Ensure more FS classes are updated for 13.1.0

- FsSrv.Impl.IResultConvertDirectory
- FsSrv.Impl.IResultConvertFile
- FsSrv.Impl.IResultConvertFileSystem
- FsSrv.Impl.SaveDataExtraDataAccessorCacheManager
- FsSrv.Impl.SaveDataExtraDataResultConvertAccessor
- FsSrv.Impl.SaveDataResultConvert
- FsSrv.Impl.SaveDataResultConvertDirectory
- FsSrv.Impl.SaveDataResultConvertFile
- FsSrv.Impl.SaveDataResultConvertFileSystem
- FsSrv.Impl.StorageInterfaceAdapter
- FsSystem.ISaveDataCommitTimeStampGetter
- FsSystem.ISaveDataExtraDataAccessor
- FsSystem.ISaveDataFileSystemCacheManager
- FsSystem.SaveDataFileSystemCacheManager
- FsSystem.SaveDataFileSystemCacheRegisterBase

src/LibHac/FsSrv/Impl/IResultConvertFileSystem.cs

@@ -6,6 +6,11 @@ using LibHac.Fs.Fsa;
 namespace LibHac.FsSrv.Impl;
 
 // ReSharper disable once InconsistentNaming
+/// <summary>
+/// Wraps an <see cref="IFile"/>, converting its returned <see cref="Result"/>s to different
+/// <see cref="Result"/>s based on the <see cref="ConvertResult"/> function.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public abstract class IResultConvertFile : IFile
 {
     protected UniqueRef<IFile> BaseFile;
@@ -56,6 +61,11 @@ public abstract class IResultConvertFile : IFile
 }
 
 // ReSharper disable once InconsistentNaming
+/// <summary>
+/// Wraps an <see cref="IDirectory"/>, converting its returned <see cref="Result"/>s to different
+/// <see cref="Result"/>s based on the <see cref="ConvertResult"/> function.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public abstract class IResultConvertDirectory : IDirectory
 {
     protected UniqueRef<IDirectory> BaseDirectory;
@@ -85,6 +95,11 @@ public abstract class IResultConvertDirectory : IDirectory
 }
 
 // ReSharper disable once InconsistentNaming
+/// <summary>
+/// Wraps an <see cref="IFileSystem"/>, converting its returned <see cref="Result"/>s to different
+/// <see cref="Result"/>s based on the <see cref="ConvertResult"/> function.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public abstract class IResultConvertFileSystem : IFileSystem
 {
     protected SharedRef<IFileSystem> BaseFileSystem;
@@ -145,6 +160,8 @@ public abstract class IResultConvertFileSystem : IFileSystem
         return ConvertResult(BaseFileSystem.Get.GetEntryType(out entryType, path));
     }
 
+    // Note: The original code uses templates to determine which type of IFile/IDirectory to return. To make things
+    // easier in C# these two functions have been made abstract functions.
     protected abstract override Result DoOpenFile(ref UniqueRef<IFile> outFile, in Path path, OpenMode mode);
 
     protected abstract override Result DoOpenDirectory(ref UniqueRef<IDirectory> outDirectory, in Path path,

src/LibHac/FsSrv/Impl/SaveDataExtraDataAccessorCacheManager.cs

@@ -10,8 +10,13 @@ namespace LibHac.FsSrv.Impl;
 /// <summary>
 /// Holds the <see cref="ISaveDataExtraDataAccessor"/>s for opened save data file systems.
 /// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public class SaveDataExtraDataAccessorCacheManager : ISaveDataExtraDataAccessorCacheObserver
 {
+    /// <summary>
+    /// Holds a single cached extra data accessor identified by its save data ID and save data space ID.
+    /// </summary>
+    /// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
     [NonCopyable]
     private struct Cache : IDisposable
     {
@@ -19,8 +24,7 @@ public class SaveDataExtraDataAccessorCacheManager : ISaveDataExtraDataAccessorC
         private readonly SaveDataSpaceId _spaceId;
         private readonly ulong _saveDataId;
 
