1 files changed, 76 insertions, 0 deletions
diff --git a/js/src/vm/ArrayBufferObjectMaybeShared.cpp b/js/src/vm/ArrayBufferObjectMaybeShared.cpp
new file mode 100644
index 0000000000..400a8baa3f
--- /dev/null
+++ b/js/src/vm/ArrayBufferObjectMaybeShared.cpp
@@ -0,0 +1,76 @@
+/* -*- 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 "mozilla/Assertions.h"  // MOZ_ASSERT
+
+#include <stdint.h>  // uint8_t, uint32_t
+
+#include "jstypes.h"  // JS_PUBLIC_API
+
+#include "js/ArrayBufferMaybeShared.h"
+#include "vm/ArrayBufferObject.h"  // js::ArrayBufferObject
+#include "vm/JSObject.h"           // JSObject
+#include "vm/SharedArrayObject.h"  // js::SharedArrayBufferObject
+#include "vm/SharedMem.h"          // SharedMem
+
+using namespace js;
+
+JS_PUBLIC_API bool JS::IsArrayBufferObjectMaybeShared(JSObject* obj) {
+  return obj->canUnwrapAs<ArrayBufferObjectMaybeShared>();
+}
+
+JS_PUBLIC_API JSObject* JS::UnwrapArrayBufferMaybeShared(JSObject* obj) {
+  return obj->maybeUnwrapIf<ArrayBufferObjectMaybeShared>();
+}
+
+JS_PUBLIC_API void JS::GetArrayBufferMaybeSharedLengthAndData(
+    JSObject* obj, size_t* length, bool* isSharedMemory, uint8_t** data) {
+  MOZ_ASSERT(obj->is<ArrayBufferObjectMaybeShared>());
+
+  if (obj->is<SharedArrayBufferObject>()) {
+    auto* buffer = &obj->as<SharedArrayBufferObject>();
+    *length = buffer->byteLength();
+    *data = buffer->dataPointerShared().unwrap();
+    *isSharedMemory = true;
+  } else {
+    auto* buffer = &obj->as<ArrayBufferObject>();
+    *length = buffer->byteLength();
+    *data = buffer->dataPointer();
+    *isSharedMemory = false;
+  }
+}
+
+JS_PUBLIC_API uint8_t* JS::GetArrayBufferMaybeSharedData(
+    JSObject* obj, bool* isSharedMemory, const JS::AutoRequireNoGC&) {
+  MOZ_ASSERT(obj->maybeUnwrapIf<ArrayBufferObjectMaybeShared>());
+
+  if (ArrayBufferObject* aobj = obj->maybeUnwrapIf<ArrayBufferObject>()) {
+    *isSharedMemory = false;
+    return aobj->dataPointer();
+  } else if (SharedArrayBufferObject* saobj =
+                 obj->maybeUnwrapIf<SharedArrayBufferObject>()) {
+    *isSharedMemory = true;
+    return saobj->dataPointerShared().unwrap();
+  }
+
+  return nullptr;
+}
+
+JS_PUBLIC_API bool JS::IsLargeArrayBufferMaybeShared(JSObject* obj) {
+#ifdef JS_64BIT
+  obj = UnwrapArrayBufferMaybeShared(obj);
+  MOZ_ASSERT(obj);
+  size_t len = obj->is<ArrayBufferObject>()
+                   ? obj->as<ArrayBufferObject>().byteLength()
+                   : obj->as<SharedArrayBufferObject>().byteLength();
+  return len > ArrayBufferObject::MaxByteLengthForSmallBuffer;
+#else
+  // Large ArrayBuffers are not supported on 32-bit.
+  static_assert(ArrayBufferObject::MaxByteLength ==
+                ArrayBufferObject::MaxByteLengthForSmallBuffer);
+  return false;
+#endif
+}