1 files changed, 118 insertions, 0 deletions
diff --git a/toolkit/components/uniffi-js/UniFFIPointer.cpp b/toolkit/components/uniffi-js/UniFFIPointer.cpp
new file mode 100644
index 0000000000..87a1d5fe69
--- /dev/null
+++ b/toolkit/components/uniffi-js/UniFFIPointer.cpp
@@ -0,0 +1,118 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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 "nsPrintfCString.h"
+#include "mozilla/EndianUtils.h"
+#include "mozilla/dom/UniFFIPointer.h"
+#include "mozilla/dom/UniFFIBinding.h"
+#include "mozilla/Logging.h"
+#include "UniFFIRust.h"
+
+static mozilla::LazyLogModule sUniFFIPointerLogger("uniffi_logger");
+
+namespace mozilla::dom {
+using uniffi::RUST_CALL_SUCCESS;
+using uniffi::RustCallStatus;
+using uniffi::UniFFIPointerType;
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_0(UniFFIPointer)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(UniFFIPointer)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(UniFFIPointer)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(UniFFIPointer)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+// Static function
+already_AddRefed<UniFFIPointer> UniFFIPointer::Create(
+    void* aPtr, const UniFFIPointerType* aType) {
+  RefPtr<UniFFIPointer> uniFFIPointer = new UniFFIPointer(aPtr, aType);
+  return uniFFIPointer.forget();
+}
+
+already_AddRefed<UniFFIPointer> UniFFIPointer::Read(
+    const ArrayBuffer& aArrayBuff, uint32_t aPosition,
+    const UniFFIPointerType* aType, ErrorResult& aError) {
+  MOZ_LOG(sUniFFIPointerLogger, LogLevel::Info,
+          ("[UniFFI] Reading Pointer from buffer"));
+
+  uint8_t data_ptr[8];
+  if (!aArrayBuff.CopyDataTo(
+          data_ptr,
+          [aPosition](size_t aLength) -> Maybe<std::pair<size_t, size_t>> {
+            CheckedUint32 end = aPosition + 8;
+            if (!end.isValid() || end.value() > aLength) {
+              return Nothing();
+            }
+            return Some(std::make_pair(aPosition, 8));
+          })) {
+    aError.ThrowRangeError("position is out of range");
+    return nullptr;
+  }
+
+  // in Rust and Write(), a pointer is converted to a void* then written as u64
+  // BigEndian we do the reverse here
+  void* ptr = (void*)mozilla::BigEndian::readUint64(data_ptr);
+  return UniFFIPointer::Create(ptr, aType);
+}
+
+void UniFFIPointer::Write(const ArrayBuffer& aArrayBuff, uint32_t aPosition,
+                          const UniFFIPointerType* aType,
+                          ErrorResult& aError) const {
+  if (!this->IsSamePtrType(aType)) {
+    aError.ThrowUnknownError(nsPrintfCString(
+        "Attempt to write pointer with wrong type: %s (expected: %s)",
+        aType->typeName.get(), this->mType->typeName.get()));
+    return;
+  }
+  MOZ_LOG(sUniFFIPointerLogger, LogLevel::Info,
+          ("[UniFFI] Writing Pointer to buffer"));
+
+  aArrayBuff.ProcessData([&](const Span<uint8_t>& aData,
+                             JS::AutoCheckCannotGC&&) {
+    CheckedUint32 end = aPosition + 8;
+    if (!end.isValid() || end.value() > aData.Length()) {
+      aError.ThrowRangeError("position is out of range");
+      return;
+    }
+    // in Rust and Read(), a u64 is read as BigEndian and then converted to
+    // a pointer we do the reverse here
+    const auto& data_ptr = aData.Subspan(aPosition, 8);
+    mozilla::BigEndian::writeUint64(data_ptr.Elements(), (uint64_t)GetPtr());
+  });
+}
+
+UniFFIPointer::UniFFIPointer(void* aPtr, const UniFFIPointerType* aType) {
+  mPtr = aPtr;
+  mType = aType;
+}
+
+JSObject* UniFFIPointer::WrapObject(JSContext* aCx,
+                                    JS::Handle<JSObject*> aGivenProto) {
+  return dom::UniFFIPointer_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+void* UniFFIPointer::GetPtr() const {
+  MOZ_LOG(sUniFFIPointerLogger, LogLevel::Info,
+          ("[UniFFI] Getting raw pointer"));
+  return this->mPtr;
+}
+
+bool UniFFIPointer::IsSamePtrType(const UniFFIPointerType* aType) const {
+  return this->mType == aType;
+}
+
+UniFFIPointer::~UniFFIPointer() {
+  MOZ_LOG(sUniFFIPointerLogger, LogLevel::Info,
+          ("[UniFFI] Destroying pointer"));
+  RustCallStatus status{};
+  this->mType->destructor(this->mPtr, &status);
+  MOZ_DIAGNOSTIC_ASSERT(status.code == RUST_CALL_SUCCESS,
+                        "UniFFI destructor call returned a non-success result");
+}
+
+}  // namespace mozilla::dom