1 files changed, 114 insertions, 0 deletions
diff --git a/ipc/glue/RawShmem.cpp b/ipc/glue/RawShmem.cpp
new file mode 100644
index 0000000000..bfb47c0832
--- /dev/null
+++ b/ipc/glue/RawShmem.cpp
@@ -0,0 +1,114 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "RawShmem.h"
+#include "mozilla/ipc/ProtocolUtils.h"
+
+namespace mozilla::ipc {
+
+UnsafeSharedMemoryHandle::UnsafeSharedMemoryHandle()
+    : mHandle(ipc::SharedMemoryBasic::NULLHandle()), mSize(0) {}
+
+UnsafeSharedMemoryHandle::UnsafeSharedMemoryHandle(
+    UnsafeSharedMemoryHandle&& aOther) noexcept
+    : mHandle(std::move(aOther.mHandle)), mSize(aOther.mSize) {
+  aOther.mHandle = ipc::SharedMemoryBasic::NULLHandle();
+  aOther.mSize = 0;
+}
+
+UnsafeSharedMemoryHandle& UnsafeSharedMemoryHandle::operator=(
+    UnsafeSharedMemoryHandle&& aOther) noexcept {
+  if (this == &aOther) {
+    return *this;
+  }
+
+  mHandle = std::move(aOther.mHandle);
+  mSize = aOther.mSize;
+  aOther.mHandle = ipc::SharedMemoryBasic::NULLHandle();
+  aOther.mSize = 0;
+  return *this;
+}
+
+Maybe<std::pair<UnsafeSharedMemoryHandle, WritableSharedMemoryMapping>>
+UnsafeSharedMemoryHandle::CreateAndMap(size_t aSize) {
+  if (aSize == 0) {
+    return Some(std::make_pair(UnsafeSharedMemoryHandle(),
+                               WritableSharedMemoryMapping()));
+  }
+
+  RefPtr<ipc::SharedMemoryBasic> shm = MakeAndAddRef<ipc::SharedMemoryBasic>();
+  if (NS_WARN_IF(!shm->Create(aSize)) || NS_WARN_IF(!shm->Map(aSize))) {
+    return Nothing();
+  }
+
+  // TODO(bug 1797039): At the moment the handle/mapping distinction is
+  // implemented on top of a single class SharedMemoryBasic. It leads to a few
+  // awkward or sub-optimal things such as how the following few lines clone
+  // then close the handle. It would be better to separate the underlying
+  // implementation or steal the handle to avoid cloning it.
+  auto handle = shm->CloneHandle();
+
+  shm->CloseHandle();
+  auto size = shm->Size();
+
+  return Some(std::make_pair(UnsafeSharedMemoryHandle(std::move(handle), size),
+                             WritableSharedMemoryMapping(std::move(shm))));
+}
+
+WritableSharedMemoryMapping::WritableSharedMemoryMapping(
+    RefPtr<ipc::SharedMemoryBasic>&& aRef)
+    : mRef(aRef) {}
+
+Maybe<WritableSharedMemoryMapping> WritableSharedMemoryMapping::Open(
+    UnsafeSharedMemoryHandle aHandle) {
+  if (aHandle.mSize == 0) {
+    return Some(WritableSharedMemoryMapping(nullptr));
+  }
+
+  RefPtr<ipc::SharedMemoryBasic> shm = MakeAndAddRef<ipc::SharedMemoryBasic>();
+  if (NS_WARN_IF(!shm->SetHandle(std::move(aHandle.mHandle),
+                                 ipc::SharedMemory::RightsReadWrite)) ||
+      NS_WARN_IF(!shm->Map(aHandle.mSize))) {
+    return Nothing();
+  }
+
+  shm->CloseHandle();
+
+  return Some(WritableSharedMemoryMapping(std::move(shm)));
+}
+
+size_t WritableSharedMemoryMapping::Size() const {
+  if (!mRef) {
+    return 0;
+  }
+
+  return mRef->Size();
+}
+
+Span<uint8_t> WritableSharedMemoryMapping::Bytes() {
+  if (!mRef) {
+    return Span<uint8_t>();
+  }
+
+  uint8_t* mem = static_cast<uint8_t*>(mRef->memory());
+  return Span(mem, mRef->Size());
+}
+
+}  // namespace mozilla::ipc
+
+namespace IPC {
+auto ParamTraits<mozilla::ipc::UnsafeSharedMemoryHandle>::Write(
+    IPC::MessageWriter* aWriter, paramType&& aVar) -> void {
+  IPC::WriteParam(aWriter, std::move(aVar.mHandle));
+  IPC::WriteParam(aWriter, aVar.mSize);
+}
+
+auto ParamTraits<mozilla::ipc::UnsafeSharedMemoryHandle>::Read(
+    IPC::MessageReader* aReader, paramType* aVar) -> bool {
+  return IPC::ReadParam(aReader, &aVar->mHandle) &&
+         IPC::ReadParam(aReader, &aVar->mSize);
+}
+
+}  // namespace IPC