Fixup some mounted-FS-related classes and update them to 13.1.0

- FileSystemAccessor
- FileAccessor
- DirectoryAccessor
- MountTable
- UserMountTable
- FileDataCacheAccessor
- IFileDataCache
- GlobalFileDataCacheAccessorReadableScopedPointer
- FileDataCache shim functions
- PathBasedFileDataCache shim functions

src/LibHac/Common/Box.cs

@@ -0,0 +1,13 @@
+namespace LibHac.Common;
+
+public class Box<T> where T : struct
+{
+    private T _value;
+
+    public ref T Value => ref _value;
+
+    public Box()
+    {
+        _value = new T();
+    }
+}

src/LibHac/Fs/FileSystemClient.cs

@@ -35,6 +35,7 @@ internal struct FileSystemClientGlobals : IDisposable
     public FsContextHandlerGlobals FsContextHandler;
     public ResultHandlingUtilityGlobals ResultHandlingUtility;
     public DirectorySaveDataFileSystemGlobals DirectorySaveDataFileSystem;
+    public FileDataCacheShim.Globals FileDataCache;
 
     public void Initialize(FileSystemClient fsClient, HorizonClient horizonClient)
     {
@@ -60,4 +61,4 @@ public readonly struct FileSystemClientImpl
     internal ref FileSystemClientGlobals Globals => ref Fs.Globals;
 
     internal FileSystemClientImpl(FileSystemClient parentClient) => Fs = parentClient;
-}
+}

src/LibHac/Fs/Fsa/DirectoryAccessor.cs

@@ -5,6 +5,10 @@ using LibHac.Fs.Fsa;
 // ReSharper disable once CheckNamespace
 namespace LibHac.Fs.Impl;
 
+/// <summary>
+/// Provides access to a directory in a mounted file system and handles closing the directory.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 internal class DirectoryAccessor : IDisposable
 {
     private UniqueRef<IDirectory> _directory;
@@ -35,4 +39,4 @@ internal class DirectoryAccessor : IDisposable
     {
         return _directory.Get.GetEntryCount(out entryCount);
     }
-}
+}

src/LibHac/Fs/Fsa/FileAccessor.cs

@@ -2,6 +2,7 @@
 using LibHac.Common;
 using LibHac.Diag;
 using LibHac.Fs.Fsa;
+using LibHac.Fs.Shim;
 using LibHac.Os;
 using static LibHac.Fs.Impl.AccessLogStrings;
 
@@ -15,6 +16,10 @@ internal enum WriteState
     Failed,
 }
 
+/// <summary>
+/// Provides access to a mount <see cref="IFile"/> and handles caching it.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 internal class FileAccessor : IDisposable
 {
     private const string NeedFlushMessage = "Error: nn::fs::CloseFile() failed because the file was not flushed.\n";
@@ -24,8 +29,7 @@ internal class FileAccessor : IDisposable
     private WriteState _writeState;
     private Result _lastResult;
     private OpenMode _openMode;
-    private FilePathHash _filePathHash;
+    private Box<FilePathHash> _filePathHash;
-    // ReSharper disable once NotAccessedField.Local
     private int _pathHashIndex;
 
     internal HorizonClient Hos { get; }
@@ -59,7 +63,7 @@ internal class FileAccessor : IDisposable
     public WriteState GetWriteState() => _writeState;
     public FileSystemAccessor GetParent() => _parentFileSystem;
 
-    public void SetFilePathHash(FilePathHash filePathHash, int index)
+    public void SetFilePathHash(Box<FilePathHash> filePathHash, int index)
     {
         _filePathHash = filePathHash;
         _pathHashIndex = index;
@@ -73,18 +77,18 @@ internal class FileAccessor : IDisposable
         return result;
     }
 
-    public Result ReadWithoutCacheAccessLog(out long bytesRead, long offset, Span<byte> destination,
-        in ReadOption option)
-    {
-        return _file.Get.Read(out bytesRead, offset, destination, in option);
-    }
-
     private Result ReadWithCacheAccessLog(out long bytesRead, long offset, Span<byte> destination,
         in ReadOption option, bool usePathCache, bool useDataCache)
     {
         throw new NotImplementedException();
     }
 
