qv4executableallocator_p.h

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// Copyright (C) 2016 The Qt Company Ltd.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

// Qt-Security score:significant

#ifndef QV4EXECUTABLEALLOCATOR_H

#define QV4EXECUTABLEALLOCATOR_H

//

//  W A R N I N G

//  -------------

//

// This file is not part of the Qt API.  It exists purely as an

// implementation detail.  This header file may change from version to

// version without notice, or even be removed.

//

// We mean it.

//

#include <QMultiMap>

#include <QHash>

#include <QList>

#include <QByteArray>

#include <QMutex>

#include <QtQml/private/qtqmlglobal_p.h>

namespace WTF {

class PageAllocation;

QT_BEGIN_NAMESPACE

namespace QV4 {

class Q_QML_AUTOTEST_EXPORT ExecutableAllocator

public:

    struct ChunkOfPages;

    struct Allocation;

    ExecutableAllocator();

    ~ExecutableAllocator();

    Allocation *allocate(size_t size);

    void free(Allocation *allocation);

    struct Allocation

        Allocation()

            : size(0)

            , free(true)

{}

        void *memoryStart() const;

        size_t memorySize() const { return size; }

        void *exceptionHandlerStart() const;

        size_t exceptionHandlerSize() const;

        void *codeStart() const;

        void invalidate() { addr = 0; }

        bool isValid() const { return addr != 0; }

        void deallocate(ExecutableAllocator *allocator);

    private:

        ~Allocation() {}

        friend class ExecutableAllocator;

        Allocation *split(size_t dividingSize);

        bool mergeNext(ExecutableAllocator *allocator);

        bool mergePrevious(ExecutableAllocator *allocator);

        quintptr addr = 0;

        uint size : 31; // More than 2GB of function code? nah :)

        uint free : 1;

        Allocation *next = nullptr;

        Allocation *prev = nullptr;

};

    // for debugging / unit-testing

    int freeAllocationCount() const { return freeAllocations.size(); }

    int chunkCount() const { return chunks.size(); }

    struct ChunkOfPages

        ChunkOfPages()

{}

        ~ChunkOfPages();

        WTF::PageAllocation *pages = nullptr;

        Allocation *firstAllocation = nullptr;

        bool contains(Allocation *alloc) const;

};

    ChunkOfPages *chunkForAllocation(Allocation *allocation) const;

private:

    QMultiMap<size_t, Allocation*> freeAllocations;

    QMap<quintptr, ChunkOfPages*> chunks;

    mutable QMutex mutex;

};

QT_END_NAMESPACE

#endif // QV4EXECUTABLEALLOCATOR_H