Source/WebKit/Platform/IPC/Encoder.h

/*
 * Copyright (C) 2010-2020 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.
 */

#pragma once

#include "Attachment.h"
#include "MessageNames.h"
#include "StringReference.h"
#include <WebCore/SharedBuffer.h>
#include <wtf/Forward.h>
#include <wtf/OptionSet.h>
#include <wtf/Vector.h>

namespace IPC {

enum class MessageFlags : uint8_t;
enum class ShouldDispatchWhenWaitingForSyncReply : uint8_t;

template<typename, typename> struct ArgumentCoder;

class Encoder final {
    WTF_MAKE_FAST_ALLOCATED;
public:
    Encoder(MessageName, uint64_t destinationID);
    ~Encoder();

    ReceiverName messageReceiverName() const { return receiverName(m_messageName); }
    MessageName messageName() const { return m_messageName; }
    uint64_t destinationID() const { return m_destinationID; }

    bool isSyncMessage() const { return messageIsSync(messageName()); }

    void setShouldDispatchMessageWhenWaitingForSyncReply(ShouldDispatchWhenWaitingForSyncReply);
    ShouldDispatchWhenWaitingForSyncReply shouldDispatchMessageWhenWaitingForSyncReply() const;

    void setFullySynchronousModeForTesting();
    void setShouldMaintainOrderingWithAsyncMessages();

    void wrapForTesting(UniqueRef<Encoder>&&);

    void encodeFixedLengthData(const uint8_t* data, size_t, size_t alignment);

    template<typename T>
    Encoder& operator<<(T&& t)
    {
        ArgumentCoder<std::remove_const_t<std::remove_reference_t<T>>, void>::encode(*this, std::forward<T>(t));
        return *this;
    }

    uint8_t* buffer() const { return m_buffer; }
    size_t bufferSize() const { return m_bufferSize; }

    void addAttachment(Attachment&&);
    Vector<Attachment> releaseAttachments();
    void reserve(size_t);

    static const bool isIPCEncoder = true;

    template<typename T>
    static RefPtr<WebCore::SharedBuffer> encodeSingleObject(const T& object)
    {
        Encoder encoder(ConstructWithoutHeader);
        encoder << object;

        if (encoder.hasAttachments()) {
            ASSERT_NOT_REACHED();
            return nullptr;
        }

        return WebCore::SharedBuffer::create(encoder.buffer(), encoder.bufferSize());
    }

private:
    enum ConstructWithoutHeaderTag { ConstructWithoutHeader };
    Encoder(ConstructWithoutHeaderTag);

    uint8_t* grow(size_t alignment, size_t);

    bool hasAttachments() const;

    void encodeHeader();
    const OptionSet<MessageFlags>& messageFlags() const;
    OptionSet<MessageFlags>& messageFlags();

    MessageName m_messageName;
    uint64_t m_destinationID;

    uint8_t m_inlineBuffer[512];

    uint8_t* m_buffer;
    uint8_t* m_bufferPointer;
    
    size_t m_bufferSize;
    size_t m_bufferCapacity;

    Vector<Attachment> m_attachments;
};

} // namespace IPC