Make IStorage interface and classes less complex

src/LibHac.Nand/Nand.cs

@@ -33,16 +33,14 @@ namespace LibHac.Nand
         {
             IStorage encStorage = ProdInfo.Open().AsStorage();
             var decStorage = new CachedStorage(new Aes128XtsStorage(encStorage, Keyset.BisKeys[0], 0x4000, true), 0x4000, 4, true);
-            decStorage.SetReadOnly();
-            return decStorage.AsStream();
+            return decStorage.AsStream(FileAccess.Read);
         }
 
         public FatFileSystemProvider OpenProdInfoF()
         {
             IStorage encStorage = ProdInfoF.Open().AsStorage();
             var decStorage = new CachedStorage(new Aes128XtsStorage(encStorage, Keyset.BisKeys[0], 0x4000, true), 0x4000, 4, true);
-            decStorage.SetReadOnly();
-            var fat = new FatFileSystem(decStorage.AsStream(), Ownership.None);
+            var fat = new FatFileSystem(decStorage.AsStream(FileAccess.Read), Ownership.None);
             return new FatFileSystemProvider(fat);
         }
 
@@ -50,8 +48,7 @@ namespace LibHac.Nand
         {
             IStorage encStorage = Safe.Open().AsStorage();
             var decStorage = new CachedStorage(new Aes128XtsStorage(encStorage, Keyset.BisKeys[1], 0x4000, true), 0x4000, 4, true);
-            decStorage.SetReadOnly();
-            var fat = new FatFileSystem(decStorage.AsStream(), Ownership.None);
+            var fat = new FatFileSystem(decStorage.AsStream(FileAccess.Read), Ownership.None);
             return new FatFileSystemProvider(fat);
         }
 
@@ -59,8 +56,7 @@ namespace LibHac.Nand
         {
             IStorage encStorage = System.Open().AsStorage();
             var decStorage = new CachedStorage(new Aes128XtsStorage(encStorage, Keyset.BisKeys[2], 0x4000, true), 0x4000, 4, true);
-            decStorage.SetReadOnly();
-            var fat = new FatFileSystem(decStorage.AsStream(), Ownership.None);
+            var fat = new FatFileSystem(decStorage.AsStream(FileAccess.Read), Ownership.None);
             return new FatFileSystemProvider(fat);
         }
 
@@ -68,8 +64,7 @@ namespace LibHac.Nand
         {
             IStorage encStorage = User.Open().AsStorage();
             var decStorage = new CachedStorage(new Aes128XtsStorage(encStorage, Keyset.BisKeys[3], 0x4000, true), 0x4000, 4, true);
-            decStorage.SetReadOnly();
-            var fat = new FatFileSystem(decStorage.AsStream(), Ownership.None);
+            var fat = new FatFileSystem(decStorage.AsStream(FileAccess.Read), Ownership.None);
             return new FatFileSystemProvider(fat);
         }
     }

src/LibHac/IO/Aes128CtrExStorage.cs

@@ -60,8 +60,6 @@ namespace LibHac.IO
             throw new NotImplementedException();
         }
 
-        public override bool CanWrite => false;
-
         private AesSubsectionEntry GetSubsectionEntry(long offset)
         {
             int index = SubsectionOffsets.BinarySearch(offset);

src/LibHac/IO/AesXtsFile.cs

@@ -31,7 +31,7 @@ namespace LibHac.IO
                 throw new ArgumentException("NAX0 key derivation failed.");
             }
 
-            Storage encStorage = new FileStorage(BaseFile).Slice(HeaderLength, Header.Size);
+            IStorage encStorage = new FileStorage(BaseFile).Slice(HeaderLength, Header.Size);
             BaseStorage = new CachedStorage(new Aes128XtsStorage(encStorage, Header.DecryptedKey1, Header.DecryptedKey2, BlockSize, true), 4, true);
         }
 

src/LibHac/IO/CachedStorage.cs

@@ -4,7 +4,7 @@ using System.Collections.Generic;
 
 namespace LibHac.IO
 {
-    public class CachedStorage : Storage
+    public class CachedStorage : StorageBase
     {
         private IStorage BaseStorage { get; }
         private int BlockSize { get; }
@@ -148,7 +148,7 @@ namespace LibHac.IO
             if (!block.Dirty) return;
 
             long offset = block.Index * BlockSize;
-            BaseStorage.Write(block.Buffer, offset, block.Length, 0);
+            BaseStorage.Write(block.Buffer.AsSpan(0, block.Length), offset);
             block.Dirty = false;
         }
 

src/LibHac/IO/ConcatenationStorage.cs

@@ -3,7 +3,7 @@ using System.Collections.Generic;
 
 namespace LibHac.IO
 {
-    public class ConcatenationStorage : Storage
+    public class ConcatenationStorage : StorageBase
     {
         private ConcatSource[] Sources { get; }
         public override long Length { get; }
@@ -72,22 +72,6 @@ namespace LibHac.IO
             }
         }
 
