26 files changed, 380 insertions, 149 deletions

diff --git a/src/burn/engine/apply.cpp b/src/burn/engine/apply.cpp
index e5b978f1..dd99a5cd 100644
--- a/src/burn/engine/apply.cpp
+++ b/src/burn/engine/apply.cpp
@@ -2333,6 +2333,8 @@ static HRESULT DoExecuteAction(
 
     HRESULT hr = S_OK;
     HANDLE rghWait[2] = { };
+    DWORD dwSignaledIndex = 0;
+    DWORD dwExitCode = 0;
     BOOTSTRAPPER_APPLY_RESTART restart = BOOTSTRAPPER_APPLY_RESTART_NONE;
     BOOL fRetry = FALSE;
     BOOL fStopWusaService = FALSE;
@@ -2356,27 +2358,23 @@ static HRESULT DoExecuteAction(
             // wait for cache sync-point
             rghWait[0] = pExecuteAction->waitCachePackage.pPackage->hCacheEvent;
             rghWait[1] = pContext->pApplyContext->hCacheThread;
-            switch (::WaitForMultipleObjects(rghWait[1] ? 2 : 1, rghWait, FALSE, INFINITE))
+
+            hr = AppWaitForMultipleObjects(rghWait[1] ? 2 : 1, rghWait, FALSE, INFINITE, &dwSignaledIndex);
+            ExitOnFailure(hr, "Failed to wait for cache check-point.");
+
+            switch (dwSignaledIndex)
             {
-            case WAIT_OBJECT_0:
+            case 0:
                 break;
-
-            case WAIT_OBJECT_0 + 1:
-                if (!::GetExitCodeThread(pContext->pApplyContext->hCacheThread, (DWORD*)&hr))
+            case 1:
+                if (!::GetExitCodeThread(pContext->pApplyContext->hCacheThread, &dwExitCode))
                 {
                     ExitWithLastError(hr, "Failed to get cache thread exit code.");
                 }
 
-                if (SUCCEEDED(hr))
-                {
-                    hr = E_UNEXPECTED;
-                }
-                ExitOnFailure(hr, "Cache thread exited unexpectedly.");
-
-            case WAIT_FAILED: __fallthrough;
-            default:
-                ExitWithLastError(hr, "Failed to wait for cache check-point.");
+                ExitWithRootFailure(hr, E_UNEXPECTED, "Cache thread exited unexpectedly with exit code: %u.", dwExitCode);
             }
+
             break;
 
         case BURN_EXECUTE_ACTION_TYPE_RELATED_BUNDLE:
diff --git a/src/burn/engine/cabextract.cpp b/src/burn/engine/cabextract.cpp
index 5a02ff8a..56146a39 100644
--- a/src/burn/engine/cabextract.cpp
+++ b/src/burn/engine/cabextract.cpp
@@ -262,10 +262,8 @@ extern "C" HRESULT CabExtractClose(
         }
 
         // wait for thread to terminate
-        if (WAIT_OBJECT_0 != ::WaitForSingleObject(pContext->Cabinet.hThread, INFINITE))
-        {
-            ExitWithLastError(hr, "Failed to wait for thread to terminate.");
-        }
+        hr = AppWaitForSingleObject(pContext->Cabinet.hThread, INFINITE);
+        ExitOnFailure(hr, "Failed to wait for thread to terminate.");
     }
 
 LExit:
@@ -306,29 +304,31 @@ static HRESULT WaitForOperation(
 {
     HRESULT hr = S_OK;
     HANDLE rghWait[2] = { };
+    DWORD dwSignaledIndex = 0;
 
     // wait for operation complete event
     rghWait[0] = pContext->Cabinet.hOperationCompleteEvent;
     rghWait[1] = pContext->Cabinet.hThread;
-    switch (::WaitForMultipleObjects(countof(rghWait), rghWait, FALSE, INFINITE))
+
+    hr = AppWaitForMultipleObjects(countof(rghWait), rghWait, FALSE, INFINITE, &dwSignaledIndex);
+    ExitOnFailure(hr, "Failed to wait for operation complete event.");
+
+    switch (dwSignaledIndex)
     {
-    case WAIT_OBJECT_0:
+    case 0:
         if (!::ResetEvent(pContext->Cabinet.hOperationCompleteEvent))
         {
             ExitWithLastError(hr, "Failed to reset operation complete event.");
         }
-        break;
 
-    case WAIT_OBJECT_0 + 1:
+        break;
+    case 1:
         if (!::GetExitCodeThread(pContext->Cabinet.hThread, (DWORD*)&hr))
         {
             ExitWithLastError(hr, "Failed to get extraction thread exit code.");
         }
-        ExitFunction();
 
-    case WAIT_FAILED: __fallthrough;
-    default:
-        ExitWithLastError(hr, "Failed to wait for operation complete event.");
+        ExitFunction();
     }
 
     // clear operation
@@ -430,10 +430,8 @@ static DWORD WINAPI ExtractThreadProc(
     }
 
     // wait for begin operation event
-    if (WAIT_FAILED == ::WaitForSingleObject(pContext->Cabinet.hBeginOperationEvent, INFINITE))
-    {
-        ExitWithLastError(hr, "Failed to wait for begin operation event.");
-    }
+    hr = AppWaitForSingleObject(pContext->Cabinet.hBeginOperationEvent, INFINITE);
+    ExitOnFailure(hr, "Failed to wait for begin operation event.");
 
     if (!::ResetEvent(pContext->Cabinet.hBeginOperationEvent))
     {
@@ -517,10 +515,8 @@ static INT_PTR CopyFileCallback(
     }
 
     // wait for begin operation event
-    if (WAIT_FAILED == ::WaitForSingleObject(pContext->Cabinet.hBeginOperationEvent, INFINITE))
-    {
-        ExitWithLastError(hr, "Failed to wait for begin operation event.");
-    }
+    hr = AppWaitForSingleObject(pContext->Cabinet.hBeginOperationEvent, INFINITE);
+    ExitOnFailure(hr, "Failed to wait for begin operation event.");
 
     if (!::ResetEvent(pContext->Cabinet.hBeginOperationEvent))
     {
@@ -552,10 +548,8 @@ static INT_PTR CopyFileCallback(
     }
 
     // wait for begin operation event
-    if (WAIT_FAILED == ::WaitForSingleObject(pContext->Cabinet.hBeginOperationEvent, INFINITE))
-    {
-        ExitWithLastError(hr, "Failed to wait for begin operation event.");
-    }
+    hr = AppWaitForSingleObject(pContext->Cabinet.hBeginOperationEvent, INFINITE);
+    ExitOnFailure(hr, "Failed to wait for begin operation event.");
 
     if (!::ResetEvent(pContext->Cabinet.hBeginOperationEvent))
     {
diff --git a/src/burn/engine/core.cpp b/src/burn/engine/core.cpp
index c1e3a12c..716e5af1 100644
--- a/src/burn/engine/core.cpp
+++ b/src/burn/engine/core.cpp
@@ -12,6 +12,9 @@ struct BURN_CACHE_THREAD_CONTEXT
 };
 