-        public Cache(in SharedRef<ISaveDataExtraDataAccessor> accessor, SaveDataSpaceId spaceId,
+        public Cache(in SharedRef<ISaveDataExtraDataAccessor> accessor, SaveDataSpaceId spaceId, ulong saveDataId)
-            ulong saveDataId)
         {
             _accessor = new WeakRef<ISaveDataExtraDataAccessor>(in accessor);
             _spaceId = spaceId;
@@ -49,7 +53,7 @@ public class SaveDataExtraDataAccessorCacheManager : ISaveDataExtraDataAccessorC
     public SaveDataExtraDataAccessorCacheManager()
     {
         _accessorList = new LinkedList<Cache>();
-        _mutex.Initialize();
+        _mutex = new SdkRecursiveMutexType();
     }
 
     public void Dispose()

src/LibHac/FsSrv/Impl/SaveDataResultConvertFileSystem.cs

@@ -6,6 +6,10 @@ using LibHac.FsSystem;
 
 namespace LibHac.FsSrv.Impl;
 
+/// <summary>
+/// Contains functions for converting internal save data <see cref="Result"/>s to external <see cref="Result"/>s.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public static class SaveDataResultConvert
 {
     private static Result ConvertCorruptedResult(Result result)
@@ -13,19 +17,19 @@ public static class SaveDataResultConvert
         if (ResultFs.IntegrityVerificationStorageCorrupted.Includes(result))
         {
             if (ResultFs.IncorrectIntegrityVerificationMagicCode.Includes(result))
-                return ResultFs.IncorrectSaveDataIntegrityVerificationMagicCode.Value;
+                return ResultFs.IncorrectSaveDataIntegrityVerificationMagicCode.LogConverted(result);
 
             if (ResultFs.InvalidZeroHash.Includes(result))
-                return ResultFs.InvalidSaveDataZeroHash.Value;
+                return ResultFs.InvalidSaveDataZeroHash.LogConverted(result);
 
             if (ResultFs.NonRealDataVerificationFailed.Includes(result))
-                return ResultFs.SaveDataNonRealDataVerificationFailed.Value;
+                return ResultFs.SaveDataNonRealDataVerificationFailed.LogConverted(result);
 
             if (ResultFs.ClearedRealDataVerificationFailed.Includes(result))
-                return ResultFs.ClearedSaveDataRealDataVerificationFailed.Value;
+                return ResultFs.ClearedSaveDataRealDataVerificationFailed.LogConverted(result);
 
             if (ResultFs.UnclearedRealDataVerificationFailed.Includes(result))
-                return ResultFs.UnclearedSaveDataRealDataVerificationFailed.Value;
+                return ResultFs.UnclearedSaveDataRealDataVerificationFailed.LogConverted(result);
 
             Assert.SdkAssert(false);
         }
@@ -33,16 +37,16 @@ public static class SaveDataResultConvert
         if (ResultFs.HostFileSystemCorrupted.Includes(result))
         {
             if (ResultFs.HostEntryCorrupted.Includes(result))
-                return ResultFs.SaveDataHostEntryCorrupted.Value;
+                return ResultFs.SaveDataHostEntryCorrupted.LogConverted(result);
 
             if (ResultFs.HostFileDataCorrupted.Includes(result))
-                return ResultFs.SaveDataHostFileDataCorrupted.Value;
+                return ResultFs.SaveDataHostFileDataCorrupted.LogConverted(result);
 
             if (ResultFs.HostFileCorrupted.Includes(result))
-                return ResultFs.SaveDataHostFileCorrupted.Value;
+                return ResultFs.SaveDataHostFileCorrupted.LogConverted(result);
 
             if (ResultFs.InvalidHostHandle.Includes(result))
-                return ResultFs.InvalidSaveDataHostHandle.Value;
+                return ResultFs.InvalidSaveDataHostHandle.LogConverted(result);
 
             Assert.SdkAssert(false);
         }
@@ -50,25 +54,25 @@ public static class SaveDataResultConvert
         if (ResultFs.DatabaseCorrupted.Includes(result))
         {
             if (ResultFs.InvalidAllocationTableBlock.Includes(result))
-                return ResultFs.InvalidSaveDataAllocationTableBlock.Value;
+                return ResultFs.InvalidSaveDataAllocationTableBlock.LogConverted(result);
 
             if (ResultFs.InvalidKeyValueListElementIndex.Includes(result))
-                return ResultFs.InvalidSaveDataKeyValueListElementIndex.Value;
+                return ResultFs.InvalidSaveDataKeyValueListElementIndex.LogConverted(result);
 
             if (ResultFs.InvalidAllocationTableChainEntry.Includes(result))
-                return ResultFs.InvalidSaveDataAllocationTableChainEntry.Value;
+                return ResultFs.InvalidSaveDataAllocationTableChainEntry.LogConverted(result);
 
