1 files changed, 105 insertions, 0 deletions
diff --git a/ipc/glue/BigBuffer.cpp b/ipc/glue/BigBuffer.cpp
new file mode 100644
index 0000000000..822ffe20fe
--- /dev/null
+++ b/ipc/glue/BigBuffer.cpp
@@ -0,0 +1,105 @@
+/* -*- 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 "mozilla/ipc/BigBuffer.h"
+
+#include "mozilla/ipc/SharedMemoryBasic.h"
+#include "nsDebug.h"
+
+namespace mozilla::ipc {
+
+BigBuffer::BigBuffer(Adopt, SharedMemory* aSharedMemory, size_t aSize)
+    : mSize(aSize), mData(AsVariant(RefPtr{aSharedMemory})) {
+  MOZ_RELEASE_ASSERT(aSharedMemory && aSharedMemory->memory(),
+                     "shared memory must be non-null and mapped");
+  MOZ_RELEASE_ASSERT(mSize <= aSharedMemory->Size(),
+                     "shared memory region isn't large enough");
+}
+
+BigBuffer::BigBuffer(Adopt, uint8_t* aData, size_t aSize)
+    : mSize(aSize), mData(AsVariant(UniqueFreePtr<uint8_t[]>{aData})) {}
+
+uint8_t* BigBuffer::Data() {
+  return mData.is<0>() ? mData.as<0>().get()
+                       : reinterpret_cast<uint8_t*>(mData.as<1>()->memory());
+}
+const uint8_t* BigBuffer::Data() const {
+  return mData.is<0>()
+             ? mData.as<0>().get()
+             : reinterpret_cast<const uint8_t*>(mData.as<1>()->memory());
+}
+
+auto BigBuffer::TryAllocBuffer(size_t aSize) -> Maybe<Storage> {
+  if (aSize <= kShmemThreshold) {
+    auto mem = UniqueFreePtr<uint8_t[]>{
+        reinterpret_cast<uint8_t*>(malloc(aSize))};  // Fallible!
+    if (!mem) return {};
+    return Some(AsVariant(std::move(mem)));
+  }
+
+  RefPtr<SharedMemory> shmem = new SharedMemoryBasic();
+  size_t capacity = SharedMemory::PageAlignedSize(aSize);
+  if (!shmem->Create(capacity) || !shmem->Map(capacity)) {
+    return {};
+  }
+  return Some(AsVariant(shmem));
+}
+
+}  // namespace mozilla::ipc
+
+void IPC::ParamTraits<mozilla::ipc::BigBuffer>::Write(MessageWriter* aWriter,
+                                                      paramType&& aParam) {
+  using namespace mozilla::ipc;
+  size_t size = std::exchange(aParam.mSize, 0);
+  auto data = std::exchange(aParam.mData, BigBuffer::NoData());
+
+  WriteParam(aWriter, size);
+  bool isShmem = data.is<1>();
+  WriteParam(aWriter, isShmem);
+
+  if (isShmem) {
+    if (!data.as<1>()->WriteHandle(aWriter)) {
+      aWriter->FatalError("Failed to write data shmem");
+    }
+  } else {
+    aWriter->WriteBytes(data.as<0>().get(), size);
+  }
+}
+
+bool IPC::ParamTraits<mozilla::ipc::BigBuffer>::Read(MessageReader* aReader,
+                                                     paramType* aResult) {
+  using namespace mozilla::ipc;
+  size_t size = 0;
+  bool isShmem = false;
+  if (!ReadParam(aReader, &size) || !ReadParam(aReader, &isShmem)) {
+    aReader->FatalError("Failed to read data size and format");
+    return false;
+  }
+
+  if (isShmem) {
+    RefPtr<SharedMemory> shmem = new SharedMemoryBasic();
+    size_t capacity = SharedMemory::PageAlignedSize(size);
+    if (!shmem->ReadHandle(aReader) || !shmem->Map(capacity)) {
+      aReader->FatalError("Failed to read data shmem");
+      return false;
+    }
+    *aResult = BigBuffer(BigBuffer::Adopt{}, shmem, size);
+    return true;
+  }
+
+  mozilla::UniqueFreePtr<uint8_t[]> buf{
+      reinterpret_cast<uint8_t*>(malloc(size))};
+  if (!buf) {
+    aReader->FatalError("Failed to allocate data buffer");
+    return false;
+  }
+  if (!aReader->ReadBytesInto(buf.get(), size)) {
+    aReader->FatalError("Failed to read data");
+    return false;
+  }
+  *aResult = BigBuffer(BigBuffer::Adopt{}, buf.release(), size);
+  return true;
+}