------------------------------------
 */

static int
ReflectClose(
    ClientData clientData,
    Tcl_Interp *interp)
{
    ReflectedChannel *rcPtr = (ReflectedChannel *)clientData;
    int result;			/* Result code for 'close' */
    Tcl_Obj *resObj;		/* Result data for 'close' */
    ReflectedChannelMap *rcmPtr;/* Map of reflected channels with handlers in
				 * this interp */

#endif

	tctPtr = ((Channel *)rcPtr->chan)->typePtr;
	if (tctPtr && tctPtr != &tclRChannelType) {
	    ckfree((char *)tctPtr);
	    ((Channel *)rcPtr->chan)->typePtr = NULL;
	}
        Tcl_EventuallyFree(rcPtr, FreeReflectedChannel);
	return EOK;
    }

    /*
     * Are we in the correct thread?
     */

    }
    Tcl_EventuallyFree(rcPtr, FreeReflectedChannel);
    return (result == TCL_OK) ? EOK : EINVAL;
}

static int
ReflectClose2(
    ClientData clientData,
    Tcl_Interp *interp,
	int flags)
{
    if ((flags & (TCL_CLOSE_READ | TCL_CLOSE_WRITE)) == 0) {
	return ReflectClose(clientData, interp);
    }
    return EINVAL;

 *	Allocates memory. Arbitrary, as it calls upon a script.
 *
 *----------------------------------------------------------------------
 */

static int
ReflectInput(
    ClientData clientData,
    char *buf,
    int toRead,
    int *errorCodePtr)
{
    ReflectedChannel *rcPtr = (ReflectedChannel *)clientData;
    Tcl_Obj *toReadObj;
    int bytec;			/* Number of returned bytes */

 *	Allocates memory. Arbitrary, as it calls upon a script.
 *
 *----------------------------------------------------------------------
 */

static int
ReflectOutput(
    ClientData clientData,
    const char *buf,
    int toWrite,
    int *errorCodePtr)
{
    ReflectedChannel *rcPtr = (ReflectedChannel *)clientData;
    Tcl_Obj *bufObj;
    Tcl_Obj *resObj;		/* Result data for 'write' */

 *	Allocates memory. Arbitrary, as it calls upon a script.
 *
 *----------------------------------------------------------------------
 */

static Tcl_WideInt
ReflectSeekWide(
    ClientData clientData,
    Tcl_WideInt offset,
    int seekMode,
    int *errorCodePtr)
{
    ReflectedChannel *rcPtr = (ReflectedChannel *)clientData;
    Tcl_Obj *offObj, *baseObj;
    Tcl_Obj *resObj;		/* Result for 'seek' */

    *errorCodePtr = EINVAL;
    newLoc = -1;
    goto stop;
}

static int
ReflectSeek(
    ClientData clientData,
    long offset,
    int seekMode,
    int *errorCodePtr)
{
    /*
     * This function can be invoked from a transformation which is based on
     * standard seeking, i.e. non-wide. Because of this we have to implement

 *	Allocates memory. Arbitrary, as it calls upon a script.
 *
 *----------------------------------------------------------------------
 */

static void
ReflectWatch(
    ClientData clientData,
    int mask)
{
    ReflectedChannel *rcPtr = (ReflectedChannel *)clientData;
    Tcl_Obj *maskObj;

    /*
     * We restrict the interest to what the channel can support. IOW there

 *	Allocates memory. Arbitrary, as it calls upon a script.
 *
 *----------------------------------------------------------------------
 */

static int
ReflectBlock(
    ClientData clientData,
    int nonblocking)
{
    ReflectedChannel *rcPtr = (ReflectedChannel *)clientData;
    Tcl_Obj *blockObj;
    int errorNum;		/* EINVAL or EOK (success). */
    Tcl_Obj *resObj;		/* Result data for 'blocking' */

 *	Allocates memory. Arbitrary, as it calls upon a script.
 *
 *----------------------------------------------------------------------
 */

static void
ReflectThread(
    ClientData clientData,
    int action)
{
    ReflectedChannel *rcPtr = (ReflectedChannel *)clientData;

    switch (action) {
    case TCL_CHANNEL_THREAD_INSERT:
        rcPtr->owner = Tcl_GetCurrentThread();

