1 files changed, 52 insertions, 0 deletions
diff --git a/ipc/glue/ByteBufUtils.h b/ipc/glue/ByteBufUtils.h
new file mode 100644
index 0000000000..4ddca81210
--- /dev/null
+++ b/ipc/glue/ByteBufUtils.h
@@ -0,0 +1,52 @@
+/* -*- 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/. */
+
+/* A type that can be sent without needing to make a copy during
+ * serialization. In addition the receiver can take ownership of the
+ * data to avoid having to make an additional copy. */
+
+#ifndef mozilla_ipc_ByteBufUtils_h
+#define mozilla_ipc_ByteBufUtils_h
+
+#include "mozilla/ipc/ByteBuf.h"
+#include "ipc/IPCMessageUtils.h"
+
+namespace IPC {
+
+template <>
+struct ParamTraits<mozilla::ipc::ByteBuf> {
+  typedef mozilla::ipc::ByteBuf paramType;
+
+  // this is where we transfer the memory from the ByteBuf to IPDL, avoiding a
+  // copy
+  static void Write(Message* aMsg, paramType&& aParam) {
+    WriteParam(aMsg, aParam.mLen);
+    // hand over ownership of the buffer to the Message
+    aMsg->WriteBytesZeroCopy(aParam.mData, aParam.mLen, aParam.mCapacity);
+    aParam.mData = nullptr;
+    aParam.mCapacity = 0;
+    aParam.mLen = 0;
+  }
+
+  static bool Read(const Message* aMsg, PickleIterator* aIter,
+                   paramType* aResult) {
+    // We make a copy from the BufferList so that we get a contigous result.
+    // For users the can handle a non-contiguous result using ExtractBuffers
+    // is an option, alternatively if the users don't need to take ownership of
+    // the data they can use the removed FlattenBytes (bug 1297981)
+    size_t length;
+    return ReadParam(aMsg, aIter, &length) && aResult->Allocate(length) &&
+           aMsg->ReadBytesInto(aIter, aResult->mData, length);
+  }
+
+  static void Log(const paramType& aParam, std::wstring* aLog) {
+    aLog->append(L"(byte buf)");
+  }
+};
+
+}  // namespace IPC
+
+#endif  // ifndef mozilla_ipc_ByteBufUtils_h