Replace PathCompare with PathCompareCanonicalized.

10 files changed, 301 insertions, 203 deletions

diff --git a/src/burn/engine/apply.cpp b/src/burn/engine/apply.cpp
index f9b33333..4ebed191 100644
--- a/src/burn/engine/apply.cpp
+++ b/src/burn/engine/apply.cpp
@@ -1350,7 +1350,7 @@ static HRESULT LayoutBundle(
     LPWSTR sczBundlePath = NULL;
     LPWSTR sczBundleDownloadUrl = NULL;
     LPWSTR sczDestinationPath = NULL;
-    int nEquivalentPaths = 0;
+    BOOL fPathEqual = FALSE;
     BOOTSTRAPPER_CACHE_OPERATION cacheOperation = BOOTSTRAPPER_CACHE_OPERATION_NONE;
     BURN_CACHE_PROGRESS_CONTEXT progress = { };
     BOOL fRetry = FALSE;
@@ -1375,10 +1375,10 @@ static HRESULT LayoutBundle(
     ExitOnFailure(hr, "Failed to concat layout path for bundle.");
 
     // If the destination path is the currently running bundle, bail.
-    hr = PathCompare(sczBundlePath, sczDestinationPath, &nEquivalentPaths);
+    hr = PathCompareCanonicalized(sczBundlePath, sczDestinationPath, &fPathEqual);
     ExitOnFailure(hr, "Failed to determine if layout bundle path was equivalent with current process path.");
 
-    if (CSTR_EQUAL == nEquivalentPaths && FileExistsEx(sczDestinationPath, NULL))
+    if (fPathEqual && FileExistsEx(sczDestinationPath, NULL))
     {
         hr = UserExperienceOnCacheContainerOrPayloadVerifyBegin(pContext->pUX, NULL, NULL);
         if (FAILED(hr))
@@ -1533,7 +1533,7 @@ static HRESULT AcquireContainerOrPayload(
     AssertSz(pContainer || pPayload, "Must provide a container or a payload.");
 
     HRESULT hr = S_OK;
-    int nEquivalentPaths = 0;
+    BOOL fPathEqual = FALSE;
     LPCWSTR wzPackageOrContainerId = pContainer ? pContainer->sczId : pPackage ? pPackage->sczId : NULL;
     LPCWSTR wzPayloadId = pPayload ? pPayload->sczKey : NULL;
     LPCWSTR wzPayloadContainerId = pPayload && pPayload->pContainer ? pPayload->pContainer->sczId : NULL;
@@ -1673,10 +1673,10 @@ static HRESULT AcquireContainerOrPayload(
     {
     case BOOTSTRAPPER_CACHE_OPERATION_COPY:
         // If the source path and destination path are different, do the copy (otherwise there's no point).
-        hr = PathCompare(pContext->rgSearchPaths[dwChosenSearchPath], wzDestinationPath, &nEquivalentPaths);
+        hr = PathCompareCanonicalized(pContext->rgSearchPaths[dwChosenSearchPath], wzDestinationPath, &fPathEqual);
         ExitOnFailure(hr, "Failed to determine if payload paths were equivalent, source: %ls, destination: %ls.", pContext->rgSearchPaths[dwChosenSearchPath], wzDestinationPath);
 
-        if (CSTR_EQUAL != nEquivalentPaths)
+        if (!fPathEqual)
         {
             hr = CopyPayload(pProgress, INVALID_HANDLE_VALUE, pContext->rgSearchPaths[dwChosenSearchPath], wzDestinationPath);
             ExitOnFailure(hr, "Failed to copy payload: %ls", wzPayloadId);
diff --git a/src/burn/engine/cache.cpp b/src/burn/engine/cache.cpp
index 04b2f0ca..b311a195 100644
--- a/src/burn/engine/cache.cpp
+++ b/src/burn/engine/cache.cpp
@@ -170,7 +170,7 @@ extern "C" HRESULT CacheInitialize(
 
     HRESULT hr = S_OK;
     LPWSTR sczAppData = NULL;
-    int nCompare = 0;
+    BOOL fPathEqual = FALSE;
 
     // Cache paths are initialized once so they cannot be changed while the engine is caching payloads.
     // Always construct the default machine package cache path so we can determine if we're redirected.
@@ -199,10 +199,10 @@ extern "C" HRESULT CacheInitialize(
         ExitOnFailure(hr, "Failed to copy default package cache directory to current package cache directory.");
     }
 