+    public Result ReadWithoutCacheAccessLog(out long bytesRead, long offset, Span<byte> destination,
+        in ReadOption option)
+    {
+        return _file.Get.Read(out bytesRead, offset, destination, in option);
+    }
+
     public Result Read(out long bytesRead, long offset, Span<byte> destination, in ReadOption option)
     {
         UnsafeHelpers.SkipParamInit(out bytesRead);
@@ -113,42 +117,36 @@ internal class FileAccessor : IDisposable
             return _lastResult;
         }
 
-        // ReSharper disable ConditionIsAlwaysTrueOrFalse
+        bool usePathCache = _parentFileSystem is not null && _filePathHash is not null;
-        bool usePathCache = _parentFileSystem is not null && _filePathHash.Data != 0;
+        bool useDataCache = Hos.Fs.Impl.IsGlobalFileDataCacheEnabled() && _parentFileSystem is not null &&
+                            _parentFileSystem.IsFileDataCacheAttachable();
 
-        // Todo: Call IsGlobalFileDataCacheEnabled
-#pragma warning disable 162
-        bool useDataCache = false && _parentFileSystem is not null && _parentFileSystem.IsFileDataCacheAttachable();
-#pragma warning restore 162
         if (usePathCache || useDataCache)
         {
             return ReadWithCacheAccessLog(out bytesRead, offset, destination, in option, usePathCache,
                 useDataCache);
         }
+
+        if (Hos.Fs.Impl.IsEnabledAccessLog() && Hos.Fs.Impl.IsEnabledHandleAccessLog(handle))
+        {
+            Tick start = Hos.Os.GetSystemTick();
+            rc = ReadWithoutCacheAccessLog(out bytesRead, offset, destination, in option);
+            Tick end = Hos.Os.GetSystemTick();
+
+            var sb = new U8StringBuilder(logBuffer, true);
+            sb.Append(LogOffset).AppendFormat(offset)
+                .Append(LogSize).AppendFormat(destination.Length)
+                .Append(LogReadSize).AppendFormat(AccessLogImpl.DereferenceOutValue(in bytesRead, rc));
+
+            Hos.Fs.Impl.OutputAccessLog(rc, start, end, handle, new U8Span(logBuffer),
+                nameof(UserFile.ReadFile));
+        }
         else
         {
-            if (Hos.Fs.Impl.IsEnabledAccessLog() && Hos.Fs.Impl.IsEnabledHandleAccessLog(handle))
+            rc = ReadWithoutCacheAccessLog(out bytesRead, offset, destination, in option);
-            {
-                Tick start = Hos.Os.GetSystemTick();
-                rc = ReadWithoutCacheAccessLog(out bytesRead, offset, destination, in option);
-                Tick end = Hos.Os.GetSystemTick();
-
-                var sb = new U8StringBuilder(logBuffer, true);
-                sb.Append(LogOffset).AppendFormat(offset)
-                    .Append(LogSize).AppendFormat(destination.Length)
-                    .Append(LogReadSize).AppendFormat(AccessLogImpl.DereferenceOutValue(in bytesRead, rc));
-
-                Hos.Fs.Impl.OutputAccessLog(rc, start, end, handle, new U8Span(logBuffer),
-                    nameof(UserFile.ReadFile));
-            }
-            else
-            {
-                rc = ReadWithoutCacheAccessLog(out bytesRead, offset, destination, in option);
-            }
-
-            return rc;
         }
-        // ReSharper restore ConditionIsAlwaysTrueOrFalse
+
+        return rc;
     }
 
     public Result Write(long offset, ReadOnlySpan<byte> source, in WriteOption option)
@@ -159,9 +157,11 @@ internal class FileAccessor : IDisposable
         using ScopedSetter<WriteState> setter =
             ScopedSetter<WriteState>.MakeScopedSetter(ref _writeState, WriteState.Failed);
 
-        if (_filePathHash.Data != 0)
+        if (_filePathHash is not null)
         {
-            throw new NotImplementedException();
+            Result rc = UpdateLastResult(Hos.Fs.Impl.WriteViaPathBasedFileDataCache(_file.Get, (int)GetOpenMode(),
+                _parentFileSystem, in _filePathHash.Value, _pathHashIndex, offset, source, in option));
+            if (rc.IsFailure()) return rc.Miss();
         }
         else
         {
@@ -193,19 +193,27 @@ internal class FileAccessor : IDisposable
         if (_lastResult.IsFailure())
             return _lastResult;
 