 
+static PFN_PROCWAITFORCOMPLETION vpfnProcWaitForCompletion = ProcWaitForCompletion;
+
+
 // internal function declarations
 
 static HRESULT CoreRecreateCommandLine(
@@ -65,9 +68,6 @@ static HRESULT DetectPackagePayloadsCached(
 static DWORD WINAPI CacheThreadProc(
     __in LPVOID lpThreadParameter
     );
-static HRESULT WaitForCacheThread(
-    __in HANDLE hCacheThread
-    );
 static void LogPackages(
     __in_opt const BURN_PACKAGE* pUpgradeBundlePackage,
     __in_opt const BURN_PACKAGE* pForwardCompatibleBundlePackage,
@@ -636,6 +636,7 @@ extern "C" HRESULT CoreApply(
     BURN_APPLY_CONTEXT applyContext = { };
     BOOL fDeleteApplyCs = FALSE;
     BURN_CACHE_THREAD_CONTEXT cacheThreadContext = { };
+    DWORD dwCacheExitCode = 0;
     BOOL fRollbackCache = FALSE;
     DWORD dwPhaseCount = 0;
     BOOTSTRAPPER_APPLYCOMPLETE_ACTION applyCompleteAction = BOOTSTRAPPER_APPLYCOMPLETE_ACTION_NONE;
@@ -744,7 +745,10 @@ extern "C" HRESULT CoreApply(
         // If we're not caching in parallel, wait for the cache thread to terminate.
         if (!pEngineState->fParallelCacheAndExecute)
         {
-            hr = WaitForCacheThread(applyContext.hCacheThread);
+            hr = ThrdWaitForCompletion(applyContext.hCacheThread, INFINITE, &dwCacheExitCode);
+            ExitOnFailure(hr, "Failed to wait for cache thread before execute.");
+
+            hr = (HRESULT)dwCacheExitCode;
             ExitOnFailure(hr, "Failed while caching, aborting execution.");
 
             ReleaseHandle(applyContext.hCacheThread);
@@ -761,10 +765,12 @@ extern "C" HRESULT CoreApply(
     // Wait for cache thread to terminate, this should return immediately unless we're waiting for layout to complete.
     if (applyContext.hCacheThread)
     {
-        HRESULT hrCached = WaitForCacheThread(applyContext.hCacheThread);
+        HRESULT hrCached = ThrdWaitForCompletion(applyContext.hCacheThread, INFINITE, &dwCacheExitCode);
+        ExitOnFailure(hrCached, "Failed to wait for cache thread after execute.");
+
         if (SUCCEEDED(hr))
         {
-            hr = hrCached;
+            hr = (HRESULT)dwCacheExitCode;
         }
     }
 
@@ -1940,6 +1946,22 @@ LExit:
     return hr;
 }
 
+extern "C" void CoreFunctionOverride(
+    __in_opt PFN_PROCWAITFORCOMPLETION pfnProcWaitForCompletion
+    )
+{
+    vpfnProcWaitForCompletion = pfnProcWaitForCompletion;
+}
+
+extern "C" HRESULT DAPI CoreWaitForProcCompletion(
+    __in HANDLE hProcess,
+    __in DWORD dwTimeout,
+    __out DWORD* pdwReturnCode
+    )
+{
+    return vpfnProcWaitForCompletion(hProcess, dwTimeout, pdwReturnCode);
+}
+
 // internal helper functions
 
 static HRESULT AppendEscapedArgumentToCommandLine(
@@ -2268,26 +2290,6 @@ LExit:
     return (DWORD)hr;
 }
 
-static HRESULT WaitForCacheThread(
-    __in HANDLE hCacheThread
-    )
-{
-    HRESULT hr = S_OK;
-
-    if (WAIT_OBJECT_0 != ::WaitForSingleObject(hCacheThread, INFINITE))
-    {
-        ExitWithLastError(hr, "Failed to wait for cache thread to terminate.");
-    }
-
-    if (!::GetExitCodeThread(hCacheThread, (DWORD*)&hr))
-    {
-        ExitWithLastError(hr, "Failed to get cache thread exit code.");
-    }
-
-LExit:
-    return hr;
-}
-
 static void LogPackages(
     __in_opt const BURN_PACKAGE* pUpgradeBundlePackage,
     __in_opt const BURN_PACKAGE* pForwardCompatibleBundlePackage,
diff --git a/src/burn/engine/core.h b/src/burn/engine/core.h
index 28d7ea78..14dbabcc 100644
--- a/src/burn/engine/core.h
+++ b/src/burn/engine/core.h
@@ -174,6 +174,12 @@ typedef struct _BURN_APPLY_CONTEXT
     DWORD dwCacheCheckpoint;
 } BURN_APPLY_CONTEXT;
 
+typedef HRESULT (DAPI *PFN_PROCWAITFORCOMPLETION)(
+    __in HANDLE hProcess,
+    __in DWORD dwTimeout,
+    __out DWORD* pReturnCode
+    );
+
 
 // function declarations
 
@@ -280,6 +286,14 @@ HRESULT CoreParseCommandLine(
     __inout HANDLE* phSectionFile,
     __inout HANDLE* phSourceEngineFile
     );
+void CoreFunctionOverride(
+    __in_opt PFN_PROCWAITFORCOMPLETION pfnProcWaitForCompletion
+    );
+HRESULT DAPI CoreWaitForProcCompletion(
+    __in HANDLE hProcess,
+    __in DWORD dwTimeout,
+    __out_opt DWORD* pdwReturnCode
+    );
 
 #if defined(__cplusplus)
 }
diff --git a/src/burn/engine/elevation.cpp b/src/burn/engine/elevation.cpp
index 4a5be8ec..e165a257 100644
--- a/src/burn/engine/elevation.cpp
+++ b/src/burn/engine/elevation.cpp
@@ -1687,15 +1687,8 @@ static HRESULT WaitForElevatedChildCacheThread(
     HRESULT hr = S_OK;
     DWORD dwExitCode = ERROR_SUCCESS;
 
-    if (WAIT_OBJECT_0 != ::WaitForSingleObject(hCacheThread, BURN_TIMEOUT))
-    {
-        ExitWithLastError(hr, "Failed to wait for cache thread to terminate.");
-    }
-
-    if (!::GetExitCodeThread(hCacheThread, &dwExitCode))
-    {
-        ExitWithLastError(hr, "Failed to get cache thread exit code.");
-    }
+    hr = ThrdWaitForCompletion(hCacheThread, BURN_TIMEOUT, &dwExitCode);
+    ExitOnFailure(hr, "Failed to wait for cache thread to complete.");
 
