1 files changed, 100 insertions, 0 deletions
diff --git a/toolkit/components/uniffi-js/OwnedRustBuffer.cpp b/toolkit/components/uniffi-js/OwnedRustBuffer.cpp
new file mode 100644
index 0000000000..4e334a966e
--- /dev/null
+++ b/toolkit/components/uniffi-js/OwnedRustBuffer.cpp
@@ -0,0 +1,100 @@
+/* -*- 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 "nsString.h"
+#include "mozilla/dom/OwnedRustBuffer.h"
+
+namespace mozilla::uniffi {
+
+using dom::ArrayBuffer;
+
+OwnedRustBuffer::OwnedRustBuffer(const RustBuffer& aBuf) {
+  mBuf = aBuf;
+  MOZ_ASSERT(IsValid());
+}
+
+Result<OwnedRustBuffer, nsCString> OwnedRustBuffer::FromArrayBuffer(
+    const ArrayBuffer& aArrayBuffer) {
+  return aArrayBuffer.ProcessData(
+      [](const Span<uint8_t>& aData,
+         JS::AutoCheckCannotGC&&) -> Result<OwnedRustBuffer, nsCString> {
+        if (aData.Length() > INT32_MAX) {
+          return Err("Input ArrayBuffer is too large"_ns);
+        }
+
+        RustCallStatus status{};
+        RustBuffer buf = uniffi_rustbuffer_alloc(
+            static_cast<int32_t>(aData.Length()), &status);
+        buf.len = aData.Length();
+        if (status.code != 0) {
+          if (status.error_buf.data) {
+            auto message = nsCString("uniffi_rustbuffer_alloc: ");
+            message.Append(nsDependentCSubstring(
+                reinterpret_cast<char*>(status.error_buf.data),
+                status.error_buf.len));
+            RustCallStatus status2{};
+            uniffi_rustbuffer_free(status.error_buf, &status2);
+            MOZ_RELEASE_ASSERT(status2.code == 0,
+                               "Freeing a rustbuffer should never fail");
+            return Err(message);
+          }
+
+          return Err("Unknown error allocating rust buffer"_ns);
+        }
+
+        memcpy(buf.data, aData.Elements(), buf.len);
+        return OwnedRustBuffer(buf);
+      });
+}
+
+OwnedRustBuffer::OwnedRustBuffer(OwnedRustBuffer&& aOther) : mBuf(aOther.mBuf) {
+  aOther.mBuf = RustBuffer{0};
+}
+
+OwnedRustBuffer& OwnedRustBuffer::operator=(OwnedRustBuffer&& aOther) {
+  if (&aOther != this) {
+    FreeData();
+  }
+  mBuf = aOther.mBuf;
+  aOther.mBuf = RustBuffer{0};
+  return *this;
+}
+
+void OwnedRustBuffer::FreeData() {
+  if (IsValid()) {
+    RustCallStatus status{};
+    uniffi_rustbuffer_free(mBuf, &status);
+    MOZ_RELEASE_ASSERT(status.code == 0,
+                       "Freeing a rustbuffer should never fail");
+    mBuf = {0};
+  }
+}
+
+OwnedRustBuffer::~OwnedRustBuffer() { FreeData(); }
+
+RustBuffer OwnedRustBuffer::IntoRustBuffer() {
+  RustBuffer rv = mBuf;
+  mBuf = {};
+  return rv;
+}
+
+JSObject* OwnedRustBuffer::IntoArrayBuffer(JSContext* cx) {
+  JS::Rooted<JSObject*> obj(cx);
+  {
+    int32_t len = mBuf.len;
+    void* data = mBuf.data;
+    auto userData = MakeUnique<OwnedRustBuffer>(std::move(*this));
+    UniquePtr<void, JS::BufferContentsDeleter> dataPtr{
+        data, {&ArrayBufferFreeFunc, userData.release()}};
+    obj = JS::NewExternalArrayBuffer(cx, len, std::move(dataPtr));
+  }
+  return obj;
+}
+
+void OwnedRustBuffer::ArrayBufferFreeFunc(void* contents, void* userData) {
+  UniquePtr<OwnedRustBuffer> buf{reinterpret_cast<OwnedRustBuffer*>(userData)};
+}
+}  // namespace mozilla::uniffi