src/objects/js-array-buffer.h - v8/v8 - Git at Google

 // Copyright 2018 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #ifndef V8_OBJECTS_JS_ARRAY_BUFFER_H_
 #define V8_OBJECTS_JS_ARRAY_BUFFER_H_

 #include "src/objects/js-objects.h"

 // Has to be the last include (doesn't have include guards):
 #include "src/objects/object-macros.h"

 namespace v8 {
 namespace internal {

 // Whether a JSArrayBuffer is a SharedArrayBuffer or not.
 enum class SharedFlag : uint32_t { kNotShared, kShared };

 class JSArrayBuffer : public JSObject {
  public:
 // The maximum length for JSArrayBuffer's supported by V8.
 // On 32-bit architectures we limit this to 2GiB, so that
 // we can continue to use CheckBounds with the Unsigned31
 // restriction for the length.
 #if V8_HOST_ARCH_32_BIT
   static constexpr size_t kMaxByteLength = kMaxInt;
 #else
   static constexpr size_t kMaxByteLength = kMaxSafeInteger;
 #endif

   // [byte_length]: length in bytes
   DECL_PRIMITIVE_ACCESSORS(byte_length, size_t)

   // [backing_store]: backing memory for this array
   DECL_ACCESSORS(backing_store, void*)

   // For non-wasm, allocation_length and allocation_base are byte_length and
   // backing_store, respectively.
   inline size_t allocation_length() const;
   inline void* allocation_base() const;

   // [bit_field]: boolean flags
   DECL_PRIMITIVE_ACCESSORS(bit_field, uint32_t)

   // Clear uninitialized padding space. This ensures that the snapshot content
   // is deterministic. Depending on the V8 build mode there could be no padding.
   V8_INLINE void clear_padding();

 // Bit positions for [bit_field].
 #define JS_ARRAY_BUFFER_BIT_FIELD_FIELDS(V, _) \
   V(IsExternalBit, bool, 1, _)                 \
   V(IsDetachableBit, bool, 1, _)               \
   V(WasDetachedBit, bool, 1, _)                \
   V(IsSharedBit, bool, 1, _)                   \
   V(IsGrowableBit, bool, 1, _)                 \
   V(IsWasmMemoryBit, bool, 1, _)
   DEFINE_BIT_FIELDS(JS_ARRAY_BUFFER_BIT_FIELD_FIELDS)
 #undef JS_ARRAY_BUFFER_BIT_FIELD_FIELDS

   // [is_external]: true indicates that the embedder is in charge of freeing the
   // backing_store, while is_external == false means that v8 will free the
   // memory block once all ArrayBuffers referencing it are collected by the GC.
   DECL_BOOLEAN_ACCESSORS(is_external)

   // [is_detachable]: false indicates that this buffer cannot be detached.
   DECL_BOOLEAN_ACCESSORS(is_detachable)

   // [was_detached]: true if the buffer was previously detached.
   DECL_BOOLEAN_ACCESSORS(was_detached)

   // [is_shared]: tells whether this is an ArrayBuffer or a SharedArrayBuffer.
   DECL_BOOLEAN_ACCESSORS(is_shared)

   // [is_growable]: indicates whether it's possible to grow this buffer.
   DECL_BOOLEAN_ACCESSORS(is_growable)

   // [is_wasm_memory]: whether the buffer is tracked by the WasmMemoryTracker.
   DECL_BOOLEAN_ACCESSORS(is_wasm_memory)

   DECL_CAST2(JSArrayBuffer)

   void Detach();

   struct Allocation {
     Allocation(void* allocation_base, size_t length, void* backing_store,
                bool is_wasm_memory)
         : allocation_base(allocation_base),
           length(length),
           backing_store(backing_store),
           is_wasm_memory(is_wasm_memory) {}

     void* allocation_base;
     size_t length;
     void* backing_store;
     bool is_wasm_memory;
   };

   void FreeBackingStoreFromMainThread();
   static void FreeBackingStore(Isolate* isolate, Allocation allocation);

   V8_EXPORT_PRIVATE static void Setup(
       Handle<JSArrayBuffer> array_buffer, Isolate* isolate, bool is_external,
       void* data, size_t allocated_length,
       SharedFlag shared_flag = SharedFlag::kNotShared,
       bool is_wasm_memory = false);