     AssertSz(dwExitCode == dwExpectedExitCode, "Cache thread should have exited with the expected exit code.");
 
diff --git a/src/burn/engine/netfxchainer.cpp b/src/burn/engine/netfxchainer.cpp
index 6f223eed..68ddb093 100644
--- a/src/burn/engine/netfxchainer.cpp
+++ b/src/burn/engine/netfxchainer.cpp
@@ -338,7 +338,8 @@ extern "C" HRESULT NetFxRunChainer(
     )
 {
     HRESULT hr = S_OK;
-    DWORD er = 0;
+    DWORD dwSignaledIndex = 0;
+    BOOL fTimedOut = 0;
     WCHAR wzGuid[GUID_STRING_LENGTH];
     LPWSTR sczEventName = NULL;
     LPWSTR sczSectionName = NULL;
@@ -381,9 +382,17 @@ extern "C" HRESULT NetFxRunChainer(
 
     for (;;)
     {
-        er = ::WaitForMultipleObjects(2, handles, FALSE, 100);
-        if (WAIT_OBJECT_0 == er)
+        hr = AppWaitForMultipleObjects(2, handles, FALSE, 100, &dwSignaledIndex);
+        ExitOnWaitObjectFailure(hr, fTimedOut, "Failed to wait for netfx chainer process to complete");
+
+        if (fTimedOut)
+        {
+            continue;
+        }
+
+        switch (dwSignaledIndex)
         {
+        case 0:
             // Process has exited
             *pdwExitCode = NetFxGetResult(pNetfxChainer, &hrInternalError);
             if (E_PENDING == *pdwExitCode)
@@ -396,21 +405,17 @@ extern "C" HRESULT NetFxRunChainer(
             else if (FAILED(hrInternalError))
             {
                 // push internal error message
-                OnNetFxError(pNetfxChainer, hrInternalError, pfnGenericMessageHandler, pvContext);
+                hr = OnNetFxError(pNetfxChainer, hrInternalError, pfnGenericMessageHandler, pvContext);
                 ExitOnFailure(hr, "Failed to send internal error message from netfx chainer.");
-            }           
+            }
 
-            break;
-        }
-        else if (WAIT_OBJECT_0 + 1 == er)
-        {
+            ExitFunction();
+        case 1:
             // Chainee has notified us of a change.
             hr = ProcessNetFxMessage(pNetfxChainer, pfnGenericMessageHandler, pvContext);
             ExitOnFailure(hr, "Failed to process netfx chainer message.");
-        }
-        else if (WAIT_FAILED == er)
-        {
-            ExitWithLastError(hr, "Failed to wait for netfx chainer process to complete");
+
+            break;
         }
     }
 
diff --git a/src/burn/engine/pipe.cpp b/src/burn/engine/pipe.cpp
index e6c9905b..9529ef40 100644
--- a/src/burn/engine/pipe.cpp
+++ b/src/burn/engine/pipe.cpp
@@ -422,6 +422,7 @@ extern "C" HRESULT PipeTerminateChildProcess(
     HRESULT hr = S_OK;
     BYTE* pbData = NULL;
     SIZE_T cbData = 0;
+    BOOL fTimedOut = FALSE;
 
     // Prepare the exit message.
     hr = BuffWriteNumber(&pbData, &cbData, dwParentExitCode);
@@ -443,31 +444,28 @@ extern "C" HRESULT PipeTerminateChildProcess(
     // If we were able to get a handle to the other process, wait for it to exit.
     if (pConnection->hProcess)
     {
-        if (WAIT_FAILED == ::WaitForSingleObject(pConnection->hProcess, PIPE_WAIT_FOR_CONNECTION * PIPE_RETRY_FOR_CONNECTION))
-        {
-            ExitWithLastError(hr, "Failed to wait for child process exit.");
-        }
+        hr = AppWaitForSingleObject(pConnection->hProcess, PIPE_WAIT_FOR_CONNECTION * PIPE_RETRY_FOR_CONNECTION);
+        ExitOnWaitObjectFailure(hr, fTimedOut, "Failed to wait for child process exit.");
+
+        AssertSz(!fTimedOut, "Timed out while waiting for child process to exit.");
+    }
 
 #ifdef DEBUG
+    if (pConnection->hProcess && !fTimedOut)
+    {
         DWORD dwChildExitCode = 0;
-        DWORD dwErrorCode = ERROR_SUCCESS;
-        BOOL fReturnedExitCode = ::GetExitCodeProcess(pConnection->hProcess, &dwChildExitCode);
-        if (!fReturnedExitCode)
-        {
-            dwErrorCode = ::GetLastError(); // if the other process is elevated and we are not, then we'll get ERROR_ACCESS_DENIED.
+        HRESULT hrDebug = S_OK;
 
-            // The unit test use a thread instead of a process so try to get the exit code from
-            // the thread because we failed to get it from the process.
-            if (ERROR_INVALID_HANDLE == dwErrorCode)
-            {
-                fReturnedExitCode = ::GetExitCodeThread(pConnection->hProcess, &dwChildExitCode);
-            }
+        hrDebug = CoreWaitForProcCompletion(pConnection->hProcess, 0, &dwChildExitCode);
+        if (E_ACCESSDENIED != hrDebug) // if the other process is elevated and we are not, then we'll get ERROR_ACCESS_DENIED.
+        {
+            TraceError(hrDebug, "Failed to wait for child process completion.");
         }
-        AssertSz((fReturnedExitCode && dwChildExitCode == dwParentExitCode) ||
-                 (!fReturnedExitCode && ERROR_ACCESS_DENIED == dwErrorCode),
+
+        AssertSz(E_ACCESSDENIED == hrDebug || dwChildExitCode == dwParentExitCode,
                  "Child elevated process did not return matching exit code to parent process.");
-#endif
     }
+#endif
 
