1 files changed, 447 insertions, 0 deletions
diff --git a/js/src/vm/ArrayBufferViewObject.cpp b/js/src/vm/ArrayBufferViewObject.cpp
new file mode 100644
index 0000000000..4bcd7890c1
--- /dev/null
+++ b/js/src/vm/ArrayBufferViewObject.cpp
@@ -0,0 +1,447 @@
+/* -*- 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/. */
+
+#include "vm/ArrayBufferViewObject.h"
+
+#include "builtin/DataViewObject.h"
+#include "gc/Nursery.h"
+#include "js/ErrorReport.h"
+#include "js/experimental/TypedData.h"  // JS_GetArrayBufferView{Data,Buffer,Length,ByteOffset}, JS_GetObjectAsArrayBufferView, JS_IsArrayBufferViewObject
+#include "js/SharedArrayBuffer.h"
+#include "vm/Compartment.h"
+#include "vm/JSContext.h"
+#include "vm/TypedArrayObject.h"
+
+#include "gc/Nursery-inl.h"
+#include "vm/ArrayBufferObject-inl.h"
+#include "vm/NativeObject-inl.h"
+
+using namespace js;
+
+// This method is used to trace TypedArrayObjects and DataViewObjects. It
+// updates the object's data pointer if it points to inline data in an object
+// that was moved.
+/* static */
+void ArrayBufferViewObject::trace(JSTracer* trc, JSObject* obj) {
+  ArrayBufferViewObject* view = &obj->as<ArrayBufferViewObject>();
+
+  // Update view's data pointer if it moved.
+  if (view->hasBuffer()) {
+    JSObject* bufferObj = &view->bufferValue().toObject();
+    ArrayBufferObject* buffer = nullptr;
+    if (gc::MaybeForwardedObjectIs<FixedLengthArrayBufferObject>(bufferObj)) {
+      buffer =
+          &gc::MaybeForwardedObjectAs<FixedLengthArrayBufferObject>(bufferObj);
+    } else if (gc::MaybeForwardedObjectIs<ResizableArrayBufferObject>(
+                   bufferObj)) {
+      buffer =
+          &gc::MaybeForwardedObjectAs<ResizableArrayBufferObject>(bufferObj);
+    }
+    if (buffer) {
+      size_t offset = view->byteOffset();
+      MOZ_ASSERT_IF(!buffer->dataPointer(), offset == 0);
+
+      // The data may or may not be inline with the buffer. The buffer can only
+      // move during a compacting GC, in which case its objectMoved hook has
+      // already updated the buffer's data pointer.
+      view->notifyBufferMoved(
+          static_cast<uint8_t*>(view->dataPointerEither_()) - offset,
+          buffer->dataPointer());
+    }
+  }
+}
+
+template <>
+bool JSObject::is<js::ArrayBufferViewObject>() const {
+  return is<DataViewObject>() || is<TypedArrayObject>();
+}
+
+void ArrayBufferViewObject::notifyBufferDetached() {
+  MOZ_ASSERT(!isSharedMemory());
+  MOZ_ASSERT(hasBuffer());
+  MOZ_ASSERT(!bufferUnshared()->isLengthPinned());
+
+  setFixedSlot(LENGTH_SLOT, PrivateValue(size_t(0)));
+  setFixedSlot(BYTEOFFSET_SLOT, PrivateValue(size_t(0)));
+  setFixedSlot(DATA_SLOT, UndefinedValue());
+}
+
+void ArrayBufferViewObject::notifyBufferMoved(uint8_t* srcBufStart,
+                                              uint8_t* dstBufStart) {
+  MOZ_ASSERT(!isSharedMemory());
+  MOZ_ASSERT(hasBuffer());
+
+  if (srcBufStart != dstBufStart) {
+    void* data = dstBufStart + byteOffset();
+    getFixedSlotRef(DATA_SLOT).unbarrieredSet(PrivateValue(data));
+  }
+}
+
+/* static */
+bool ArrayBufferViewObject::ensureNonInline(
+    JSContext* cx, Handle<ArrayBufferViewObject*> view) {
+  MOZ_ASSERT(!view->isSharedMemory());
+  // Create an ArrayBuffer for the data if it was in the view.