 *	Arbitrary, as it calls upon a Tcl script.
 *
 *----------------------------------------------------------------------
 */

static int
ReflectSetOption(
    ClientData clientData,	/* Channel to query */
    Tcl_Interp *interp,		/* Interpreter to leave error messages in */
    const char *optionName,	/* Name of requested option */
    const char *newValue)	/* The new value */
{
    ReflectedChannel *rcPtr = (ReflectedChannel *)clientData;
    Tcl_Obj *optionObj, *valueObj;
    int result;			/* Result code for 'configure' */

 *	Arbitrary, as it calls upon a Tcl script.
 *
 *----------------------------------------------------------------------
 */

static int
ReflectGetOption(
    ClientData clientData,	/* Channel to query */
    Tcl_Interp *interp,		/* Interpreter to leave error messages in */
    const char *optionName,	/* Name of reuqested option */
    Tcl_DString *dsPtr)		/* String to place the result into */
{
    /*
     * This code is special. It has regular passing of Tcl result, and errors.
     * The bypass functions are not required.
     */

    ReflectedChannel *rcPtr = (ReflectedChannel *)clientData;
    Tcl_Obj *optionObj;
    Tcl_Obj *resObj;		/* Result data for 'configure' */

    int listc, result = TCL_OK;
    Tcl_Obj **listv;
    MethodName method;

    /*
     * Are we in the correct thread?
     */

{
    ReflectedChannelMap *rcmPtr = (ReflectedChannelMap *)Tcl_GetAssocData(interp, RCMKEY, NULL);

    if (rcmPtr == NULL) {
	rcmPtr = (ReflectedChannelMap *)ckalloc(sizeof(ReflectedChannelMap));
	Tcl_InitHashTable(&rcmPtr->map, TCL_STRING_KEYS);
	Tcl_SetAssocData(interp, RCMKEY,
		(Tcl_InterpDeleteProc *) DeleteReflectedChannelMap, rcmPtr);
    }
    return rcmPtr;
}

/*
 *----------------------------------------------------------------------
 *

	rcPtr->cmd = NULL;
    }
    rcPtr->dead = 1;
}

static void
DeleteReflectedChannelMap(
    ClientData clientData,	/* The per-interpreter data structure. */
    Tcl_Interp *interp)		/* The interpreter being deleted. */
{
    ReflectedChannelMap *rcmPtr = (ReflectedChannelMap *)clientData;
				/* The map */
    Tcl_HashSearch hSearch;	 /* Search variable. */
    Tcl_HashEntry *hPtr;	 /* Search variable. */
    ReflectedChannel *rcPtr;

 *	Deletes the hash table of channels.
 *
 *----------------------------------------------------------------------
 */

static void
DeleteThreadReflectedChannelMap(
    ClientData dummy)	/* The per-thread data structure. */
{
    Tcl_HashSearch hSearch;	 /* Search variable. */
    Tcl_HashEntry *hPtr;	 /* Search variable. */
    Tcl_ThreadId self = Tcl_GetCurrentThread();
    ReflectedChannelMap *rcmPtr; /* The map */
    ForwardingResult *resultPtr;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

	    }
	    paramPtr->input.toRead = -1;
	} else {
	    /*
	     * Process a regular result.
	     */

	    int bytec;			/* Number of returned bytes */
	    unsigned char *bytev;	/* Array of returned bytes */

	    bytev = Tcl_GetByteArrayFromObj(resObj, &bytec);

	    if (paramPtr->input.toRead < bytec) {
		ForwardSetStaticError(paramPtr, msg_read_toomuch);
		paramPtr->input.toRead = -1;

    }

    return 1;
}

static void
SrcExitProc(
    ClientData clientData)
{
    ForwardingEvent *evPtr = (ForwardingEvent *)clientData;
    ForwardingResult *resultPtr;
    ForwardParam *paramPtr;

    /*
     * NOTE (2): Can this handler be called with the originator blocked?