-    hr = PathCompare(pCache->sczDefaultMachinePackageCache, pCache->sczCurrentMachinePackageCache, &nCompare);
+    hr = PathCompareCanonicalized(pCache->sczDefaultMachinePackageCache, pCache->sczCurrentMachinePackageCache, &fPathEqual);
     ExitOnFailure(hr, "Failed to compare default and current package cache directories.");
 
-    pCache->fCustomMachinePackageCache = CSTR_EQUAL != nCompare;
+    pCache->fCustomMachinePackageCache = !fPathEqual;
 
 
     hr = PathGetKnownFolder(CSIDL_LOCAL_APPDATA, &sczAppData);
@@ -241,7 +241,7 @@ extern "C" HRESULT CacheInitializeSources(
     LPWSTR sczCompletedPath = NULL;
     LPWSTR sczOriginalSource = NULL;
     LPWSTR sczOriginalSourceFolder = NULL;
-    int nCompare = 0;
+    BOOL fPathEqual = FALSE;
     LPCWSTR wzSourceProcessPath = pInternalCommand->sczSourceProcessPath;
 
     hr = PathForCurrentProcess(&sczCurrentPath, NULL);
@@ -254,10 +254,10 @@ extern "C" HRESULT CacheInitializeSources(
     hr = PathConcatRelativeToBase(sczCompletedFolder, pRegistration->sczExecutableName, &sczCompletedPath);
     ExitOnFailure(hr, "Failed to combine working path with engine file name.");
 
-    hr = PathCompare(sczCurrentPath, sczCompletedPath, &nCompare);
+    hr = PathCompareCanonicalized(sczCurrentPath, sczCompletedPath, &fPathEqual);
     ExitOnFailure(hr, "Failed to compare current path for bundle: %ls", sczCurrentPath);
 
-    pCache->fRunningFromCache = (CSTR_EQUAL == nCompare);
+    pCache->fRunningFromCache = fPathEqual;
 
     // If a source process path was not provided (e.g. we are not being
     // run in a clean room) then use the current process path as the
@@ -959,7 +959,7 @@ extern "C" HRESULT CacheCompleteBundle(
     )
 {
     HRESULT hr = S_OK;
-    int nCompare = 0;
+    BOOL fPathEqual = FALSE;
     LPWSTR sczTargetDirectory = NULL;
     LPWSTR sczTargetPath = NULL;
     LPWSTR sczSourceDirectory = NULL;
@@ -976,10 +976,10 @@ extern "C" HRESULT CacheCompleteBundle(
 
     // If the bundle is running out of the package cache then we don't need to copy it there
     // (and don't want to since it'll be in use) so bail.
-    hr = PathCompare(wzSourceBundlePath, sczTargetPath, &nCompare);
+    hr = PathCompareCanonicalized(wzSourceBundlePath, sczTargetPath, &fPathEqual);
     ExitOnFailure(hr, "Failed to compare completed cache path for bundle: %ls", wzSourceBundlePath);
 
