Tcl Source Code

} CloseCallback;

/*
 * Static functions in this file:
 */

static ChannelBuffer *	AllocChannelBuffer(int length);
static void		PreserveChannelBuffer(ChannelBuffer *bufPtr);
static void		ReleaseChannelBuffer(ChannelBuffer *bufPtr);
static void		ChannelTimerProc(ClientData clientData);
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,

ChanRead(
    Channel *chanPtr,
    char *dst,
    int dstSize,
    int *errnoPtr)
{
    if (WillRead(chanPtr) < 0) {
	*errnoPtr = Tcl_GetErrno();
        return -1;
    }

    return chanPtr->typePtr->inputProc(chanPtr->instanceData, dst, dstSize,
	    errnoPtr);
}

    n = length + CHANNELBUFFER_HEADER_SIZE + BUFFER_PADDING + BUFFER_PADDING;
    bufPtr = ckalloc(n);
    bufPtr->nextAdded	= BUFFER_PADDING;
    bufPtr->nextRemoved	= BUFFER_PADDING;
    bufPtr->bufLength	= length + BUFFER_PADDING;
    bufPtr->nextPtr	= NULL;
    bufPtr->refCount	= 1;
    return bufPtr;
}

static void
PreserveChannelBuffer(
    ChannelBuffer *bufPtr)
{
    bufPtr->refCount++;
}

static void
ReleaseChannelBuffer(
    ChannelBuffer *bufPtr)
{
    if (--bufPtr->refCount) {
	return;
    }
    ckfree(bufPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * RecycleBuffer --
 *
 *	Helper function to recycle input and output buffers. Ensures that two

				 * always. */
{
    /*
     * Do we have to free the buffer to the OS?
     */

    if (mustDiscard) {
	ReleaseChannelBuffer(bufPtr);
	return;
    }

    /*
     * Only save buffers which are at least as big as the requested buffersize
     * for the channel. This is to honor dynamic changes of the buffersize
     * made by the user.
     */

    if ((bufPtr->bufLength - BUFFER_PADDING) < statePtr->bufSize) {
	ReleaseChannelBuffer(bufPtr);
	return;
    }

    /*
     * Only save buffers for the input queue if the channel is readable.
     */

	}
    }

    /*
     * If we reached this code we return the buffer to the OS.
     */

    ReleaseChannelBuffer(bufPtr);
    return;

  keepBuffer:
    bufPtr->nextRemoved = BUFFER_PADDING;
    bufPtr->nextAdded = BUFFER_PADDING;
    bufPtr->nextPtr = NULL;
}

	    break;		/* Out of the "while (1)". */
	}

	/*
	 * Produce the output on the channel.
	 */

	PreserveChannelBuffer(bufPtr);
	toWrite = BytesLeft(bufPtr);
	if (toWrite == 0) {
            written = 0;
	} else {
	    written = ChanWrite(chanPtr, RemovePoint(bufPtr), toWrite,
		    &errorCode);
	}

	if (IsBufferEmpty(bufPtr)) {
	    statePtr->outQueueHead = bufPtr->nextPtr;
	    if (statePtr->outQueueHead == NULL) {
		statePtr->outQueueTail = NULL;
	    }
	    RecycleBuffer(statePtr, bufPtr, 0);
	}
	ReleaseChannelBuffer(bufPtr);
    }	/* Closes "while (1)". */

    /*
     * If we wrote some data while flushing in the background, we are done.
     * We can't finish the background flush until we run out of data and the
     * channel becomes writable again. This ensures that all of the pending
     * data has been flushed at the system level.

