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/*
* Copyright (C) 2020 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "DisplayListReaderHandle.h"
#include <wtf/CheckedArithmetic.h>
namespace WebKit {
using namespace WebCore;
std::optional<size_t> DisplayListReaderHandle::advance(size_t amount)
{
auto previousUnreadBytes = header().unreadBytes.exchangeSub(amount);
if (UNLIKELY(previousUnreadBytes < amount))
return std::nullopt;
return previousUnreadBytes - amount;
}
std::unique_ptr<DisplayList::DisplayList> DisplayListReaderHandle::displayListForReading(size_t offset, size_t capacity, DisplayList::ItemBufferReadingClient& client) const
{
auto checkedExtent = checkedSum<size_t>(offset, capacity);
if (UNLIKELY(checkedExtent.hasOverflowed() || checkedExtent > sharedMemory().size()))
return nullptr;
auto displayList = makeUnique<DisplayList::DisplayList>(DisplayList::ItemBufferHandles {{ identifier(), data() + offset, capacity }});
displayList->setItemBufferReadingClient(&client);
return displayList;
}
} // namespace WebKit
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