-    if (CSTR_EQUAL == nCompare)
+    if (fPathEqual)
     {
         ExitFunction();
     }
diff --git a/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj b/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj
index ba9e801e..8a6f3b13 100644
--- a/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj
+++ b/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj
@@ -66,6 +66,7 @@
       <DisableSpecificWarnings>4091;4458</DisableSpecificWarnings>
     </ClCompile>
     <ClCompile Include="eseutil.cpp" />
+    <ClCompile Include="file2utl.cpp" />
     <ClCompile Include="fileutil.cpp" />
     <ClCompile Include="gdiputil.cpp" />
     <ClCompile Include="guidutil.cpp" />
diff --git a/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj.filters b/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj.filters
index 6444b19c..dbbe68f4 100644
--- a/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj.filters
+++ b/src/libs/dutil/WixToolset.DUtil/dutil.vcxproj.filters
@@ -69,6 +69,9 @@
     <ClCompile Include="eseutil.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="file2utl.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="fileutil.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
diff --git a/src/libs/dutil/WixToolset.DUtil/file2utl.cpp b/src/libs/dutil/WixToolset.DUtil/file2utl.cpp
new file mode 100644
index 00000000..88f8377c
--- /dev/null
+++ b/src/libs/dutil/WixToolset.DUtil/file2utl.cpp
@@ -0,0 +1,164 @@
+// 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 FileExitOnLastError(x, s, ...) ExitOnLastErrorSource(DUTIL_SOURCE_FILEUTIL, x, s, __VA_ARGS__)
+#define FileExitOnLastErrorDebugTrace(x, s, ...) ExitOnLastErrorDebugTraceSource(DUTIL_SOURCE_FILEUTIL, x, s, __VA_ARGS__)
+#define FileExitWithLastError(x, s, ...) ExitWithLastErrorSource(DUTIL_SOURCE_FILEUTIL, x, s, __VA_ARGS__)
+#define FileExitOnFailure(x, s, ...) ExitOnFailureSource(DUTIL_SOURCE_FILEUTIL, x, s, __VA_ARGS__)
+#define FileExitOnRootFailure(x, s, ...) ExitOnRootFailureSource(DUTIL_SOURCE_FILEUTIL, x, s, __VA_ARGS__)
+#define FileExitOnFailureDebugTrace(x, s, ...) ExitOnFailureDebugTraceSource(DUTIL_SOURCE_FILEUTIL, x, s, __VA_ARGS__)
+#define FileExitOnNull(p, x, e, s, ...) ExitOnNullSource(DUTIL_SOURCE_FILEUTIL, p, x, e, s, __VA_ARGS__)
+#define FileExitOnNullWithLastError(p, x, s, ...) ExitOnNullWithLastErrorSource(DUTIL_SOURCE_FILEUTIL, p, x, s, __VA_ARGS__)
+#define FileExitOnNullDebugTrace(p, x, e, s, ...)  ExitOnNullDebugTraceSource(DUTIL_SOURCE_FILEUTIL, p, x, e, s, __VA_ARGS__)
+#define FileExitOnInvalidHandleWithLastError(p, x, s, ...) ExitOnInvalidHandleWithLastErrorSource(DUTIL_SOURCE_FILEUTIL, p, x, s, __VA_ARGS__)
+#define FileExitOnWin32Error(e, x, s, ...) ExitOnWin32ErrorSource(DUTIL_SOURCE_FILEUTIL, e, x, s, __VA_ARGS__)
+#define FileExitOnGdipFailure(g, x, s, ...) ExitOnGdipFailureSource(DUTIL_SOURCE_FILEUTIL, g, x, s, __VA_ARGS__)
+
+// constants
+
+const LPCWSTR REGISTRY_PENDING_FILE_RENAME_KEY = L"SYSTEM\\CurrentControlSet\\Control\\Session Manager";
+const LPCWSTR REGISTRY_PENDING_FILE_RENAME_VALUE = L"PendingFileRenameOperations";
+
+
+/*******************************************************************
+ FileExistsAfterRestart - checks that a file exists and will continue
+                          to exist after restart.
+
+********************************************************************/
+extern "C" BOOL DAPI FileExistsAfterRestart(
+    __in_z LPCWSTR wzPath,
+    __out_opt DWORD *pdwAttributes
+    )
+{
+    HRESULT hr = S_OK;
+    BOOL fExists = FALSE;
+    HKEY hkPendingFileRename = NULL;
+    LPWSTR* rgsczRenames = NULL;
+    DWORD cRenames = 0;
+    BOOL fPathEqual = FALSE;
+
+    fExists = FileExistsEx(wzPath, pdwAttributes);
+    if (fExists)
+    {
+        hr = RegOpen(HKEY_LOCAL_MACHINE, REGISTRY_PENDING_FILE_RENAME_KEY, KEY_QUERY_VALUE, &hkPendingFileRename);
+        if (E_FILENOTFOUND == hr)
+        {
+            ExitFunction1(hr = S_OK);
+        }
+        FileExitOnFailure(hr, "Failed to open pending file rename registry key.");
+
+        hr = RegReadStringArray(hkPendingFileRename, REGISTRY_PENDING_FILE_RENAME_VALUE, &rgsczRenames, &cRenames);