 LExit:
     return hr;
diff --git a/src/burn/engine/precomp.h b/src/burn/engine/precomp.h
index bc7046f6..e2d1b5cd 100644
--- a/src/burn/engine/precomp.h
+++ b/src/burn/engine/precomp.h
@@ -46,6 +46,7 @@
 #include <srputil.h>
 #include <strutil.h>
 #include <svcutil.h>
+#include <thrdutil.h>
 #include <userutil.h>
 #include <wiutil.h>
 #include <wuautil.h>
diff --git a/src/burn/test/BurnUnitTest/ElevationTest.cpp b/src/burn/test/BurnUnitTest/ElevationTest.cpp
index 97d76b7d..ce34b4b1 100644
--- a/src/burn/test/BurnUnitTest/ElevationTest.cpp
+++ b/src/burn/test/BurnUnitTest/ElevationTest.cpp
@@ -54,7 +54,6 @@ namespace Bootstrapper
             HRESULT hr = S_OK;
             BURN_ENGINE_STATE engineState = { };
             BURN_PIPE_CONNECTION* pConnection = &engineState.companionConnection;
-            HANDLE hEvent = NULL;
             DWORD dwResult = S_OK;
 
             engineState.sczBundleEngineWorkingPath = L"tests\\ignore\\this\\path\\to\\burn.exe";
@@ -62,6 +61,7 @@ namespace Bootstrapper
             try
             {
                 ShelFunctionOverride(ElevateTest_ShellExecuteExW);
+                CoreFunctionOverride(ThrdWaitForCompletion);
 
                 PipeConnectionInitialize(pConnection);
 
@@ -87,7 +87,6 @@ namespace Bootstrapper
             finally
             {
                 PipeConnectionUninitialize(pConnection);
-                ReleaseHandle(hEvent);
             }
         }
     };
diff --git a/src/burn/test/BurnUnitTest/precomp.h b/src/burn/test/BurnUnitTest/precomp.h
index 92c8c4c0..69c62cb2 100644
--- a/src/burn/test/BurnUnitTest/precomp.h
+++ b/src/burn/test/BurnUnitTest/precomp.h
@@ -28,6 +28,7 @@
 #include <resrutil.h>
 #include <shelutil.h>
 #include <strutil.h>
+#include <thrdutil.h>
 #include <wiutil.h>
 #include <xmlutil.h>
 #include <dictutil.h>
diff --git a/src/libs/dutil/WixToolset.DUtil/apputil.cpp b/src/libs/dutil/WixToolset.DUtil/apputil.cpp
index 9e75082a..42f589dc 100644
--- a/src/libs/dutil/WixToolset.DUtil/apputil.cpp
+++ b/src/libs/dutil/WixToolset.DUtil/apputil.cpp
@@ -313,6 +313,74 @@ LExit:
     return hr;
 }
 
+DAPI_(HRESULT) AppWaitForSingleObject(
+    __in HANDLE hHandle,
+    __in DWORD dwMilliseconds
+    )
+{
+    HRESULT hr = S_OK;
+    DWORD dwResult = 0;
+
+    dwResult = ::WaitForSingleObject(hHandle, dwMilliseconds);
+    if (WAIT_TIMEOUT == dwResult)
+    {
+        ExitFunction1(hr = HRESULT_FROM_WIN32(dwResult));
+    }
+    else if (WAIT_ABANDONED == dwResult)
+    {
+        AppExitOnWin32Error(dwResult, hr, "Abandoned wait for single object.");
+    }
+    else if (WAIT_OBJECT_0 != dwResult)
+    {
+        AssertSz(WAIT_FAILED == dwResult, "Unexpected return code from WaitForSingleObject.");
+        AppExitWithLastError(hr, "Failed to wait for single object.");
+    }
+
+LExit:
+    return hr;
+}
+
+DAPI_(HRESULT) AppWaitForMultipleObjects(
+    __in DWORD dwCount,
+    __in const HANDLE* rghHandles,
+    __in BOOL fWaitAll,
+    __in DWORD dwMilliseconds,
+    __out_opt DWORD* pdwSignaledIndex
+    )
+{
+    HRESULT hr = S_OK;
+    DWORD dwResult = 0;
+    DWORD dwSignaledIndex = dwCount;
+
+    dwResult = ::WaitForMultipleObjects(dwCount, rghHandles, fWaitAll, dwMilliseconds);
+    if (WAIT_TIMEOUT == dwResult)
+    {
+        ExitFunction1(hr = HRESULT_FROM_WIN32(dwResult));
+    }
+    else if (WAIT_ABANDONED_0 <= dwResult && (WAIT_ABANDONED_0 + dwCount) > dwResult)
+    {
+        dwSignaledIndex = dwResult - WAIT_ABANDONED_0;
+        AppExitOnWin32Error(dwResult, hr, "Abandoned wait for multiple objects, index: %u.", dwSignaledIndex);
+    }
+    else if (WAIT_OBJECT_0 <= dwResult && (WAIT_OBJECT_0 + dwCount) > dwResult)
+    {
+        dwSignaledIndex = dwResult - WAIT_OBJECT_0;
+    }
+    else
+    {
+        AssertSz(WAIT_FAILED == dwResult, "Unexpected return code from WaitForMultipleObjects.");
+        AppExitWithLastError(hr, "Failed to wait for multiple objects.");
+    }
+
+LExit:
+    if (pdwSignaledIndex)
+    {
+        *pdwSignaledIndex = dwSignaledIndex;
+    }
+
+    return hr;
+}
+
 static HRESULT EscapeCommandLineArgument(
     __in_z LPCWSTR wzArgument,
     __out_z LPWSTR* psczEscaped
diff --git a/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj b/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj
index 3e3c42b7..c84b98fe 100644
--- a/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj
+++ b/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj
@@ -104,6 +104,7 @@
     <ClCompile Include="strutil.cpp" />
     <ClCompile Include="svcutil.cpp" />
     <ClCompile Include="thmutil.cpp" />
+    <ClCompile Include="thrdutil.cpp" />
     <ClCompile Include="timeutil.cpp" />
     <ClCompile Include="uncutil.cpp" />
     <ClCompile Include="uriutil.cpp" />
@@ -164,6 +165,7 @@
     <ClInclude Include="inc\strutil.h" />
     <ClInclude Include="inc\svcutil.h" />
     <ClInclude Include="inc\thmutil.h" />
+    <ClInclude Include="inc\thrdutil.h" />
     <ClInclude Include="inc\timeutil.h" />
     <ClInclude Include="inc\uriutil.h" />
     <ClInclude Include="inc\userutil.h" />
diff --git a/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj.filters b/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj.filters
index 07698f9e..efadef6f 100644
--- a/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj.filters
+++ b/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj.filters
@@ -162,6 +162,9 @@
     <ClCompile Include="thmutil.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="thrdutil.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="timeutil.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
@@ -344,6 +347,9 @@
     <ClInclude Include="inc\thmutil.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="inc\thrdutil.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
     <ClInclude Include="inc\timeutil.h">
       <Filter>Header Files</Filter>
     </ClInclude>
diff --git a/src/libs/dutil/WixToolset.DUtil/inc/apputil.h b/src/libs/dutil/WixToolset.DUtil/inc/apputil.h
index 95a98e73..e2812ee4 100644
--- a/src/libs/dutil/WixToolset.DUtil/inc/apputil.h
+++ b/src/libs/dutil/WixToolset.DUtil/inc/apputil.h
@@ -84,6 +84,27 @@ HRESULT DAPI AppEscapeCommandLineArgumentFormattedArgs(
     __in va_list args
     );
 
