Source/JavaScriptCore/runtime/ArrayBuffer.h

/*
 * Copyright (C) 2009-2021 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. ``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
 * 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 "ArrayBufferSharingMode.h"
#include "GCIncomingRefCounted.h"
#include "Watchpoint.h"
#include "Weak.h"
#include <wtf/CagedPtr.h>
#include <wtf/CheckedArithmetic.h>
#include <wtf/PackedRefPtr.h>
#include <wtf/SharedTask.h>
#include <wtf/StdIntExtras.h>
#include <wtf/StdLibExtras.h>
#include <wtf/ThreadSafeRefCounted.h>
#include <wtf/text/WTFString.h>

namespace JSC {

#if USE(LARGE_TYPED_ARRAYS)
static_assert(sizeof(size_t) == sizeof(uint64_t));
#define MAX_ARRAY_BUFFER_SIZE (1ull << 32)
#else
static_assert(sizeof(size_t) == sizeof(uint32_t));
// Because we are using a size_t to store the size in bytes of array buffers, we cannot support 4GB on 32-bit platforms.
// So we are sticking with 2GB. It should in theory be possible to support up to (4GB - 1B) if anyone cares.
#define MAX_ARRAY_BUFFER_SIZE 0x7fffffffu
#endif

class VM;
class ArrayBuffer;
class ArrayBufferView;
class JSArrayBuffer;

using ArrayBufferDestructorFunction = RefPtr<SharedTask<void(void*)>>;

class SharedArrayBufferContents final : public ThreadSafeRefCounted<SharedArrayBufferContents> {
public:
    SharedArrayBufferContents(void* data, size_t size, ArrayBufferDestructorFunction&& destructor)
        : m_data(data, size)
        , m_destructor(WTFMove(destructor))
        , m_sizeInBytes(size)
    {
    }

    ~SharedArrayBufferContents()
    {
        if (m_destructor) {
            // FIXME: we shouldn't use getUnsafe here https://bugs.webkit.org/show_bug.cgi?id=197698
            m_destructor->run(m_data.getUnsafe());
        }
    }
    
    void* data() const { return m_data.getMayBeNull(m_sizeInBytes); }
    
private:
    using DataType = CagedPtr<Gigacage::Primitive, void, tagCagedPtr>;
    DataType m_data;
    ArrayBufferDestructorFunction m_destructor;
    size_t m_sizeInBytes;
};

class ArrayBufferContents final {
    WTF_MAKE_NONCOPYABLE(ArrayBufferContents);
public:
    ArrayBufferContents() = default;
    ArrayBufferContents(void* data, size_t sizeInBytes, ArrayBufferDestructorFunction&& destructor)
        : m_data(data, sizeInBytes)
        , m_destructor(WTFMove(destructor))
        , m_sizeInBytes(sizeInBytes)
    {
        RELEASE_ASSERT(m_sizeInBytes <= MAX_ARRAY_BUFFER_SIZE);
    }
    
    ArrayBufferContents(ArrayBufferContents&& other)
    {
        swap(other);
    }

    ArrayBufferContents& operator=(ArrayBufferContents&& other)
    {
        ArrayBufferContents moved(WTFMove(other));
        swap(moved);
        return *this;
    }

    ~ArrayBufferContents()
    {
        if (m_destructor) {
            // FIXME: We shouldn't use getUnsafe here: https://bugs.webkit.org/show_bug.cgi?id=197698
            m_destructor->run(m_data.getUnsafe());
        }
    }
    
    explicit operator bool() { return !!m_data; }
    
    void* data() const { return m_data.getMayBeNull(sizeInBytes()); }
    void* dataWithoutPACValidation() const { return m_data.getUnsafe(); }
    size_t sizeInBytes() const { return m_sizeInBytes; }
    
    bool isShared() const { return m_shared; }
    
    void swap(ArrayBufferContents& other)
    {
        using std::swap;
        swap(m_data, other.m_data);
        swap(m_destructor, other.m_destructor);
        swap(m_shared, other.m_shared);
        swap(m_sizeInBytes, other.m_sizeInBytes);
    }

private:
    void reset()
    {
        m_data = nullptr;
        m_destructor = nullptr;
        m_shared = nullptr;
        m_sizeInBytes = 0;
    }

    friend class ArrayBuffer;

    enum InitializationPolicy {
        ZeroInitialize,
        DontInitialize
    };

    void tryAllocate(size_t numElements, unsigned elementByteSize, InitializationPolicy);
    
    void makeShared();
    void copyTo(ArrayBufferContents&);
    void shareWith(ArrayBufferContents&);

    using DataType = CagedPtr<Gigacage::Primitive, void, tagCagedPtr>;
    DataType m_data { nullptr };
    ArrayBufferDestructorFunction m_destructor { nullptr };
    RefPtr<SharedArrayBufferContents> m_shared { nullptr };
    size_t m_sizeInBytes { 0 };
};

class ArrayBuffer final : public GCIncomingRefCounted<ArrayBuffer> {
public:
    JS_EXPORT_PRIVATE static Ref<ArrayBuffer> create(size_t numElements, unsigned elementByteSize);
    JS_EXPORT_PRIVATE static Ref<ArrayBuffer> create(ArrayBuffer&);
    JS_EXPORT_PRIVATE static Ref<ArrayBuffer> create(const void* source, size_t byteLength);
    JS_EXPORT_PRIVATE static Ref<ArrayBuffer> create(ArrayBufferContents&&);
    JS_EXPORT_PRIVATE static Ref<ArrayBuffer> createAdopted(const void* data, size_t byteLength);
    JS_EXPORT_PRIVATE static Ref<ArrayBuffer> createFromBytes(const void* data, size_t byteLength, ArrayBufferDestructorFunction&&);
    JS_EXPORT_PRIVATE static RefPtr<ArrayBuffer> tryCreate(size_t numElements, unsigned elementByteSize);
    JS_EXPORT_PRIVATE static RefPtr<ArrayBuffer> tryCreate(ArrayBuffer&);
    JS_EXPORT_PRIVATE static RefPtr<ArrayBuffer> tryCreate(const void* source, size_t byteLength);