+  ArrayBufferObjectMaybeShared* buffer = ensureBufferObject(cx, view);
+  if (!buffer) {
+    return false;
+  }
+  Rooted<ArrayBufferObject*> unsharedBuffer(cx,
+                                            &buffer->as<ArrayBufferObject>());
+  return ArrayBufferObject::ensureNonInline(cx, unsharedBuffer);
+}
+
+/* static */
+ArrayBufferObjectMaybeShared* ArrayBufferViewObject::ensureBufferObject(
+    JSContext* cx, Handle<ArrayBufferViewObject*> thisObject) {
+  if (thisObject->is<TypedArrayObject>()) {
+    Rooted<TypedArrayObject*> typedArray(cx,
+                                         &thisObject->as<TypedArrayObject>());
+    if (!TypedArrayObject::ensureHasBuffer(cx, typedArray)) {
+      return nullptr;
+    }
+  }
+  return thisObject->bufferEither();
+}
+
+bool ArrayBufferViewObject::init(JSContext* cx,
+                                 ArrayBufferObjectMaybeShared* buffer,
+                                 size_t byteOffset, size_t length,
+                                 uint32_t bytesPerElement) {
+  MOZ_ASSERT_IF(!buffer, byteOffset == 0);
+  MOZ_ASSERT_IF(buffer, !buffer->isDetached());
+
+  MOZ_ASSERT(byteOffset <= ArrayBufferObject::ByteLengthLimit);
+  MOZ_ASSERT(length <= ArrayBufferObject::ByteLengthLimit);
+  MOZ_ASSERT(byteOffset + length <= ArrayBufferObject::ByteLengthLimit);
+
+  MOZ_ASSERT_IF(is<TypedArrayObject>(),
+                length <= TypedArrayObject::ByteLengthLimit / bytesPerElement);
+
+  // The isSharedMemory property is invariant.  Self-hosting code that
+  // sets BUFFER_SLOT or the private slot (if it does) must maintain it by
+  // always setting those to reference shared memory.
+  if (buffer && buffer->is<SharedArrayBufferObject>()) {
+    setIsSharedMemory();
+  }
+
+  initFixedSlot(BYTEOFFSET_SLOT, PrivateValue(byteOffset));
+  initFixedSlot(LENGTH_SLOT, PrivateValue(length));
+  if (buffer) {
+    initFixedSlot(BUFFER_SLOT, ObjectValue(*buffer));
+  } else {
+    MOZ_ASSERT(!isSharedMemory());
+    initFixedSlot(BUFFER_SLOT, JS::FalseValue());
+  }
+
+  if (buffer) {
+    SharedMem<uint8_t*> ptr = buffer->dataPointerEither();
+    initDataPointer(ptr + byteOffset);
+
+    // Only ArrayBuffers used for inline typed objects can have
+    // nursery-allocated data and we shouldn't see such buffers here.
+    MOZ_ASSERT_IF(buffer->byteLength() > 0, !cx->nursery().isInside(ptr));
+  } else {
+    MOZ_ASSERT(is<FixedLengthTypedArrayObject>());
+    MOZ_ASSERT(length * bytesPerElement <=
+               FixedLengthTypedArrayObject::INLINE_BUFFER_LIMIT);
+    void* data = fixedData(FixedLengthTypedArrayObject::FIXED_DATA_START);
+    initReservedSlot(DATA_SLOT, PrivateValue(data));
+    memset(data, 0, length * bytesPerElement);
+#ifdef DEBUG
+    if (length == 0) {
+      uint8_t* elements = static_cast<uint8_t*>(data);
+      elements[0] = ZeroLengthArrayData;
+    }
+#endif
+  }
+
+#ifdef DEBUG
+  if (buffer) {
+    size_t viewByteLength = length * bytesPerElement;
+    size_t viewByteOffset = byteOffset;
+    size_t bufferByteLength = buffer->byteLength();
+    // Unwraps are safe: both are for the pointer value.