             if (ResultFs.InvalidAllocationTableOffset.Includes(result))
-                return ResultFs.InvalidSaveDataAllocationTableOffset.Value;
+                return ResultFs.InvalidSaveDataAllocationTableOffset.LogConverted(result);
 
             if (ResultFs.InvalidAllocationTableBlockCount.Includes(result))
-                return ResultFs.InvalidSaveDataAllocationTableBlockCount.Value;
+                return ResultFs.InvalidSaveDataAllocationTableBlockCount.LogConverted(result);
 
             if (ResultFs.InvalidKeyValueListEntryIndex.Includes(result))
-                return ResultFs.InvalidSaveDataKeyValueListEntryIndex.Value;
+                return ResultFs.InvalidSaveDataKeyValueListEntryIndex.LogConverted(result);
 
             if (ResultFs.InvalidBitmapIndex.Includes(result))
-                return ResultFs.InvalidSaveDataBitmapIndex.Value;
+                return ResultFs.InvalidSaveDataBitmapIndex.LogConverted(result);
 
             Assert.SdkAssert(false);
         }
@@ -76,7 +80,7 @@ public static class SaveDataResultConvert
         if (ResultFs.ZeroBitmapFileCorrupted.Includes(result))
         {
             if (ResultFs.IncompleteBlockInZeroBitmapHashStorageFile.Includes(result))
-                return ResultFs.IncompleteBlockInZeroBitmapHashStorageFileSaveData.Value;
+                return ResultFs.IncompleteBlockInZeroBitmapHashStorageFileSaveData.LogConverted(result);
 
             Assert.SdkAssert(false);
         }
@@ -84,13 +88,13 @@ public static class SaveDataResultConvert
         return result;
     }
 
-    public static Result ConvertSaveFsDriverPublicResult(Result result)
+    public static Result ConvertSaveFsDriverPrivateResult(Result result)
     {
         if (result.IsSuccess())
             return result;
 
         if (ResultFs.UnsupportedVersion.Includes(result))
-            return ResultFs.UnsupportedSaveDataVersion.Value;
+            return ResultFs.UnsupportedSaveDataVersion.LogConverted(result);
 
         if (ResultFs.IntegrityVerificationStorageCorrupted.Includes(result) ||
             ResultFs.BuiltInStorageCorrupted.Includes(result) ||
@@ -105,21 +109,21 @@ public static class SaveDataResultConvert
             return result;
 
         if (ResultFs.NotFound.Includes(result))
-            return ResultFs.PathNotFound.Value;
+            return ResultFs.PathNotFound.LogConverted(result);
 
         if (ResultFs.AllocationTableFull.Includes(result))
-            return ResultFs.UsableSpaceNotEnough.Value;
+            return ResultFs.UsableSpaceNotEnough.LogConverted(result);
 
         if (ResultFs.AlreadyExists.Includes(result))
-            return ResultFs.PathAlreadyExists.Value;
+            return ResultFs.PathAlreadyExists.LogConverted(result);
 
         if (ResultFs.InvalidOffset.Includes(result))
-            return ResultFs.OutOfRange.Value;
+            return ResultFs.OutOfRange.LogConverted(result);
 
         if (ResultFs.IncompatiblePath.Includes(result) ||
             ResultFs.FileNotFound.Includes(result))
         {
-            return ResultFs.PathNotFound.Value;
+            return ResultFs.PathNotFound.LogConverted(result);
         }
 
         return result;
@@ -130,6 +134,7 @@ public static class SaveDataResultConvert
 /// Wraps an <see cref="IFile"/>, converting its returned <see cref="Result"/>s
 /// to save-data-specific <see cref="Result"/>s.
 /// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public class SaveDataResultConvertFile : IResultConvertFile
 {
     public SaveDataResultConvertFile(ref UniqueRef<IFile> baseFile) : base(ref baseFile)
@@ -138,7 +143,7 @@ public class SaveDataResultConvertFile : IResultConvertFile
 
     protected override Result ConvertResult(Result result)
     {
-        return SaveDataResultConvert.ConvertSaveFsDriverPublicResult(result);
+        return SaveDataResultConvert.ConvertSaveFsDriverPrivateResult(result);
     }
 }
 
