iokit/Kernel/IOSharedDataQueue.cpp

/*
 * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
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 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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#include <IOKit/IOSharedDataQueue.h>
#include <IOKit/IODataQueueShared.h>
#include <IOKit/IOLib.h>
#include <IOKit/IOMemoryDescriptor.h>

#ifdef enqueue
#undef enqueue
#endif

#ifdef dequeue
#undef dequeue
#endif

#define super IODataQueue

OSDefineMetaClassAndStructors(IOSharedDataQueue, IODataQueue)

IOSharedDataQueue *IOSharedDataQueue::withCapacity(UInt32 size)
{
    IOSharedDataQueue *dataQueue = new IOSharedDataQueue;

    if (dataQueue) {
        if  (!dataQueue->initWithCapacity(size)) {
            dataQueue->release();
            dataQueue = 0;
        }
    }

    return dataQueue;
}

IOSharedDataQueue *IOSharedDataQueue::withEntries(UInt32 numEntries, UInt32 entrySize)
{
    IOSharedDataQueue *dataQueue = new IOSharedDataQueue;

    if (dataQueue) {
        if (!dataQueue->initWithEntries(numEntries, entrySize)) {
            dataQueue->release();
            dataQueue = 0;
        }
    }

    return dataQueue;
}

Boolean IOSharedDataQueue::initWithCapacity(UInt32 size)
{
    IODataQueueAppendix *   appendix;
    vm_size_t               allocSize;

    if (!super::init()) {
        return false;
    }

    _reserved = (ExpansionData *)IOMalloc(sizeof(struct ExpansionData));
    if (!_reserved) {
        return false;
    }

    if (size > UINT32_MAX - DATA_QUEUE_MEMORY_HEADER_SIZE - DATA_QUEUE_MEMORY_APPENDIX_SIZE) {
        return false;
    }

    allocSize = round_page(size + DATA_QUEUE_MEMORY_HEADER_SIZE + DATA_QUEUE_MEMORY_APPENDIX_SIZE);

    if (allocSize < size) {
        return false;
    }

    dataQueue = (IODataQueueMemory *)IOMallocAligned(allocSize, PAGE_SIZE);
    if (dataQueue == 0) {
        return false;
    }
    bzero(dataQueue, allocSize);

    dataQueue->queueSize    = size;
//  dataQueue->head         = 0;
//  dataQueue->tail         = 0;

    if (!setQueueSize(size)) {
        return false;
    }

    appendix            = (IODataQueueAppendix *)((UInt8 *)dataQueue + size + DATA_QUEUE_MEMORY_HEADER_SIZE);
    appendix->version   = 0;

    if (!notifyMsg) {
        notifyMsg = IOMalloc(sizeof(mach_msg_header_t));
        if (!notifyMsg)
            return false;
    }
    bzero(notifyMsg, sizeof(mach_msg_header_t));

    setNotificationPort(MACH_PORT_NULL);

    return true;
}

void IOSharedDataQueue::free()
{
    if (dataQueue) {
        IOFreeAligned(dataQueue, round_page(getQueueSize() + DATA_QUEUE_MEMORY_HEADER_SIZE + DATA_QUEUE_MEMORY_APPENDIX_SIZE));
        dataQueue = NULL;
        if (notifyMsg) {
            IOFree(notifyMsg, sizeof(mach_msg_header_t));
            notifyMsg = NULL;
        }
    }

    if (_reserved) {
        IOFree (_reserved, sizeof(struct ExpansionData));
        _reserved = NULL;
    }

    super::free();
}

IOMemoryDescriptor *IOSharedDataQueue::getMemoryDescriptor()
{
    IOMemoryDescriptor *descriptor = 0;

    if (dataQueue != 0) {
        descriptor = IOMemoryDescriptor::withAddress(dataQueue, getQueueSize() + DATA_QUEUE_MEMORY_HEADER_SIZE + DATA_QUEUE_MEMORY_APPENDIX_SIZE, kIODirectionOutIn);
    }

    return descriptor;
}


IODataQueueEntry * IOSharedDataQueue::peek()
{
    IODataQueueEntry *entry = 0;

    if (dataQueue && (dataQueue->head != dataQueue->tail)) {
        IODataQueueEntry *  head        = 0;
        UInt32              headSize    = 0;
        UInt32              headOffset  = dataQueue->head;
        UInt32              queueSize   = getQueueSize();

        if (headOffset >= queueSize) {
            return NULL;
        }

        head         = (IODataQueueEntry *)((char *)dataQueue->queue + headOffset);
        headSize     = head->size;

        // Check if there's enough room before the end of the queue for a header.
        // If there is room, check if there's enough room to hold the header and
        // the data.

        if ((headOffset > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
            (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize) ||
            (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > UINT32_MAX - headSize) ||
            (headOffset + headSize + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize)) {
            // No room for the header or the data, wrap to the beginning of the queue.
            // Note: wrapping even with the UINT32_MAX checks, as we have to support
            // queueSize of UINT32_MAX
            entry = dataQueue->queue;
        } else {
            entry = head;
        }
    }

    return entry;
}

Boolean IOSharedDataQueue::enqueue(void * data, UInt32 dataSize)
{
    const UInt32       head      = dataQueue->head;  // volatile
    const UInt32       tail      = dataQueue->tail;
    const UInt32       entrySize = dataSize + DATA_QUEUE_ENTRY_HEADER_SIZE;
    IODataQueueEntry * entry;

    // Check for overflow of entrySize
    if (dataSize > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) {
        return false;
    }
    // Check for underflow of (getQueueSize() - tail)
    if (getQueueSize() < tail || getQueueSize() < head) {
        return false;
    }

    if ( tail >= head )
    {
        // Is there enough room at the end for the entry?
        if ((entrySize <= UINT32_MAX - tail) &&
            ((tail + entrySize) <= getQueueSize()) )
        {
            entry = (IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail);

            entry->size = dataSize;
            memcpy(&entry->data, data, dataSize);

            // The tail can be out of bound when the size of the new entry
            // exactly matches the available space at the end of the queue.
            // The tail can range from 0 to dataQueue->queueSize inclusive.