+    MOZ_ASSERT_IF(buffer->is<ArrayBufferObject>(),
+                  buffer->dataPointerEither().unwrap(/*safe*/) <=
+                      dataPointerEither().unwrap(/*safe*/));
+    MOZ_ASSERT(bufferByteLength - viewByteOffset >= viewByteLength);
+    MOZ_ASSERT(viewByteOffset <= bufferByteLength);
+  }
+#endif
+
+  // ArrayBufferObjects track their views to support detaching.
+  if (buffer && buffer->is<ArrayBufferObject>()) {
+    if (!buffer->as<ArrayBufferObject>().addView(cx, this)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool ArrayBufferViewObject::hasResizableBuffer() const {
+  if (auto* buffer = bufferEither()) {
+    return buffer->isResizable();
+  }
+  return false;
+}
+
+#if defined(DEBUG) || defined(JS_JITSPEW)
+void ArrayBufferViewObject::dumpOwnFields(js::JSONPrinter& json) const {
+  json.formatProperty("length", "%zu",
+                      size_t(getFixedSlot(LENGTH_SLOT).toPrivate()));
+  json.formatProperty("byteOffset", "%zu",
+                      size_t(getFixedSlot(BYTEOFFSET_SLOT).toPrivate()));
+  void* data = dataPointerEither_();
+  if (data) {
+    json.formatProperty("data", "0x%p", data);
+  } else {
+    json.nullProperty("data");
+  }
+}
+
+void ArrayBufferViewObject::dumpOwnStringContent(
+    js::GenericPrinter& out) const {
+  out.printf("length=%zu, byteOffset=%zu, ",
+             size_t(getFixedSlot(LENGTH_SLOT).toPrivate()),
+             size_t(getFixedSlot(BYTEOFFSET_SLOT).toPrivate()));
+  void* data = dataPointerEither_();
+  if (data) {
+    out.printf("data=0x%p", data);
+  } else {
+    out.put("data=null");
+  }
+}
+#endif
+
+/* JS Public API */
+
+JS_PUBLIC_API bool JS_IsArrayBufferViewObject(JSObject* obj) {
+  return obj->canUnwrapAs<ArrayBufferViewObject>();
+}
+
+JS_PUBLIC_API JSObject* js::UnwrapArrayBufferView(JSObject* obj) {
+  return obj->maybeUnwrapIf<ArrayBufferViewObject>();
+}
+
+JS_PUBLIC_API void* JS_GetArrayBufferViewData(JSObject* obj,
+                                              bool* isSharedMemory,
+                                              const JS::AutoRequireNoGC&) {
+  ArrayBufferViewObject* view = obj->maybeUnwrapAs<ArrayBufferViewObject>();
+  if (!view) {
+    return nullptr;
+  }
+
+  *isSharedMemory = view->isSharedMemory();
+  return view->dataPointerEither().unwrap(
+      /*safe - caller sees isSharedMemory flag*/);
+}
+
+JS_PUBLIC_API uint8_t* JS_GetArrayBufferViewFixedData(JSObject* obj,
+                                                      uint8_t* buffer,
+                                                      size_t bufSize) {
+  ArrayBufferViewObject* view = obj->maybeUnwrapAs<ArrayBufferViewObject>();
+  if (!view) {
+    return nullptr;
+  }
+
+  // Disallow shared memory until it is needed.
+  if (view->isSharedMemory()) {
+    return nullptr;
+  }
+
+  // TypedArrays (but not DataViews) can have inline data, in which case we
+  // need to copy into the given buffer.