@@ -146,6 +151,7 @@ public class SaveDataResultConvertFile : IResultConvertFile
 /// Wraps an <see cref="IDirectory"/>, converting its returned <see cref="Result"/>s
 /// to save-data-specific <see cref="Result"/>s.
 /// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public class SaveDataResultConvertDirectory : IResultConvertDirectory
 {
     public SaveDataResultConvertDirectory(ref UniqueRef<IDirectory> baseDirectory) : base(ref baseDirectory)
@@ -154,7 +160,7 @@ public class SaveDataResultConvertDirectory : IResultConvertDirectory
 
     protected override Result ConvertResult(Result result)
     {
-        return SaveDataResultConvert.ConvertSaveFsDriverPublicResult(result);
+        return SaveDataResultConvert.ConvertSaveFsDriverPrivateResult(result);
     }
 }
 
@@ -162,6 +168,7 @@ public class SaveDataResultConvertDirectory : IResultConvertDirectory
 /// Wraps an <see cref="IFileSystem"/>, converting its returned <see cref="Result"/>s
 /// to save-data-specific <see cref="Result"/>s.
 /// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public class SaveDataResultConvertFileSystem : IResultConvertFileSystem
 {
     public SaveDataResultConvertFileSystem(ref SharedRef<IFileSystem> baseFileSystem)
@@ -192,7 +199,7 @@ public class SaveDataResultConvertFileSystem : IResultConvertFileSystem
 
     protected override Result ConvertResult(Result result)
     {
-        return SaveDataResultConvert.ConvertSaveFsDriverPublicResult(result);
+        return SaveDataResultConvert.ConvertSaveFsDriverPrivateResult(result);
     }
 }
 
@@ -200,6 +207,7 @@ public class SaveDataResultConvertFileSystem : IResultConvertFileSystem
 /// Wraps an <see cref="ISaveDataExtraDataAccessor"/>, converting its returned <see cref="Result"/>s
 /// to save-data-specific <see cref="Result"/>s.
 /// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public class SaveDataExtraDataResultConvertAccessor : ISaveDataExtraDataAccessor
 {
     private SharedRef<ISaveDataExtraDataAccessor> _accessor;
@@ -217,19 +225,19 @@ public class SaveDataExtraDataResultConvertAccessor : ISaveDataExtraDataAccessor
     public Result WriteExtraData(in SaveDataExtraData extraData)
     {
         Result rc = _accessor.Get.WriteExtraData(in extraData);
-        return SaveDataResultConvert.ConvertSaveFsDriverPublicResult(rc);
+        return SaveDataResultConvert.ConvertSaveFsDriverPrivateResult(rc);
     }
 
     public Result CommitExtraData(bool updateTimeStamp)
     {
         Result rc = _accessor.Get.CommitExtraData(updateTimeStamp);
-        return SaveDataResultConvert.ConvertSaveFsDriverPublicResult(rc);
+        return SaveDataResultConvert.ConvertSaveFsDriverPrivateResult(rc);
     }
 
     public Result ReadExtraData(out SaveDataExtraData extraData)
     {
         Result rc = _accessor.Get.ReadExtraData(out extraData);
-        return SaveDataResultConvert.ConvertSaveFsDriverPublicResult(rc);
+        return SaveDataResultConvert.ConvertSaveFsDriverPrivateResult(rc);
     }
 
     public void RegisterCacheObserver(ISaveDataExtraDataAccessorCacheObserver observer, SaveDataSpaceId spaceId,

src/LibHac/FsSrv/Impl/StorageInterfaceAdapter.cs

@@ -8,6 +8,10 @@ using IStorageSf = LibHac.FsSrv.Sf.IStorage;
 
 namespace LibHac.FsSrv.Impl;
 
+/// <summary>
+/// Wraps an <see cref="IStorage"/> to allow interfacing with it via the <see cref="IStorageSf"/> interface over IPC.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public class StorageInterfaceAdapter : IStorageSf
 {
     private SharedRef<IStorage> _baseStorage;
@@ -32,6 +36,9 @@ public class StorageInterfaceAdapter : IStorageSf
         if (destination.Size < 0)
             return ResultFs.InvalidSize.Log();
 
+        if (destination.Size < size)
+            return ResultFs.InvalidSize.Log();
+
         Result rc = Result.Success;
 
         for (int tryNum = 0; tryNum < maxTryCount; tryNum++)
@@ -54,6 +61,9 @@ public class StorageInterfaceAdapter : IStorageSf
         if (source.Size < 0)
             return ResultFs.InvalidSize.Log();
 