-        public override Storage Slice(long start, long length, bool leaveOpen)
-        {
-            ConcatSource startSource = FindSource(start);
-            ConcatSource endSource = FindSource(start + length - 1);
-
-            if (startSource != endSource)
-            {
-                return base.Slice(start, length, leaveOpen);
-            }
-
-            Storage storage = startSource.Storage.Slice(start - startSource.StartOffset, length, true);
-            if (!leaveOpen) storage.ToDispose.Add(this);
-
-            return storage;
-        }
-
         private ConcatSource FindSource(long offset)
         {
             foreach (ConcatSource info in Sources)

src/LibHac/IO/DeltaFragment.cs

@@ -57,7 +57,7 @@ namespace LibHac.IO
                 IStorage source = segment.IsInOriginal ? Original : Delta;
 
                 // todo Do this without tons of SubStorages
-                Storage sub = source.Slice(segment.SourceOffset, segment.Size);
+                IStorage sub = source.Slice(segment.SourceOffset, segment.Size);
 
                 storages.Add(sub);
             }

src/LibHac/IO/FileStorage.cs

@@ -2,7 +2,7 @@
 
 namespace LibHac.IO
 {
-    public class FileStorage : Storage
+    public class FileStorage : StorageBase
     {
         private IFile BaseFile { get; }
 

src/LibHac/IO/HierarchicalIntegrityVerificationStorage.cs

@@ -6,7 +6,7 @@ using System.Text;
 
 namespace LibHac.IO
 {
-    public class HierarchicalIntegrityVerificationStorage : Storage
+    public class HierarchicalIntegrityVerificationStorage : StorageBase
     {
         public IStorage[] Levels { get; }
         public IStorage DataLevel { get; }
@@ -128,7 +128,7 @@ namespace LibHac.IO
                 if (validities[i] == Validity.Unchecked)
                 {
                     int toRead = (int)Math.Min(storage.Length - blockSize * i, buffer.Length);
-                    storage.Read(buffer, blockSize * i, toRead, 0, IntegrityCheckLevel.IgnoreOnInvalid);
+                    storage.Read(buffer.AsSpan(0, toRead), blockSize * i, IntegrityCheckLevel.IgnoreOnInvalid);
                 }
 
                 if (validities[i] == Validity.Invalid)
@@ -209,6 +209,9 @@ namespace LibHac.IO
             }
 
             SaltSource = reader.ReadBytes(0x20);
+
+            if (reader.BaseStream.Position + 0x20 >= reader.BaseStream.Length) return;
+
             MasterHash = reader.ReadBytes(0x20);
         }
 

src/LibHac/IO/IStorage.cs

@@ -12,16 +12,6 @@ namespace LibHac.IO
         /// <param name="offset">The offset in the <see cref="IStorage"/> to begin reading from.</param>
         void Read(Span<byte> destination, long offset);
 
-        /// <summary>
-        /// Reads a sequence of bytes from the current <see cref="IStorage"/>.
-        /// </summary>
-        /// <param name="buffer">The buffer where the read bytes will be stored.</param>
-        /// <param name="offset">The zero-based byte offset in <paramref name="buffer"/>
-        /// at which to begin storing the data read from the current <see cref="IStorage"/>.</param>
-        /// <param name="count">The number of bytes to be read from the <see cref="IStorage"/>.</param>
-        /// <param name="bufferOffset">The offset in the <see cref="IStorage"/> to begin reading from.</param>
-        void Read(byte[] buffer, long offset, int count, int bufferOffset);
-
         /// <summary>
         /// Writes a sequence of bytes to the current <see cref="IStorage"/>.
         /// </summary>
@@ -29,16 +19,6 @@ namespace LibHac.IO
         /// <param name="offset">The offset in the <see cref="IStorage"/> to begin writing to.</param>
         void Write(ReadOnlySpan<byte> source, long offset);
 
