tclio.c

linux系统下的音频通信

                (chanPtr->flags & BG_FLUSH_SCHEDULED)) {
            return 0;
        }

        /*
         * If the output queue is still empty, break out of the while loop.
         */

        if (bufPtr == (ChannelBuffer *) NULL) {
            break;	/* Out of the "while (1)". */
        }

        /*
         * Produce the output on the channel.
         */
        
        toWrite = bufPtr->nextAdded - bufPtr->nextRemoved;
        written = (chanPtr->typePtr->outputProc) (chanPtr->instanceData,
                bufPtr->buf + bufPtr->nextRemoved, toWrite, &errorCode);
            
	/*
         * If the write failed completely attempt to start the asynchronous
         * flush mechanism and break out of this loop - do not attempt to
         * write any more output at this time.
         */

        if (written < 0) {
            
            /*
             * If the last attempt to write was interrupted, simply retry.
             */
            
            if (errorCode == EINTR) {
                errorCode = 0;
                continue;
            }

            /*
             * If the channel is non-blocking and we would have blocked,
             * start a background flushing handler and break out of the loop.
             */

            if ((errorCode == EWOULDBLOCK) || (errorCode == EAGAIN)) {
		if (chanPtr->flags & CHANNEL_NONBLOCKING) {
		    if (!(chanPtr->flags & BG_FLUSH_SCHEDULED)) {
			chanPtr->flags |= BG_FLUSH_SCHEDULED;
			UpdateInterest(chanPtr);
                    }
                    errorCode = 0;
                    break;
		} else {
		    panic("Blocking channel driver did not block on output");
                }
            }

            /*
             * Decide whether to report the error upwards or defer it.
             */

            if (calledFromAsyncFlush) {
                if (chanPtr->unreportedError == 0) {
                    chanPtr->unreportedError = errorCode;
                }
            } else {
                Tcl_SetErrno(errorCode);
		if (interp != NULL) {
		    Tcl_SetResult(interp,
			    Tcl_PosixError(interp), TCL_VOLATILE);
		}
            }

            /*
             * When we get an error we throw away all the output
             * currently queued.
             */

            DiscardOutputQueued(chanPtr);
            continue;
        }

        bufPtr->nextRemoved += written;

        /*
         * If this buffer is now empty, recycle it.
         */

        if (bufPtr->nextRemoved == bufPtr->nextAdded) {
            chanPtr->outQueueHead = bufPtr->nextPtr;
            if (chanPtr->outQueueHead == (ChannelBuffer *) NULL) {
                chanPtr->outQueueTail = (ChannelBuffer *) NULL;
            }
            RecycleBuffer(chanPtr, bufPtr, 0);
        }
    }	/* Closes "while (1)". */
    
    /*
     * If the queue became empty and we have the asynchronous flushing
     * mechanism active, cancel the asynchronous flushing.
     */

    if ((chanPtr->outQueueHead == (ChannelBuffer *) NULL) &&
            (chanPtr->flags & BG_FLUSH_SCHEDULED)) {
        chanPtr->flags &= (~(BG_FLUSH_SCHEDULED));
	(chanPtr->typePtr->watchProc)(chanPtr->instanceData,
		chanPtr->interestMask);
    }

    /*
     * If the channel is flagged as closed, delete it when the refCount
     * drops to zero, the output queue is empty and there is no output
     * in the current output buffer.
     */

    if ((chanPtr->flags & CHANNEL_CLOSED) && (chanPtr->refCount <= 0) &&
            (chanPtr->outQueueHead == (ChannelBuffer *) NULL) &&
            ((chanPtr->curOutPtr == (ChannelBuffer *) NULL) ||
                    (chanPtr->curOutPtr->nextAdded ==
                            chanPtr->curOutPtr->nextRemoved))) {
        return CloseChannel(interp, chanPtr, errorCode);
    }
    return errorCode;
}