    // Only for use by Uint8ClampedArray::tryCreateUninitialized and FragmentedSharedBuffer::tryCreateArrayBuffer.
    JS_EXPORT_PRIVATE static Ref<ArrayBuffer> createUninitialized(size_t numElements, unsigned elementByteSize);
    JS_EXPORT_PRIVATE static RefPtr<ArrayBuffer> tryCreateUninitialized(size_t numElements, unsigned elementByteSize);

    inline void* data();
    inline const void* data() const;
    inline size_t byteLength() const;

    inline void* dataWithoutPACValidation();
    inline const void* dataWithoutPACValidation() const;
    
    void makeShared();
    void setSharingMode(ArrayBufferSharingMode);
    inline bool isShared() const;
    inline ArrayBufferSharingMode sharingMode() const { return isShared() ? ArrayBufferSharingMode::Shared : ArrayBufferSharingMode::Default; }

    inline size_t gcSizeEstimateInBytes() const;

    JS_EXPORT_PRIVATE RefPtr<ArrayBuffer> slice(double begin, double end) const;
    JS_EXPORT_PRIVATE RefPtr<ArrayBuffer> slice(double begin) const;
    JS_EXPORT_PRIVATE RefPtr<ArrayBuffer> sliceWithClampedIndex(size_t begin, size_t end) const;
    
    inline void pin();
    inline void unpin();
    inline void pinAndLock();
    inline bool isLocked();

    void makeWasmMemory();
    inline bool isWasmMemory();

    JS_EXPORT_PRIVATE bool transferTo(VM&, ArrayBufferContents&);
    JS_EXPORT_PRIVATE bool shareWith(ArrayBufferContents&);

    void detach(VM&);
    bool isDetached() { return !m_contents.m_data; }
    InlineWatchpointSet& detachingWatchpointSet() { return m_detachingWatchpointSet; }

    static ptrdiff_t offsetOfData() { return OBJECT_OFFSETOF(ArrayBuffer, m_contents) + OBJECT_OFFSETOF(ArrayBufferContents, m_data); }

    ~ArrayBuffer() { }

    JS_EXPORT_PRIVATE static Ref<SharedTask<void(void*)>> primitiveGigacageDestructor();

private:
    static Ref<ArrayBuffer> create(size_t numElements, unsigned elementByteSize, ArrayBufferContents::InitializationPolicy);
    static Ref<ArrayBuffer> createInternal(ArrayBufferContents&&, const void*, size_t);
    static RefPtr<ArrayBuffer> tryCreate(size_t numElements, unsigned elementByteSize, ArrayBufferContents::InitializationPolicy);
    ArrayBuffer(ArrayBufferContents&&);
    inline size_t clampIndex(double index) const;
    static inline size_t clampValue(double x, size_t left, size_t right);

    void notifyDetaching(VM&);

    ArrayBufferContents m_contents;
    InlineWatchpointSet m_detachingWatchpointSet { IsWatched };
public:
    Weak<JSArrayBuffer> m_wrapper;
private:
    Checked<unsigned> m_pinCount { 0 };
    bool m_isWasmMemory { false };
    // m_locked == true means that some API user fetched m_contents directly from a TypedArray object,
    // the buffer is backed by a WebAssembly.Memory, or is a SharedArrayBuffer.
    bool m_locked { false };
};

void* ArrayBuffer::data()
{
    return m_contents.data();
}

const void* ArrayBuffer::data() const
{
    return m_contents.data();
}

void* ArrayBuffer::dataWithoutPACValidation()
{
    return m_contents.dataWithoutPACValidation();
}

const void* ArrayBuffer::dataWithoutPACValidation() const
{
    return m_contents.dataWithoutPACValidation();
}

size_t ArrayBuffer::byteLength() const
{
    return m_contents.sizeInBytes();
}

bool ArrayBuffer::isShared() const
{
    return m_contents.isShared();
}

size_t ArrayBuffer::gcSizeEstimateInBytes() const
{
    // FIXME: We probably want to scale this by the shared ref count or something.
    return sizeof(ArrayBuffer) + byteLength();
}

void ArrayBuffer::pin()
{
    m_pinCount++;
}

void ArrayBuffer::unpin()
{
    m_pinCount--;
}

void ArrayBuffer::pinAndLock()
{
    m_locked = true;
}

bool ArrayBuffer::isLocked()
{
    return m_locked;
}

bool ArrayBuffer::isWasmMemory()
{
    return m_isWasmMemory;
}

JS_EXPORT_PRIVATE ASCIILiteral errorMesasgeForTransfer(ArrayBuffer*);

} // namespace JSC

using JSC::ArrayBuffer;