1 files changed, 166 insertions, 0 deletions
diff --git a/js/src/vm/ArrayBufferViewObject.h b/js/src/vm/ArrayBufferViewObject.h
new file mode 100644
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+++ b/js/src/vm/ArrayBufferViewObject.h
@@ -0,0 +1,166 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef vm_ArrayBufferViewObject_h
+#define vm_ArrayBufferViewObject_h
+
+#include "builtin/TypedArrayConstants.h"
+#include "vm/ArrayBufferObject.h"
+#include "vm/NativeObject.h"
+#include "vm/SharedArrayObject.h"
+#include "vm/SharedMem.h"
+
+namespace js {
+
+/*
+ * ArrayBufferViewObject
+ *
+ * Common base class for all array buffer views (DataViewObject and
+ * TypedArrayObject).
+ */
+
+class ArrayBufferViewObject : public NativeObject {
+ public:
+  // Underlying (Shared)ArrayBufferObject.
+  static constexpr size_t BUFFER_SLOT = 0;
+  static_assert(BUFFER_SLOT == JS_TYPEDARRAYLAYOUT_BUFFER_SLOT,
+                "self-hosted code with burned-in constants must get the "
+                "right buffer slot");
+
+  // Slot containing length of the view in number of typed elements.
+  static constexpr size_t LENGTH_SLOT = 1;
+
+  // Offset of view within underlying (Shared)ArrayBufferObject.
+  static constexpr size_t BYTEOFFSET_SLOT = 2;
+
+  // Pointer to raw buffer memory.
+  static constexpr size_t DATA_SLOT = 3;
+
+  static constexpr size_t RESERVED_SLOTS = 4;
+
+#ifdef DEBUG
+  static const uint8_t ZeroLengthArrayData = 0x4A;
+#endif
+
+  static constexpr int bufferOffset() {
+    return NativeObject::getFixedSlotOffset(BUFFER_SLOT);
+  }
+  static constexpr int lengthOffset() {
+    return NativeObject::getFixedSlotOffset(LENGTH_SLOT);
+  }
+  static constexpr int byteOffsetOffset() {
+    return NativeObject::getFixedSlotOffset(BYTEOFFSET_SLOT);
+  }
+  static constexpr int dataOffset() {
+    return NativeObject::getFixedSlotOffset(DATA_SLOT);
+  }
+
+ private:
+  void* dataPointerEither_() const {
+    // Note, do not check whether shared or not
+    // Keep synced with js::Get<Type>ArrayLengthAndData in jsfriendapi.h!
+    return maybePtrFromReservedSlot<void>(DATA_SLOT);
+  }
+
+ public:
+  [[nodiscard]] bool init(JSContext* cx, ArrayBufferObjectMaybeShared* buffer,
+                          size_t byteOffset, size_t length,
+                          uint32_t bytesPerElement);
+
+  static ArrayBufferObjectMaybeShared* bufferObject(
+      JSContext* cx, Handle<ArrayBufferViewObject*> obj);
+
+  void notifyBufferDetached();
+
+  void initDataPointer(SharedMem<uint8_t*> viewData) {
+    // Install a pointer to the buffer location that corresponds
+    // to offset zero within the typed array.
+    //
+    // The following unwrap is safe because the DATA_SLOT is
+    // accessed only from jitted code and from the
+    // dataPointerEither_() accessor above; in neither case does the
+    // raw pointer escape untagged into C++ code.
+    void* data = viewData.unwrap(/*safe - see above*/);
+    initReservedSlot(DATA_SLOT, PrivateValue(data));
+  }
+
+  SharedMem<void*> dataPointerShared() const {
+    return SharedMem<void*>::shared(dataPointerEither_());
+  }
+  SharedMem<void*> dataPointerEither() const {
+    if (isSharedMemory()) {
+      return SharedMem<void*>::shared(dataPointerEither_());
+    }
+    return SharedMem<void*>::unshared(dataPointerEither_());
+  }
+  void* dataPointerUnshared() const {
+    MOZ_ASSERT(!isSharedMemory());
+    return dataPointerEither_();
+  }
+
+  Value bufferValue() const { return getFixedSlot(BUFFER_SLOT); }
+  bool hasBuffer() const { return bufferValue().isObject(); }
+
+  ArrayBufferObject* bufferUnshared() const {
+    MOZ_ASSERT(!isSharedMemory());
+    ArrayBufferObjectMaybeShared* obj = bufferEither();
+    if (!obj) {
+      return nullptr;
+    }
+    return &obj->as<ArrayBufferObject>();
+  }
+  SharedArrayBufferObject* bufferShared() const {
+    MOZ_ASSERT(isSharedMemory());
+    ArrayBufferObjectMaybeShared* obj = bufferEither();
+    if (!obj) {
+      return nullptr;
+    }
+    return &obj->as<SharedArrayBufferObject>();
+  }
+  ArrayBufferObjectMaybeShared* bufferEither() const {
+    JSObject* obj = bufferValue().toObjectOrNull();
+    if (!obj) {
+      return nullptr;
+    }
+    MOZ_ASSERT(isSharedMemory() ? obj->is<SharedArrayBufferObject>()
+                                : obj->is<ArrayBufferObject>());
+    return &obj->as<ArrayBufferObjectMaybeShared>();
+  }
+
+  bool hasDetachedBuffer() const {
+    // Shared buffers can't be detached.
+    if (isSharedMemory()) {
+      return false;
+    }
+
+    // A typed array with a null buffer has never had its buffer exposed to
+    // become detached.
+    ArrayBufferObject* buffer = bufferUnshared();
+    if (!buffer) {
+      return false;
+    }
+
+    return buffer->isDetached();
+  }
+
+  size_t byteOffset() const {
+    return size_t(getFixedSlot(BYTEOFFSET_SLOT).toPrivate());
+  }
+
+  Value byteOffsetValue() const {
+    size_t offset = byteOffset();
+    return NumberValue(offset);
+  }
+
+  static void trace(JSTracer* trc, JSObject* obj);
+};
+
+}  // namespace js
+
+template <>
+bool JSObject::is<js::ArrayBufferViewObject>() const;
+
+#endif  // vm_ArrayBufferViewObject_h