-        /// <summary>
-        /// Writes a sequence of bytes to the current <see cref="IStorage"/>.
-        /// </summary>
-        /// <param name="buffer"></param>
-        /// <param name="offset">The zero-based byte offset in <paramref name="buffer"/>
-        /// at which to begin begin copying bytes to the current <see cref="IStorage"/>.</param>
-        /// <param name="count">The number of bytes to be written to the <see cref="IStorage"/>.</param>
-        /// <param name="bufferOffset">The offset in the <see cref="IStorage"/> to begin writing to.</param>
-        void Write(byte[] buffer, long offset, int count, int bufferOffset);
-
         /// <summary>
         /// Causes any buffered data to be written to the underlying device.
         /// </summary>

src/LibHac/IO/IndirectStorage.cs

@@ -4,7 +4,7 @@ using System.Linq;
 
 namespace LibHac.IO
 {
-    public class IndirectStorage : Storage
+    public class IndirectStorage : StorageBase
     {
         private List<RelocationEntry> RelocationEntries { get; }
         private List<long> RelocationOffsets { get; }
@@ -62,8 +62,6 @@ namespace LibHac.IO
             throw new NotImplementedException();
         }
 
-        public override bool CanWrite => false;
-
         public override long Length { get; }
 
         private RelocationEntry GetRelocationEntry(long offset)

src/LibHac/IO/IntegrityVerificationStorage.cs

@@ -116,16 +116,10 @@ namespace LibHac.IO
 
         public void Read(Span<byte> destination, long offset, IntegrityCheckLevel integrityCheckLevel)
         {
-            ValidateSpanParameters(destination, offset);
+            ValidateParameters(destination, offset);
             ReadImpl(destination, offset, integrityCheckLevel);
         }
 
-        public void Read(byte[] buffer, long offset, int count, int bufferOffset, IntegrityCheckLevel integrityCheckLevel)
-        {
-            ValidateArrayParameters(buffer, offset, count, bufferOffset);
-            ReadImpl(buffer.AsSpan(bufferOffset, count), offset, integrityCheckLevel);
-        }
-
         protected override void WriteImpl(ReadOnlySpan<byte> source, long offset)
         {
             long blockIndex = offset / SectorSize;

src/LibHac/IO/MemoryStorage.cs

@@ -2,7 +2,7 @@
 
 namespace LibHac.IO
 {
-    public class MemoryStorage : Storage
+    public class MemoryStorage : StorageBase
     {
         private byte[] Buffer { get; }
         private int Start { get; }

src/LibHac/IO/NullStorage.cs

@@ -5,7 +5,7 @@ namespace LibHac.IO
     /// <summary>
     /// An <see cref="IStorage"/> that returns all zeros when read, and does nothing on write.
     /// </summary>
-    public class NullStorage : Storage
+    public class NullStorage : StorageBase
     {
         public NullStorage() { }
         public NullStorage(long length) => Length = length;

src/LibHac/IO/Save/AllocationTable.cs

@@ -34,8 +34,8 @@ namespace LibHac.IO.Save
             }
         }
 
-        public IStorage GetBaseStorage() => BaseStorage.WithAccess(FileAccess.Read);
-        public IStorage GetHeaderStorage() => HeaderStorage.WithAccess(FileAccess.Read);
+        public IStorage GetBaseStorage() => BaseStorage.AsReadOnly();
+        public IStorage GetHeaderStorage() => HeaderStorage.AsReadOnly();
     }
 
     public class AllocationTableEntry

src/LibHac/IO/Save/AllocationTableStorage.cs

@@ -2,7 +2,7 @@
 
 namespace LibHac.IO.Save
 {
-    public class AllocationTableStorage : Storage
+    public class AllocationTableStorage : StorageBase
     {
         private IStorage BaseStorage { get; }
         private int BlockSize { get; }

src/LibHac/IO/Save/DuplexStorage.cs

@@ -2,7 +2,7 @@
 
 namespace LibHac.IO.Save
 {
-    public class DuplexStorage : Storage
+    public class DuplexStorage : StorageBase
     {
         private int BlockSize { get; }
         private IStorage BitmapStorage { get; }