+/********************************************************************
+AppWaitForSingleObject - wrapper for ::WaitForSingleObject.
+
+********************************************************************/
+HRESULT DAPI AppWaitForSingleObject(
+    __in HANDLE hHandle,
+    __in DWORD dwMilliseconds
+    );
+
+/********************************************************************
+AppWaitForMultipleObjects - wrapper for ::WaitForMultipleObjects.
+
+********************************************************************/
+HRESULT DAPI AppWaitForMultipleObjects(
+    __in DWORD dwCount,
+    __in const HANDLE* rghHandles,
+    __in BOOL fWaitAll,
+    __in DWORD dwMilliseconds,
+    __out_opt DWORD* pdwSignaledIndex
+    );
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/libs/dutil/WixToolset.DUtil/inc/dutil.h b/src/libs/dutil/WixToolset.DUtil/inc/dutil.h
index 6f099f35..2db64812 100644
--- a/src/libs/dutil/WixToolset.DUtil/inc/dutil.h
+++ b/src/libs/dutil/WixToolset.DUtil/inc/dutil.h
@@ -130,6 +130,7 @@ void DAPI Dutil_RootFailure(__in_z LPCSTR szFile, __in int iLine, __in HRESULT h
 #define ExitOnWin32ErrorSource(d, e, x, s, ...) if (ERROR_SUCCESS != e) { x = HRESULT_FROM_WIN32(e); if (!FAILED(x)) { x = E_FAIL; } Dutil_RootFailure(__FILE__, __LINE__, x); ExitTraceSource(d, x, s, __VA_ARGS__); goto LExit; }
 #define ExitOnOptionalXmlQueryFailureSource(d, x, b, s, ...) { { if (S_FALSE == x || E_NOTFOUND == x) { b = FALSE; x = S_OK; } else { b = SUCCEEDED(x); } }; ExitOnRootFailureSource(d, x, s, __VA_ARGS__); }
 #define ExitOnRequiredXmlQueryFailureSource(d, x, s, ...) { if (S_FALSE == x) { x = E_NOTFOUND; } ExitOnRootFailureSource(d, x, s, __VA_ARGS__); }
+#define ExitOnWaitObjectFailureSource(d, x, b, s, ...) { { if (HRESULT_FROM_WIN32(WAIT_TIMEOUT) == x) { b = TRUE; x = S_OK; } else { b = FALSE; } }; ExitOnFailureSource(d, x, s, __VA_ARGS__); }
 
 #define ExitOnLastError(x, s, ...) ExitOnLastErrorSource(DUTIL_SOURCE_DEFAULT, x, s, __VA_ARGS__)
 #define ExitOnLastErrorDebugTrace(x, s, ...) ExitOnLastErrorDebugTraceSource(DUTIL_SOURCE_DEFAULT, x, s, __VA_ARGS__)
@@ -145,6 +146,7 @@ void DAPI Dutil_RootFailure(__in_z LPCSTR szFile, __in int iLine, __in HRESULT h
 #define ExitOnWin32Error(e, x, s, ...) ExitOnWin32ErrorSource(DUTIL_SOURCE_DEFAULT, e, x, s, __VA_ARGS__)
 #define ExitOnOptionalXmlQueryFailure(x, b, s, ...) ExitOnOptionalXmlQueryFailureSource(DUTIL_SOURCE_DEFAULT, x, b, s, __VA_ARGS__)
 #define ExitOnRequiredXmlQueryFailure(x, s, ...) ExitOnRequiredXmlQueryFailureSource(DUTIL_SOURCE_DEFAULT, x, s, __VA_ARGS__)
+#define ExitOnWaitObjectFailure(x, b, s, ...) ExitOnWaitObjectFailureSource(DUTIL_SOURCE_DEFAULT, x, b, s, __VA_ARGS__)
 
 // release macros
 #define ReleaseObject(x) if (x) { x->Release(); }
diff --git a/src/libs/dutil/WixToolset.DUtil/inc/dutilsources.h b/src/libs/dutil/WixToolset.DUtil/inc/dutilsources.h
index f1dd5d1a..664c21e5 100644
--- a/src/libs/dutil/WixToolset.DUtil/inc/dutilsources.h
+++ b/src/libs/dutil/WixToolset.DUtil/inc/dutilsources.h
@@ -63,6 +63,7 @@ typedef enum DUTIL_SOURCE
     DUTIL_SOURCE_VERUTIL,
     DUTIL_SOURCE_WNDUTIL,
     DUTIL_SOURCE_ENVUTIL,
+    DUTIL_SOURCE_THRDUTIL,
 
     DUTIL_SOURCE_EXTERNAL = 256,
 } DUTIL_SOURCE;
diff --git a/src/libs/dutil/WixToolset.DUtil/inc/procutil.h b/src/libs/dutil/WixToolset.DUtil/inc/procutil.h
index d5ab9242..d61d91b5 100644
--- a/src/libs/dutil/WixToolset.DUtil/inc/procutil.h
+++ b/src/libs/dutil/WixToolset.DUtil/inc/procutil.h
@@ -58,7 +58,7 @@ HRESULT DAPI ProcExecute(
 HRESULT DAPI ProcWaitForCompletion(
     __in HANDLE hProcess,
     __in DWORD dwTimeout,
-    __out DWORD *pReturnCode
+    __out_opt DWORD* pdwReturnCode
     );
 HRESULT DAPI ProcWaitForIds(
     __in_ecount(cProcessIds) const DWORD* pdwProcessIds,
diff --git a/src/libs/dutil/WixToolset.DUtil/inc/thrdutil.h b/src/libs/dutil/WixToolset.DUtil/inc/thrdutil.h
new file mode 100644
index 00000000..47e159a1
--- /dev/null
+++ b/src/libs/dutil/WixToolset.DUtil/inc/thrdutil.h
@@ -0,0 +1,22 @@
+#pragma once
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/********************************************************************
+ ThrdWaitForCompletion - waits for thread to complete and gets return code.
+
+ *******************************************************************/
+HRESULT DAPI ThrdWaitForCompletion(
+    __in HANDLE hThread,
+    __in DWORD dwTimeout,
+    __out_opt DWORD* pdwReturnCode
+    );
+
+#ifdef __cplusplus
+}
+#endif
+
diff --git a/src/libs/dutil/WixToolset.DUtil/monutil.cpp b/src/libs/dutil/WixToolset.DUtil/monutil.cpp
index 6ad75b56..10954164 100644
--- a/src/libs/dutil/WixToolset.DUtil/monutil.cpp
+++ b/src/libs/dutil/WixToolset.DUtil/monutil.cpp
@@ -16,6 +16,7 @@
 #define MonExitOnInvalidHandleWithLastError(p, x, s, ...) ExitOnInvalidHandleWithLastErrorSource(DUTIL_SOURCE_MONUTIL, p, x, s, __VA_ARGS__)
 #define MonExitOnWin32Error(e, x, s, ...) ExitOnWin32ErrorSource(DUTIL_SOURCE_MONUTIL, e, x, s, __VA_ARGS__)
 #define MonExitOnGdipFailure(g, x, s, ...) ExitOnGdipFailureSource(DUTIL_SOURCE_MONUTIL, g, x, s, __VA_ARGS__)
+#define MonExitOnWaitObjectFailure(x, b, s, ...) ExitOnWaitObjectFailureSource(DUTIL_SOURCE_MONUTIL, x, b, s, __VA_ARGS__)
 
