ipc/mscom/Utils.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_mscom_Utils_h
   8 #define mozilla_mscom_Utils_h
   9
  10 #if defined(MOZILLA_INTERNAL_API)
  11 #  include "nsString.h"
  12 #endif  // defined(MOZILLA_INTERNAL_API)
  13
  14 #include "mozilla/Attributes.h"
  15 #include <guiddef.h>
  16 #include <stdint.h>
  17
  18 struct IStream;
  19 struct IUnknown;
  20
  21 namespace mozilla {
  22 namespace mscom {
  23 namespace detail {
  24
  25 enum class GuidType {
  26   CLSID,
  27   AppID,
  28 };
  29
  30 long BuildRegGuidPath(REFGUID aGuid, const GuidType aGuidType, wchar_t* aBuf,
  31                       const size_t aBufLen);
  32
  33 }  // namespace detail
  34
  35 bool IsCOMInitializedOnCurrentThread();
  36 bool IsCurrentThreadMTA();
  37 bool IsCurrentThreadExplicitMTA();
  38 bool IsCurrentThreadImplicitMTA();
  39 #if defined(MOZILLA_INTERNAL_API)
  40 bool IsCurrentThreadNonMainMTA();
  41 #endif  // defined(MOZILLA_INTERNAL_API)
  42 bool IsProxy(IUnknown* aUnknown);
  43 bool IsValidGUID(REFGUID aCheckGuid);
  44 uintptr_t GetContainingModuleHandle();
  45
  46 template <size_t N>
  47 inline long BuildAppidPath(REFGUID aAppId, wchar_t (&aPath)[N]) {
  48   return detail::BuildRegGuidPath(aAppId, detail::GuidType::AppID, aPath, N);
  49 }
  50
  51 template <size_t N>
  52 inline long BuildClsidPath(REFCLSID aClsid, wchar_t (&aPath)[N]) {
  53   return detail::BuildRegGuidPath(aClsid, detail::GuidType::CLSID, aPath, N);
  54 }
  55
  56 /**
  57  * Given a buffer, create a new IStream object.
  58  * @param aBuf Buffer containing data to initialize the stream. This parameter
  59  *             may be nullptr, causing the stream to be created with aBufLen
  60  *             bytes of uninitialized data.
  61  * @param aBufLen Length of data in aBuf, or desired stream size if aBuf is
  62  *                nullptr.
  63  * @param aOutStream Outparam to receive the newly created stream.
  64  * @return HRESULT error code.
  65  */
  66 long CreateStream(const uint8_t* aBuf, const uint32_t aBufLen,
  67                   IStream** aOutStream);
  68
  69 /**
  70  * Length of a stringified GUID as formatted for the registry, i.e. including
  71  * curly-braces and dashes.
  72  */
  73 constexpr size_t kGuidRegFormatCharLenInclNul = 39;
  74
  75 #if defined(MOZILLA_INTERNAL_API)
  76 /**
  77  * Checks the registry to see if |aClsid| is a thread-aware in-process server.
  78  *
  79  * In DCOM, an in-process server is a server that is implemented inside a DLL
  80  * that is loaded into the client's process for execution. If |aClsid| declares
  81  * itself to be a local server (that is, a server that resides in another
  82  * process), this function returns false.
  83  *
  84  * For the server to be thread-aware, its registry entry must declare a
  85  * ThreadingModel that is one of "Free", "Both", or "Neutral". If the threading
  86  * model is "Apartment" or some other, invalid value, the class is treated as
  87  * being single-threaded.
  88  *
  89  * NB: This function cannot check CLSIDs that were registered via manifests,
  90  * as unfortunately there is not a documented API available to query for those.
  91  * This should not be an issue for most CLSIDs that Gecko is interested in, as
  92  * we typically instantiate system CLSIDs which are available in the registry.
  93  *
  94  * @param aClsid The CLSID of the COM class to be checked.
  95  * @return true if the class meets the above criteria, otherwise false.
  96  */
  97 bool IsClassThreadAwareInprocServer(REFCLSID aClsid);
  98
  99 void GUIDToString(REFGUID aGuid, nsAString& aOutString);
 100
 101 /**
 102  * Converts an IID to a human-readable string for the purposes of diagnostic
 103  * tools such as the profiler. For some special cases, we output a friendly
 104  * string that describes the purpose of the interface. If no such description
 105  * exists, we simply fall back to outputting the IID as a string formatted by
 106  * GUIDToString().
 107  */
 108 void DiagnosticNameForIID(REFIID aIid, nsACString& aOutString);
 109 #else
 110 void GUIDToString(REFGUID aGuid,
 111                   wchar_t (&aOutBuf)[kGuidRegFormatCharLenInclNul]);
 112 #endif  // defined(MOZILLA_INTERNAL_API)
 113
 114 /**
 115  * Execute cleanup code when going out of scope if a condition is met.
 116  * This is useful when, for example, particular cleanup needs to be performed
 117  * whenever a call returns a failure HRESULT.
 118  * Both the condition and cleanup code are provided as functions (usually
 119  * lambdas).
 120  */
 121 template <typename CondFnT, typename ExeFnT>
 122 class MOZ_RAII ExecuteWhen final {
 123  public:
 124   ExecuteWhen(CondFnT& aCondFn, ExeFnT& aExeFn)
 125       : mCondFn(aCondFn), mExeFn(aExeFn) {}
 126
 127   ~ExecuteWhen() {
 128     if (mCondFn()) {
 129       mExeFn();
 130     }
 131   }
 132
 133   ExecuteWhen(const ExecuteWhen&) = delete;
 134   ExecuteWhen(ExecuteWhen&&) = delete;
 135   ExecuteWhen& operator=(const ExecuteWhen&) = delete;
 136   ExecuteWhen& operator=(ExecuteWhen&&) = delete;
 137
 138  private:
 139   CondFnT& mCondFn;
 140   ExeFnT& mExeFn;
 141 };
 142
 143 }  // namespace mscom
 144 }  // namespace mozilla
 145
 146 #endif  // mozilla_mscom_Utils_h