+        if (source.Size < size)
+            return ResultFs.InvalidSize.Log();
+
         using var scopedPriorityChanger = new ScopedThreadPriorityChangerByAccessPriority(
             ScopedThreadPriorityChangerByAccessPriority.AccessMode.Write);
 

src/LibHac/FsSystem/ISaveDataCommitTimeStampGetter.cs

@@ -1,5 +1,9 @@
 namespace LibHac.FsSystem;
 
+/// <summary>
+/// Gets Unix timestamps used to update a save data's commit time. 
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public interface ISaveDataCommitTimeStampGetter
 {
     Result Get(out long timeStamp);

src/LibHac/FsSystem/ISaveDataExtraDataAccessor.cs

@@ -3,6 +3,10 @@ using LibHac.Fs;
 
 namespace LibHac.FsSystem;
 
+/// <summary>
+/// Provides read/write access to a save data file system's extra data.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public interface ISaveDataExtraDataAccessor : IDisposable
 {
     Result WriteExtraData(in SaveDataExtraData extraData);

src/LibHac/FsSystem/ISaveDataExtraDataAccessorCacheObserver.cs

@@ -1,8 +1,15 @@
 using System;
 using LibHac.Fs;
+using LibHac.FsSrv.Impl;
 
 namespace LibHac.FsSystem;
 
+/// <summary>
+/// Used when adding an <see cref="ISaveDataExtraDataAccessor"/> to the
+/// <see cref="SaveDataExtraDataAccessorCacheManager"/>. When an extra data accessor is disposed, the accessor will
+/// use this interface to notify the cache manager that it should be removed from the extra data cache.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public interface ISaveDataExtraDataAccessorCacheObserver : IDisposable
 {
     void Unregister(SaveDataSpaceId spaceId, ulong saveDataId);

src/LibHac/FsSystem/ISaveDataFileSystemCacheManager.cs

@@ -4,6 +4,10 @@ using LibHac.Fs;
 
 namespace LibHac.FsSystem;
 
+/// <summary>
+/// Provides a mechanism for caching save data file systems.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public interface ISaveDataFileSystemCacheManager : IDisposable
 {
     bool GetCache(ref SharedRef<SaveDataFileSystemHolder> outFileSystem, SaveDataSpaceId spaceId, ulong saveDataId);

src/LibHac/FsSystem/SaveDataFileSystemCacheManager.cs

@@ -5,8 +5,17 @@ using LibHac.Os;
 
 namespace LibHac.FsSystem;
 
+/// <summary>
+/// Manages a list of cached save data file systems. Each file system is registered and retrieved
+/// based on its save data ID and save data space ID.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public class SaveDataFileSystemCacheManager : ISaveDataFileSystemCacheManager
 {
+    /// <summary>
+    /// Holds a single cached file system identified by its save data ID and save data space ID.
+    /// </summary>
+    /// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
     [NonCopyable]
     private struct Cache
     {
@@ -26,9 +35,9 @@ public class SaveDataFileSystemCacheManager : ISaveDataFileSystemCacheManager
             return _fileSystem.HasValue && _spaceId == spaceId && _saveDataId == saveDataId;
         }
 
-        public void Move(ref SharedRef<SaveDataFileSystemHolder> outFileSystem)
+        public SharedRef<SaveDataFileSystemHolder> Move()
         {
-            outFileSystem.SetByMove(ref _fileSystem);
+            return SharedRef<SaveDataFileSystemHolder>.CreateMove(ref _fileSystem);
         }
 
         public void Register(ref SharedRef<SaveDataFileSystemHolder> fileSystem)
@@ -52,7 +61,7 @@ public class SaveDataFileSystemCacheManager : ISaveDataFileSystemCacheManager
 
     public SaveDataFileSystemCacheManager()
     {
-        _mutex.Initialize();
+        _mutex = new SdkRecursiveMutexType();
     }
 
     public void Dispose()
@@ -77,11 +86,12 @@ public class SaveDataFileSystemCacheManager : ISaveDataFileSystemCacheManager
         Assert.SdkAssert(_cachedFileSystems is null);
 