src/LibHac/IO/Save/HierarchicalDuplexStorage.cs

@@ -2,7 +2,7 @@
 
 namespace LibHac.IO.Save
 {
-    public class HierarchicalDuplexStorage : Storage
+    public class HierarchicalDuplexStorage : StorageBase
     {
         private DuplexStorage[] Layers { get; }
         private DuplexStorage DataLayer { get; }

src/LibHac/IO/Save/JournalMap.cs

@@ -50,11 +50,11 @@ namespace LibHac.IO.Save
             return map;
         }
 
-        public IStorage GetMapStorage() => MapStorage.WithAccess(FileAccess.Read);
-        public IStorage GetHeaderStorage() => HeaderStorage.WithAccess(FileAccess.Read);
-        public IStorage GetModifiedPhysicalBlocksStorage() => ModifiedPhysicalBlocks.WithAccess(FileAccess.Read);
-        public IStorage GetModifiedVirtualBlocksStorage() => ModifiedVirtualBlocks.WithAccess(FileAccess.Read);
-        public IStorage GetFreeBlocksStorage() => FreeBlocks.WithAccess(FileAccess.Read);
+        public IStorage GetMapStorage() => MapStorage.AsReadOnly();
+        public IStorage GetHeaderStorage() => HeaderStorage.AsReadOnly();
+        public IStorage GetModifiedPhysicalBlocksStorage() => ModifiedPhysicalBlocks.AsReadOnly();
+        public IStorage GetModifiedVirtualBlocksStorage() => ModifiedVirtualBlocks.AsReadOnly();
+        public IStorage GetFreeBlocksStorage() => FreeBlocks.AsReadOnly();
     }
 
     public class JournalMapHeader

src/LibHac/IO/Save/JournalStorage.cs

@@ -3,7 +3,7 @@ using System.IO;
 
 namespace LibHac.IO.Save
 {
-    public class JournalStorage : Storage
+    public class JournalStorage : StorageBase
     {
         private IStorage BaseStorage { get; }
         private IStorage HeaderStorage { get; }
@@ -80,8 +80,8 @@ namespace LibHac.IO.Save
             BaseStorage.Flush();
         }
 
-        public IStorage GetBaseStorage() => BaseStorage.WithAccess(FileAccess.Read);
-        public IStorage GetHeaderStorage() => HeaderStorage.WithAccess(FileAccess.Read);
+        public IStorage GetBaseStorage() => BaseStorage.AsReadOnly();
+        public IStorage GetHeaderStorage() => HeaderStorage.AsReadOnly();
     }
 
     public class JournalHeader

src/LibHac/IO/Save/RemapStorage.cs

@@ -4,7 +4,7 @@ using System.IO;
 
 namespace LibHac.IO.Save
 {
-    public class RemapStorage : Storage
+    public class RemapStorage : StorageBase
     {
         private IStorage BaseStorage { get; }
         private IStorage HeaderStorage { get; }
@@ -102,9 +102,9 @@ namespace LibHac.IO.Save
             BaseStorage.Flush();
         }
 
-        public IStorage GetBaseStorage() => BaseStorage.WithAccess(FileAccess.Read);
-        public IStorage GetHeaderStorage() => HeaderStorage.WithAccess(FileAccess.Read);
-        public IStorage GetMapEntryStorage() => MapEntryStorage.WithAccess(FileAccess.Read);
+        public IStorage GetBaseStorage() => BaseStorage.AsReadOnly();
+        public IStorage GetHeaderStorage() => HeaderStorage.AsReadOnly();
+        public IStorage GetMapEntryStorage() => MapEntryStorage.AsReadOnly();
 
         private static RemapSegment[] InitSegments(RemapHeader header, MapEntry[] mapEntries)
         {

src/LibHac/IO/Save/SaveDataFileSystemCore.cs

@@ -152,8 +152,8 @@ namespace LibHac.IO.Save
             throw new System.NotImplementedException();
         }
 