# -*- tcl -*-
# Commands covered: open, close, gets, read, puts, seek, tell, eof, flush,
#		    fblocked, fconfigure, open, channel, fcopy
#
# This file contains a collection of tests for one or more of the Tcl
# built-in commands.  Sourcing this file into Tcl runs the tests and
# generates output for errors.  No output means no errors were found.
#
# Copyright (c) 1991-1994 The Regents of the University of California.
# Copyright (c) 1994-1996 Sun Microsystems, Inc.
# Copyright (c) 1998-1999 by Scriptics Corporation.
#
# See the file "license.terms" for information on usage and redistribution
# of this file, and for a DISCLAIMER OF ALL WARRANTIES.

if {"::tcltest" ni [namespace children]} {
    package require tcltest 2.5
    namespace import -force ::tcltest::*

    close $f
    string compare [string tolower $x] \
	[list 1 [format "channel \"%s\" wasn't opened for reading" $f] none]
} 0
test iocmd-4.12 {read command} -setup {
    set f [open $path(test1)]
} -body {
    list [catch {read $f 12z} msg] $msg $::errorCode
} -cleanup {
    close $f
} -result {1 {expected non-negative integer but got "12z"} {TCL VALUE NUMBER}}

test iocmd-5.1 {seek command} -returnCodes error -body {
    seek
} -result {wrong # args: should be "seek channelId offset ?origin?"}
test iocmd-5.2 {seek command} -returnCodes error -body {
    seek a b c d e f g
} -result {wrong # args: should be "seek channelId offset ?origin?"}

    puts $f \u0248		;# gets truncated to \u0048
    close $f
    set f [open $path(test1) r]
    fconfigure $f -translation binary
    set result [read -nonewline $f]
    close $f
    set result
} \u0048

test iocmd-13.1 {errors in open command} {
    list [catch {open} msg] $msg
} {1 {wrong # args: should be "open fileName ?access? ?permissions?"}}
test iocmd-13.2 {errors in open command} {
    list [catch {open a b c d} msg] $msg
} {1 {wrong # args: should be "open fileName ?access? ?permissions?"}}

    set fid [open $f rb]
    append d [read $fid]
    close $fid
    return $d
} -cleanup {
    removeFile $f
} -result 341234x6


test iocmd-14.1 {file id parsing errors} {
    list [catch {eof gorp} msg] $msg $::errorCode
} {1 {can not find channel named "gorp"} {TCL LOOKUP CHANNEL gorp}}
test iocmd-14.2 {file id parsing errors} {
    list [catch {eof filex} msg] $msg
} {1 {can not find channel named "filex"}}

    }
    set c [chan create {r w} foo]
    note [read $c 10]
    close $c
    rename foo {}
    set res
} -result {{read rc* 4096} {read rc* 4096} snarfsnarf}
test iocmd-23.2 {chan read, bad data return, to much} -match glob -body {
    set res {}
    proc foo {args} {
	oninit; onfinal; track
	return [string repeat snarf 1000]
    }
    set c [chan create {r w} foo]
    note [catch {read $c 2} msg]; note $msg

    rename foo {}
    set res
} -result {{unmatched open brace in list}}
test iocmd-31.6 {chan postevent, posted events do happen} -match glob -body {
    set res {}
    proc foo {args} {oninit; onfinal; track; return}
    set c [chan create {r w} foo]

    note [fileevent $c readable {note TOCK}]
    set stop [after 15000 {note TIMEOUT}]
    after  1000 {note [chan postevent $c r]}
    vwait ::res
    catch {after cancel $stop}
    close $c
    rename foo {}
    set res
} -result {{watch rc* read} {} TOCK {} {watch rc* {}}}
test iocmd-31.7 {chan postevent, posted events do happen} -match glob -body {
    set res {}
    proc foo {args} {oninit; onfinal; track; return}
    set c [chan create {r w} foo]
    note [fileevent $c writable {note TOCK}]
    set stop [after 15000 {note TIMEOUT}]
    after  1000 {note [chan postevent $c w]}
    vwait ::res
    catch {after cancel $stop}
    close $c
    rename foo {}
    set res
} -result {{watch rc* write} {} TOCK {} {watch rc* {}}}
test iocmd-31.8 {chan postevent after close throws error} -match glob -setup {
    proc foo {args} {oninit; onfinal; track; return}

	note [read $c 10]
	close $c
	notes
    } c]
    rename foo {}
    set res
} -constraints {testchannel thread} -result {{read rc* 4096} {read rc* 4096} snarfsnarf}
test iocmd.tf-23.2 {chan read, bad data return, to much} -match glob -body {
    set res {}
    proc foo {args} {
	oninit; onfinal; track
	return [string repeat snarf 1000]
    }
    set c [chan create {r w} foo]
    notes [inthread $c {