+  if (view->is<FixedLengthTypedArrayObject>()) {
+    auto* ta = &view->as<FixedLengthTypedArrayObject>();
+    if (ta->hasInlineElements()) {
+      size_t bytes = ta->byteLength();
+      if (bytes > bufSize) {
+        return nullptr;  // Does not fit.
+      }
+      memcpy(buffer, view->dataPointerUnshared(), bytes);
+      return buffer;
+    }
+  }
+
+  return static_cast<uint8_t*>(view->dataPointerUnshared());
+}
+
+JS_PUBLIC_API JSObject* JS_GetArrayBufferViewBuffer(JSContext* cx,
+                                                    HandleObject obj,
+                                                    bool* isSharedMemory) {
+  AssertHeapIsIdle();
+  CHECK_THREAD(cx);
+  cx->check(obj);
+
+  Rooted<ArrayBufferViewObject*> unwrappedView(
+      cx, obj->maybeUnwrapAs<ArrayBufferViewObject>());
+  if (!unwrappedView) {
+    ReportAccessDenied(cx);
+    return nullptr;
+  }
+
+  ArrayBufferObjectMaybeShared* unwrappedBuffer;
+  {
+    AutoRealm ar(cx, unwrappedView);
+    unwrappedBuffer =
+        ArrayBufferViewObject::ensureBufferObject(cx, unwrappedView);
+    if (!unwrappedBuffer) {
+      return nullptr;
+    }
+  }
+  *isSharedMemory = unwrappedBuffer->is<SharedArrayBufferObject>();
+
+  RootedObject buffer(cx, unwrappedBuffer);
+  if (!cx->compartment()->wrap(cx, &buffer)) {
+    return nullptr;
+  }
+
+  return buffer;
+}
+
+JS_PUBLIC_API size_t JS_GetArrayBufferViewByteLength(JSObject* obj) {
+  obj = obj->maybeUnwrapAs<ArrayBufferViewObject>();
+  if (!obj) {
+    return 0;
+  }
+  size_t length = obj->is<DataViewObject>()
+                      ? obj->as<DataViewObject>().byteLength().valueOr(0)
+                      : obj->as<TypedArrayObject>().byteLength().valueOr(0);
+  return length;
+}
+
+bool JS::ArrayBufferView::isDetached() const {
+  MOZ_ASSERT(obj);
+  return obj->as<ArrayBufferViewObject>().hasDetachedBuffer();
+}
+
+bool JS::ArrayBufferView::isResizable() const {
+  MOZ_ASSERT(obj);
+  return obj->as<ArrayBufferViewObject>().hasResizableBuffer();
+}
+
+JS_PUBLIC_API size_t JS_GetArrayBufferViewByteOffset(JSObject* obj) {
+  obj = obj->maybeUnwrapAs<ArrayBufferViewObject>();
+  if (!obj) {
+    return 0;
+  }
+  size_t offset = obj->is<DataViewObject>()
+                      ? obj->as<DataViewObject>().byteOffset().valueOr(0)
+                      : obj->as<TypedArrayObject>().byteOffset().valueOr(0);
+  return offset;
+}
+
+JS_PUBLIC_API mozilla::Span<uint8_t> JS::ArrayBufferView::getData(
+    bool* isSharedMemory, const AutoRequireNoGC&) {
+  MOZ_ASSERT(obj->is<ArrayBufferViewObject>());
+  size_t byteLength = obj->is<DataViewObject>()
+                          ? obj->as<DataViewObject>().byteLength().valueOr(0)
+                          : obj->as<TypedArrayObject>().byteLength().valueOr(0);
+  ArrayBufferViewObject& view = obj->as<ArrayBufferViewObject>();
+  *isSharedMemory = view.isSharedMemory();
+  return {static_cast<uint8_t*>(view.dataPointerEither().unwrap(
+              /*safe - caller sees isShared flag*/)),
+          byteLength};
+}
+
+JS_PUBLIC_API JSObject* JS_GetObjectAsArrayBufferView(JSObject* obj,
