gecko-dev/ipc/mscom/Utils.h
Aaron Klotz b36ad40063 Bug 1570701: Part 1 - Add IsClassThreadAwareInprocServer utility function to MSCOM; r=Jamie
We want to ensure that the code being added in part 2 is only used when it is
reasonable and safe to do so. One way to ensure this is to add a check that the
desired CLSID is an in-process, thread-aware server.

Differential Revision: https://phabricator.services.mozilla.com/D44518

--HG--
extra : moz-landing-system : lando
2019-09-03 23:58:39 +00:00

126 lines
4.3 KiB
C++

/* -*- 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_Utils_h
#define mozilla_mscom_Utils_h
#if defined(MOZILLA_INTERNAL_API)
# include "nsString.h"
#endif // defined(MOZILLA_INTERNAL_API)
#include "mozilla/Attributes.h"
#include <guiddef.h>
struct IStream;
struct IUnknown;
namespace mozilla {
namespace mscom {
bool IsCOMInitializedOnCurrentThread();
bool IsCurrentThreadMTA();
bool IsCurrentThreadExplicitMTA();
bool IsCurrentThreadImplicitMTA();
bool IsProxy(IUnknown* aUnknown);
bool IsValidGUID(REFGUID aCheckGuid);
uintptr_t GetContainingModuleHandle();
/**
* Given a buffer, create a new IStream object.
* @param aBuf Buffer containing data to initialize the stream. This parameter
* may be nullptr, causing the stream to be created with aBufLen
* bytes of uninitialized data.
* @param aBufLen Length of data in aBuf, or desired stream size if aBuf is
* nullptr.
* @param aOutStream Outparam to receive the newly created stream.
* @return HRESULT error code.
*/
uint32_t CreateStream(const uint8_t* aBuf, const uint32_t aBufLen,
IStream** aOutStream);
/**
* Creates a deep copy of a proxy contained in a stream.
* @param aInStream Stream containing the proxy to copy. Its seek pointer must
* be positioned to point at the beginning of the proxy data.
* @param aOutStream Outparam to receive the newly created stream.
* @return HRESULT error code.
*/
uint32_t CopySerializedProxy(IStream* aInStream, IStream** aOutStream);
#if defined(MOZILLA_INTERNAL_API)
/**
* Checks the registry to see if |aClsid| is a thread-aware in-process server.
*
* In DCOM, an in-process server is a server that is implemented inside a DLL
* that is loaded into the client's process for execution. If |aClsid| declares
* itself to be a local server (that is, a server that resides in another
* process), this function returns false.
*
* For the server to be thread-aware, its registry entry must declare a
* ThreadingModel that is one of "Free", "Both", or "Neutral". If the threading
* model is "Apartment" or some other, invalid value, the class is treated as
* being single-threaded.
*
* NB: This function cannot check CLSIDs that were registered via manifests,
* as unfortunately there is not a documented API available to query for those.
* This should not be an issue for most CLSIDs that Gecko is interested in, as
* we typically instantiate system CLSIDs which are available in the registry.
*
* @param aClsid The CLSID of the COM class to be checked.
* @return true if the class meets the above criteria, otherwise false.
*/
bool IsClassThreadAwareInprocServer(REFCLSID aClsid);
void GUIDToString(REFGUID aGuid, nsAString& aOutString);
#endif // defined(MOZILLA_INTERNAL_API)
#if defined(ACCESSIBILITY)
bool IsVtableIndexFromParentInterface(REFIID aInterface,
unsigned long aVtableIndex);
# if defined(MOZILLA_INTERNAL_API)
bool IsCallerExternalProcess();
bool IsInterfaceEqualToOrInheritedFrom(REFIID aInterface, REFIID aFrom,
unsigned long aVtableIndexHint);
# endif // defined(MOZILLA_INTERNAL_API)
#endif // defined(ACCESSIBILITY)
/**
* Execute cleanup code when going out of scope if a condition is met.
* This is useful when, for example, particular cleanup needs to be performed
* whenever a call returns a failure HRESULT.
* Both the condition and cleanup code are provided as functions (usually
* lambdas).
*/
template <typename CondFnT, typename ExeFnT>
class MOZ_RAII ExecuteWhen final {
public:
ExecuteWhen(CondFnT& aCondFn, ExeFnT& aExeFn)
: mCondFn(aCondFn), mExeFn(aExeFn) {}
~ExecuteWhen() {
if (mCondFn()) {
mExeFn();
}
}
ExecuteWhen(const ExecuteWhen&) = delete;
ExecuteWhen(ExecuteWhen&&) = delete;
ExecuteWhen& operator=(const ExecuteWhen&) = delete;
ExecuteWhen& operator=(ExecuteWhen&&) = delete;
private:
CondFnT& mCondFn;
ExeFnT& mExeFn;
};
} // namespace mscom
} // namespace mozilla
#endif // mozilla_mscom_Utils_h