-        WriteState oldWriteState = _writeState;
+        WriteState originalWriteState = _writeState;
         using ScopedSetter<WriteState> setter =
             ScopedSetter<WriteState>.MakeScopedSetter(ref _writeState, WriteState.Failed);
 
-        Result rc = UpdateLastResult(_file.Get.SetSize(size));
+        if (_filePathHash is not null)
-        if (rc.IsFailure()) return rc;
-
-        if (_filePathHash.Data != 0)
         {
-            throw new NotImplementedException();
+            using UniqueLock lk = Hos.Fs.Impl.LockPathBasedFileDataCacheEntries();
+
+            Result rc = UpdateLastResult(_file.Get.SetSize(size));
+            if (rc.IsFailure()) return rc.Miss();
+
+            Hos.Fs.Impl.InvalidatePathBasedFileDataCacheEntry(_parentFileSystem, in _filePathHash.Value, _pathHashIndex);
+            if (rc.IsFailure()) return rc.Miss();
+        }
+        else
+        {
+            Result rc = UpdateLastResult(_file.Get.SetSize(size));
+            if (rc.IsFailure()) return rc;
         }
 
-        setter.Set(oldWriteState);
+        setter.Set(originalWriteState);
         return Result.Success;
     }
 
@@ -224,4 +232,4 @@ internal class FileAccessor : IDisposable
     {
         return _file.Get.OperateRange(outBuffer, operationId, offset, size, inBuffer);
     }
-}
+}

src/LibHac/Fs/Fsa/FileSystemAccessor.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using LibHac.Common;
 using LibHac.Diag;
 using LibHac.Fs.Fsa;
+using LibHac.Fs.Shim;
 using LibHac.Os;
 using LibHac.Util;
 using IFileSystemSf = LibHac.FsSrv.Sf.IFileSystem;
@@ -10,6 +11,13 @@ using IFileSystemSf = LibHac.FsSrv.Sf.IFileSystem;
 // ReSharper disable once CheckNamespace
 namespace LibHac.Fs.Impl;
 
+/// <summary>
+/// Provides access to a mounted <see cref="IFileSystem"/> and contains metadata and objects related to it.
+/// This data includes the mount name, open files and directories, whether the access log is enabled for this file
+/// system, whether caching is being used, how to get a save file system's <see cref="SaveDataAttribute"/> and
+/// the target used to include a save file system in a multi-commit operation.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 internal class FileSystemAccessor : IDisposable
 {
     private const string EmptyMountNameMessage = "Error: Mount failed because the mount name was empty.\n";
@@ -31,7 +39,7 @@ internal class FileSystemAccessor : IDisposable
     private bool _isPathCacheAttached;
     private IMultiCommitTarget _multiCommitTarget;
     private PathFlags _pathFlags;
-    private Optional<Ncm.DataId> _dataId;
+    private IStorage _storageForPurgeFileDataCache;
 
     internal HorizonClient Hos { get; }
 
@@ -44,7 +52,7 @@ internal class FileSystemAccessor : IDisposable
         _fileSystem = new UniqueRef<IFileSystem>(ref fileSystem);
         _openFiles = new LinkedList<FileAccessor>();
         _openDirectories = new LinkedList<DirectoryAccessor>();
-        _openListLock.Initialize();
+        _openListLock = new SdkMutexType();
         _mountNameGenerator = new UniqueRef<ICommonMountNameGenerator>(ref mountNameGenerator);
         _saveDataAttributeGetter = new UniqueRef<ISaveDataAttributeGetter>(ref saveAttributeGetter);
         _multiCommitTarget = multiCommitTarget;
@@ -90,7 +98,8 @@ internal class FileSystemAccessor : IDisposable
 
             if (_isPathCacheAttached)
             {
-                throw new NotImplementedException();
+                using UniqueLock lk = Hos.Fs.Impl.LockPathBasedFileDataCacheEntries();
+                Hos.Fs.Impl.InvalidatePathBasedFileDataCacheEntries(this);
             }
         }
 