+        if (E_FILENOTFOUND == hr)
+        {
+            ExitFunction1(hr = S_OK);
+        }
+        FileExitOnFailure(hr, "Failed to read pending file renames.");
+
+        // The pending file renames array is pairs of source and target paths. We only care
+        // about checking the source paths so skip the target paths (i += 2).
+        for (DWORD i = 0; i < cRenames; i += 2)
+        {
+            LPWSTR wzRename = rgsczRenames[i];
+            if (wzRename && *wzRename)
+            {
+                hr = PathCompareCanonicalized(wzPath, wzRename, &fPathEqual);
+                FileExitOnFailure(hr, "Failed to compare path from pending file rename to check path.");
+
+                if (fPathEqual)
+                {
+                    fExists = FALSE;
+                    break;
+                }
+            }
+        }
+    }
+
+LExit:
+    ReleaseStrArray(rgsczRenames, cRenames);
+    ReleaseRegKey(hkPendingFileRename);
+
+    return fExists;
+}
+
+
+/*******************************************************************
+ FileRemoveFromPendingRename - removes the file path from the pending
+                               file rename list.
+
+********************************************************************/
+extern "C" HRESULT DAPI FileRemoveFromPendingRename(
+    __in_z LPCWSTR wzPath
+    )
+{
+    HRESULT hr = S_OK;
+    HKEY hkPendingFileRename = NULL;
+    LPWSTR* rgsczRenames = NULL;
+    DWORD cRenames = 0;
+    BOOL fPathEqual = FALSE;
+    BOOL fRemoved = FALSE;
+    DWORD cNewRenames = 0;
+
+    hr = RegOpen(HKEY_LOCAL_MACHINE, REGISTRY_PENDING_FILE_RENAME_KEY, KEY_QUERY_VALUE | KEY_SET_VALUE, &hkPendingFileRename);
+    if (E_FILENOTFOUND == hr)
+    {
+        ExitFunction1(hr = S_OK);
+    }
+    FileExitOnFailure(hr, "Failed to open pending file rename registry key.");
+
+    hr = RegReadStringArray(hkPendingFileRename, REGISTRY_PENDING_FILE_RENAME_VALUE, &rgsczRenames, &cRenames);
+    if (E_FILENOTFOUND == hr)
+    {
+        ExitFunction1(hr = S_OK);
+    }
+    FileExitOnFailure(hr, "Failed to read pending file renames.");
+
+    // The pending file renames array is pairs of source and target paths. We only care
+    // about checking the source paths so skip the target paths (i += 2).
+    for (DWORD i = 0; i < cRenames; i += 2)
+    {
+        LPWSTR wzRename = rgsczRenames[i];
+        if (wzRename && *wzRename)
+        {
+            hr = PathCompareCanonicalized(wzPath, wzRename, &fPathEqual);
+            FileExitOnFailure(hr, "Failed to compare path from pending file rename to check path.");
+
+            // If we find our path in the list, null out the source and target slot and
+            // we'll compact the array next.
+            if (fPathEqual)
+            {
+                ReleaseNullStr(rgsczRenames[i]);
+                ReleaseNullStr(rgsczRenames[i + 1]);
+                fRemoved = TRUE;
+            }
+        }
+    }
+
+    if (fRemoved)
+    {
+        // Compact the array by removing any nulls.
+        for (DWORD i = 0; i < cRenames; ++i)
+        {
+            LPWSTR wzRename = rgsczRenames[i];
+            if (wzRename)
+            {
+                rgsczRenames[cNewRenames] = wzRename;
+                ++cNewRenames;
+            }
+        }
+
+        cRenames = cNewRenames; // ignore the pointers on the end of the array since an early index points to them already.
+
+        // Write the new array back to the pending file rename key.
+        hr = RegWriteStringArray(hkPendingFileRename, REGISTRY_PENDING_FILE_RENAME_VALUE, rgsczRenames, cRenames);
+        FileExitOnFailure(hr, "Failed to update pending file renames.");
+    }
+
+LExit:
+    ReleaseStrArray(rgsczRenames, cRenames);
+    ReleaseRegKey(hkPendingFileRename);
+
+    return hr;
+}
diff --git a/src/libs/dutil/WixToolset.DUtil/fileutil.cpp b/src/libs/dutil/WixToolset.DUtil/fileutil.cpp
index 2fe04de1..9f68ee52 100644
--- a/src/libs/dutil/WixToolset.DUtil/fileutil.cpp
+++ b/src/libs/dutil/WixToolset.DUtil/fileutil.cpp
@@ -22,9 +22,6 @@
 const BYTE UTF8BOM[] = {0xEF, 0xBB, 0xBF};
 const BYTE UTF16BOM[] = {0xFF, 0xFE};
 