   // Initialize the object as empty one to avoid confusing heap verifier if
   // the failure happened in the middle of JSArrayBuffer construction.
   V8_EXPORT_PRIVATE static void SetupAsEmpty(Handle<JSArrayBuffer> array_buffer,
                                              Isolate* isolate);

   // Returns false if array buffer contents could not be allocated.
   // In this case, |array_buffer| will not be set up.
   static bool SetupAllocatingData(
       Handle<JSArrayBuffer> array_buffer, Isolate* isolate,
       size_t allocated_length, bool initialize = true,
       SharedFlag shared_flag = SharedFlag::kNotShared) V8_WARN_UNUSED_RESULT;

   // Dispatched behavior.
   DECL_PRINTER(JSArrayBuffer)
   DECL_VERIFIER(JSArrayBuffer)

 // Layout description.
 #define JS_ARRAY_BUFFER_FIELDS(V)                                           \
   V(kEndOfTaggedFieldsOffset, 0)                                            \
   /* Raw data fields. */                                                    \
   V(kByteLengthOffset, kUIntptrSize)                                        \
   V(kBackingStoreOffset, kSystemPointerSize)                                \
   V(kBitFieldOffset, kInt32Size)                                            \
   /* Pads header size to be a multiple of kTaggedSize. */                   \
   V(kOptionalPaddingOffset, OBJECT_POINTER_PADDING(kOptionalPaddingOffset)) \
   /* Header size. */                                                        \
   V(kHeaderSize, 0)

   DEFINE_FIELD_OFFSET_CONSTANTS(JSObject::kHeaderSize, JS_ARRAY_BUFFER_FIELDS)
 #undef JS_ARRAY_BUFFER_FIELDS

   static const int kSizeWithEmbedderFields =
       kHeaderSize +
       v8::ArrayBuffer::kEmbedderFieldCount * kEmbedderDataSlotSize;

   class BodyDescriptor;

   OBJECT_CONSTRUCTORS(JSArrayBuffer, JSObject);
 };

 class JSArrayBufferView : public JSObject {
  public:
   // [buffer]: ArrayBuffer that this typed array views.
   DECL_ACCESSORS(buffer, Object)

   // [byte_offset]: offset of typed array in bytes.
   DECL_PRIMITIVE_ACCESSORS(byte_offset, size_t)

   // [byte_length]: length of typed array in bytes.
   DECL_PRIMITIVE_ACCESSORS(byte_length, size_t)

   DECL_CAST2(JSArrayBufferView)

   DECL_VERIFIER(JSArrayBufferView)

   inline bool WasDetached() const;

 // Layout description.
 #define JS_ARRAY_BUFFER_VIEW_FIELDS(V) \
   V(kBufferOffset, kTaggedSize)        \
   V(kEndOfTaggedFieldsOffset, 0)       \
   /* Raw data fields. */               \
   V(kByteOffsetOffset, kUIntptrSize)   \
   V(kByteLengthOffset, kUIntptrSize)   \
   /* Header size. */                   \
   V(kHeaderSize, 0)

   DEFINE_FIELD_OFFSET_CONSTANTS(JSObject::kHeaderSize,
                                 JS_ARRAY_BUFFER_VIEW_FIELDS)
 #undef JS_ARRAY_BUFFER_VIEW_FIELDS

   class BodyDescriptor;

   OBJECT_CONSTRUCTORS(JSArrayBufferView, JSObject);
 };

 class JSTypedArray : public JSArrayBufferView {
  public:
   // [length]: length of typed array in elements.
   DECL_ACCESSORS(length, Object)
   inline size_t length_value() const;

   // ES6 9.4.5.3
   V8_WARN_UNUSED_RESULT static Maybe<bool> DefineOwnProperty(
       Isolate* isolate, Handle<JSTypedArray> o, Handle<Object> key,
       PropertyDescriptor* desc, ShouldThrow should_throw);

   DECL_CAST2(JSTypedArray)

   ExternalArrayType type();
   V8_EXPORT_PRIVATE size_t element_size();