    DiscardInputQueued(statePtr, 1);

    /*
     * Discard a leftover buffer in the current output buffer field.
     */

    if (statePtr->curOutPtr != NULL) {
	ReleaseChannelBuffer(statePtr->curOutPtr);
	statePtr->curOutPtr = NULL;
    }

    /*
     * The caller guarantees that there are no more buffers queued for output.
     */

    }
}

static int
WillRead(
    Channel *chanPtr)
{
    if (chanPtr->typePtr == NULL) {
	/* Prevent read attempts on a closed channel */
	Tcl_SetErrno(EINVAL);
	return -1;
    }
    if ((chanPtr->typePtr->seekProc != NULL)
            && (Tcl_OutputBuffered((Tcl_Channel) chanPtr) > 0)) {
        if ((chanPtr->state->curOutPtr != NULL)
                && IsBufferReady(chanPtr->state->curOutPtr)) {
            SetFlag(chanPtr->state, BUFFER_READY);
        }
        if (FlushChannel(NULL, chanPtr, 0) != 0) {

	     * that we need to stick at the beginning of this buffer.
	     */

	    memcpy(InsertPoint(bufPtr), safe, (size_t) saved);
	    bufPtr->nextAdded += saved;
	    saved = 0;
	}
	PreserveChannelBuffer(bufPtr);
	dst = InsertPoint(bufPtr);
	dstLen = SpaceLeft(bufPtr);

	result = Tcl_UtfToExternal(NULL, encoding, src, srcLimit,
		statePtr->outputEncodingFlags,
		&statePtr->outputEncodingState, dst,
		dstLen + BUFFER_PADDING, &srcRead, &dstWrote, NULL);

	/* See chan-io-1.[89]. Tcl Bug 506297. */
	statePtr->outputEncodingFlags &= ~TCL_ENCODING_START;
	
	if ((result != TCL_OK) && (srcRead + dstWrote == 0)) {
	    /* We're reading from invalid/incomplete UTF-8 */
	    ReleaseChannelBuffer(bufPtr);
	    if (total == 0) {
		Tcl_SetErrno(EINVAL);
		return -1;
	    }
	    break;
	}

		return -1;
	    }
	    flushed += statePtr->bufSize;
	    if (saved == 0 || src[-1] != '\n') {
		needNlFlush = 0;
	    }
	}
	ReleaseChannelBuffer(bufPtr);
    }
    if ((flushed < total) && (GotFlag(statePtr, CHANNEL_UNBUFFERED) ||
	    (needNlFlush && GotFlag(statePtr, CHANNEL_LINEBUFFERED)))) {
	SetFlag(statePtr, BUFFER_READY);
	if (FlushChannel(NULL, chanPtr, 0) != 0) {
	    return -1;
	}

    /*
     * If discardSavedBuffers is nonzero, must also discard any previously
     * saved buffer in the saveInBufPtr field.
     */

    if (discardSavedBuffers && statePtr->saveInBufPtr != NULL) {
	ReleaseChannelBuffer(statePtr->saveInBufPtr);
	statePtr->saveInBufPtr = NULL;
    }
}

/*
 *---------------------------------------------------------------------------
 *

	 * Check the actual buffersize against the requested buffersize.
	 * Buffers which are smaller than requested are squashed. This is done
	 * to honor dynamic changes of the buffersize made by the user.
	 */

	if ((bufPtr != NULL)
		&& (bufPtr->bufLength - BUFFER_PADDING < statePtr->bufSize)) {
	    ReleaseChannelBuffer(bufPtr);
	    bufPtr = NULL;
	}

	if (bufPtr == NULL) {
	    bufPtr = AllocChannelBuffer(statePtr->bufSize);
	}
	bufPtr->nextPtr = NULL;

	 */

	nread = -1;
	result = EWOULDBLOCK;
    } else
#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
    {
	PreserveChannelBuffer(bufPtr);
	nread = ChanRead(chanPtr, InsertPoint(bufPtr), toRead, &result);
    }

    if (nread > 0) {
	result = 0;
	bufPtr->nextAdded += nread;

	/*
	 * If we get a short read, signal up that we may be BLOCKED. We should
	 * avoid calling the driver because on some platforms we will block in
	 * the low level reading code even though the channel is set into
	 * nonblocking mode.

