Implement MemoryStorageCreator and NspRootFileSystemCreator

src/LibHac/Fs/MemoryStorage.cs

@@ -93,3 +93,91 @@ public class MemoryStorage : IStorage
         }
     }
 }
+
+/// <summary>
+/// Allows interacting with a <see cref="Memory{T}"/> via the <see cref="IStorage"/> interface.
+/// </summary>
+/// <remarks>Based on nnSdk 16.2.0 (FS 16.0.0)</remarks>
+internal class MemoryStorageFromMemory : IStorage
+{
+    private Memory<byte> _buffer;
+    private int _size;
+
+    public MemoryStorageFromMemory(Memory<byte> buffer)
+    {
+        _buffer = buffer;
+        _size = buffer.Length;
+    }
+
+    public MemoryStorageFromMemory(Memory<byte> buffer, int size)
+    {
+        Assert.SdkRequiresInRange(size, 0, buffer.Length);
+
+        // ReSharper disable once ConditionIsAlwaysTrueOrFalse
+        Abort.DoAbortUnless(0 <= size && size < buffer.Length);
+
+        _buffer = buffer;
+        _size = size;
+    }
+
+    public override Result Read(long offset, Span<byte> destination)
+    {
+        if (destination.Length == 0)
+            return Result.Success;
+
+        Result res = CheckAccessRange(offset, destination.Length, _size);
+        if (res.IsFailure()) return res.Miss();
+
+        _buffer.Span.Slice((int)offset, destination.Length).CopyTo(destination);
+
+        return Result.Success;
+    }
+
+    public override Result Write(long offset, ReadOnlySpan<byte> source)
+    {
+        if (source.Length == 0)
+            return Result.Success;
+
+        Result res = CheckAccessRange(offset, source.Length, _size);
+        if (res.IsFailure()) return res.Miss();
+
+        source.CopyTo(_buffer.Span.Slice((int)offset));
+
+        return Result.Success;
+    }
+
+    public override Result Flush()
+    {
+        return Result.Success;
+    }
+
+    public override Result SetSize(long size)
+    {
+        return ResultFs.UnsupportedSetSizeForMemoryStorage.Log();
+    }
+
+    public override Result GetSize(out long size)
+    {
+        size = _size;
+
+        return Result.Success;
+    }
+
+    public override Result OperateRange(Span<byte> outBuffer, OperationId operationId, long offset, long size,
+        ReadOnlySpan<byte> inBuffer)
+    {
+        switch (operationId)
+        {
+            case OperationId.InvalidateCache:
+                return Result.Success;
+            case OperationId.QueryRange:
+                if (outBuffer.Length != Unsafe.SizeOf<QueryRangeInfo>())
+                    return ResultFs.InvalidSize.Log();
+
+                Unsafe.As<byte, QueryRangeInfo>(ref MemoryMarshal.GetReference(outBuffer)).Clear();
+                return Result.Success;
+            default:
+                return ResultFs.UnsupportedOperateRangeForMemoryStorage.Log();
+        }
+    }
+}

src/LibHac/FsSrv/FsCreator/IMemoryStorageCreator.cs

@@ -1,10 +1,20 @@
 using System;
+using LibHac.Common;
 using LibHac.Fs;
 
 namespace LibHac.FsSrv.FsCreator;
 
 public interface IMemoryStorageCreator
 {
-    Result Create(out IStorage storage, out Memory<byte> buffer, int storageId);
-    Result RegisterBuffer(int storageId, Memory<byte> buffer);
+    public enum MemoryStorageId
+    {
+        UserPartitionFatFs,
+        SignedSystemPartitionRaw,
+        SystemPartitionFatFs,
+        Id4,
+        Count
+    }
+
+    Result Create(ref SharedRef<IStorage> outStorage, out Memory<byte> outBuffer, MemoryStorageId id);
+    Result RegisterBuffer(MemoryStorageId id, Memory<byte> buffer);
 }

src/LibHac/FsSrv/FsCreator/INspRootFileSystemCreator.cs

@@ -4,6 +4,10 @@ using LibHac.Fs.Fsa;
 
 namespace LibHac.FsSrv.FsCreator;
 