-        public IStorage GetBaseStorage() => BaseStorage.WithAccess(FileAccess.Read);
-        public IStorage GetHeaderStorage() => HeaderStorage.WithAccess(FileAccess.Read);
+        public IStorage GetBaseStorage() => BaseStorage.AsReadOnly();
+        public IStorage GetHeaderStorage() => HeaderStorage.AsReadOnly();
 
         private void ReadFileInfo()
         {

src/LibHac/IO/SectorStorage.cs

@@ -2,7 +2,7 @@
 
 namespace LibHac.IO
 {
-    public class SectorStorage : Storage
+    public class SectorStorage : StorageBase
     {
         protected IStorage BaseStorage { get; }
 

src/LibHac/IO/Storage.cs

@@ -1,114 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-
-namespace LibHac.IO
-{
-    public abstract class Storage : IStorage
-    {
-        private bool _isDisposed;
-        protected internal List<IDisposable> ToDispose { get; } = new List<IDisposable>();
-
-        protected abstract void ReadImpl(Span<byte> destination, long offset);
-        protected abstract void WriteImpl(ReadOnlySpan<byte> source, long offset);
-        public abstract void Flush();
-        public abstract long Length { get; }
-
-        protected FileAccess Access { get; set; } = FileAccess.ReadWrite;
-
-        public void Read(Span<byte> destination, long offset)
-        {
-            EnsureCanRead();
-            ValidateSpanParameters(destination, offset);
-            ReadImpl(destination, offset);
-        }
-
-        public virtual void Read(byte[] buffer, long offset, int count, int bufferOffset)
-        {
-            ValidateArrayParameters(buffer, offset, count, bufferOffset);
-            Read(buffer.AsSpan(bufferOffset, count), offset);
-        }
-
-        public void Write(ReadOnlySpan<byte> source, long offset)
-        {
-            EnsureCanWrite();
-            ValidateSpanParameters(source, offset);
-            WriteImpl(source, offset);
-        }
-
-        public virtual void Write(byte[] buffer, long offset, int count, int bufferOffset)
-        {
-            ValidateArrayParameters(buffer, offset, count, bufferOffset);
-            Write(buffer.AsSpan(bufferOffset, count), offset);
-        }
-
-        public virtual Storage Slice(long start, long length, bool leaveOpen)
-        {
-            return new SubStorage(this, start, length, leaveOpen);
-        }
-
-        protected virtual void Dispose(bool disposing)
-        {
-            if (_isDisposed) return;
-
-            if (disposing)
-            {
-                Flush();
-                foreach (IDisposable item in ToDispose)
-                {
-                    item?.Dispose();
-                }
-            }
-
-            _isDisposed = true;
-        }
-
-        public void SetReadOnly() => Access = FileAccess.Read;
-
-        public virtual bool CanRead => (Access & FileAccess.Read) != 0;
-        public virtual bool CanWrite => (Access & FileAccess.Write) != 0;
-
-        private void EnsureCanRead()
-        {
-            if (!CanRead) throw new InvalidOperationException("Storage is not readable");
-        }
-
-        private void EnsureCanWrite()
-        {
-            if (!CanWrite) throw new InvalidOperationException("Storage is not writable");
-        }
-
-        public void Dispose()
-        {
-            Dispose(true);
-            GC.SuppressFinalize(this);
-        }
-
-        protected void ValidateArrayParameters(byte[] buffer, long offset, int count, int bufferOffset)
-        {
-            if (_isDisposed) throw new ObjectDisposedException(null);
-            if (buffer == null) throw new ArgumentNullException(nameof(buffer));
-            if (offset < 0) throw new ArgumentOutOfRangeException(nameof(offset), "Argument must be non-negative.");
-            if (count < 0) throw new ArgumentOutOfRangeException(nameof(count), "Argument must be non-negative.");
-            if (bufferOffset < 0) throw new ArgumentOutOfRangeException(nameof(bufferOffset), "Argument must be non-negative.");
-            if (buffer.Length - bufferOffset < count) throw new ArgumentException("bufferOffset, length, and count were out of bounds for the array.");
-
-            if (Length != -1)
-            {
-                if (offset + count > Length) throw new ArgumentException("The given offset and count exceed the length of the Storage");
-            }
-        }
-
-        protected void ValidateSpanParameters(ReadOnlySpan<byte> destination, long offset)
-        {
-            if (_isDisposed) throw new ObjectDisposedException(null);
-            if (destination == null) throw new ArgumentNullException(nameof(destination));
-            if (offset < 0) throw new ArgumentOutOfRangeException(nameof(offset), "Argument must be non-negative.");
-
-            if (Length != -1)
-            {
-                if (offset + destination.Length > Length) throw new ArgumentException("The given offset and count exceed the length of the Storage");
-            }
-        }
-    }
-}

