Tcl Source Code

    int written;		/* Amount of output data actually written in
				 * current round. */
    int errorCode = 0;		/* Stores POSIX error codes from channel
				 * driver operations. */
    int wroteSome = 0;		/* Set to one if any data was written to the
				 * driver. */

    int bufExists;
    /*
     * Prevent writing on a dead channel -- a channel that has been closed but
     * not yet deallocated. This can occur if the exit handler for the channel
     * deallocation runs before all channels are deregistered in all
     * interpreters.
     */

	    }

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


	    ReleaseChannelBuffer(bufPtr);
	    DiscardOutputQueued(statePtr);
	    break;
	} else {
	    /*
	     * TODO: Consider detecting and reacting to short writes on
	     * blocking channels.  Ought not happen.  See iocmd-24.2.
	     */

	    wroteSome = 1;
	}

	bufExists = bufPtr->refCount > 1;
	ReleaseChannelBuffer(bufPtr);
	if (bufExists) {
	    /* There is still a reference to this buffer other than the one
	     * this routine just released, meaning that final cleanup of the
	     * buffer hasn't been ordered by, e.g. by a reflected channel
	     * closing the channel from within one of its handler scripts (not
	     * something one would expecte, but it must be considered).  Normal
	     * operations on the buffer can proceed.
	     */

	    bufPtr->nextRemoved += written;

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

	    if (IsBufferEmpty(bufPtr)) {
		statePtr->outQueueHead = bufPtr->nextPtr;
		if (statePtr->outQueueHead == NULL) {
		    statePtr->outQueueTail = NULL;
		}
		RecycleBuffer(statePtr, bufPtr, 0);
	    }
	}

    }	/* Closes "while". */

    /*
     * 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.

	statePtr->inQueueTail = bufPtr;
    } else {
	toRead = SpaceLeft(bufPtr);
    }

    PreserveChannelBuffer(bufPtr);
    nread = ChanRead(chanPtr, InsertPoint(bufPtr), toRead);
    ReleaseChannelBuffer(bufPtr);

    if (nread < 0) {
	result = Tcl_GetErrno();
    } else {
	result = 0;
	if (statePtr->inQueueTail != NULL) {
	    statePtr->inQueueTail->nextAdded += nread;
	}
    }

    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_Seek --