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/* -*- 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
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