Implement NGC service (#5681)

* Implement NGC service

* Use raw byte arrays instead of string for _wordSeparators

* Silence IDE0230 for _wordSeparators

* Try to silence warning about _rangeValuesCount not being read on SparseSet

* Make AcType enum private

* Add abstract methods and one TODO that I forgot

* PR feedback

* More PR feedback

* More PR feedback

src/Ryujinx.HLE/HOS/Horizon.cs

@@ -327,8 +327,10 @@ namespace Ryujinx.HLE.HOS
 
         private void StartNewServices()
         {
+            HorizonFsClient fsClient = new(this);
+
             ServiceTable = new ServiceTable();
-            var services = ServiceTable.GetServices(new HorizonOptions(Device.Configuration.IgnoreMissingServices, LibHacHorizonManager.BcatClient));
+            var services = ServiceTable.GetServices(new HorizonOptions(Device.Configuration.IgnoreMissingServices, LibHacHorizonManager.BcatClient, fsClient));
 
             foreach (var service in services)
             {

src/Ryujinx.HLE/HOS/HorizonFsClient.cs

@@ -0,0 +1,119 @@
+using LibHac.Common;
+using LibHac.Fs.Fsa;
+using LibHac.FsSystem;
+using LibHac.Ncm;
+using LibHac.Tools.FsSystem.NcaUtils;
+using Ryujinx.HLE.FileSystem;
+using Ryujinx.Horizon;
+using Ryujinx.Horizon.Common;
+using Ryujinx.Horizon.Sdk.Fs;
+using System;
+using System.Collections.Concurrent;
+using System.IO;
+
+namespace Ryujinx.HLE.HOS
+{
+    class HorizonFsClient : IFsClient
+    {
+        private readonly Horizon _system;
+        private readonly LibHac.Fs.FileSystemClient _fsClient;
+        private readonly ConcurrentDictionary<string, LocalStorage> _mountedStorages;
+
+        public HorizonFsClient(Horizon system)
+        {
+            _system = system;
+            _fsClient = _system.LibHacHorizonManager.FsClient.Fs;
+            _mountedStorages = new();
+        }
+
+        public void CloseFile(FileHandle handle)
+        {
+            _fsClient.CloseFile((LibHac.Fs.FileHandle)handle.Value);
+        }
+
+        public Result GetFileSize(out long size, FileHandle handle)
+        {
+            return _fsClient.GetFileSize(out size, (LibHac.Fs.FileHandle)handle.Value).ToHorizonResult();
+        }
+
+        public Result MountSystemData(string mountName, ulong dataId)
+        {
+            string contentPath = _system.ContentManager.GetInstalledContentPath(dataId, StorageId.BuiltInSystem, NcaContentType.PublicData);
+            string installPath = VirtualFileSystem.SwitchPathToSystemPath(contentPath);
+
+            if (!string.IsNullOrWhiteSpace(installPath))
+            {
+                string ncaPath = installPath;
+
+                if (File.Exists(ncaPath))
+                {
+                    LocalStorage ncaStorage = null;
+
+                    try
+                    {
+                        ncaStorage = new LocalStorage(ncaPath, FileAccess.Read, FileMode.Open);
+
+                        Nca nca = new(_system.KeySet, ncaStorage);
+
+                        using var ncaFileSystem = nca.OpenFileSystem(NcaSectionType.Data, _system.FsIntegrityCheckLevel);
+                        using var ncaFsRef = new UniqueRef<IFileSystem>(ncaFileSystem);
+
+                        Result result = _fsClient.Register(mountName.ToU8Span(), ref ncaFsRef.Ref).ToHorizonResult();
+                        if (result.IsFailure)
+                        {
+                            ncaStorage.Dispose();
+                        }
+                        else
+                        {
+                            _mountedStorages.TryAdd(mountName, ncaStorage);
+                        }
+
+                        return result;
+                    }
+                    catch (HorizonResultException ex)
+                    {
+                        ncaStorage?.Dispose();
+
+                        return ex.ResultValue.ToHorizonResult();
+                    }
+                }
+            }
+
+            // TODO: Return correct result here, this is likely wrong.
+
+            return LibHac.Fs.ResultFs.TargetNotFound.Handle().ToHorizonResult();
+        }
+
+        public Result OpenFile(out FileHandle handle, string path, OpenMode openMode)
+        {
+            var result = _fsClient.OpenFile(out var libhacHandle, path.ToU8Span(), (LibHac.Fs.OpenMode)openMode);
+            handle = new(libhacHandle);
+
+            return result.ToHorizonResult();
+        }
+
+        public Result QueryMountSystemDataCacheSize(out long size, ulong dataId)
+        {
+            // TODO.
+
+            size = 0;
+
+            return Result.Success;
+        }
+
+        public Result ReadFile(FileHandle handle, long offset, Span<byte> destination)
+        {
+            return _fsClient.ReadFile((LibHac.Fs.FileHandle)handle.Value, offset, destination).ToHorizonResult();
+        }
+
+        public void Unmount(string mountName)
+        {
+            if (_mountedStorages.TryRemove(mountName, out LocalStorage ncaStorage))
+            {
+                ncaStorage.Dispose();
+            }
+
+            _fsClient.Unmount(mountName.ToU8Span());
+        }
+    }
+}