1 files changed, 44 insertions, 0 deletions
diff --git a/dom/ipc/MemMapSnapshot.cpp b/dom/ipc/MemMapSnapshot.cpp
new file mode 100644
index 0000000000..7a104c420e
--- /dev/null
+++ b/dom/ipc/MemMapSnapshot.cpp
@@ -0,0 +1,44 @@
+/* -*- 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 "MemMapSnapshot.h"
+
+#include "mozilla/AutoMemMap.h"
+#include "mozilla/ResultExtensions.h"
+#include "mozilla/ipc/FileDescriptor.h"
+
+namespace mozilla::ipc {
+
+Result<Ok, nsresult> MemMapSnapshot::Init(size_t aSize) {
+  MOZ_ASSERT(!mInitialized);
+
+  if (NS_WARN_IF(!mMem.CreateFreezeable(aSize))) {
+    return Err(NS_ERROR_FAILURE);
+  }
+  if (NS_WARN_IF(!mMem.Map(aSize))) {
+    return Err(NS_ERROR_FAILURE);
+  }
+
+  mInitialized = true;
+  return Ok();
+}
+
+Result<Ok, nsresult> MemMapSnapshot::Finalize(loader::AutoMemMap& aMem) {
+  MOZ_ASSERT(mInitialized);
+
+  if (NS_WARN_IF(!mMem.Freeze())) {
+    return Err(NS_ERROR_FAILURE);
+  }
+  // TakeHandle resets mMem, so call max_size first.
+  size_t size = mMem.max_size();
+  FileDescriptor memHandle(mMem.TakeHandle());
+  MOZ_TRY(aMem.initWithHandle(memHandle, size));
+
+  mInitialized = false;
+  return Ok();
+}
+
+}  // namespace mozilla::ipc