-const LPCWSTR REGISTRY_PENDING_FILE_RENAME_KEY = L"SYSTEM\\CurrentControlSet\\Control\\Session Manager";
-const LPCWSTR REGISTRY_PENDING_FILE_RENAME_VALUE = L"PendingFileRenameOperations";
-
 
 /*******************************************************************
 FileStripExtension - Strip extension from filename
@@ -527,159 +524,6 @@ extern "C" BOOL DAPI FileExistsEx(
 
 
 /*******************************************************************
- FileExistsAfterRestart - checks that a file exists and will continue
-                          to exist after restart.
-
-********************************************************************/
-extern "C" BOOL DAPI FileExistsAfterRestart(
-    __in_z LPCWSTR wzPath,
-    __out_opt DWORD *pdwAttributes
-    )
-{
-    HRESULT hr = S_OK;
-    BOOL fExists = FALSE;
-    HKEY hkPendingFileRename = NULL;
-    LPWSTR* rgsczRenames = NULL;
-    DWORD cRenames = 0;
-    int nCompare = 0;
-
-    fExists = FileExistsEx(wzPath, pdwAttributes);
-    if (fExists)
-    {
-        hr = RegOpen(HKEY_LOCAL_MACHINE, REGISTRY_PENDING_FILE_RENAME_KEY, KEY_QUERY_VALUE, &hkPendingFileRename);
-        if (E_FILENOTFOUND == hr)
-        {
-            ExitFunction1(hr = S_OK);
-        }
-        FileExitOnFailure(hr, "Failed to open pending file rename registry key.");
-
-        hr = RegReadStringArray(hkPendingFileRename, REGISTRY_PENDING_FILE_RENAME_VALUE, &rgsczRenames, &cRenames);
-        if (E_FILENOTFOUND == hr)
-        {
-            ExitFunction1(hr = S_OK);
-        }
-        FileExitOnFailure(hr, "Failed to read pending file renames.");
-
-        // The pending file renames array is pairs of source and target paths. We only care
-        // about checking the source paths so skip the target paths (i += 2).
-        for (DWORD i = 0; i < cRenames; i += 2)
-        {
-            LPWSTR wzRename = rgsczRenames[i];
-            if (wzRename && *wzRename)
-            {
-                // Skip the long path designator if present.
-                if (L'\\' == wzRename[0] && L'?' == wzRename[1] && L'?' == wzRename[2] && L'\\' == wzRename[3])
-                {
-                    wzRename += 4;
-                }
-
-                hr = PathCompare(wzPath, wzRename, &nCompare);
-                FileExitOnFailure(hr, "Failed to compare path from pending file rename to check path.");
-
-                if (CSTR_EQUAL == nCompare)
-                {
-                    fExists = FALSE;
-                    break;
-                }
-            }
-        }
-    }
-
-LExit:
-    ReleaseStrArray(rgsczRenames, cRenames);
-    ReleaseRegKey(hkPendingFileRename);
-
-    return fExists;
-}
-
-
-/*******************************************************************
- FileRemoveFromPendingRename - removes the file path from the pending
-                               file rename list.
-
-********************************************************************/
-extern "C" HRESULT DAPI FileRemoveFromPendingRename(
-    __in_z LPCWSTR wzPath
-    )
-{
-    HRESULT hr = S_OK;
-    HKEY hkPendingFileRename = NULL;
-    LPWSTR* rgsczRenames = NULL;
-    DWORD cRenames = 0;
-    int nCompare = 0;
-    BOOL fRemoved = FALSE;
-    DWORD cNewRenames = 0;
-
-    hr = RegOpen(HKEY_LOCAL_MACHINE, REGISTRY_PENDING_FILE_RENAME_KEY, KEY_QUERY_VALUE | KEY_SET_VALUE, &hkPendingFileRename);
-    if (E_FILENOTFOUND == hr)
-    {
-        ExitFunction1(hr = S_OK);
-    }
-    FileExitOnFailure(hr, "Failed to open pending file rename registry key.");
-
-    hr = RegReadStringArray(hkPendingFileRename, REGISTRY_PENDING_FILE_RENAME_VALUE, &rgsczRenames, &cRenames);
-    if (E_FILENOTFOUND == hr)
-    {
-        ExitFunction1(hr = S_OK);
-    }
-    FileExitOnFailure(hr, "Failed to read pending file renames.");
-
-    // The pending file renames array is pairs of source and target paths. We only care
-    // about checking the source paths so skip the target paths (i += 2).
-    for (DWORD i = 0; i < cRenames; i += 2)
-    {
-        LPWSTR wzRename = rgsczRenames[i];
-        if (wzRename && *wzRename)
-        {
-            // Skip the long path designator if present.
-            if (L'\\' == wzRename[0] && L'?' == wzRename[1] && L'?' == wzRename[2] && L'\\' == wzRename[3])
-            {
-                wzRename += 4;
-            }
-
-            hr = PathCompare(wzPath, wzRename, &nCompare);
-            FileExitOnFailure(hr, "Failed to compare path from pending file rename to check path.");
-
-            // If we find our path in the list, null out the source and target slot and
-            // we'll compact the array next.
-            if (CSTR_EQUAL == nCompare)
-            {
-                ReleaseNullStr(rgsczRenames[i]);
-                ReleaseNullStr(rgsczRenames[i + 1]);
-                fRemoved = TRUE;
-            }
-        }
-    }
-
-    if (fRemoved)
-    {
-        // Compact the array by removing any nulls.
-        for (DWORD i = 0; i < cRenames; ++i)
-        {
-            LPWSTR wzRename = rgsczRenames[i];
-            if (wzRename)
-            {
-                rgsczRenames[cNewRenames] = wzRename;
-                ++cNewRenames;
-            }
-        }
-
-        cRenames = cNewRenames; // ignore the pointers on the end of the array since an early index points to them already.
-
-        // Write the new array back to the pending file rename key.
-        hr = RegWriteStringArray(hkPendingFileRename, REGISTRY_PENDING_FILE_RENAME_VALUE, rgsczRenames, cRenames);
-        FileExitOnFailure(hr, "Failed to update pending file renames.");
-    }
-
-LExit:
-    ReleaseStrArray(rgsczRenames, cRenames);
-    ReleaseRegKey(hkPendingFileRename);
-
-    return hr;
-}
-
-
-/*******************************************************************
  FileRead - read a file into memory
 