+/// <summary>
+/// Creates an <see cref="IFileSystem"/> from an <see cref="IStorage"/> containing a partition filesystem of version 0 or version 1.
+/// </summary>
+/// <remarks>Based on nnSdk 18.3.0 (FS 18.0.0)</remarks>
 public interface INspRootFileSystemCreator
 {
     Result Create(ref SharedRef<IFileSystem> outFileSystem, ref readonly SharedRef<IStorage> baseStorage);

src/LibHac/FsSrv/FsCreator/MemoryStorageCreator.cs

@@ -0,0 +1,78 @@
+using System;
+using LibHac.Common;
+using LibHac.Common.FixedArrays;
+using LibHac.Diag;
+using LibHac.Fs;
+using LibHac.Os;
+
+namespace LibHac.FsSrv.FsCreator;
+
+/// <summary>
+/// Creates <see cref="MemoryStorage"/>s from registered memory buffers.
+/// </summary>
+/// <remarks>
+/// <para>Used for in-memory System and User partitions when booting in safe mode.
+/// On startup, FS registers buffers which can be used later if needed.</para>
+/// <para>Based on nnSdk 18.3.0 (FS 18.0.0)</para>
+/// </remarks>
+public class MemoryStorageCreator : IMemoryStorageCreator
+{
+    private SdkMutexType _mutex;
+    private Array4<Buffer> _bufferArray;
+
+    private struct Buffer
+    {
+        public Memory<byte> MemoryBuffer;
+        public bool IsInUse; // Each registered buffer can only be used to create a MemoryStorage a single time
+
+        public Buffer()
+        {
+            MemoryBuffer = default;
+            IsInUse = false;
+        }
+    }
+
+    public MemoryStorageCreator()
+    {
+        _mutex = new SdkMutexType();
+
+        for (int i = 0; i < _bufferArray.Length; i++)
+        {
+            _bufferArray[i] = new Buffer();
+        }
+    }
+
+    public Result Create(ref SharedRef<IStorage> outStorage, out Memory<byte> outBuffer, IMemoryStorageCreator.MemoryStorageId id)
+    {
+        UnsafeHelpers.SkipParamInit(out outBuffer);
+
+        using ScopedLock<SdkMutexType> scopedLock = ScopedLock.Lock(ref _mutex);
+
+        ref Buffer buffer = ref _bufferArray[(int)id];
+
+        if (buffer.IsInUse)
+            return ResultFs.AllocationMemoryFailed.Log();
+
+        if (buffer.MemoryBuffer.IsEmpty)
+            return ResultFs.AllocationMemoryFailed.Log();
+
+        using var storage = new SharedRef<MemoryStorageFromMemory>(new MemoryStorageFromMemory(buffer.MemoryBuffer));
+        buffer.MemoryBuffer.Span.Clear();
+
+        outStorage.SetByMove(ref storage.Ref);
+        outBuffer = buffer.MemoryBuffer;
+        buffer.IsInUse = true;
+
+        return Result.Success;
+    }
+
+    public Result RegisterBuffer(IMemoryStorageCreator.MemoryStorageId id, Memory<byte> buffer)
+    {
+        Assert.SdkAssert(id < IMemoryStorageCreator.MemoryStorageId.Count);
+        Assert.SdkAssert(_bufferArray[(int)id].MemoryBuffer.IsEmpty);
+
+        _bufferArray[(int)id].MemoryBuffer = buffer;
+
+        return Result.Success;
+    }
+}

src/LibHac/FsSrv/FsCreator/NspRootFileSystemCreator.cs

@@ -0,0 +1,23 @@
+using LibHac.Common;
+using LibHac.Fs;
+using LibHac.Fs.Fsa;
+using LibHac.FsSystem;
+
+namespace LibHac.FsSrv.FsCreator;
+
+/// <inheritdoc cref="INspRootFileSystemCreator"/>
+public class NspRootFileSystemCreator : INspRootFileSystemCreator
+{
+    public Result Create(ref SharedRef<IFileSystem> outFileSystem, ref readonly SharedRef<IStorage> baseStorage)
+    {
+        using var nspFs = new SharedRef<NintendoSubmissionPackageRootFileSystem>(new NintendoSubmissionPackageRootFileSystem());
+        if (!nspFs.HasValue)
+            return ResultFs.AllocationMemoryFailedInPartitionFileSystemCreatorA.Log();
+
+        Result res = nspFs.Get.Initialize(in baseStorage);
+        if (res.IsFailure()) return res.Miss();
+
+        outFileSystem.SetByMove(ref nspFs.Ref);
+        return Result.Success;
+    }
+}