@@ -113,7 +122,16 @@ internal class FileSystemAccessor : IDisposable
     }
 
     public void SetAccessLog(bool isEnabled) => _isAccessLogEnabled = isEnabled;
-    public void SetFileDataCacheAttachable(bool isAttachable) => _isDataCacheAttachable = isAttachable;
+
+    public void SetFileDataCacheAttachable(bool isAttachable, IStorage storageForPurgeFileDataCache)
+    {
+        if (isAttachable)
+            Assert.SdkAssert(storageForPurgeFileDataCache is not null);
+
+        _isDataCacheAttachable = isAttachable;
+        _storageForPurgeFileDataCache = storageForPurgeFileDataCache;
+    }
+
     public void SetPathBasedFileDataCacheAttachable(bool isAttachable) => _isPathCacheAttachable = isAttachable;
 
     public bool IsEnabledAccessLog() => _isAccessLogEnabled;
@@ -126,10 +144,7 @@ internal class FileSystemAccessor : IDisposable
             _isPathCacheAttached = true;
     }
 
-    public Optional<Ncm.DataId> GetDataId() => _dataId;
+    private Result SetUpPath(ref Path path, U8Span pathBuffer)
-    public void SetDataId(Optional<Ncm.DataId> dataId) => _dataId = dataId;
-
-    public Result SetUpPath(ref Path path, U8Span pathBuffer)
     {
         Result rc = PathFormatter.IsNormalized(out bool isNormalized, out _, pathBuffer, _pathFlags);
 
@@ -168,7 +183,12 @@ internal class FileSystemAccessor : IDisposable
 
         if (_isPathCacheAttached)
         {
-            throw new NotImplementedException();
+            using UniqueLock lk = Hos.Fs.Impl.LockPathBasedFileDataCacheEntries();
+
+            rc = _fileSystem.Get.CreateFile(in pathNormalized, size, option);
+            if (rc.IsFailure()) return rc.Miss();
+
+            Hos.Fs.Impl.InvalidatePathBasedFileDataCacheEntry(this, in pathNormalized);
         }
         else
         {
@@ -251,7 +271,12 @@ internal class FileSystemAccessor : IDisposable
 
         if (_isPathCacheAttached)
         {
-            throw new NotImplementedException();
+            using UniqueLock lk = Hos.Fs.Impl.LockPathBasedFileDataCacheEntries();
+
+            rc = _fileSystem.Get.RenameFile(in currentPathNormalized, in newPathNormalized);
+            if (rc.IsFailure()) return rc.Miss();
+
+            Hos.Fs.Impl.InvalidatePathBasedFileDataCacheEntry(this, in newPathNormalized);
         }
         else
         {
@@ -274,7 +299,12 @@ internal class FileSystemAccessor : IDisposable
 
         if (_isPathCacheAttached)
         {
-            throw new NotImplementedException();
+            using UniqueLock lk = Hos.Fs.Impl.LockPathBasedFileDataCacheEntries();
+
+            rc = _fileSystem.Get.RenameDirectory(in currentPathNormalized, in newPathNormalized);
+            if (rc.IsFailure()) return rc.Miss();
+
+            Hos.Fs.Impl.InvalidatePathBasedFileDataCacheEntries(this);
         }
         else
         {
@@ -347,11 +377,17 @@ internal class FileSystemAccessor : IDisposable
         {
             if (mode.HasFlag(OpenMode.AllowAppend))
             {
-                throw new NotImplementedException();
+                using UniqueLock lk = Hos.Fs.Impl.LockPathBasedFileDataCacheEntries();
+                Hos.Fs.Impl.InvalidatePathBasedFileDataCacheEntry(this, in pathNormalized);
             }
             else
             {
-                throw new NotImplementedException();
+                var hash = new Box<FilePathHash>();
+
+                if (Hos.Fs.Impl.FindPathBasedFileDataCacheEntry(out hash.Value, out int hashIndex, this, in pathNormalized))
+                {
+                    accessor.SetFilePathHash(hash, hashIndex);
+                }
             }
         }
 
@@ -432,6 +468,13 @@ internal class FileSystemAccessor : IDisposable
         return Result.Success;
     }
 