src/LibHac/IO/StorageBase.cs

@@ -0,0 +1,62 @@
+using System;
+using System.Collections.Generic;
+
+namespace LibHac.IO
+{
+    public abstract class StorageBase : IStorage
+    {
+        private bool _isDisposed;
+        protected internal List<IDisposable> ToDispose { get; } = new List<IDisposable>();
+
+        protected abstract void ReadImpl(Span<byte> destination, long offset);
+        protected abstract void WriteImpl(ReadOnlySpan<byte> source, long offset);
+        public abstract void Flush();
+        public abstract long Length { get; }
+
+        public void Read(Span<byte> destination, long offset)
+        {
+            ValidateParameters(destination, offset);
+            ReadImpl(destination, offset);
+        }
+
+        public void Write(ReadOnlySpan<byte> source, long offset)
+        {
+            ValidateParameters(source, offset);
+            WriteImpl(source, offset);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (_isDisposed) return;
+
+            if (disposing)
+            {
+                Flush();
+                foreach (IDisposable item in ToDispose)
+                {
+                    item?.Dispose();
+                }
+            }
+
+            _isDisposed = true;
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        protected void ValidateParameters(ReadOnlySpan<byte> span, long offset)
+        {
+            if (_isDisposed) throw new ObjectDisposedException(null);
+            if (span == null) throw new ArgumentNullException(nameof(span));
+            if (offset < 0) throw new ArgumentOutOfRangeException(nameof(offset), "Argument must be non-negative.");
+
+            if (Length != -1)
+            {
+                if (offset + span.Length > Length) throw new ArgumentException("The given offset and count exceed the length of the Storage");
+            }
+        }
+    }
+}

src/LibHac/IO/StorageExtensions.cs

@@ -6,7 +6,7 @@ namespace LibHac.IO
 {
     public static class StorageExtensions
     {
-        public static Storage Slice(this IStorage storage, long start)
+        public static IStorage Slice(this IStorage storage, long start)
         {
             if (storage.Length == -1)
             {
@@ -16,33 +16,29 @@ namespace LibHac.IO
             return storage.Slice(start, storage.Length - start);
         }
 
-        public static Storage Slice(this IStorage storage, long start, long length)
+        public static IStorage Slice(this IStorage storage, long start, long length)
         {
             return storage.Slice(start, length, true);
         }
 
-        public static Storage Slice(this IStorage storage, long start, long length, bool leaveOpen)
+        public static IStorage Slice(this IStorage storage, long start, long length, bool leaveOpen)
         {
-            if (storage is Storage s)
-            {
-                return s.Slice(start, length, leaveOpen);
-            }
-
             return new SubStorage(storage, start, length, leaveOpen);
         }
 
-        public static Storage WithAccess(this IStorage storage, FileAccess access)
+        public static IStorage AsReadOnly(this IStorage storage)
         {
-            return storage.WithAccess(access, true);
+            return storage.AsReadOnly(true);
         }
 
-        public static Storage WithAccess(this IStorage storage, FileAccess access, bool leaveOpen)
+        public static IStorage AsReadOnly(this IStorage storage, bool leaveOpen)
         {
-            return new SubStorage(storage, 0, storage.Length, leaveOpen, access);
+            return new SubStorage(storage, 0, storage.Length, leaveOpen, FileAccess.Read);
         }
 
-        public static Stream AsStream(this IStorage storage) => new StorageStream(storage, true);
-        public static Stream AsStream(this IStorage storage, bool keepOpen) => new StorageStream(storage, keepOpen);
+        public static Stream AsStream(this IStorage storage) => new StorageStream(storage, FileAccess.ReadWrite, true);
+        public static Stream AsStream(this IStorage storage, FileAccess access) => new StorageStream(storage, access, true);
+        public static Stream AsStream(this IStorage storage, FileAccess access, bool keepOpen) => new StorageStream(storage, access, keepOpen);
 
         public static void CopyTo(this IStorage input, IStorage output, IProgressReport progress = null)
         {
@@ -96,7 +92,7 @@ namespace LibHac.IO
             while (remaining > 0)
             {
                 int toWrite = (int) Math.Min(buffer.Length, remaining);
-                input.Read(buffer, inOffset, toWrite, 0);
+                input.Read(buffer.AsSpan(0, toWrite), inOffset);
 
                 output.Write(buffer, 0, toWrite);
                 remaining -= toWrite;
@@ -107,31 +103,31 @@ namespace LibHac.IO
 
         public static void CopyToStream(this IStorage input, Stream output) => CopyToStream(input, output, input.Length);
 
