Setup solution

ModernKeePassLib/Cryptography/HashingStreamEx.cs

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+/*
+  KeePass Password Safe - The Open-Source Password Manager
+  Copyright (C) 2003-2019 Dominik Reichl <dominik.reichl@t-online.de>
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.Text;
+
+#if !KeePassUAP
+using System.Security.Cryptography;
+#endif
+
+using ModernKeePassLib.Utility;
+
+namespace ModernKeePassLib.Cryptography
+{
+	public sealed class HashingStreamEx : Stream
+	{
+		private readonly Stream m_sBaseStream;
+		private readonly bool m_bWriting;
+		private HashAlgorithm m_hash;
+
+		private byte[] m_pbFinalHash = null;
+
+		public byte[] Hash
+		{
+			get { return m_pbFinalHash; }
+		}
+
+		public override bool CanRead
+		{
+			get { return !m_bWriting; }
+		}
+
+		public override bool CanSeek
+		{
+			get { return false; }
+		}
+
+		public override bool CanWrite
+		{
+			get { return m_bWriting; }
+		}
+
+		public override long Length
+		{
+			get { return m_sBaseStream.Length; }
+		}
+
+		public override long Position
+		{
+			get { return m_sBaseStream.Position; }
+			set { Debug.Assert(false); throw new NotSupportedException(); }
+		}
+
+		public HashingStreamEx(Stream sBaseStream, bool bWriting, HashAlgorithm hashAlgorithm)
+		{
+			if(sBaseStream == null) throw new ArgumentNullException("sBaseStream");
+
+			m_sBaseStream = sBaseStream;
+			m_bWriting = bWriting;
+
+#if !KeePassLibSD
+			m_hash = (hashAlgorithm ?? new SHA256Managed());
+#else // KeePassLibSD
+			m_hash = null;
+
+			try { m_hash = HashAlgorithm.Create("SHA256"); }
+			catch(Exception) { }
+			try { if(m_hash == null) m_hash = HashAlgorithm.Create(); }
+			catch(Exception) { }
+#endif
+			if(m_hash == null) { Debug.Assert(false); return; }
+
+			// Validate hash algorithm
+			if(!m_hash.CanReuseTransform || !m_hash.CanTransformMultipleBlocks)
+			{
+				Debug.Assert(false);
+				m_hash = null;
+			}
+		}
+
+		protected override void Dispose(bool disposing)
+		{
+			if(disposing)
+			{
+				if(m_hash != null)
+				{
+					try
+					{
+						m_hash.TransformFinalBlock(MemUtil.EmptyByteArray, 0, 0);
+						m_pbFinalHash = m_hash.Hash;
+						m_hash.Clear();
+					}
+					catch(Exception) { Debug.Assert(false); }
+
+					m_hash = null;
+				}
+
+				m_sBaseStream.Dispose();
+			}
+
+			base.Dispose(disposing);
+		}
+
+		public override void Flush()
+		{
+			m_sBaseStream.Flush();
+		}
+
+		public override long Seek(long lOffset, SeekOrigin soOrigin)
+		{
+			Debug.Assert(false);
+			throw new NotSupportedException();
+		}
+
+		public override void SetLength(long lValue)
+		{
+			Debug.Assert(false);
+			throw new NotSupportedException();
+		}
+
+		public override int Read(byte[] pbBuffer, int nOffset, int nCount)
+		{
+			if(m_bWriting) { Debug.Assert(false); throw new InvalidOperationException(); }
+
+			int nRead = m_sBaseStream.Read(pbBuffer, nOffset, nCount);
+			int nPartialRead = nRead;
+			while((nRead < nCount) && (nPartialRead != 0))
+			{
+				nPartialRead = m_sBaseStream.Read(pbBuffer, nOffset + nRead,
+					nCount - nRead);
+				nRead += nPartialRead;
+			}
+
+#if DEBUG
+			byte[] pbOrg = new byte[pbBuffer.Length];
+			Array.Copy(pbBuffer, pbOrg, pbBuffer.Length);
+#endif
+
+			if((m_hash != null) && (nRead > 0))
+				m_hash.TransformBlock(pbBuffer, nOffset, nRead, pbBuffer, nOffset);
+
+#if DEBUG
+			Debug.Assert(MemUtil.ArraysEqual(pbBuffer, pbOrg));
+#endif
+
+			return nRead;
+		}
+
+		public override void Write(byte[] pbBuffer, int nOffset, int nCount)
+		{
+			if(!m_bWriting) { Debug.Assert(false); throw new InvalidOperationException(); }
+
+#if DEBUG
+			byte[] pbOrg = new byte[pbBuffer.Length];
+			Array.Copy(pbBuffer, pbOrg, pbBuffer.Length);
+#endif
+
+			if((m_hash != null) && (nCount > 0))
+				m_hash.TransformBlock(pbBuffer, nOffset, nCount, pbBuffer, nOffset);
+
+#if DEBUG
+			Debug.Assert(MemUtil.ArraysEqual(pbBuffer, pbOrg));
+#endif
+
+			m_sBaseStream.Write(pbBuffer, nOffset, nCount);
+		}
+	}
+}