Initial

MareSynchronos/Utils/HashingStream.cs

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+using System.Security.Cryptography;
+
+namespace MareSynchronos.Utils;
+
+// Calculates the hash of content read or written to a stream
+public class HashingStream : Stream
+{
+    private readonly Stream _stream;
+    private readonly HashAlgorithm _hashAlgo;
+    private bool _finished = false;
+    public bool DisposeUnderlying { get; set; } = true;
+
+    public Stream UnderlyingStream { get => _stream; }
+
+    public HashingStream(Stream underlyingStream, HashAlgorithm hashAlgo)
+    {
+        _stream = underlyingStream;
+        _hashAlgo = hashAlgo;
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        base.Dispose(disposing);
+        if (!DisposeUnderlying)
+            return;
+        if (!_finished)
+            _stream.Dispose();
+        _hashAlgo.Dispose();
+    }
+
+    public override bool CanRead => _stream.CanRead;
+    public override bool CanSeek => false;
+    public override bool CanWrite => _stream.CanWrite;
+    public override long Length => _stream.Length;
+
+    public override long Position { get => _stream.Position; set => throw new NotSupportedException(); }
+
+    public override void Flush()
+    {
+        _stream.Flush();
+    }
+
+    public override int Read(byte[] buffer, int offset, int count)
+    {
+        ObjectDisposedException.ThrowIf(_finished, this);
+        int n = _stream.Read(buffer, offset, count);
+        if (n > 0)
+            _hashAlgo.TransformBlock(buffer, offset, n, buffer, offset);
+        return n;
+    }
+
+    public override long Seek(long offset, SeekOrigin origin)
+    {
+        throw new NotSupportedException();
+    }
+
+    public override void SetLength(long value)
+    {
+        ObjectDisposedException.ThrowIf(_finished, this);
+        _stream.SetLength(value);
+    }
+
+    public override void Write(byte[] buffer, int offset, int count)
+    {
+        ObjectDisposedException.ThrowIf(_finished, this);
+        _stream.Write(buffer, offset, count);
+        _hashAlgo.TransformBlock(buffer, offset, count, buffer, offset);
+    }
+
+    public byte[] Finish()
+    {
+        if (_finished)
+            return _hashAlgo.Hash!;
+        _hashAlgo.TransformFinalBlock(Array.Empty<byte>(), 0, 0);
+        _finished = true;
+        if (DisposeUnderlying)
+            _stream.Dispose();
+        return _hashAlgo.Hash!;
+    }
+}