1 files changed, 137 insertions, 0 deletions
diff --git a/toolkit/components/uniffi-js/UniFFICallbacks.cpp b/toolkit/components/uniffi-js/UniFFICallbacks.cpp
new file mode 100644
index 0000000000..c8014558a7
--- /dev/null
+++ b/toolkit/components/uniffi-js/UniFFICallbacks.cpp
@@ -0,0 +1,137 @@
+/* -*- 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 "nsString.h"
+#include "nsThreadUtils.h"
+#include "mozilla/dom/OwnedRustBuffer.h"
+#include "mozilla/dom/RootedDictionary.h"
+#include "mozilla/dom/UniFFIBinding.h"
+#include "mozilla/dom/UniFFICallbacks.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/Logging.h"
+#include "mozilla/RefPtr.h"
+
+static mozilla::LazyLogModule UNIFFI_INVOKE_CALLBACK_LOGGER("uniffi");
+
+namespace mozilla::uniffi {
+
+using dom::ArrayBuffer;
+using dom::RootedDictionary;
+using dom::UniFFICallbackHandler;
+using dom::UniFFIScaffoldingCallCode;
+
+static Maybe<CallbackInterfaceInfo> GetCallbackInterfaceInfo(
+    uint64_t aInterfaceId) {
+  const Maybe<CallbackInterfaceInfo> cbiInfo =
+      UniFFIGetCallbackInterfaceInfo(aInterfaceId);
+#ifdef MOZ_UNIFFI_FIXTURES
+  if (!cbiInfo) {
+    return UniFFIFixturesGetCallbackInterfaceInfo(aInterfaceId);
+  }
+#endif
+  return cbiInfo;
+}
+
+void RegisterCallbackHandler(uint64_t aInterfaceId,
+                             UniFFICallbackHandler& aCallbackHandler,
+                             ErrorResult& aError) {
+  // We should only be mutating mHandler on the main thread
+  MOZ_ASSERT(NS_IsMainThread());
+
+  Maybe<CallbackInterfaceInfo> cbiInfo = GetCallbackInterfaceInfo(aInterfaceId);
+  if (!cbiInfo.isSome()) {
+    aError.ThrowUnknownError(
+        nsPrintfCString("Unknown interface id: %" PRIu64, aInterfaceId));
+    return;
+  }
+
+  if (*cbiInfo->mHandler) {
+    MOZ_LOG(UNIFFI_INVOKE_CALLBACK_LOGGER, LogLevel::Error,
+            ("[UniFFI] Callback handler already registered for %s",
+             cbiInfo->mName));
+    return;
+  }
+  *cbiInfo->mHandler = &aCallbackHandler;
+  RustCallStatus status = {0};
+  cbiInfo->mInitForeignCallback(cbiInfo->mForeignCallback, &status);
+  // Just use MOZ_DIAGNOSTIC_ASSERT to check the status, since the call should
+  // always succeed. The RustCallStatus out param only exists because UniFFI
+  // adds it to all FFI calls.
+  MOZ_DIAGNOSTIC_ASSERT(status.code == RUST_CALL_SUCCESS);
+}
+
+void DeregisterCallbackHandler(uint64_t aInterfaceId, ErrorResult& aError) {
+  // We should only be mutating mHandler on the main thread
+  MOZ_ASSERT(NS_IsMainThread());
+
+  Maybe<CallbackInterfaceInfo> cbiInfo = GetCallbackInterfaceInfo(aInterfaceId);
+  if (!cbiInfo.isSome()) {
+    aError.ThrowUnknownError(
+        nsPrintfCString("Unknown interface id: %" PRIu64, aInterfaceId));
+    return;
+  }
+  *cbiInfo->mHandler = nullptr;
+}
+
+MOZ_CAN_RUN_SCRIPT
+static void QueueCallbackInner(uint64_t aInterfaceId, uint64_t aHandle,
+                               uint32_t aMethod, OwnedRustBuffer aArgs) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  Maybe<CallbackInterfaceInfo> cbiInfo = GetCallbackInterfaceInfo(aInterfaceId);
+  if (!cbiInfo.isSome()) {
+    MOZ_LOG(UNIFFI_INVOKE_CALLBACK_LOGGER, LogLevel::Error,
+            ("[UniFFI] Unknown inferface id: %" PRIu64, aInterfaceId));
+    return;
+  }
+
+  // Take our own reference to the callback handler to ensure that it stays
+  // alive for the duration of this call
+  RefPtr<UniFFICallbackHandler> ihandler = *cbiInfo->mHandler;
+
+  if (!ihandler) {
+    MOZ_LOG(UNIFFI_INVOKE_CALLBACK_LOGGER, LogLevel::Error,
+            ("[UniFFI] JS handler for %s not registered", cbiInfo->mName));
+    return;
+  }
+
+  JSObject* global = ihandler->CallbackGlobalOrNull();
+  if (!global) {
+    MOZ_LOG(UNIFFI_INVOKE_CALLBACK_LOGGER, LogLevel::Error,
+            ("[UniFFI] JS handler for %s has null global", cbiInfo->mName));
+    return;
+  }
+
+  dom::AutoEntryScript aes(global, cbiInfo->mName);
+  IgnoredErrorResult error;
+  JS::Rooted<JSObject*> args(aes.cx(), aArgs.IntoArrayBuffer(aes.cx()));
+
+  ihandler->Call(aHandle, aMethod, args, error);
+
+  if (error.Failed()) {
+    MOZ_LOG(UNIFFI_INVOKE_CALLBACK_LOGGER, LogLevel::Error,
+            ("[UniFFI] Error invoking JS handler for %s", cbiInfo->mName));
+    return;
+  }
+}
+
+void QueueCallback(uint64_t aInterfaceId, uint64_t aHandle, uint32_t aMethod,
+                   RustBuffer aArgs) {
+  nsresult dispatchResult =
+      GetMainThreadSerialEventTarget()->Dispatch(NS_NewRunnableFunction(
+          "UniFFI callback", [=]() MOZ_CAN_RUN_SCRIPT_BOUNDARY {
+            QueueCallbackInner(aInterfaceId, aHandle, aMethod,
+                               OwnedRustBuffer(aArgs));
+          }));
+
+  if (NS_FAILED(dispatchResult)) {
+    MOZ_LOG(UNIFFI_INVOKE_CALLBACK_LOGGER, LogLevel::Error,
+            ("[UniFFI] Error dispatching UniFFI callback task"));
+  }
+}
+
+}  // namespace mozilla::uniffi