+    public void PurgeFileDataCache(FileDataCacheAccessor accessor)
+    {
+        Assert.SdkAssert(_storageForPurgeFileDataCache is not null);
+
+        accessor.Purge(_storageForPurgeFileDataCache);
+    }
+
     public U8Span GetName()
     {
         return new U8Span(_mountName.Name);
@@ -470,11 +513,6 @@ internal class FileSystemAccessor : IDisposable
         }
     }
 
-    public void PurgeFileDataCache(FileDataCacheAccessor cacheAccessor)
-    {
-        cacheAccessor.Purge(_fileSystem.Get);
-    }
-
     internal void NotifyCloseFile(FileAccessor file)
     {
         using ScopedLock<SdkMutexType> scopedLock = ScopedLock.Lock(ref _openListLock);
@@ -673,4 +711,4 @@ internal class FileSystemAccessor : IDisposable
             }
         }
     }
-}
+}

src/LibHac/Fs/Fsa/MountTable.cs

@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.Runtime.CompilerServices;
 using LibHac.Common;
 using LibHac.Diag;
-using LibHac.Ncm;
 using LibHac.Os;
 using LibHac.Util;
 
@@ -14,7 +13,7 @@ namespace LibHac.Fs.Impl;
 /// Holds a list of <see cref="FileSystemAccessor"/>s that are indexed by their name.
 /// These may be retrieved or removed using their name as a key.
 /// </summary>
-/// <remarks>Based on FS 12.1.0 (nnSdk 12.3.1)</remarks>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 internal class MountTable : IDisposable
 {
     private LinkedList<FileSystemAccessor> _fileSystemList;
@@ -76,9 +75,11 @@ internal class MountTable : IDisposable
             currentNode is not null;
             currentNode = currentNode.Next)
         {
-            if (!Matches(currentNode.Value, name)) continue;
+            if (Matches(currentNode.Value, name))
-            accessor = currentNode.Value;
+            {
-            return Result.Success;
+                accessor = currentNode.Value;
+                return Result.Success;
+            }
         }
 
         return ResultFs.NotMounted.Log();
@@ -121,44 +122,4 @@ internal class MountTable : IDisposable
 
         return true;
     }
-
-    public int GetDataIdCount()
-    {
-        using ScopedLock<SdkMutexType> scopedLock = ScopedLock.Lock(ref _mutex);
-
-        int count = 0;
-
-        for (LinkedListNode<FileSystemAccessor> currentNode = _fileSystemList.First;
-            currentNode is not null;
-            currentNode = currentNode.Next)
-        {
-            if (currentNode.Value.GetDataId().HasValue)
-                count++;
-        }
-
-        return count;
-    }
-
-    public Result ListDataId(out int dataIdCount, Span<DataId> dataIdBuffer)
-    {
-        using ScopedLock<SdkMutexType> scopedLock = ScopedLock.Lock(ref _mutex);
-
-        int count = 0;
-
-        for (LinkedListNode<FileSystemAccessor> currentNode = _fileSystemList.First;
-            currentNode is not null && count < dataIdBuffer.Length;
-            currentNode = currentNode.Next)
-        {
-            Optional<DataId> dataId = currentNode.Value.GetDataId();
-
-            if (dataId.HasValue)
-            {
-                dataIdBuffer[count] = dataId.Value;
-                count++;
-            }
-        }
-
-        dataIdCount = count;
-        return Result.Success;
-    }
 }

src/LibHac/Fs/Fsa/Registrar.cs

@@ -97,9 +97,9 @@ public static class Registrar
         if (!accessor.HasValue)
             return ResultFs.AllocationMemoryFailedInRegisterB.Log();
 
-        accessor.Get.SetFileDataCacheAttachable(useDataCache);
+        // accessor.Get.SetFileDataCacheAttachable(useDataCache);
         accessor.Get.SetPathBasedFileDataCacheAttachable(usePathCache);
-        accessor.Get.SetDataId(dataId);
+        // accessor.Get.SetDataId(dataId);
 
         Result rc = fs.Impl.Register(ref accessor.Ref());
         if (rc.IsFailure()) return rc.Miss();
@@ -111,4 +111,4 @@ public static class Registrar
     {
         fs.Impl.Unregister(name);
     }
-}
+}

src/LibHac/Fs/Fsa/UserMountTable.cs

@@ -1,7 +1,5 @@
-using System;
+using LibHac.Common;
-using LibHac.Common;
 using LibHac.Fs.Impl;
-using LibHac.Ncm;
 
 namespace LibHac.Fs.Fsa;
 