   Handle<JSArrayBuffer> GetBuffer();

   // Whether the buffer's backing store is on-heap or off-heap.
   inline bool is_on_heap() const;

   static inline MaybeHandle<JSTypedArray> Validate(Isolate* isolate,
                                                    Handle<Object> receiver,
                                                    const char* method_name);

   // Dispatched behavior.
   DECL_PRINTER(JSTypedArray)
   DECL_VERIFIER(JSTypedArray)

 // Layout description.
 #define JS_TYPED_ARRAY_FIELDS(V)       \
   /* Raw data fields. */               \
   V(kLengthOffset, kSystemPointerSize) \
   /* Header size. */                   \
   V(kHeaderSize, 0)

   DEFINE_FIELD_OFFSET_CONSTANTS(JSArrayBufferView::kHeaderSize,
                                 JS_TYPED_ARRAY_FIELDS)
 #undef JS_TYPED_ARRAY_FIELDS

   static const int kSizeWithEmbedderFields =
       kHeaderSize +
       v8::ArrayBufferView::kEmbedderFieldCount * kEmbedderDataSlotSize;

  private:
   static Handle<JSArrayBuffer> MaterializeArrayBuffer(
       Handle<JSTypedArray> typed_array);
 #ifdef VERIFY_HEAP
   DECL_ACCESSORS(raw_length, Object)
 #endif

   OBJECT_CONSTRUCTORS(JSTypedArray, JSArrayBufferView);
 };

 class JSDataView : public JSArrayBufferView {
  public:
   DECL_CAST2(JSDataView)

   // Dispatched behavior.
   DECL_PRINTER(JSDataView)
   DECL_VERIFIER(JSDataView)

   // Layout description.
   static const int kSizeWithEmbedderFields =
       kHeaderSize +
       v8::ArrayBufferView::kEmbedderFieldCount * kEmbedderDataSlotSize;

   OBJECT_CONSTRUCTORS(JSDataView, JSArrayBufferView);
 };

 }  // namespace internal
 }  // namespace v8

 #include "src/objects/object-macros-undef.h"

 #endif  // V8_OBJECTS_JS_ARRAY_BUFFER_H_
	// Copyright 2018 the V8 project authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#ifndef V8_OBJECTS_JS_ARRAY_BUFFER_H_
	#define V8_OBJECTS_JS_ARRAY_BUFFER_H_

	#include "src/objects/js-objects.h"

	// Has to be the last include (doesn't have include guards):
	#include "src/objects/object-macros.h"

	namespace v8 {
	namespace internal {

	// Whether a JSArrayBuffer is a SharedArrayBuffer or not.
	enum class SharedFlag : uint32_t { kNotShared, kShared };

	class JSArrayBuffer : public JSObject {
	public:
	// The maximum length for JSArrayBuffer's supported by V8.
	// On 32-bit architectures we limit this to 2GiB, so that
	// we can continue to use CheckBounds with the Unsigned31
	// restriction for the length.
	#if V8_HOST_ARCH_32_BIT
	static constexpr size_t kMaxByteLength = kMaxInt;
	#else
	static constexpr size_t kMaxByteLength = kMaxSafeInteger;
	#endif

	// [byte_length]: length in bytes
	DECL_PRIMITIVE_ACCESSORS(byte_length, size_t)

	// [backing_store]: backing memory for this array
	DECL_ACCESSORS(backing_store, void*)

	// For non-wasm, allocation_length and allocation_base are byte_length and
	// backing_store, respectively.
	inline size_t allocation_length() const;
	inline void* allocation_base() const;

	// [bit_field]: boolean flags
	DECL_PRIMITIVE_ACCESSORS(bit_field, uint32_t)

	// Clear uninitialized padding space. This ensures that the snapshot content
	// is deterministic. Depending on the V8 build mode there could be no padding.
	V8_INLINE void clear_padding();