 ********************************************************************/
diff --git a/src/libs/dutil/WixToolset.DUtil/inc/pathutil.h b/src/libs/dutil/WixToolset.DUtil/inc/pathutil.h
index 871e706b..e64c8ef3 100644
--- a/src/libs/dutil/WixToolset.DUtil/inc/pathutil.h
+++ b/src/libs/dutil/WixToolset.DUtil/inc/pathutil.h
@@ -258,13 +258,14 @@ DAPI_(HRESULT) PathConcatRelativeToBase(
     );
 
 /*******************************************************************
- PathCompare - compares the fully expanded path of the two paths using
-               ::CompareStringW().
+ PathCompareCanonicalized - canonicalizes the two paths using PathCanonicalizeForComparison
+    which does not resolve relative paths into fully qualified paths.
+    The strings are then compared using ::CompareStringW().
 *******************************************************************/
-DAPI_(HRESULT) PathCompare(
+DAPI_(HRESULT) PathCompareCanonicalized(
     __in_z LPCWSTR wzPath1,
     __in_z LPCWSTR wzPath2,
-    __out int* pnResult
+    __out BOOL* pfEqual
     );
 
 /*******************************************************************
diff --git a/src/libs/dutil/WixToolset.DUtil/path2utl.cpp b/src/libs/dutil/WixToolset.DUtil/path2utl.cpp
index 61c1803a..1957a8c5 100644
--- a/src/libs/dutil/WixToolset.DUtil/path2utl.cpp
+++ b/src/libs/dutil/WixToolset.DUtil/path2utl.cpp
@@ -118,11 +118,19 @@ DAPI_(HRESULT) PathCanonicalizeForComparison(
         PathExitOnFailure(hr, "Failed to backslash terminate the canonicalized path");
     }
 
-    if ((PATH_CANONICALIZE_APPEND_LONG_PATH_PREFIX & dwCanonicalizeFlags) &&
-        PathIsFullyQualified(*psczCanonicalized, &fHasPrefix) && !fHasPrefix)
+    if (PathIsFullyQualified(*psczCanonicalized, &fHasPrefix) && !fHasPrefix &&
+        (PATH_CANONICALIZE_APPEND_LONG_PATH_PREFIX & dwCanonicalizeFlags))
     {
         hr = PathPrefix(psczCanonicalized);
         PathExitOnFailure(hr, "Failed to ensure the long path prefix on the canonicalized path");
+
+        fHasPrefix = TRUE;
+    }
+
+    if (fHasPrefix)
+    {
+        // Canonicalize \??\ into \\?\.
+        (*psczCanonicalized)[1] = L'\\';
     }
 
