1 files changed, 239 insertions, 0 deletions
diff --git a/ipc/mscom/StructStream.h b/ipc/mscom/StructStream.h
new file mode 100644
index 0000000000..45a32c7687
--- /dev/null
+++ b/ipc/mscom/StructStream.h
@@ -0,0 +1,239 @@
+/* -*- 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/. */
+
+#ifndef mozilla_mscom_StructStream_h
+#define mozilla_mscom_StructStream_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/UniquePtr.h"
+#include "nscore.h"
+
+#include <memory.h>
+#include <midles.h>
+#include <objidl.h>
+#include <rpc.h>
+
+/**
+ * This code is used for (de)serializing data structures that have been
+ * declared using midl, thus allowing us to use Microsoft RPC for marshaling
+ * data for our COM handlers that may run in other processes that are not ours.
+ */
+
+namespace mozilla {
+namespace mscom {
+
+namespace detail {
+
+typedef ULONG EncodedLenT;
+
+}  // namespace detail
+
+class MOZ_NON_TEMPORARY_CLASS StructToStream {
+ public:
+  /**
+   * This constructor variant represents an empty/null struct to be serialized.
+   */
+  StructToStream()
+      : mStatus(RPC_S_OK), mHandle(nullptr), mBuffer(nullptr), mEncodedLen(0) {}
+
+  template <typename StructT>
+  StructToStream(StructT& aSrcStruct, void (*aEncodeFnPtr)(handle_t, StructT*))
+      : mStatus(RPC_X_INVALID_BUFFER),
+        mHandle(nullptr),
+        mBuffer(nullptr),
+        mEncodedLen(0) {
+    mStatus =
+        ::MesEncodeDynBufferHandleCreate(&mBuffer, &mEncodedLen, &mHandle);
+    if (mStatus != RPC_S_OK) {
+      return;
+    }
+
+    MOZ_SEH_TRY { aEncodeFnPtr(mHandle, &aSrcStruct); }
+#ifdef HAVE_SEH_EXCEPTIONS
+    MOZ_SEH_EXCEPT(EXCEPTION_EXECUTE_HANDLER) {
+      mStatus = ::RpcExceptionCode();
+      return;
+    }
+#endif
+
+    if (!mBuffer || !mEncodedLen) {
+      mStatus = RPC_X_NO_MEMORY;
+      return;
+    }
+  }
+
+  ~StructToStream() {
+    if (mHandle) {
+      ::MesHandleFree(mHandle);
+    }
+    if (mBuffer) {
+      // Bug 1440564: You'd think that MesHandleFree would free the buffer,
+      // since it was created by RPC, but it doesn't.
+      midl_user_free(mBuffer);
+    }
+  }
+
+  static unsigned long GetEmptySize() { return sizeof(detail::EncodedLenT); }
+
+  static HRESULT WriteEmpty(IStream* aDestStream) {
+    StructToStream emptyStruct;
+    return emptyStruct.Write(aDestStream);
+  }
+
+  explicit operator bool() const { return mStatus == RPC_S_OK; }
+
+  bool IsEmpty() const { return mStatus == RPC_S_OK && !mEncodedLen; }
+
+  unsigned long GetSize() const { return sizeof(mEncodedLen) + mEncodedLen; }
+
+  HRESULT Write(IStream* aDestStream) {
+    if (!aDestStream) {
+      return E_INVALIDARG;
+    }
+    if (mStatus != RPC_S_OK) {
+      return E_FAIL;
+    }
+
+    ULONG bytesWritten;
+    HRESULT hr =
+        aDestStream->Write(&mEncodedLen, sizeof(mEncodedLen), &bytesWritten);
+    if (FAILED(hr)) {
+      return hr;
+    }
+    if (bytesWritten != sizeof(mEncodedLen)) {
+      return E_UNEXPECTED;
+    }
+
+    if (mBuffer && mEncodedLen) {
+      hr = aDestStream->Write(mBuffer, mEncodedLen, &bytesWritten);
+      if (FAILED(hr)) {
+        return hr;
+      }
+      if (bytesWritten != mEncodedLen) {
+        return E_UNEXPECTED;
+      }
+    }
+
+    return hr;
+  }
+
+  StructToStream(const StructToStream&) = delete;
+  StructToStream(StructToStream&&) = delete;
+  StructToStream& operator=(const StructToStream&) = delete;
+  StructToStream& operator=(StructToStream&&) = delete;
+
+ private:
+  RPC_STATUS mStatus;
+  handle_t mHandle;
+  char* mBuffer;
+  detail::EncodedLenT mEncodedLen;
+};
+
+class MOZ_NON_TEMPORARY_CLASS StructFromStream {
+  struct AlignedFreeDeleter {
+    void operator()(void* aPtr) { ::_aligned_free(aPtr); }
+  };
+
+  static const detail::EncodedLenT kRpcReqdBufAlignment = 8;
+
+ public:
+  explicit StructFromStream(IStream* aStream)
+      : mStatus(RPC_X_INVALID_BUFFER), mHandle(nullptr) {
+    MOZ_ASSERT(aStream);
+
+    // Read the length of the encoded data first
+    detail::EncodedLenT encodedLen = 0;
+    ULONG bytesRead = 0;
+    HRESULT hr = aStream->Read(&encodedLen, sizeof(encodedLen), &bytesRead);
+    if (FAILED(hr)) {
+      return;
+    }
+
+    // NB: Some implementations of IStream return S_FALSE to indicate EOF,
+    // other implementations return S_OK and set the number of bytes read to 0.