            OSAddAtomic(entrySize, (SInt32 *)&dataQueue->tail);
        }
        else if ( head > entrySize )     // Is there enough room at the beginning?
        {
            // Wrap around to the beginning, but do not allow the tail to catch
            // up to the head.

            dataQueue->queue->size = dataSize;

            // We need to make sure that there is enough room to set the size before
            // doing this. The user client checks for this and will look for the size
            // at the beginning if there isn't room for it at the end.

            if ( ( getQueueSize() - tail ) >= DATA_QUEUE_ENTRY_HEADER_SIZE )
            {
                ((IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail))->size = dataSize;
            }

            memcpy(&dataQueue->queue->data, data, dataSize);
            OSCompareAndSwap(dataQueue->tail, entrySize, &dataQueue->tail);
        }
        else
        {
            return false;    // queue is full
        }
    }
    else
    {
        // Do not allow the tail to catch up to the head when the queue is full.
        // That's why the comparison uses a '>' rather than '>='.

        if ( (head - tail) > entrySize )
        {
            entry = (IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail);

            entry->size = dataSize;
            memcpy(&entry->data, data, dataSize);
            OSAddAtomic(entrySize, (SInt32 *)&dataQueue->tail);
        }
        else
        {
            return false;    // queue is full
        }
    }

    // Send notification (via mach message) that data is available.

    if ( ( head == tail )                                                   /* queue was empty prior to enqueue() */
        ||   ( dataQueue->head == tail ) )   /* queue was emptied during enqueue() */
    {
        sendDataAvailableNotification();
    }

    return true;
}

Boolean IOSharedDataQueue::dequeue(void *data, UInt32 *dataSize)
{
    Boolean             retVal          = TRUE;
    IODataQueueEntry *  entry           = 0;
    UInt32              entrySize       = 0;
    UInt32              newHeadOffset   = 0;

    if (dataQueue) {
        if (dataQueue->head != dataQueue->tail) {
            IODataQueueEntry *  head        = 0;
            UInt32              headSize    = 0;
            UInt32              headOffset  = dataQueue->head;
            UInt32              queueSize   = getQueueSize();

            if (headOffset > queueSize) {
                return false;
            }

            head         = (IODataQueueEntry *)((char *)dataQueue->queue + headOffset);
            headSize     = head->size;

            // we wrapped around to beginning, so read from there
            // either there was not even room for the header
            if ((headOffset > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
                (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize) ||
                // or there was room for the header, but not for the data
                (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > UINT32_MAX - headSize) ||
                (headOffset + headSize + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize)) {
                // Note: we have to wrap to the beginning even with the UINT32_MAX checks
                // because we have to support a queueSize of UINT32_MAX.
                entry           = dataQueue->queue;
                entrySize       = entry->size;
                if ((entrySize > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
                    (entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize)) {
                    return false;
                }
                newHeadOffset   = entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE;
                // else it is at the end
            } else {
                entry           = head;
                entrySize       = entry->size;
                if ((entrySize > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
                    (entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE > UINT32_MAX - headOffset) ||
                    (entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE + headOffset > queueSize)) {
                    return false;
                }
                newHeadOffset   = headOffset + entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE;
            }
        }

        if (entry) {
            if (data) {
                if (dataSize) {
                    if (entrySize <= *dataSize) {
                        memcpy(data, &(entry->data), entrySize);
                        OSCompareAndSwap( dataQueue->head, newHeadOffset, (SInt32 *)&dataQueue->head);
                    } else {
                        retVal = FALSE;
                    }
                } else {
                    retVal = FALSE;
                }
            } else {
                OSCompareAndSwap( dataQueue->head, newHeadOffset, (SInt32 *)&dataQueue->head);
            }

            if (dataSize) {
                *dataSize = entrySize;
            }
        } else {
            retVal = FALSE;
        }
    } else {
        retVal = FALSE;
    }

    return retVal;
}

UInt32 IOSharedDataQueue::getQueueSize()
{
    if (!_reserved) {
        return 0;
    }
    return _reserved->queueSize;
}

Boolean IOSharedDataQueue::setQueueSize(UInt32 size)
{
    if (!_reserved) {
        return false;
    }
    _reserved->queueSize = size;
    return true;
}

OSMetaClassDefineReservedUnused(IOSharedDataQueue, 0);
OSMetaClassDefineReservedUnused(IOSharedDataQueue, 1);
OSMetaClassDefineReservedUnused(IOSharedDataQueue, 2);
OSMetaClassDefineReservedUnused(IOSharedDataQueue, 3);
OSMetaClassDefineReservedUnused(IOSharedDataQueue, 4);
OSMetaClassDefineReservedUnused(IOSharedDataQueue, 5);
OSMetaClassDefineReservedUnused(IOSharedDataQueue, 6);
OSMetaClassDefineReservedUnused(IOSharedDataQueue, 7);