1 files changed, 69 insertions, 0 deletions
diff --git a/toolkit/components/uniffi-js/UniFFIPointer.h b/toolkit/components/uniffi-js/UniFFIPointer.h
new file mode 100644
index 0000000000..59acc0ca66
--- /dev/null
+++ b/toolkit/components/uniffi-js/UniFFIPointer.h
@@ -0,0 +1,69 @@
+/* -*- 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 mozilla_dom_UniFFIPointer_h
+#define mozilla_dom_UniFFIPointer_h
+
+#include "nsISupports.h"
+#include "nsWrapperCache.h"
+#include "nsString.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/dom/TypedArray.h"
+#include "mozilla/dom/UniFFIPointerType.h"
+
+namespace mozilla::dom {
+
+class UniFFIPointer final : public nsISupports, public nsWrapperCache {
+ public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(UniFFIPointer)
+
+  static already_AddRefed<UniFFIPointer> Create(
+      void* aPtr, const uniffi::UniFFIPointerType* aType);
+  static already_AddRefed<UniFFIPointer> Read(
+      const ArrayBuffer& aArrayBuff, uint32_t aPosition,
+      const uniffi::UniFFIPointerType* aType, ErrorResult& aError);
+  void Write(const ArrayBuffer& aArrayBuff, uint32_t aPosition,
+             const uniffi::UniFFIPointerType* aType, ErrorResult& aError) const;
+
+  UniFFIPointer(void* aPtr, const uniffi::UniFFIPointerType* aType);
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+  nsISupports* GetParentObject() { return nullptr; }
+
+  /**
+   * returns the raw pointer `UniFFIPointer` holds
+   * This is safe because:
+   * - The pointer was allocated in Rust as a reference counted `Arc<T>`
+   * - Rust cloned the pointer without destructing it when passed into C++
+   * - Eventually, when the destructor of `UniFFIPointer` runs, we return
+   * ownership to Rust, which then decrements the count and deallocates the
+   * memory the pointer points to.
+   */
+  void* GetPtr() const;
+
+  /**
+   * Returns true if the pointer type `this` holds is the same as the argument
+   * it does so using pointer comparison, as there is **exactly** one static
+   * `UniFFIPointerType` per type exposed in the UniFFI interface
+   */
+  bool IsSamePtrType(const uniffi::UniFFIPointerType* type) const;
+
+ private:
+  const uniffi::UniFFIPointerType* mType;
+  void* mPtr;
+
+ protected:
+  /**
+   * Destructs the `UniFFIPointer`, making sure to give back ownership of the
+   * raw pointer back to Rust, which deallocates the pointer
+   */
+  ~UniFFIPointer();
+};
+}  // namespace mozilla::dom
+
+#endif /* mozilla_dom_UniFFIPointer_h */