/*
 *----------------------------------------------------------------------
 *
 * CloseChannel --
 *
 *	Utility procedure to close a channel and free its associated
 *	resources.
 *
 * Results:
 *	0 on success or a POSIX error code if the operation failed.
 *
 * Side effects:
 *	May close the actual channel; may free memory.
 *
 *----------------------------------------------------------------------
 */

static int
CloseChannel(interp, chanPtr, errorCode)
    Tcl_Interp *interp;			/* For error reporting. */
    Channel *chanPtr;			/* The channel to close. */
    int errorCode;			/* Status of operation so far. */
{
    int result = 0;			/* Of calling driver close
                                         * operation. */
    Channel *prevChanPtr;		/* Preceding channel in list of
                                         * all channels - used to splice a
                                         * channel out of the list on close. */
        
    if (chanPtr == NULL) {
        return result;
    }
    
    /*
     * No more input can be consumed so discard any leftover input.
     */

    DiscardInputQueued(chanPtr, 1);

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

    if (chanPtr->curOutPtr != (ChannelBuffer *) NULL) {
        ckfree((char *) chanPtr->curOutPtr);
        chanPtr->curOutPtr = (ChannelBuffer *) NULL;
    }
    
    /*
     * The caller guarantees that there are no more buffers
     * queued for output.
     */

    if (chanPtr->outQueueHead != (ChannelBuffer *) NULL) {
        panic("TclFlush, closed channel: queued output left");
    }

    /*
     * If the EOF character is set in the channel, append that to the
     * output device.
     */

    if ((chanPtr->outEofChar != 0) && (chanPtr->flags & TCL_WRITABLE)) {
        int dummy;
        char c;

        c = (char) chanPtr->outEofChar;
        (chanPtr->typePtr->outputProc) (chanPtr->instanceData, &c, 1, &dummy);
    }

    /*
     * Remove TCL_READABLE and TCL_WRITABLE from chanPtr->flags, so
     * that close callbacks can not do input or output (assuming they
     * squirreled the channel away in their clientData). This also
     * prevents infinite loops if the callback calls any C API that
     * could call FlushChannel.
     */

    chanPtr->flags &= (~(TCL_READABLE|TCL_WRITABLE));
        
    /*
     * Splice this channel out of the list of all channels.
     */

    if (chanPtr == firstChanPtr) {
        firstChanPtr = chanPtr->nextChanPtr;
    } else {
        for (prevChanPtr = firstChanPtr;
                 (prevChanPtr != (Channel *) NULL) &&
                     (prevChanPtr->nextChanPtr != chanPtr);
                 prevChanPtr = prevChanPtr->nextChanPtr) {
            /* Empty loop body. */
        }
        if (prevChanPtr == (Channel *) NULL) {
            panic("FlushChannel: damaged channel list");
        }
        prevChanPtr->nextChanPtr = chanPtr->nextChanPtr;
    }

    /*
     * OK, close the channel itself.
     */
        
    result = (chanPtr->typePtr->closeProc) (chanPtr->instanceData, interp);
    
    if (chanPtr->channelName != (char *) NULL) {
        ckfree(chanPtr->channelName);
    }
    
    /*
     * If we are being called synchronously, report either
     * any latent error on the channel or the current error.
     */
        
    if (chanPtr->unreportedError != 0) {
        errorCode = chanPtr->unreportedError;
    }
    if (errorCode == 0) {
        errorCode = result;
        if (errorCode != 0) {
            Tcl_SetErrno(errorCode);
        }
    }

    /*
     * Cancel any outstanding timer.
     */

    Tcl_DeleteTimerHandler(chanPtr->timer);

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

    chanPtr->typePtr = NULL;