+    // We must handle both.
+    if (hr == S_FALSE || !bytesRead) {
+      mStatus = RPC_S_OBJECT_NOT_FOUND;
+      return;
+    }
+
+    if (bytesRead != sizeof(encodedLen)) {
+      return;
+    }
+
+    if (!encodedLen) {
+      mStatus = RPC_S_OBJECT_NOT_FOUND;
+      return;
+    }
+
+    MOZ_ASSERT(encodedLen % kRpcReqdBufAlignment == 0);
+    if (encodedLen % kRpcReqdBufAlignment) {
+      return;
+    }
+
+    // This memory allocation is fallible
+    mEncodedBuffer.reset(static_cast<char*>(
+        ::_aligned_malloc(encodedLen, kRpcReqdBufAlignment)));
+    if (!mEncodedBuffer) {
+      return;
+    }
+
+    ULONG bytesReadFromStream = 0;
+    hr = aStream->Read(mEncodedBuffer.get(), encodedLen, &bytesReadFromStream);
+    if (FAILED(hr) || bytesReadFromStream != encodedLen) {
+      return;
+    }
+
+    mStatus = ::MesDecodeBufferHandleCreate(mEncodedBuffer.get(), encodedLen,
+                                            &mHandle);
+  }
+
+  ~StructFromStream() {
+    if (mHandle) {
+      ::MesHandleFree(mHandle);
+    }
+  }
+
+  explicit operator bool() const { return mStatus == RPC_S_OK || IsEmpty(); }
+
+  bool IsEmpty() const { return mStatus == RPC_S_OBJECT_NOT_FOUND; }
+
+  template <typename StructT>
+  bool Read(StructT* aDestStruct, void (*aDecodeFnPtr)(handle_t, StructT*)) {
+    if (!aDestStruct || !aDecodeFnPtr || mStatus != RPC_S_OK) {
+      return false;
+    }
+
+    // NB: Deserialization will fail with BSTRs unless the destination data
+    //     is zeroed out!
+    ZeroMemory(aDestStruct, sizeof(StructT));
+
+    MOZ_SEH_TRY { aDecodeFnPtr(mHandle, aDestStruct); }
+#ifdef HAVE_SEH_EXCEPTIONS
+    MOZ_SEH_EXCEPT(EXCEPTION_EXECUTE_HANDLER) {
+      mStatus = ::RpcExceptionCode();
+      return false;
+    }
+#endif
+
+    return true;
+  }
+
+  StructFromStream(const StructFromStream&) = delete;
+  StructFromStream(StructFromStream&&) = delete;
+  StructFromStream& operator=(const StructFromStream&) = delete;
+  StructFromStream& operator=(StructFromStream&&) = delete;
+
+ private:
+  RPC_STATUS mStatus;
+  handle_t mHandle;
+  UniquePtr<char, AlignedFreeDeleter> mEncodedBuffer;
+};
+
+}  // namespace mscom
+}  // namespace mozilla
+
+#endif  // mozilla_mscom_StructStream_h