 const int MON_THREAD_GROWTH = 5;
 const int MON_ARRAY_GROWTH = 40;
@@ -1101,11 +1102,12 @@ static DWORD WINAPI WaiterThread(
 {
     HRESULT hr = S_OK;
     HRESULT hrTemp = S_OK;
-    DWORD dwRet = 0;
     BOOL fAgain = FALSE;
     BOOL fContinue = TRUE;
     BOOL fNotify = FALSE;
     BOOL fRet = FALSE;
+    BOOL fTimedOut = FALSE;
+    DWORD dwSignaledIndex = 0;
     MSG msg = { };
     MON_ADD_MESSAGE *pAddMessage = NULL;
     MON_REMOVE_MESSAGE *pRemoveMessage = NULL;
@@ -1128,13 +1130,14 @@ static DWORD WINAPI WaiterThread(
 
     do
     {
-        dwRet = ::WaitForMultipleObjects(pWaiterContext->cHandles - pWaiterContext->cRequestsFailing, pWaiterContext->rgHandles, FALSE, pWaiterContext->cRequestsPending > 0 ? dwWait : INFINITE);
+        hr = AppWaitForMultipleObjects(pWaiterContext->cHandles - pWaiterContext->cRequestsFailing, pWaiterContext->rgHandles, FALSE, pWaiterContext->cRequestsPending > 0 ? dwWait : INFINITE, &dwSignaledIndex);
+        MonExitOnWaitObjectFailure(hr, fTimedOut, "Failed to wait for multiple objects.");
 
         uCurrentTime = ::GetTickCount();
         uDeltaInMs = uCurrentTime - uLastTimeInMs;
         uLastTimeInMs = uCurrentTime;
 
-        if (WAIT_OBJECT_0 == dwRet)
+        if (!fTimedOut && 0 == dwSignaledIndex)
         {
             do
             {
@@ -1391,10 +1394,10 @@ static DWORD WINAPI WaiterThread(
                 }
             } while (fAgain);
         }
-        else if (dwRet > WAIT_OBJECT_0 && dwRet - WAIT_OBJECT_0 < pWaiterContext->cHandles)
+        else if (!fTimedOut)
         {
             // OK a handle fired - only notify if it's the actual target, and not just some parent waiting for the target child to exist
-            dwRequestIndex = dwRet - WAIT_OBJECT_0 - 1;
+            dwRequestIndex = dwSignaledIndex - 1;
             fNotify = (pWaiterContext->rgRequests[dwRequestIndex].dwPathHierarchyIndex == pWaiterContext->rgRequests[dwRequestIndex].cPathHierarchy - 1);
 
             // Initiate re-waits before we notify callback, to ensure we don't miss a single update
@@ -1426,10 +1429,6 @@ static DWORD WINAPI WaiterThread(
                 }
             }
         }
-        else if (WAIT_TIMEOUT != dwRet)
-        {
-            MonExitWithLastError(hr, "Failed to wait for multiple objects with return code %u", dwRet);
-        }
 
         // OK, now that we've checked all triggered handles (resetting silence period timers appropriately), check for any pending notifications that we can finally fire
         // And set dwWait appropriately so we awaken at the right time to fire the next pending notification (in case no further writes occur during that time)
@@ -1726,10 +1725,10 @@ static LRESULT CALLBACK MonWndProc(
     DEV_BROADCAST_HANDLE *pHandle = NULL;
     DEV_BROADCAST_VOLUME *pVolume = NULL;
     DWORD dwUnitMask = 0;
-    DWORD er = ERROR_SUCCESS;
     WCHAR chDrive = L'\0';
     BOOL fArrival = FALSE;
     BOOL fReturnTrue = FALSE;
+    BOOL fTimedOut = FALSE;
     CREATESTRUCT *pCreateStruct = NULL;
     MON_WAITER_CONTEXT *pWaiterContext = NULL;
     MON_STRUCT *pm = NULL;
@@ -1821,24 +1820,23 @@ static LRESULT CALLBACK MonWndProc(
                     }
                 }
 
-                er = ::WaitForSingleObject(pm->internalWait.hWait, MON_THREAD_WAIT_REMOVE_DEVICE);
+                hr = AppWaitForSingleObject(pm->internalWait.hWait, MON_THREAD_WAIT_REMOVE_DEVICE);
+                MonExitOnWaitObjectFailure(hr, fTimedOut, "WaitForSingleObject failed with non-timeout reason while waiting for response from waiter thread");
+
                 // Make sure any waiter thread processing really old messages can immediately know that we're no longer waiting for a response
-                if (WAIT_OBJECT_0 == er)
+                if (!fTimedOut)
                 {
                     // If the response ID matches what we sent, we actually got a valid reply!
                     if (pm->internalWait.dwReceiveIteration != pm->internalWait.dwSendIteration)
                     {
-                        TraceError(HRESULT_FROM_WIN32(er), "Waiter thread received wrong ID reply");
+                        TraceError(E_UNEXPECTED, "Waiter thread received wrong ID reply");
                     }
                 }
-                else if (WAIT_TIMEOUT == er)
-                {
-                    TraceError(HRESULT_FROM_WIN32(er), "No response from any waiter thread for query remove message");
-                }
                 else
                 {
-                    MonExitWithLastError(hr, "WaitForSingleObject failed with non-timeout reason while waiting for response from waiter thread");
+                    TraceError(HRESULT_FROM_WIN32(WAIT_TIMEOUT), "No response from any waiter thread for query remove message");
                 }
+
                 ++pm->internalWait.dwSendIteration;
             }
         }
diff --git a/src/libs/dutil/WixToolset.DUtil/precomp.h b/src/libs/dutil/WixToolset.DUtil/precomp.h
index c9e4f74a..b628d271 100644
--- a/src/libs/dutil/WixToolset.DUtil/precomp.h
+++ b/src/libs/dutil/WixToolset.DUtil/precomp.h
@@ -90,6 +90,7 @@
 #include "timeutil.h"
 #include "wndutil.h"
 #include "thmutil.h"
+#include "thrdutil.h"
 #include "uncutil.h"
 #include "uriutil.h"
 #include "userutil.h"
diff --git a/src/libs/dutil/WixToolset.DUtil/procutil.cpp b/src/libs/dutil/WixToolset.DUtil/procutil.cpp
index 340a0cda..29f575ae 100644
--- a/src/libs/dutil/WixToolset.DUtil/procutil.cpp
+++ b/src/libs/dutil/WixToolset.DUtil/procutil.cpp
@@ -17,6 +17,7 @@
 #define ProcExitOnInvalidHandleWithLastError(p, x, s, ...) ExitOnInvalidHandleWithLastErrorSource(DUTIL_SOURCE_PROCUTIL, p, x, s, __VA_ARGS__)
 #define ProcExitOnWin32Error(e, x, s, ...) ExitOnWin32ErrorSource(DUTIL_SOURCE_PROCUTIL, e, x, s, __VA_ARGS__)
 #define ProcExitOnGdipFailure(g, x, s, ...) ExitOnGdipFailureSource(DUTIL_SOURCE_PROCUTIL, g, x, s, __VA_ARGS__)
+#define ProcExitOnWaitObjectFailure(x, b, s, ...) ExitOnWaitObjectFailureSource(DUTIL_SOURCE_PROCUTIL, x, b, s, __VA_ARGS__)
 