 LExit:
@@ -171,6 +179,40 @@ LExit:
     return hr;
 }
 
+DAPI_(HRESULT) PathCompareCanonicalized(
+    __in_z LPCWSTR wzPath1,
+    __in_z LPCWSTR wzPath2,
+    __out BOOL* pfEqual
+    )
+{
+    HRESULT hr = S_OK;
+    LPWSTR sczCanonicalized1 = NULL;
+    LPWSTR sczCanonicalized2 = NULL;
+    DWORD dwDefaultFlags = PATH_CANONICALIZE_APPEND_LONG_PATH_PREFIX | PATH_CANONICALIZE_KEEP_UNC_ROOT;
+    int nResult = 0;
+
+    if (!wzPath1 || !wzPath2)
+    {
+        PathExitWithRootFailure(hr, E_INVALIDARG, "Both paths are required.");
+    }
+
+    hr = PathCanonicalizeForComparison(wzPath1, dwDefaultFlags, &sczCanonicalized1);
+    PathExitOnFailure(hr, "Failed to canonicalize wzPath1.");
+
+    hr = PathCanonicalizeForComparison(wzPath2, dwDefaultFlags, &sczCanonicalized2);
+    PathExitOnFailure(hr, "Failed to canonicalize wzPath2.");
+
+    nResult = ::CompareStringW(LOCALE_NEUTRAL, NORM_IGNORECASE, sczCanonicalized1, -1, sczCanonicalized2, -1);
+    PathExitOnNullWithLastError(nResult, hr, "Failed to compare canonicalized paths.");
+
+    *pfEqual = CSTR_EQUAL == nResult;
+
+LExit:
+    ReleaseStr(sczCanonicalized1);
+    ReleaseStr(sczCanonicalized2);
+    return hr;
+}
+
 DAPI_(HRESULT) PathDirectoryContainsPath(
     __in_z LPCWSTR wzDirectory,
     __in_z LPCWSTR wzPath
diff --git a/src/libs/dutil/WixToolset.DUtil/pathutil.cpp b/src/libs/dutil/WixToolset.DUtil/pathutil.cpp
index a9a19b9f..abbf4d4b 100644
--- a/src/libs/dutil/WixToolset.DUtil/pathutil.cpp
+++ b/src/libs/dutil/WixToolset.DUtil/pathutil.cpp
@@ -1080,32 +1080,6 @@ LExit:
 }
 
 
-DAPI_(HRESULT) PathCompare(
-    __in_z LPCWSTR wzPath1,
-    __in_z LPCWSTR wzPath2,
-    __out int* pnResult
-    )
-{
-    HRESULT hr = S_OK;
-    LPWSTR sczPath1 = NULL;
-    LPWSTR sczPath2 = NULL;
-
-    hr = PathExpand(&sczPath1, wzPath1, PATH_EXPAND_ENVIRONMENT | PATH_EXPAND_FULLPATH);
-    PathExitOnFailure(hr, "Failed to expand path1.");
-
-    hr = PathExpand(&sczPath2, wzPath2, PATH_EXPAND_ENVIRONMENT | PATH_EXPAND_FULLPATH);
-    PathExitOnFailure(hr, "Failed to expand path2.");
-
-    *pnResult = ::CompareStringW(LOCALE_NEUTRAL, NORM_IGNORECASE, sczPath1, -1, sczPath2, -1);
-
-LExit:
-    ReleaseStr(sczPath2);
-    ReleaseStr(sczPath1);
-
-    return hr;
-}
-
-
 DAPI_(HRESULT) PathCompress(
     __in_z LPCWSTR wzPath
     )
diff --git a/src/libs/dutil/test/DUtilUnitTest/PathUtilTest.cpp b/src/libs/dutil/test/DUtilUnitTest/PathUtilTest.cpp
index 554c6f00..2505c6bf 100644
--- a/src/libs/dutil/test/DUtilUnitTest/PathUtilTest.cpp
+++ b/src/libs/dutil/test/DUtilUnitTest/PathUtilTest.cpp
@@ -151,6 +151,10 @@ namespace DutilTests
                 NativeAssert::Succeeded(hr, "Failed to canonicalize path");
                 NativeAssert::StringEqual(L"\\\\otherdir\\unc.exe", sczCanonicalized);
 
+                hr = PathCanonicalizeForComparison(L"\\??\\UNC\\server\\share\\dir", PATH_CANONICALIZE_KEEP_UNC_ROOT, &sczCanonicalized);
+                NativeAssert::Succeeded(hr, "Failed to canonicalize path");
+                NativeAssert::StringEqual(L"\\\\?\\UNC\\server\\share\\dir", sczCanonicalized);
+
                 hr = PathCanonicalizeForComparison(L"\\\\?\\UNC\\server\\share\\..\\..\\otherdir\\unc.exe", PATH_CANONICALIZE_KEEP_UNC_ROOT, &sczCanonicalized);
                 NativeAssert::Succeeded(hr, "Failed to canonicalize path");
                 NativeAssert::StringEqual(L"\\\\?\\UNC\\server\\share\\otherdir\\unc.exe", sczCanonicalized);
@@ -203,6 +207,10 @@ namespace DutilTests
                 NativeAssert::Succeeded(hr, "Failed to canonicalize path");
                 NativeAssert::StringEqual(L"\\\\?\\invalidlongpath.exe", sczCanonicalized);
 