-        public static Storage AsStorage(this Stream stream)
+        public static IStorage AsStorage(this Stream stream)
         {
             if (stream == null) return null;
             return new StreamStorage(stream, true);
         }
 
-        public static Storage AsStorage(this Stream stream, bool keepOpen)
+        public static IStorage AsStorage(this Stream stream, bool keepOpen)
         {
             if (stream == null) return null;
             return new StreamStorage(stream, keepOpen);
         }
 
-        public static Storage AsStorage(this Stream stream, long start)
+        public static IStorage AsStorage(this Stream stream, long start)
         {
             if (stream == null) return null;
             return new StreamStorage(stream, true).Slice(start);
         }
 
-        public static Storage AsStorage(this Stream stream, long start, int length)
+        public static IStorage AsStorage(this Stream stream, long start, int length)
         {
             if (stream == null) return null;
             return new StreamStorage(stream, true).Slice(start, length);
         }
 
-        public static Storage AsStorage(this Stream stream, long start, int length, bool keepOpen)
+        public static IStorage AsStorage(this Stream stream, long start, int length, bool keepOpen)
         {
             if (stream == null) return null;
             return new StreamStorage(stream, keepOpen).Slice(start, length);

src/LibHac/IO/StorageStream.cs

@@ -8,17 +8,20 @@ namespace LibHac.IO
         private IStorage BaseStorage { get; }
         private bool LeaveOpen { get; }
 
-        public StorageStream(IStorage baseStorage, bool leaveOpen)
+        public StorageStream(IStorage baseStorage, FileAccess access, bool leaveOpen)
         {
             BaseStorage = baseStorage;
             LeaveOpen = leaveOpen;
             Length = baseStorage.Length;
+
+            CanRead = access.HasFlag(FileAccess.Read);
+            CanWrite = access.HasFlag(FileAccess.Write);
         }
 
         public override int Read(byte[] buffer, int offset, int count)
         {
             int toRead = (int) Math.Min(count, Length - Position);
-            BaseStorage.Read(buffer, Position, toRead, offset);
+            BaseStorage.Read(buffer.AsSpan(offset, count), Position);
 
             Position += toRead;
             return toRead;
@@ -26,7 +29,7 @@ namespace LibHac.IO
 
         public override void Write(byte[] buffer, int offset, int count)
         {
-            BaseStorage.Write(buffer, Position, count, offset);
+            BaseStorage.Write(buffer.AsSpan(offset, count), Position);
             Position += count;
         }
 
@@ -58,9 +61,9 @@ namespace LibHac.IO
             throw new NotImplementedException();
         }
 
-        public override bool CanRead => (BaseStorage as Storage)?.CanRead ?? true;
+        public override bool CanRead { get; }
         public override bool CanSeek => true;
-        public override bool CanWrite => (BaseStorage as Storage)?.CanWrite ?? true;
+        public override bool CanWrite { get; }
         public override long Length { get; }
         public override long Position { get; set; }
 

src/LibHac/IO/StreamStorage.cs

@@ -7,7 +7,7 @@ using System.Buffers;
 
 namespace LibHac.IO
 {
-    public class StreamStorage : Storage
+    public class StreamStorage : StorageBase
     {
         private Stream BaseStream { get; }
         private object Locker { get; } = new object();
@@ -20,24 +20,6 @@ namespace LibHac.IO
             if (!leaveOpen) ToDispose.Add(BaseStream);
         }
 
-        public override void Read(byte[] buffer, long offset, int count, int bufferOffset)
-        {
-            lock (Locker)
-            {
-                BaseStream.Position = offset;
-                BaseStream.Read(buffer, bufferOffset, count);
-            }
-        }
-
-        public override void Write(byte[] buffer, long offset, int count, int bufferOffset)
-        {
-            lock (Locker)
-            {
-                BaseStream.Position = offset;
-                BaseStream.Write(buffer, bufferOffset, count);
-            }
-        }
-
         protected override void ReadImpl(Span<byte> destination, long offset)
         {
 #if STREAM_SPAN
@@ -54,9 +36,17 @@ namespace LibHac.IO
             byte[] buffer = ArrayPool<byte>.Shared.Rent(destination.Length);
             try
             {
-                Read(buffer, offset, destination.Length, 0);
+                lock (Locker)
+                {
+                    if (BaseStream.Position != offset)
+                    {
+                        BaseStream.Position = offset;
+                    }
 