 
 // private functions
@@ -403,30 +404,25 @@ LExit:
 extern "C" HRESULT DAPI ProcWaitForCompletion(
     __in HANDLE hProcess,
     __in DWORD dwTimeout,
-    __out DWORD *pReturnCode
+    __out_opt DWORD* pdwReturnCode
     )
 {
     HRESULT hr = S_OK;
-    DWORD er = ERROR_SUCCESS;
+    BOOL fTimedOut = FALSE;
 
-    // Wait for everything to finish
-    er = ::WaitForSingleObject(hProcess, dwTimeout);
-    if (WAIT_FAILED == er)
-    {
-        ProcExitWithLastError(hr, "Failed to wait for process to complete.");
-    }
-    else if (WAIT_TIMEOUT == er)
+    // Wait for everything to finish.
+    hr = AppWaitForSingleObject(hProcess, dwTimeout);
+    ProcExitOnWaitObjectFailure(hr, fTimedOut, "Failed to wait for process to complete.");
+
+    if (fTimedOut)
     {
-        ExitFunction1(hr = HRESULT_FROM_WIN32(er));
+        hr = HRESULT_FROM_WIN32(WAIT_TIMEOUT);
     }
-
-    if (!::GetExitCodeProcess(hProcess, &er))
+    else if (pdwReturnCode && !::GetExitCodeProcess(hProcess, pdwReturnCode))
     {
         ProcExitWithLastError(hr, "Failed to get process return code.");
     }
 
-    *pReturnCode = er;
-
 LExit:
     return hr;
 }
@@ -442,10 +438,10 @@ extern "C" HRESULT DAPI ProcWaitForIds(
     )
 {
     HRESULT hr = S_OK;
-    DWORD er = ERROR_SUCCESS;
     HANDLE hProcess = NULL;
-    HANDLE * rghProcesses = NULL;
+    HANDLE* rghProcesses = NULL;
     DWORD cProcesses = 0;
+    BOOL fTimedOut = FALSE;
 
     rghProcesses =  static_cast<HANDLE*>(MemAlloc(sizeof(DWORD) * cProcessIds, TRUE));
     ProcExitOnNull(rgdwProcessIds, hr, E_OUTOFMEMORY, "Failed to allocate array for process ID Handles.");
@@ -459,16 +455,14 @@ extern "C" HRESULT DAPI ProcWaitForIds(
         }
     }
 