@@ -18,7 +16,7 @@ internal struct UserMountTableGlobals
 /// <summary>
 /// Contains functions for adding, removing and retrieving <see cref="FileSystemAccessor"/>s from the mount table.
 /// </summary>
-/// <remarks>Based on FS 12.1.0 (nnSdk 12.3.1)</remarks>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 internal static class UserMountTable
 {
     public static Result Register(this FileSystemClientImpl fs, ref UniqueRef<FileSystemAccessor> fileSystem)
@@ -35,15 +33,4 @@ internal static class UserMountTable
     {
         fs.Globals.UserMountTable.MountTable.Unmount(name);
     }
-
+}
-    public static int GetMountedDataIdCount(this FileSystemClientImpl fs)
-    {
-        return fs.Globals.UserMountTable.MountTable.GetDataIdCount();
-    }
-
-    public static Result ListMountedDataId(this FileSystemClientImpl fs, out int dataIdCount,
-        Span<DataId> dataIdBuffer)
-    {
-        return fs.Globals.UserMountTable.MountTable.ListDataId(out dataIdCount, dataIdBuffer);
-    }
-}

src/LibHac/Fs/Impl/FileDataCacheAccessor.cs

@@ -3,9 +3,13 @@ using LibHac.Fs.Fsa;
 
 namespace LibHac.Fs.Impl;
 
+/// <summary>
+/// Provides access to an <see cref="IFileDataCache"/>.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 internal class FileDataCacheAccessor
 {
-    private IFileDataCache _cache;
+    private readonly IFileDataCache _cache;
 
     public FileDataCacheAccessor(IFileDataCache cache)
     {
@@ -18,8 +22,8 @@ internal class FileDataCacheAccessor
         return _cache.Read(file, out bytesRead, offset, destination, in option, ref cacheAccessResult);
     }
 
-    public void Purge(IFileSystem fileSystem)
+    public void Purge(IStorage storage)
     {
-        _cache.Purge(fileSystem);
+        _cache.Purge(storage);
     }
-}
+}

src/LibHac/Fs/Impl/FilePathHash.cs

@@ -1,6 +1,8 @@
-namespace LibHac.Fs.Impl;
+using LibHac.Common.FixedArrays;
+
+namespace LibHac.Fs.Impl;
 
 public struct FilePathHash
 {
-    public int Data;
+    public Array4<byte> Data;
-}
+}

src/LibHac/Fs/Impl/IFileDataCache.cs

@@ -7,11 +7,15 @@ using LibHac.Fs.Fsa;
 namespace LibHac.Fs.Impl;
 
 // ReSharper disable once InconsistentNaming
+/// <summary>
+/// Provides a system for caching reads to one or more file systems.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 internal abstract class IFileDataCache : IDisposable
 {
     public abstract void Dispose();
 
-    public abstract void Purge(IFileSystem fileSystem);
+    public abstract void Purge(IStorage storage);
 
     protected abstract Result DoRead(IFile file, out long bytesRead, long offset, Span<byte> destination,
         in ReadOption option, ref FileDataCacheAccessResult cacheAccessResult);
@@ -88,4 +92,4 @@ internal struct FileDataCacheAccessResult
             _regionCount++;
         }
     }
-}
+}