         _maxCachedFileSystemCount = maxCacheCount;
-        if (maxCacheCount <= 0)
+        if (maxCacheCount > 0)
-            return Result.Success;
+        {
-
             // Note: The original checks for overflow here
             _cachedFileSystems = new Cache[maxCacheCount];
+        }
+
         return Result.Success;
     }
 
@@ -96,7 +106,9 @@ public class SaveDataFileSystemCacheManager : ISaveDataFileSystemCacheManager
         {
             if (_cachedFileSystems[i].IsCached(spaceId, saveDataId))
             {
-                _cachedFileSystems[i].Move(ref outFileSystem);
+                using SharedRef<SaveDataFileSystemHolder> cachedFs = _cachedFileSystems[i].Move();
+                outFileSystem.SetByMove(ref cachedFs.Ref());
+
                 return true;
             }
         }

src/LibHac/FsSystem/SaveDataFileSystemCacheRegisterBase.cs

@@ -1,5 +1,5 @@
 using System;
-using InlineIL;
+using System.Runtime.CompilerServices;
 using LibHac.Common;
 using LibHac.Diag;
 using LibHac.Fs;
@@ -14,6 +14,7 @@ namespace LibHac.FsSystem;
 /// </summary>
 /// <typeparam name="T">The type of the base file system. Must be one of <see cref="SaveDataFileSystem"/>,
 /// <see cref="ApplicationTemporaryFileSystem"/> or <see cref="DirectorySaveDataFileSystem"/>.</typeparam>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public class SaveDataFileSystemCacheRegisterBase<T> : IFileSystem where T : IFileSystem
 {
     private SharedRef<T> _baseFileSystem;
@@ -36,11 +37,11 @@ public class SaveDataFileSystemCacheRegisterBase<T> : IFileSystem where T : IFil
     {
         if (typeof(T) == typeof(SaveDataFileSystemHolder))
         {
-            _cacheManager.Register(ref GetBaseFileSystemNormal());
+            _cacheManager.Register(ref Unsafe.As<SharedRef<T>, SharedRef<SaveDataFileSystemHolder>>(ref _baseFileSystem));
         }
         else if (typeof(T) == typeof(ApplicationTemporaryFileSystem))
         {
-            _cacheManager.Register(ref GetBaseFileSystemTemp());
+            _cacheManager.Register(ref Unsafe.As<SharedRef<T>, SharedRef<ApplicationTemporaryFileSystem>>(ref _baseFileSystem));
         }
         else
         {
@@ -48,23 +49,6 @@ public class SaveDataFileSystemCacheRegisterBase<T> : IFileSystem where T : IFil
         }
     }
 
-    // Hack around not being able to use Unsafe.As on ref structs
-    private ref SharedRef<SaveDataFileSystemHolder> GetBaseFileSystemNormal()
-    {
-        IL.Emit.Ldarg_0();
-        IL.Emit.Ldflda(new FieldRef(typeof(SaveDataFileSystemCacheRegisterBase<T>), nameof(_baseFileSystem)));
-        IL.Emit.Ret();
-        throw IL.Unreachable();
-    }
-
-    private ref SharedRef<ApplicationTemporaryFileSystem> GetBaseFileSystemTemp()
-    {
-        IL.Emit.Ldarg_0();
-        IL.Emit.Ldflda(new FieldRef(typeof(SaveDataFileSystemCacheRegisterBase<T>), nameof(_baseFileSystem)));
-        IL.Emit.Ret();
-        throw IL.Unreachable();
-    }
-
     protected override Result DoOpenFile(ref UniqueRef<IFile> outFile, in Path path, OpenMode mode)
     {
         return _baseFileSystem.Get.OpenFile(ref outFile, path, mode);

src/LibHac/FsSystem/SaveDataFileSystemHolder.cs

@@ -6,6 +6,13 @@ using LibHac.Fs.Fsa;
 
 namespace LibHac.FsSystem;
 
+/// <summary>
+/// Holds a file system for adding to the save data file system cache.
+/// </summary>
+/// <remarks> Nintendo uses concrete types in <see cref="ISaveDataFileSystemCacheManager"/> instead of an interface.
+/// This class allows <see cref="DirectorySaveDataFileSystem"/> to be cached in a way that changes the original
+/// design as little as possible.
+/// </remarks>
 public class SaveDataFileSystemHolder : ForwardingFileSystem
 {
     public SaveDataFileSystemHolder(ref SharedRef<IFileSystem> baseFileSystem) : base(ref baseFileSystem)