-    er = ::WaitForMultipleObjects(cProcesses, rghProcesses, TRUE, dwMilliseconds);
-    if (WAIT_FAILED == er)
-    {
-        ProcExitWithLastError(hr, "Failed to wait for process to complete.");
-    }
-    else if (WAIT_TIMEOUT == er)
+    hr = AppWaitForMultipleObjects(cProcesses, rghProcesses, TRUE, dwMilliseconds, NULL);
+    ProcExitOnWaitObjectFailure(hr, fTimedOut, "Failed to wait for processes to complete.");
+
+    if (fTimedOut)
     {
-        ProcExitOnWin32Error(er, hr, "Timed out while waiting for process to complete.");
+        ProcExitWithRootFailure(hr, HRESULT_FROM_WIN32(WAIT_TIMEOUT), "Timed out while waiting for processes to complete.");
     }
-    
+
 LExit:
     if (rghProcesses)
     {
diff --git a/src/libs/dutil/WixToolset.DUtil/thrdutil.cpp b/src/libs/dutil/WixToolset.DUtil/thrdutil.cpp
new file mode 100644
index 00000000..a8933a48
--- /dev/null
+++ b/src/libs/dutil/WixToolset.DUtil/thrdutil.cpp
@@ -0,0 +1,46 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+#include "precomp.h"
+
+
+// Exit macros
+#define ThrdExitOnLastError(x, s, ...) ExitOnLastErrorSource(DUTIL_SOURCE_THRDUTIL, x, s, __VA_ARGS__)
+#define ThrdExitOnLastErrorDebugTrace(x, s, ...) ExitOnLastErrorDebugTraceSource(DUTIL_SOURCE_THRDUTIL, x, s, __VA_ARGS__)
+#define ThrdExitWithLastError(x, s, ...) ExitWithLastErrorSource(DUTIL_SOURCE_THRDUTIL, x, s, __VA_ARGS__)
+#define ThrdExitOnFailure(x, s, ...) ExitOnFailureSource(DUTIL_SOURCE_THRDUTIL, x, s, __VA_ARGS__)
+#define ThrdExitOnRootFailure(x, s, ...) ExitOnRootFailureSource(DUTIL_SOURCE_THRDUTIL, x, s, __VA_ARGS__)
+#define ThrdExitWithRootFailure(x, e, s, ...) ExitWithRootFailureSource(DUTIL_SOURCE_THRDUTIL, x, e, s, __VA_ARGS__)
+#define ThrdExitOnFailureDebugTrace(x, s, ...) ExitOnFailureDebugTraceSource(DUTIL_SOURCE_THRDUTIL, x, s, __VA_ARGS__)
+#define ThrdExitOnNull(p, x, e, s, ...) ExitOnNullSource(DUTIL_SOURCE_THRDUTIL, p, x, e, s, __VA_ARGS__)
+#define ThrdExitOnNullWithLastError(p, x, s, ...) ExitOnNullWithLastErrorSource(DUTIL_SOURCE_THRDUTIL, p, x, s, __VA_ARGS__)
+#define ThrdExitOnNullDebugTrace(p, x, e, s, ...)  ExitOnNullDebugTraceSource(DUTIL_SOURCE_THRDUTIL, p, x, e, s, __VA_ARGS__)
+#define ThrdExitOnInvalidHandleWithLastError(p, x, s, ...) ExitOnInvalidHandleWithLastErrorSource(DUTIL_SOURCE_THRDUTIL, p, x, s, __VA_ARGS__)
+#define ThrdExitOnWin32Error(e, x, s, ...) ExitOnWin32ErrorSource(DUTIL_SOURCE_THRDUTIL, e, x, s, __VA_ARGS__)
+#define ThrdExitOnGdipFailure(g, x, s, ...) ExitOnGdipFailureSource(DUTIL_SOURCE_THRDUTIL, g, x, s, __VA_ARGS__)
+#define ThrdExitOnWaitObjectFailure(x, b, s, ...) ExitOnWaitObjectFailureSource(DUTIL_SOURCE_THRDUTIL, x, b, s, __VA_ARGS__)
+
+DAPI_(HRESULT) ThrdWaitForCompletion(
+    __in HANDLE hThread,
+    __in DWORD dwTimeout,
+    __out_opt DWORD *pdwReturnCode
+    )
+{
+    HRESULT hr = S_OK;
+    BOOL fTimedOut = FALSE;
+
+    // Wait for everything to finish.
+    hr = AppWaitForSingleObject(hThread, dwTimeout);
+    ThrdExitOnWaitObjectFailure(hr, fTimedOut, "Failed to wait for thread to complete.");
+
+    if (fTimedOut)
+    {
+        hr = HRESULT_FROM_WIN32(WAIT_TIMEOUT);
+    }
+    else if (pdwReturnCode && !::GetExitCodeThread(hThread, pdwReturnCode))
+    {
+        ThrdExitWithLastError(hr, "Failed to get thread return code.");
+    }
+
+LExit:
+    return hr;
+}
diff --git a/src/libs/dutil/test/DUtilUnitTest/AppUtilTests.cpp b/src/libs/dutil/test/DUtilUnitTest/AppUtilTests.cpp
new file mode 100644
index 00000000..e8c23469
--- /dev/null
+++ b/src/libs/dutil/test/DUtilUnitTest/AppUtilTests.cpp
@@ -0,0 +1,60 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+#include "precomp.h"
+
+namespace DutilTests
+{
+    using namespace System;
+    using namespace Xunit;
+    using namespace WixBuildTools::TestSupport;
+
+    public ref class AppUtil
+    {
+    public:
+        [Fact]
+        void WaitForMultipleObjectsTest()
+        {
+            HRESULT hr = S_OK;
+            HANDLE hOne = NULL;
+            HANDLE hTwo = NULL;
+            HANDLE rghHandles[2] = { };
+            DWORD dwSignaledIndex = 0;
+
+            try
+            {
+                hOne = ::CreateEventW(NULL, TRUE, FALSE, NULL);
+                if (!hOne)
+                {
+                    hr = HRESULT_FROM_WIN32(::GetLastError());
+                    NativeAssert::Succeeded(FAILED(hr) ? hr : E_FAIL, "Failed to create event.");
+                }
+
+                hTwo = ::CreateEventW(NULL, TRUE, TRUE, NULL);
+                if (!hTwo)
+                {
+                    hr = HRESULT_FROM_WIN32(::GetLastError());
+                    NativeAssert::Succeeded(FAILED(hr) ? hr : E_FAIL, "Failed to create event.");
+                }
+
+                rghHandles[0] = hOne;
+                rghHandles[1] = hTwo;
+
+                hr = AppWaitForMultipleObjects(countof(rghHandles), rghHandles, FALSE, 0, &dwSignaledIndex);
+                NativeAssert::Succeeded(hr, "Failed to wait for multiple objects.");
+                Assert::Equal<DWORD>(1, dwSignaledIndex);
+
+                rghHandles[0] = hTwo;
+                rghHandles[1] = hOne;
+
+                hr = AppWaitForMultipleObjects(countof(rghHandles), rghHandles, FALSE, 0, &dwSignaledIndex);
+                NativeAssert::Succeeded(hr, "Failed to wait for multiple objects.");
+                Assert::Equal<DWORD>(0, dwSignaledIndex);
+            }
+            finally
+            {
+                ReleaseHandle(hOne);
+                ReleaseHandle(hTwo);
+            }
+        }
+    };
+}
diff --git a/src/libs/dutil/test/DUtilUnitTest/DUtilUnitTest.vcxproj b/src/libs/dutil/test/DUtilUnitTest/DUtilUnitTest.vcxproj
index a1f13239..210f50f5 100644
--- a/src/libs/dutil/test/DUtilUnitTest/DUtilUnitTest.vcxproj
+++ b/src/libs/dutil/test/DUtilUnitTest/DUtilUnitTest.vcxproj
@@ -44,6 +44,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <ClCompile Include="AppUtilTests.cpp" />
     <ClCompile Include="ApupUtilTests.cpp" />
     <ClCompile Include="AssemblyInfo.cpp" />
     <ClCompile Include="DictUtilTest.cpp" />
diff --git a/src/libs/dutil/test/DUtilUnitTest/DUtilUnitTest.vcxproj.filters b/src/libs/dutil/test/DUtilUnitTest/DUtilUnitTest.vcxproj.filters
index cb0c8a73..f1d9c307 100644
--- a/src/libs/dutil/test/DUtilUnitTest/DUtilUnitTest.vcxproj.filters
+++ b/src/libs/dutil/test/DUtilUnitTest/DUtilUnitTest.vcxproj.filters
@@ -15,6 +15,9 @@
     </Filter>
   </ItemGroup>
   <ItemGroup>
+    <ClCompile Include="AppUtilTests.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="ApupUtilTests.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
diff --git a/src/libs/dutil/test/DUtilUnitTest/precomp.h b/src/libs/dutil/test/DUtilUnitTest/precomp.h
index ac57cdd4..a5542774 100644
--- a/src/libs/dutil/test/DUtilUnitTest/precomp.h
+++ b/src/libs/dutil/test/DUtilUnitTest/precomp.h
@@ -13,6 +13,7 @@
 #include <dutil.h>
 
 #include <verutil.h>
+#include <apputil.h>
 #include <atomutil.h>
 #include <dictutil.h>
 #include <dirutil.h>