Fix CreateJunction when the target is a volume-prefixed path

src/AlphaFS/Device/Device.cs

@@ -352,7 +352,12 @@ internal static void ToggleCompressionCore(KernelTransaction transaction, bool i
       /// <summary>[AlphaFS] Creates an NTFS directory junction (similar to CMD command: "MKLINK /J").</summary>
       internal static void CreateDirectoryJunction(SafeFileHandle safeHandle, string directoryPath)
       {
-         var targetDirBytes = Encoding.Unicode.GetBytes(Path.NonInterpretedPathPrefix + Path.GetRegularPathCore(directoryPath, GetFullPathOptions.AddTrailingDirectorySeparator, false));
+         var targetDir = Path.GetRegularPathCore(directoryPath, GetFullPathOptions.AddTrailingDirectorySeparator, false);
+         // junctions to volume-prefixed paths need the long path prefix removed. Correct: \??\Volume{000...}\foo, wrong: \??\\\?\Volume{000...}\foo
+         if (targetDir.StartsWith(Path.VolumePrefix))
+            targetDir = targetDir.Substring(Path.LongPathPrefix.Length);
+         targetDir = Path.NonInterpretedPathPrefix + targetDir;
+         var targetDirBytes = Encoding.Unicode.GetBytes(targetDir);
 
          var header = new NativeMethods.ReparseDataBufferHeader
          {

tests/AlphaFS.UnitTest/AlphaFS Junctions, Links/AlphaFS_DirectoryInfo.CreateJunction_And_ExistsJunction_And_DeleteJunction.cs

@@ -31,20 +31,41 @@ public partial class AlphaFS_JunctionsLinksTest
 
       [TestMethod]
       public void AlphaFS_DirectoryInfo_CreateJunction_And_ExistsJunction_And_DeleteJunction_Local_Success()
+      {
+         AlphaFS_DirectoryInfo_CreateJunction_And_ExistsJunction_And_DeleteJunction_Local_Success_core(false);
+      }
+
+      [TestMethod]
+      public void AlphaFS_DirectoryInfo_CreateJunction_And_ExistsJunction_And_DeleteJunction_Local_VolumePath_Success()
+      {
+         AlphaFS_DirectoryInfo_CreateJunction_And_ExistsJunction_And_DeleteJunction_Local_Success_core(true);
+      }
+
+      private void AlphaFS_DirectoryInfo_CreateJunction_And_ExistsJunction_And_DeleteJunction_Local_Success_core(bool volumeTarget)
       {
          using (var tempRoot = new TemporaryDirectory())
          {
             var toDelete = tempRoot.Directory.CreateSubdirectory("ToDelete");
             var junction = System.IO.Path.Combine(toDelete.FullName, "MyJunctionPoint");
-            var target = tempRoot.Directory.CreateSubdirectory("JunctionTarget");
+            var target = tempRoot.Directory.CreateSubdirectory("JunctionTarget").FullName;
+
+            if (volumeTarget)
+            {
+               var volumeGuidPath = Alphaleonis.Win32.Filesystem.Volume.GetUniqueVolumeNameForPath(target);
+               var volumePath = Alphaleonis.Win32.Filesystem.Volume.GetVolumePathName(target);
+               var targetNew = target.Replace(volumePath, volumeGuidPath);
+               if (targetNew == target || !targetNew.StartsWith(Alphaleonis.Win32.Filesystem.Path.VolumePrefix))
+                  Assert.Inconclusive(@"Failed to construct a \\?\Volume style path for this test");
+               target = targetNew;
+            }
 
             Console.WriteLine("Input Directory JunctionPoint  Path: [{0}]", junction);
             Console.WriteLine("Input Directory JunctionTarget Path: [{0}]", target);
 
 
             #region CreateJunction
 
-            var dirInfo = new Alphaleonis.Win32.Filesystem.DirectoryInfo(target.FullName);
+            var dirInfo = new Alphaleonis.Win32.Filesystem.DirectoryInfo(target);
 
 
             // On success, dirInfo.FullName now points to the directory junction.
@@ -87,7 +108,7 @@ public void AlphaFS_DirectoryInfo_CreateJunction_And_ExistsJunction_And_DeleteJu
             const string subFolder = "Test folder";
             dirInfo.CreateSubdirectory(subFolder);
 
-            Assert.IsTrue(System.IO.Directory.Exists(System.IO.Path.Combine(target.FullName, subFolder)));
+            Assert.IsTrue(System.IO.Directory.Exists(System.IO.Path.Combine(target, subFolder)));
 
             #endregion // CreateJunction