src/LibHac/Fs/Shim/FileDataCache.cs

@@ -0,0 +1,183 @@
+// ReSharper disable UnusedMember.Local
+using System;
+using LibHac.Common;
+using LibHac.Diag;
+using LibHac.Fs.Impl;
+using LibHac.Os;
+
+namespace LibHac.Fs.Impl
+{
+    /// <summary>
+    /// Handles getting scoped read access to the global file data cache.
+    /// </summary>
+    /// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
+    internal struct GlobalFileDataCacheAccessorReadableScopedPointer : IDisposable
+    {
+        private FileDataCacheAccessor _accessor;
+        private ReaderWriterLock _lock;
+
+        public void Dispose()
+        {
+            _lock?.ReleaseReadLock();
+        }
+
+        public readonly FileDataCacheAccessor Get() => _accessor;
+
+        public void Set(FileDataCacheAccessor accessor, ReaderWriterLock rwLock)
+        {
+            if (_lock is not null && _lock != rwLock)
+                _lock.ReleaseReadLock();
+
+            _accessor = accessor;
+            _lock = rwLock;
+        }
+    }
+}
+
+namespace LibHac.Fs.Shim
+{
+    public static class FileDataCacheShim
+    {
+        internal struct Globals : IDisposable
+        {
+            public nint FileSystemProxyServiceObjectInitGuard;
+            public GlobalFileDataCacheAccessorHolder GlobalFileDataCacheAccessorHolder;
+
+            public void Dispose()
+            {
+                GlobalFileDataCacheAccessorHolder.Dispose();
+            }
+        }
+
+        internal class GlobalFileDataCacheAccessorHolder
+        {
+            private FileDataCacheAccessor _accessor;
+            private ReaderWriterLock _accessorLock;
+            private long _cacheSize;
+            private bool _isDefault;
+
+            public GlobalFileDataCacheAccessorHolder(HorizonClient hos)
+            {
+                _accessorLock = new ReaderWriterLock(hos.Os);
+            }
+
+            public void Dispose()
+            {
+                _accessorLock?.Dispose();
+            }
+
+            public ReaderWriterLock GetLock() => _accessorLock;
+
+            public bool HasAccessor()
+            {
+                Assert.SdkAssert(_accessorLock.IsReadLockHeld() || _accessorLock.IsWriteLockHeldByCurrentThread());
+
+                return _accessor is not null;
+            }
+
+            public void SetAccessor()
+            {
+                Assert.SdkAssert(_accessorLock.IsWriteLockHeldByCurrentThread());
+
+                _accessor = null;
+            }
+
+            public void SetAccessor(FileDataCacheAccessor accessor, long cacheSize, bool isDefault)
+            {
+                Assert.SdkAssert(_accessorLock.IsWriteLockHeldByCurrentThread());
+
+                _accessor = accessor;
+                _cacheSize = cacheSize;
+                _isDefault = isDefault;
+            }
+
+            public FileDataCacheAccessor GetAccessor()
+            {
+                Assert.SdkAssert(_accessorLock.IsReadLockHeld() || _accessorLock.IsWriteLockHeldByCurrentThread());
+
+                return _accessor;
+            }
+
+            public long GetCacheSize()
+            {
+                Assert.SdkAssert(_accessorLock.IsReadLockHeld() || _accessorLock.IsWriteLockHeldByCurrentThread());
+
+                return _cacheSize;
+            }
+
+            public bool IsDefaultGlobalFileDataCache()
+            {
+                Assert.SdkAssert(_accessorLock.IsReadLockHeld() || _accessorLock.IsWriteLockHeldByCurrentThread());
+                Assert.SdkNotNull(_accessor);
+
+                return _isDefault;
+            }
+        }
+
+        private static GlobalFileDataCacheAccessorHolder GetGlobalFileDataCacheAccessorHolder(FileSystemClient fs)
+        {
+            ref Globals g = ref fs.Globals.FileDataCache;
+            using var guard = new InitializationGuard(ref g.FileSystemProxyServiceObjectInitGuard,
+                fs.Globals.InitMutex);
+
+            if (!guard.IsInitialized)
+            {
+                g.GlobalFileDataCacheAccessorHolder = new GlobalFileDataCacheAccessorHolder(fs.Hos);
+            }
+
+            return g.GlobalFileDataCacheAccessorHolder;
+        }
+
+        private static Result EnableGlobalFileDataCacheImpl(FileSystemClient fs, Memory<byte> buffer, bool isDefault)
+        {
+            throw new NotImplementedException();
+        }
+
+        private static Result DisableGlobalFileDataCacheImpl(FileSystemClient fs)
+        {
+            throw new NotImplementedException();
+        }
+
+        private static int PrintDefaultGlobalFileDataCacheAccessLog(Span<byte> textBuffer)
+        {
+            throw new NotImplementedException();
+        }
+
+        internal static bool IsGlobalFileDataCacheEnabled(this FileSystemClientImpl fs)
+        {
+            return false;
+        }
+
+        internal static bool TryGetGlobalFileDataCacheAccessor(this FileSystemClientImpl fs,
+            ref GlobalFileDataCacheAccessorReadableScopedPointer scopedPointer)
+        {
+            throw new NotImplementedException();
+        }
+
+        internal static void SetGlobalFileDataCacheAccessorForDebug(this FileSystemClientImpl fs,
+            FileDataCacheAccessor accessor)
+        {
+            throw new NotImplementedException();
+        }
+
+        public static void EnableGlobalFileDataCache(this FileSystemClient fs, Memory<byte> buffer)
+        {
+            throw new NotImplementedException();
+        }
+
+        public static void DisableGlobalFileDataCache(this FileSystemClient fs)
+        {
+            throw new NotImplementedException();
+        }
+
+        public static void EnableDefaultGlobalFileDataCache(this FileSystemClient fs, Memory<byte> buffer)
+        {
+            throw new NotImplementedException();
+        }
+
+        public static bool IsDefaultGlobalFileDataCacheEnabled(this FileSystemClient fs)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