	// Bit positions for [bit_field].
	#define JS_ARRAY_BUFFER_BIT_FIELD_FIELDS(V, _) \
	V(IsExternalBit, bool, 1, _) \
	V(IsDetachableBit, bool, 1, _) \
	V(WasDetachedBit, bool, 1, _) \
	V(IsSharedBit, bool, 1, _) \
	V(IsGrowableBit, bool, 1, _) \
	V(IsWasmMemoryBit, bool, 1, _)
	DEFINE_BIT_FIELDS(JS_ARRAY_BUFFER_BIT_FIELD_FIELDS)
	#undef JS_ARRAY_BUFFER_BIT_FIELD_FIELDS

	// [is_external]: true indicates that the embedder is in charge of freeing the
	// backing_store, while is_external == false means that v8 will free the
	// memory block once all ArrayBuffers referencing it are collected by the GC.
	DECL_BOOLEAN_ACCESSORS(is_external)

	// [is_detachable]: false indicates that this buffer cannot be detached.
	DECL_BOOLEAN_ACCESSORS(is_detachable)

	// [was_detached]: true if the buffer was previously detached.
	DECL_BOOLEAN_ACCESSORS(was_detached)

	// [is_shared]: tells whether this is an ArrayBuffer or a SharedArrayBuffer.
	DECL_BOOLEAN_ACCESSORS(is_shared)

	// [is_growable]: indicates whether it's possible to grow this buffer.
	DECL_BOOLEAN_ACCESSORS(is_growable)

	// [is_wasm_memory]: whether the buffer is tracked by the WasmMemoryTracker.
	DECL_BOOLEAN_ACCESSORS(is_wasm_memory)

	DECL_CAST2(JSArrayBuffer)

	void Detach();

	struct Allocation {
	Allocation(void* allocation_base, size_t length, void* backing_store,
	bool is_wasm_memory)
	: allocation_base(allocation_base),
	length(length),
	backing_store(backing_store),
	is_wasm_memory(is_wasm_memory) {}

	void* allocation_base;
	size_t length;
	void* backing_store;
	bool is_wasm_memory;
	};

	void FreeBackingStoreFromMainThread();
	static void FreeBackingStore(Isolate* isolate, Allocation allocation);

	V8_EXPORT_PRIVATE static void Setup(
	Handle<JSArrayBuffer> array_buffer, Isolate* isolate, bool is_external,
	void* data, size_t allocated_length,
	SharedFlag shared_flag = SharedFlag::kNotShared,
	bool is_wasm_memory = false);

	// Initialize the object as empty one to avoid confusing heap verifier if
	// the failure happened in the middle of JSArrayBuffer construction.
	V8_EXPORT_PRIVATE static void SetupAsEmpty(Handle<JSArrayBuffer> array_buffer,
	Isolate* isolate);

	// Returns false if array buffer contents could not be allocated.
	// In this case, \|array_buffer\| will not be set up.
	static bool SetupAllocatingData(
	Handle<JSArrayBuffer> array_buffer, Isolate* isolate,
	size_t allocated_length, bool initialize = true,
	SharedFlag shared_flag = SharedFlag::kNotShared) V8_WARN_UNUSED_RESULT;

	// Dispatched behavior.
	DECL_PRINTER(JSArrayBuffer)
	DECL_VERIFIER(JSArrayBuffer)

	// Layout description.
	#define JS_ARRAY_BUFFER_FIELDS(V) \
	V(kEndOfTaggedFieldsOffset, 0) \
	/* Raw data fields. */ \
	V(kByteLengthOffset, kUIntptrSize) \
	V(kBackingStoreOffset, kSystemPointerSize) \
	V(kBitFieldOffset, kInt32Size) \
	/* Pads header size to be a multiple of kTaggedSize. */ \
	V(kOptionalPaddingOffset, OBJECT_POINTER_PADDING(kOptionalPaddingOffset)) \
	/* Header size. */ \
	V(kHeaderSize, 0)

	DEFINE_FIELD_OFFSET_CONSTANTS(JSObject::kHeaderSize, JS_ARRAY_BUFFER_FIELDS)
	#undef JS_ARRAY_BUFFER_FIELDS

	static const int kSizeWithEmbedderFields =
	kHeaderSize +
	v8::ArrayBuffer::kEmbedderFieldCount * kEmbedderDataSlotSize;

	class BodyDescriptor;