	     * [Bug 943274]: We have read the available data, clear flag.
	     */

	    ResetFlag(statePtr, CHANNEL_HAS_MORE_DATA);
	}
#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
    } else if (nread == 0) {
	result = 0;
	SetFlag(statePtr, CHANNEL_EOF);
	statePtr->inputEncodingFlags |= TCL_ENCODING_END;
    } else if (nread < 0) {
	if ((result == EWOULDBLOCK) || (result == EAGAIN)) {
	    SetFlag(statePtr, CHANNEL_BLOCKED);
	    result = EAGAIN;
	}
	Tcl_SetErrno(result);

    }
    ReleaseChannelBuffer(bufPtr);
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_Seek --
 *

/*
 * struct ChannelBuffer:
 *
 * Buffers data being sent to or from a channel.
 */

typedef struct ChannelBuffer {
    int refCount;		/* Current uses count */
    int nextAdded;		/* The next position into which a character
				 * will be put in the buffer. */
    int nextRemoved;		/* Position of next byte to be removed from
				 * the buffer. */
    int bufLength;		/* How big is the buffer? */
    struct ChannelBuffer *nextPtr;
    				/* Next buffer in chain. */

	    newline = 1;
#endif
	}
    }

    resultPtr = Tcl_NewObj();
    Tcl_IncrRefCount(resultPtr);
    Tcl_Preserve(chan);
    charactersRead = Tcl_ReadChars(chan, resultPtr, toRead, 0);
    if (charactersRead < 0) {
	/*
	 * TIP #219.
	 * Capture error messages put by the driver into the bypass area and
	 * put them into the regular interpreter result. Fall back to the
	 * regular message if nothing was found in the bypass.
	 */

	if (!TclChanCaughtErrorBypass(interp, chan)) {
	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		    "error reading \"%s\": %s",
		    TclGetString(chanObjPtr), Tcl_PosixError(interp)));
	}
	Tcl_Release(chan);
	Tcl_DecrRefCount(resultPtr);
	return TCL_ERROR;
    }

    /*
     * If requested, remove the last newline in the channel if at EOF.
     */

    if ((charactersRead > 0) && (newline != 0)) {
	const char *result;
	int length;

	result = TclGetStringFromObj(resultPtr, &length);
	if (result[length - 1] == '\n') {
	    Tcl_SetObjLength(resultPtr, length - 1);
	}
    }
    Tcl_SetObjResult(interp, resultPtr);
    Tcl_Release(chan);
    Tcl_DecrRefCount(resultPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *

    set ch [chan create {read write} foo]
} -body {
    list [catch {chan configure $ch -blocking 0} m] $m
} -cleanup {
    close $ch
    rename foo {}
} -match glob -result {1 {*nested eval*}}
test iocmd-21.21 {[close] in [read] segfaults} -setup {
    proc foo {method chan args} {
	switch -- $method initialize {
	    return {initialize finalize watch read}
	} finalize {} watch {} read {
	    close $chan
	    return a
	}
    }
    set ch [chan create read foo]
} -body {
    read $ch 0
} -cleanup {
    close $ch
    rename foo {}
} -result {}
test iocmd-21.22 {[close] in [read] segfaults} -setup {
    proc foo {method chan args} {
	switch -- $method initialize {
	    return {initialize finalize watch read}
	} finalize {} watch {} read {
	    catch {close $chan}
	    return a
	}
    }
    set ch [chan create read foo]
} -body {
    read $ch 1
} -returnCodes error -cleanup {
    catch {close $ch}
    rename foo {}
} -match glob -result {*invalid argument*}

# --- --- --- --------- --------- ---------
# Helper commands to record the arguments to handler methods.

# Stored in a script so that the threads and interpreters needing this
# code do not need their own copy but can access this variable.