src/LibHac/Fs/Shim/PathBasedFileDataCache.cs

@@ -0,0 +1,62 @@
+using System;
+using LibHac.Common;
+using LibHac.Fs.Fsa;
+using LibHac.Fs.Impl;
+
+namespace LibHac.Fs.Shim;
+
+public static class PathBasedFileDataCacheShim
+{
+    internal static UniqueLock LockPathBasedFileDataCacheEntries(this FileSystemClientImpl fs)
+    {
+        throw new NotImplementedException();
+    }
+
+    internal static void InvalidatePathBasedFileDataCacheEntries(this FileSystemClientImpl fs,
+        FileSystemAccessor fsAccessor)
+    {
+        throw new NotImplementedException();
+    }
+
+    internal static void InvalidatePathBasedFileDataCacheEntry(this FileSystemClientImpl fs,
+        FileSystemAccessor fsAccessor, in Path path)
+    {
+        throw new NotImplementedException();
+    }
+
+    internal static void InvalidatePathBasedFileDataCacheEntry(this FileSystemClientImpl fs,
+        FileSystemAccessor fsAccessor, in FilePathHash hash, int hashIndex)
+    {
+        throw new NotImplementedException();
+    }
+
+    internal static bool FindPathBasedFileDataCacheEntry(this FileSystemClientImpl fs, out FilePathHash outHash,
+        out int outHashIndex, FileSystemAccessor fsAccessor, in Path path)
+    {
+        throw new NotImplementedException();
+    }
+
+    internal static Result ReadViaPathBasedFileDataCache(this FileSystemClientImpl fs, IFile file, int openMode,
+        FileSystemAccessor fileSystem, in FilePathHash hash, int hashIndex, out long bytesRead, long offset,
+        Span<byte> buffer, in ReadOption option, ref FileDataCacheAccessResult outCacheAccessResult)
+    {
+        throw new NotImplementedException();
+    }
+
+    internal static Result WriteViaPathBasedFileDataCache(this FileSystemClientImpl fs, IFile file, int openMode,
+        FileSystemAccessor fileSystem, in FilePathHash hash, int hashIndex, long offset, ReadOnlySpan<byte> buffer,
+        in WriteOption option)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static Result EnableIndividualFileDataCache(this FileSystemClient fs, U8Span path, Memory<byte> buffer)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void DisableIndividualFileDataCache(this FileSystemClient fs, U8Span path)
+    {
+        throw new NotImplementedException();
+    }
+}

src/LibHac/Os/ReaderWriterLock.cs

@@ -98,7 +98,7 @@ public static class ReaderWriterLockApi
     }
 }
 
-public class ReaderWriterLock : ISharedMutex
+public class ReaderWriterLock : ISharedMutex, IDisposable
 {
     public const int ReaderWriterLockCountMax = (1 << 15) - 1;
     public const int ReadWriteLockWaiterCountMax = (1 << 8) - 1;
@@ -112,6 +112,11 @@ public class ReaderWriterLock : ISharedMutex
         _os.InitializeReaderWriterLock(ref _rwLock);
     }
 
+    public void Dispose()
+    {
+        _os.FinalizeReaderWriterLock(ref _rwLock);
+    }
+
     public void AcquireReadLock()
     {
         _os.AcquireReadLock(ref _rwLock);
@@ -191,4 +196,4 @@ public class ReaderWriterLock : ISharedMutex
     {
         return ref _rwLock;
     }
-}
+}