+                                                      size_t* length,
+                                                      bool* isSharedMemory,
+                                                      uint8_t** data) {
+  obj = obj->maybeUnwrapIf<ArrayBufferViewObject>();
+  if (!obj) {
+    return nullptr;
+  }
+
+  js::GetArrayBufferViewLengthAndData(obj, length, isSharedMemory, data);
+  return obj;
+}
+
+JS_PUBLIC_API void js::GetArrayBufferViewLengthAndData(JSObject* obj,
+                                                       size_t* length,
+                                                       bool* isSharedMemory,
+                                                       uint8_t** data) {
+  JS::AutoAssertNoGC nogc;
+  auto span =
+      JS::ArrayBufferView::fromObject(obj).getData(isSharedMemory, nogc);
+  *data = span.data();
+  *length = span.Length();
+}
+
+JS_PUBLIC_API bool JS::IsArrayBufferViewShared(JSObject* obj) {
+  ArrayBufferViewObject* view = obj->maybeUnwrapAs<ArrayBufferViewObject>();
+  if (!view) {
+    return false;
+  }
+  return view->isSharedMemory();
+}
+
+JS_PUBLIC_API bool JS::IsLargeArrayBufferView(JSObject* obj) {
+#ifdef JS_64BIT
+  obj = &obj->unwrapAs<ArrayBufferViewObject>();
+  size_t len = obj->is<DataViewObject>()
+                   ? obj->as<DataViewObject>().byteLength().valueOr(0)
+                   : obj->as<TypedArrayObject>().byteLength().valueOr(0);
+  return len > ArrayBufferObject::ByteLengthLimitForSmallBuffer;
+#else
+  // Large ArrayBuffers are not supported on 32-bit.
+  static_assert(ArrayBufferObject::ByteLengthLimit ==
+                ArrayBufferObject::ByteLengthLimitForSmallBuffer);
+  return false;
+#endif
+}
+
+JS_PUBLIC_API bool JS::IsResizableArrayBufferView(JSObject* obj) {
+  auto* view = &obj->unwrapAs<ArrayBufferViewObject>();
+  if (auto* buffer = view->bufferEither()) {
+    return buffer->isResizable();
+  }
+  return false;
+}
+
+JS_PUBLIC_API bool JS::PinArrayBufferOrViewLength(JSObject* obj, bool pin) {
+  ArrayBufferObjectMaybeShared* buffer =
+      obj->maybeUnwrapIf<ArrayBufferObjectMaybeShared>();
+  if (buffer) {
+    return buffer->pinLength(pin);
+  }
+
+  ArrayBufferViewObject* view = obj->maybeUnwrapAs<ArrayBufferViewObject>();
+  if (view) {
+    return view->pinLength(pin);
+  }
+
+  return false;
+}
+
+JS_PUBLIC_API bool JS::EnsureNonInlineArrayBufferOrView(JSContext* cx,
+                                                        JSObject* obj) {
+  if (obj->is<SharedArrayBufferObject>()) {
+    // Always locked and out of line.
+    return true;
+  }
+
+  auto* buffer = obj->maybeUnwrapIf<ArrayBufferObject>();
+  if (buffer) {
+    Rooted<ArrayBufferObject*> rootedBuffer(cx, buffer);
+    return ArrayBufferObject::ensureNonInline(cx, rootedBuffer);
+  }
+
+  auto* view = obj->maybeUnwrapIf<ArrayBufferViewObject>();
+  if (view) {
+    if (view->isSharedMemory()) {
+      // Always locked and out of line.
+      return true;
+    }
+    Rooted<ArrayBufferViewObject*> rootedView(cx, view);
+    return ArrayBufferViewObject::ensureNonInline(cx, rootedView);
+  }
+
+  JS_ReportErrorASCII(cx, "unhandled type");
+  return false;
+}