Improved memory management

Author: d2dyno1

SecureFolderFS.Backend/ViewModels/Pages/VaultDashboardPageViewModel.cs

@@ -8,11 +8,9 @@
 using SecureFolderFS.Backend.ViewModels.Pages.DashboardPages;
 using SecureFolderFS.Core.VaultLoader.Routine;
 
-#nullable enable
-
 namespace SecureFolderFS.Backend.ViewModels.Pages
 {
-    public class VaultDashboardPageViewModel : BasePageViewModel, IRecipient<DashboardNavigationFinishedMessage>
+    public sealed class VaultDashboardPageViewModel : BasePageViewModel, IRecipient<DashboardNavigationFinishedMessage>
     {
         public NavigationBreadcrumbViewModel NavigationBreadcrumbViewModel { get; }
 

SecureFolderFS.Core/Chunks/Factory/AesCtrHmacChunkFactory.cs

@@ -1,4 +1,5 @@
 using SecureFolderFS.Core.Chunks.Implementation;
+using System;
 
 namespace SecureFolderFS.Core.Chunks.Factory
 {
@@ -14,9 +15,9 @@ public ICleartextChunk FromCleartextChunkBuffer(byte[] cleartextChunkBuffer, int
             return new CleartextAesCtrHmacChunk(cleartextChunkBuffer, actualLength);
         }
 
-        public ICiphertextChunk FromCiphertextChunkBuffer(byte[] ciphertextChunkBuffer)
+        public ICiphertextChunk FromCiphertextChunkBuffer(ReadOnlyMemory<byte> ciphertextChunkBuffer)
         {
-            return CiphertextAesCtrHmacChunk.FromCiphertextChunkBuffer(ciphertextChunkBuffer);
+            return new CiphertextAesCtrHmacChunk(ciphertextChunkBuffer);
         }
     }
 }

SecureFolderFS.Core/Chunks/Factory/AesGcmChunkFactory.cs

@@ -1,4 +1,5 @@
 using SecureFolderFS.Core.Chunks.Implementation;
+using System;
 
 namespace SecureFolderFS.Core.Chunks.Factory
 {
@@ -14,9 +15,9 @@ public ICleartextChunk FromCleartextChunkBuffer(byte[] cleartextChunkBuffer, int
             return new CleartextAesGcmChunk(cleartextChunkBuffer, actualLength);
         }
 
-        public ICiphertextChunk FromCiphertextChunkBuffer(byte[] ciphertextChunkBuffer)
+        public ICiphertextChunk FromCiphertextChunkBuffer(ReadOnlyMemory<byte> ciphertextChunkBuffer)
         {
-            return CiphertextAesGcmChunk.FromCiphertextChunkBuffer(ciphertextChunkBuffer);
+            return new CiphertextAesGcmChunk(ciphertextChunkBuffer);
         }
     }
 }

SecureFolderFS.Core/Chunks/Factory/XChaCha20ChunkFactory.cs

@@ -1,4 +1,5 @@
 using SecureFolderFS.Core.Chunks.Implementation;
+using System;
 
 namespace SecureFolderFS.Core.Chunks.Factory
 {
@@ -14,9 +15,9 @@ public ICleartextChunk FromCleartextChunkBuffer(byte[] cleartextChunkBuffer, int
             return new CleartextXChaCha20Chunk(cleartextChunkBuffer, actualLength);
         }
 
-        public ICiphertextChunk FromCiphertextChunkBuffer(byte[] ciphertextChunkBuffer)
+        public ICiphertextChunk FromCiphertextChunkBuffer(ReadOnlyMemory<byte> ciphertextChunkBuffer)
         {
-            return CiphertextXChaCha20Chunk.FromCiphertextChunkBuffer(ciphertextChunkBuffer);
+            return new CiphertextXChaCha20Chunk(ciphertextChunkBuffer);
         }
     }
 }

SecureFolderFS.Core/Chunks/IChunkFactory.cs

@@ -1,11 +1,13 @@
-namespace SecureFolderFS.Core.Chunks
+using System;
+
+namespace SecureFolderFS.Core.Chunks
 {
     internal interface IChunkFactory
     {
         ICleartextChunk FromCleartextChunkBuffer(byte[] cleartextChunkBuffer);
 
         ICleartextChunk FromCleartextChunkBuffer(byte[] cleartextChunkBuffer, int actualLength);
 
-        ICiphertextChunk FromCiphertextChunkBuffer(byte[] ciphertextChunkBuffer);
+        ICiphertextChunk FromCiphertextChunkBuffer(ReadOnlyMemory<byte> ciphertextChunkBuffer);
     }
 }

SecureFolderFS.Core/Chunks/ICiphertextChunk.cs

@@ -2,8 +2,8 @@
 
 namespace SecureFolderFS.Core.Chunks
 {
-    internal interface ICiphertextChunk : IDisposable
+    internal interface ICiphertextChunk
     {
-        byte[] ToArray();
+        ReadOnlyMemory<byte> Buffer { get; }
     }
 }

SecureFolderFS.Core/Chunks/ICleartextChunk.cs

@@ -11,12 +11,10 @@ internal interface ICleartextChunk : IDisposable
 
         void CopyTo(MemoryStream destinationStream, int offset);
 