	OBJECT_CONSTRUCTORS(JSArrayBuffer, JSObject);
	};

	class JSArrayBufferView : public JSObject {
	public:
	// [buffer]: ArrayBuffer that this typed array views.
	DECL_ACCESSORS(buffer, Object)

	// [byte_offset]: offset of typed array in bytes.
	DECL_PRIMITIVE_ACCESSORS(byte_offset, size_t)

	// [byte_length]: length of typed array in bytes.
	DECL_PRIMITIVE_ACCESSORS(byte_length, size_t)

	DECL_CAST2(JSArrayBufferView)

	DECL_VERIFIER(JSArrayBufferView)

	inline bool WasDetached() const;

	// Layout description.
	#define JS_ARRAY_BUFFER_VIEW_FIELDS(V) \
	V(kBufferOffset, kTaggedSize) \
	V(kEndOfTaggedFieldsOffset, 0) \
	/* Raw data fields. */ \
	V(kByteOffsetOffset, kUIntptrSize) \
	V(kByteLengthOffset, kUIntptrSize) \
	/* Header size. */ \
	V(kHeaderSize, 0)

	DEFINE_FIELD_OFFSET_CONSTANTS(JSObject::kHeaderSize,
	JS_ARRAY_BUFFER_VIEW_FIELDS)
	#undef JS_ARRAY_BUFFER_VIEW_FIELDS

	class BodyDescriptor;

	OBJECT_CONSTRUCTORS(JSArrayBufferView, JSObject);
	};

	class JSTypedArray : public JSArrayBufferView {
	public:
	// [length]: length of typed array in elements.
	DECL_ACCESSORS(length, Object)
	inline size_t length_value() const;

	// ES6 9.4.5.3
	V8_WARN_UNUSED_RESULT static Maybe<bool> DefineOwnProperty(
	Isolate* isolate, Handle<JSTypedArray> o, Handle<Object> key,
	PropertyDescriptor* desc, ShouldThrow should_throw);

	DECL_CAST2(JSTypedArray)

	ExternalArrayType type();
	V8_EXPORT_PRIVATE size_t element_size();

	Handle<JSArrayBuffer> GetBuffer();

	// Whether the buffer's backing store is on-heap or off-heap.
	inline bool is_on_heap() const;

	static inline MaybeHandle<JSTypedArray> Validate(Isolate* isolate,
	Handle<Object> receiver,
	const char* method_name);

	// Dispatched behavior.
	DECL_PRINTER(JSTypedArray)
	DECL_VERIFIER(JSTypedArray)

	// Layout description.
	#define JS_TYPED_ARRAY_FIELDS(V) \
	/* Raw data fields. */ \
	V(kLengthOffset, kSystemPointerSize) \
	/* Header size. */ \
	V(kHeaderSize, 0)

	DEFINE_FIELD_OFFSET_CONSTANTS(JSArrayBufferView::kHeaderSize,
	JS_TYPED_ARRAY_FIELDS)
	#undef JS_TYPED_ARRAY_FIELDS

	static const int kSizeWithEmbedderFields =
	kHeaderSize +
	v8::ArrayBufferView::kEmbedderFieldCount * kEmbedderDataSlotSize;

	private:
	static Handle<JSArrayBuffer> MaterializeArrayBuffer(
	Handle<JSTypedArray> typed_array);
	#ifdef VERIFY_HEAP
	DECL_ACCESSORS(raw_length, Object)
	#endif

	OBJECT_CONSTRUCTORS(JSTypedArray, JSArrayBufferView);
	};

	class JSDataView : public JSArrayBufferView {
	public:
	DECL_CAST2(JSDataView)

	// Dispatched behavior.
	DECL_PRINTER(JSDataView)
	DECL_VERIFIER(JSDataView)

	// Layout description.
	static const int kSizeWithEmbedderFields =
	kHeaderSize +
	v8::ArrayBufferView::kEmbedderFieldCount * kEmbedderDataSlotSize;

	OBJECT_CONSTRUCTORS(JSDataView, JSArrayBufferView);
	};

	} // namespace internal
	} // namespace v8

	#include "src/objects/object-macros-undef.h"

	#endif // V8_OBJECTS_JS_ARRAY_BUFFER_H_