-                new Span<byte>(buffer, 0, destination.Length).CopyTo(destination);
+                    BaseStream.Read(buffer, 0, destination.Length);
+                }
+
+                buffer.AsSpan(0, destination.Length).CopyTo(destination);
             }
             finally { ArrayPool<byte>.Shared.Return(buffer); }
 #endif
@@ -66,8 +56,12 @@ namespace LibHac.IO
         {
 #if STREAM_SPAN
             lock (Locker)
+            {
+                if (BaseStream.Position != offset)
                 {
                     BaseStream.Position = offset;
+                }
+
                 BaseStream.Write(source);
             }
 #else
@@ -75,7 +69,16 @@ namespace LibHac.IO
             try
             {
                 source.CopyTo(buffer);
-                Write(buffer, offset, source.Length, 0);
+
+                lock (Locker)
+                {
+                    if (BaseStream.Position != offset)
+                    {
+                        BaseStream.Position = offset;
+                    }
+
+                    BaseStream.Write(buffer, 0, source.Length);
+                }
             }
             finally { ArrayPool<byte>.Shared.Return(buffer); }
 #endif

src/LibHac/IO/SubStorage.cs

@@ -3,11 +3,12 @@ using System.IO;
 
 namespace LibHac.IO
 {
-    public class SubStorage : Storage
+    public class SubStorage : StorageBase
     {
         private IStorage BaseStorage { get; }
         private long Offset { get; }
         public override long Length { get; }
+        private FileAccess Access { get; } = FileAccess.ReadWrite;
 
         public SubStorage(IStorage baseStorage, long offset, long length)
         {
@@ -16,6 +17,13 @@ namespace LibHac.IO
             Length = length;
         }
 
+        public SubStorage(SubStorage baseStorage, long offset, long length)
+        {
+            BaseStorage = baseStorage.BaseStorage;
+            Offset = baseStorage.Offset + offset;
+            Length = length;
+        }
+
         public SubStorage(IStorage baseStorage, long offset, long length, bool leaveOpen)
             : this(baseStorage, offset, length)
         {
@@ -30,11 +38,13 @@ namespace LibHac.IO
 
         protected override void ReadImpl(Span<byte> destination, long offset)
         {
+            if((Access & FileAccess.Read) == 0) throw new InvalidOperationException("Storage is not readable");
             BaseStorage.Read(destination, offset + Offset);
         }
 
         protected override void WriteImpl(ReadOnlySpan<byte> source, long offset)
         {
+            if((Access & FileAccess.Write) == 0) throw new InvalidOperationException("Storage is not writable");
             BaseStorage.Write(source, offset + Offset);
         }
 
@@ -42,13 +52,5 @@ namespace LibHac.IO
         {
             BaseStorage.Flush();
         }
-
-        public override Storage Slice(long start, long length, bool leaveOpen)
-        {
-            Storage storage = BaseStorage.Slice(Offset + start, length, true);
-            if (!leaveOpen) storage.ToDispose.Add(this);
-
-            return storage;
-        }
     }
 }

src/LibHac/Nca.cs

@@ -75,7 +75,7 @@ namespace LibHac
         /// <returns>The <see cref="IStorage"/> that provides access to the entire raw NCA file.</returns>
         public IStorage GetStorage()
         {
-            return BaseStorage.WithAccess(FileAccess.Read);
+            return BaseStorage.AsReadOnly();
         }
 
         public bool CanOpenSection(int index)

src/NandReaderGui/ViewModel/NandViewModel.cs

@@ -46,8 +46,7 @@ namespace NandReaderGui.ViewModel
         {
             DiskInfo disk = SelectedDisk;
             var storage = new CachedStorage(new DeviceStream(disk.PhysicalName, disk.Length).AsStorage(), disk.SectorSize * 100, 4, true);
-            storage.SetReadOnly();
-            Stream stream = storage.AsStream();
+            Stream stream = storage.AsStream(FileAccess.Read);
 
             Keyset keyset = OpenKeyset();
             var nand = new Nand(stream, keyset);