    Tcl_EventuallyFree((ClientData) chanPtr, TCL_DYNAMIC);

    return errorCode;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_Close --
 *
 *	Closes a channel.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	Closes the channel if this is the last reference.
 *
 * NOTE:
 *	Tcl_Close removes the channel as far as the user is concerned.
 *	However, it may continue to exist for a while longer if it has
 *	a background flush scheduled. The device itself is eventually
 *	closed and the channel record removed, in CloseChannel, above.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_Close(interp, chan)
    Tcl_Interp *interp;			/* Interpreter for errors. */
    Tcl_Channel chan;			/* The channel being closed. Must
                                         * not be referenced in any
                                         * interpreter. */
{
    ChannelHandler *chPtr, *chNext;	/* Iterate over channel handlers. */
    CloseCallback *cbPtr;		/* Iterate over close callbacks
                                         * for this channel. */
    EventScriptRecord *ePtr, *eNextPtr;	/* Iterate over eventscript records. */
    Channel *chanPtr;			/* The real IO channel. */
    int result;				/* Of calling FlushChannel. */
    NextChannelHandler *nhPtr;

    if (chan == (Tcl_Channel) NULL) {
        return TCL_OK;
    }
    
    /*
     * Perform special handling for standard channels being closed. If the
     * refCount is now 1 it means that the last reference to the standard
     * channel is being explicitly closed, so bump the refCount down
     * artificially to 0. This will ensure that the channel is actually
     * closed, below. Also set the static pointer to NULL for the channel.
     */

    CheckForStdChannelsBeingClosed(chan);

    chanPtr = (Channel *) chan;
    if (chanPtr->refCount > 0) {
        panic("called Tcl_Close on channel with refCount > 0");
    }

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

    for (nhPtr = nestedHandlerPtr;
             nhPtr != (NextChannelHandler *) NULL;
             nhPtr = nhPtr->nestedHandlerPtr) {
        if (nhPtr->nextHandlerPtr &&
		(nhPtr->nextHandlerPtr->chanPtr == chanPtr)) {
	    nhPtr->nextHandlerPtr = NULL;
        }
    }

    /*
     * Remove all the channel handler records attached to the channel
     * itself.
     */
        
    for (chPtr = chanPtr->chPtr;
             chPtr != (ChannelHandler *) NULL;
             chPtr = chNext) {
        chNext = chPtr->nextPtr;
        ckfree((char *) chPtr);
    }
    chanPtr->chPtr = (ChannelHandler *) NULL;
    
    
    /*
     * Cancel any pending copy operation.
     */

    StopCopy(chanPtr->csPtr);

    /*
     * Must set the interest mask now to 0, otherwise infinite loops
     * will occur if Tcl_DoOneEvent is called before the channel is
     * finally deleted in FlushChannel. This can happen if the channel
     * has a background flush active.
     */
        
    chanPtr->interestMask = 0;
    
    /*
     * Remove any EventScript records for this channel.
     */

    for (ePtr = chanPtr->scriptRecordPtr;
             ePtr != (EventScriptRecord *) NULL;
             ePtr = eNextPtr) {
        eNextPtr = ePtr->nextPtr;
	ckfree(ePtr->script);
        ckfree((char *) ePtr);
    }
    chanPtr->scriptRecordPtr = (EventScriptRecord *) NULL;
        
    /*
     * Invoke the registered close callbacks and delete their records.
     */

    while (chanPtr->closeCbPtr != (CloseCallback *) NULL) {
        cbPtr = chanPtr->closeCbPtr;
        chanPtr->closeCbPtr = cbPtr->nextPtr;
        (cbPtr->proc) (cbPtr->clientData);
        ckfree((char *) cbPtr);
    }

    /*
     * Ensure that the last output buffer will be flushed.
     */
    
    if ((chanPtr->curOutPtr != (ChannelBuffer *) NULL) &&
           (chanPtr->curOutPtr->nextAdded > chanPtr->curOutPtr->nextRemoved)) {
        chanPtr->flags |= BUFFER_READY;
    }

    /*
     * The call to FlushChannel will flush any queued output and invoke
     * the close function of the channel driver, or it will set up the
     * channel to be flushed and closed asynchronously.
     */
    
    chanPtr->flags |= CHANNEL_CLOSED;
    result = Flu