Bug 781256 - 'Share FileDescriptors across processes in preparation for OS-level sandbox'. r=khuey+cjones.

ipc/glue/InputStreamUtils.cpp

@@ -0,0 +1,79 @@
+/* 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 "InputStreamUtils.h"
+
+#include "nsIIPCSerializableInputStream.h"
+
+#include "mozilla/Assertions.h"
+#include "nsComponentManagerUtils.h"
+#include "nsDebug.h"
+#include "nsID.h"
+#include "nsMultiplexInputStream.h"
+#include "nsNetCID.h"
+#include "nsStringStream.h"
+#include "nsThreadUtils.h"
+
+using namespace mozilla::ipc;
+
+namespace {
+
+NS_DEFINE_CID(kStringInputStreamCID, NS_STRINGINPUTSTREAM_CID);
+NS_DEFINE_CID(kFileInputStreamCID, NS_LOCALFILEINPUTSTREAM_CID);
+NS_DEFINE_CID(kPartialFileInputStreamCID, NS_PARTIALLOCALFILEINPUTSTREAM_CID);
+NS_DEFINE_CID(kMultiplexInputStreamCID, NS_MULTIPLEXINPUTSTREAM_CID);
+
+} // anonymous namespace
+
+namespace mozilla {
+namespace ipc {
+
+already_AddRefed<nsIInputStream>
+DeserializeInputStream(const InputStreamParams& aParams)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  nsCOMPtr<nsIIPCSerializableInputStream> serializable;
+
+  switch (aParams.type()) {
+    case InputStreamParams::T__None:
+      NS_WARNING("This union has no type!");
+      return nullptr;
+
+    case InputStreamParams::TStringInputStreamParams:
+      serializable = do_CreateInstance(kStringInputStreamCID);
+      break;
+
+    case InputStreamParams::TFileInputStreamParams:
+      serializable = do_CreateInstance(kFileInputStreamCID);
+      break;
+
+    case InputStreamParams::TPartialFileInputStreamParams:
+      serializable = do_CreateInstance(kPartialFileInputStreamCID);
+      break;
+
+    case InputStreamParams::TMultiplexInputStreamParams:
+      serializable = do_CreateInstance(kMultiplexInputStreamCID);
+      break;
+
+    default:
+      NS_WARNING("Unknown params!");
+      return nullptr;
+  }
+
+  MOZ_ASSERT(serializable);
+
+  if (!serializable->Deserialize(aParams)) {
+    NS_WARNING("Deserialize failed!");
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIInputStream> stream = do_QueryInterface(serializable);
+  MOZ_ASSERT(stream);
+
+  return stream.forget();
+}
+
+} // namespace ipc
+} // namespace mozilla