-        int CopyFrom(MemoryStream sourceStream, int offset);
-
-        void CopyFrom2(ReadOnlySpan<byte> sourceBuffer, int offset, ref int positionInBuffer);
+        void CopyFrom(ReadOnlySpan<byte> sourceBuffer, int offset, ref int positionInBuffer);
 
         void SetActualLength(int length);
 
-        byte[] ToArray();
+        ReadOnlySpan<byte> AsSpan();
     }
 }

SecureFolderFS.Core/Chunks/IO/ChunkReader.cs

@@ -2,7 +2,6 @@
 using SecureFolderFS.Core.Security;
 using SecureFolderFS.Core.FileHeaders;
 using SecureFolderFS.Core.Tracking;
-using SecureFolderFS.Shared.Extensions;
 using SecureFolderFS.Core.Streams.Management;
 
 namespace SecureFolderFS.Core.Chunks.IO
@@ -34,28 +33,31 @@ public ICleartextChunk ReadChunk(long chunkNumber)
         {
             AssertNotDisposed();
 
+            // Calculate
             var payloadSize = _security.ContentCryptor.FileContentCryptor.ChunkCleartextSize;
             var chunkSize = _security.ContentCryptor.FileContentCryptor.ChunkFullCiphertextSize;
-
             var ciphertextPosition = _security.ContentCryptor.FileHeaderCryptor.HeaderSize + (chunkNumber * chunkSize);
+
+            // Initialize buffer
             var ciphertextBuffer = new byte[chunkSize];
+            var ciphertextBufferMemory = ciphertextBuffer.AsMemory();
 
+            // Read from stream
             var ciphertextFileStream = _ciphertextStreamsManager.EnsureReadOnlyStreamInstance();
             ciphertextFileStream.Position = ciphertextPosition;
-            var read = ciphertextFileStream.Read(ciphertextBuffer, 0, ciphertextBuffer.Length);
+            var read = ciphertextFileStream.Read(ciphertextBufferMemory.Span);
 
+            // Check for end-of-file
             if (read == Constants.IO.FILE_EOF)
             {
                 return _chunkFactory.FromCleartextChunkBuffer(new byte[payloadSize], 0);
             }
 
             _fileSystemStatsTracker?.AddBytesRead(read);
 
-            var actualCiphertextBuffer = new byte[read];
-            actualCiphertextBuffer.EmplaceArrays(ciphertextBuffer);
-
+            // Decrypt
             var cleartextChunk = _security.ContentCryptor.FileContentCryptor.DecryptChunk(
-                _chunkFactory.FromCiphertextChunkBuffer(actualCiphertextBuffer),
+                _chunkFactory.FromCiphertextChunkBuffer(ciphertextBufferMemory.Slice(0, read)),
                 chunkNumber,
                 _fileHeader,
                 Constants.Security.ALWAYS_CHECK_CHUNK_INTEGRITY);

SecureFolderFS.Core/Chunks/IO/ChunkWriter.cs

@@ -38,15 +38,13 @@ public void WriteChunk(long chunkNumber, ICleartextChunk cleartextChunk)
                         chunkNumber,
                         _fileHeader);
 
-                byte[] ciphertextChunkBuffer = ciphertextChunk.ToArray();
-
                 _fileSystemStatsTracker?.AddBytesEncrypted(cleartextChunk.ActualLength);
 
                 var ciphertextFileStream = _ciphertextStreamsManager.EnsureReadWriteStreamInstance();
                 ciphertextFileStream.Position = ciphertextPosition;
-                ciphertextFileStream.Write(ciphertextChunkBuffer, 0, ciphertextChunkBuffer.Length);
+                ciphertextFileStream.Write(ciphertextChunk.Buffer.Span);
 
-                _fileSystemStatsTracker?.AddBytesWritten(ciphertextChunkBuffer.Length);
+                _fileSystemStatsTracker?.AddBytesWritten(ciphertextChunk.Buffer.Length);
             }
         }
 

SecureFolderFS.Core/Chunks/Implementation/BaseCiphertextChunk.cs

@@ -1,36 +1,20 @@
 using System;
-using SecureFolderFS.Shared.Extensions;
 
 namespace SecureFolderFS.Core.Chunks.Implementation
 {
     internal abstract class BaseCiphertextChunk : ICiphertextChunk
     {
-        public byte[] Nonce { get; }
+        public ReadOnlyMemory<byte> Buffer { get; }
 
-        public byte[] Payload { get; }
-
-        public byte[] Auth { get; }
-
-        protected BaseCiphertextChunk(byte[] nonce, byte[] payload, byte[] auth)
+        protected BaseCiphertextChunk(ReadOnlyMemory<byte> buffer)
         {
-            this.Nonce = nonce;
-            this.Payload = payload;
-            this.Auth = auth;
+            this.Buffer = buffer;
         }
 
-        public virtual byte[] ToArray()
-        {
-            var fullChunk = new byte[Nonce.Length + Payload.Length + Auth.Length];
-            fullChunk.EmplaceArrays(Nonce, Payload, Auth);
+        public abstract ReadOnlySpan<byte> GetNonceAsSpan();
 
-            return fullChunk;
-        }
+        public abstract ReadOnlySpan<byte> GetPayloadAsSpan();
 
-        public virtual void Dispose()
-        {
-            Array.Clear(Nonce);
-            Array.Clear(Payload);
-            Array.Clear(Auth);
-        }
+        public abstract ReadOnlySpan<byte> GetAuthAsSpan();
     }
 }