+                hr = PathCanonicalizeForComparison(L"\\??\\test\\..\\invalidlongpath.exe", 0, &sczCanonicalized);
+                NativeAssert::Succeeded(hr, "Failed to canonicalize path");
+                NativeAssert::StringEqual(L"\\\\?\\invalidlongpath.exe", sczCanonicalized);
+
                 hr = PathCanonicalizeForComparison(L"C:\\.\\invalid:pathchars?.exe", 0, &sczCanonicalized);
                 NativeAssert::Succeeded(hr, "Failed to canonicalize path");
                 NativeAssert::StringEqual(L"C:\\invalid:pathchars?.exe", sczCanonicalized);
@@ -264,6 +272,67 @@ namespace DutilTests
         }
 
         [Fact]
+        void PathCompareCanonicalizeEqualTest()
+        {
+            HRESULT hr = S_OK;
+            LPWSTR sczPath = NULL;
+            BOOL fEqual = FALSE;
+            LPCWSTR rgwzPaths[14] =
+            {
+                L"C:\\simplepath", L"C:\\simplepath",
+                L"\\\\server\\share\\dir\\dir2\\..\\otherdir\\unc.exe", L"\\\\server\\share\\dir\\otherdir\\unc.exe",
+                L"\\\\server\\share\\..\\..\\otherdir\\unc.exe", L"\\\\server\\share\\otherdir\\unc.exe",
+                L"\\\\?\\UNC\\server\\share\\..\\..\\otherdir\\unc.exe", L"\\\\?\\UNC\\server\\share\\otherdir\\unc.exe",
+                L"C:\\dir\\subdir\\..\\..\\..\\otherdir\\pastroot.exe", L"C:\\otherdir\\pastroot.exe",
+                L"\\\\?\\C:\\dir\\subdir\\..\\..\\..\\otherdir\\pastroot.exe", L"C:\\..\\otherdir\\pastroot.exe",
+                L"\\??\\C:\\dir", L"\\\\?\\C:\\dir",
+            };
+
+            try
+            {
+                for (DWORD i = 0; i < countof(rgwzPaths); i += 2)
+                {
+                    hr = PathCompareCanonicalized(rgwzPaths[i], rgwzPaths[i + 1], &fEqual);
+                    NativeAssert::Succeeded(hr, "PathCompareCanonicalized: {0}, {1}", rgwzPaths[i], rgwzPaths[i + 1]);
+                    Assert::True(fEqual, String::Format("PathCompareCanonicalized: {0}, {1}", gcnew String(rgwzPaths[i]), gcnew String(rgwzPaths[i + 1])));
+                }
+            }
+            finally
+            {
+                ReleaseStr(sczPath);
+            }
+        }
+
+        [Fact]
+        void PathCompareCanonicalizeNotEqualTest()
+        {
+            HRESULT hr = S_OK;
+            LPWSTR sczPath = NULL;
+            BOOL fEqual = FALSE;
+            LPCWSTR rgwzPaths[8] =
+            {
+                L"C:\\simplepath", L"D:\\simplepath",
+                L"\\\\.\\share\\otherdir\\unc.exe", L"\\\\share\\otherdir\\unc.exe",
+                L"\\\\server\\.\\otherdir\\unc.exe", L"\\\\server\\otherdir\\unc.exe",
+                L"\\\\server\\\\otherdir\\unc.exe", L"\\\\server\\otherdir\\unc.exe",
+            };
+
+            try
+            {
+                for (DWORD i = 0; i < countof(rgwzPaths); i += 2)
+                {
+                    hr = PathCompareCanonicalized(rgwzPaths[i], rgwzPaths[i + 1], &fEqual);
+                    NativeAssert::Succeeded(hr, "PathCompareCanonicalized: {0}, {1}", rgwzPaths[i], rgwzPaths[i + 1]);
+                    Assert::False(fEqual, String::Format("PathCompareCanonicalized: {0}, {1}", gcnew String(rgwzPaths[i]), gcnew String(rgwzPaths[i + 1])));
+                }
+            }
+            finally
+            {
+                ReleaseStr(sczPath);
+            }
+        }
+
+        [Fact]
         void PathConcatRelativeToBaseTest()
         {
             HRESULT hr = S_OK;