Adding logic to the inflator and deflator streams to use pooled buffers if possible and clear memory on Dispose()

src/ICSharpCode.SharpZipLib/Zip/Compression/Streams/DeflaterOutputStream.cs

@@ -1,5 +1,6 @@
 using ICSharpCode.SharpZipLib.Encryption;
 using System;
+using System.Buffers;
 using System.IO;
 using System.Security.Cryptography;
 using System.Text;
@@ -83,7 +84,16 @@ public DeflaterOutputStream(Stream baseOutputStream, Deflater deflater, int buff
 			}
 
 			baseOutputStream_ = baseOutputStream;
-			buffer_ = new byte[bufferSize];
+
+			if(ArrayPool<byte>.Shared != null)
+			{
+				buffer_ = ArrayPool<byte>.Shared.Rent(bufferSize);
+				isBufferOwnedByArrayPool_ = true;
+			}
+			else
+			{
+				buffer_ = new byte[bufferSize];
+			}
 			deflater_ = deflater ?? throw new ArgumentNullException(nameof(deflater));
 		}
 
@@ -226,7 +236,10 @@ public Encoding ZipCryptoEncoding {
 		/// </param>
 		protected void EncryptBlock(byte[] buffer, int offset, int length)
 		{
-		    if(cryptoTransform_ is null) return;
+			if(cryptoTransform_ is null)
+			{
+				return;
+			}
 			cryptoTransform_.TransformBlock(buffer, 0, length, buffer, 0);
 		}
 
@@ -432,6 +445,13 @@ protected override void Dispose(bool disposing)
 						baseOutputStream_.Dispose();
 					}
 				}
+
+				// Ensure buffer is returned to the pool if it was rented from it.
+				if(isBufferOwnedByArrayPool_)
+				{
+					ArrayPool<byte>.Shared.Return(buffer_);
+				}
+				buffer_ = null;
 			}
 		}
 
@@ -540,6 +560,11 @@ public override async Task WriteAsync(byte[] buffer, int offset, int count, Canc
 		/// </summary>
 		private byte[] buffer_;
 
+		/// <summary>
+		/// If true, this buffer is owned by the array pool and should be returned there on Dispose.
+		/// </summary>
+		private bool isBufferOwnedByArrayPool_;
+
 		/// <summary>
 		/// The deflater which is used to deflate the stream.
 		/// </summary>

src/ICSharpCode.SharpZipLib/Zip/Compression/Streams/InflaterInputStream.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Buffers;
 using System.IO;
 using System.Security.Cryptography;
 using ICSharpCode.SharpZipLib.Core;
@@ -11,7 +12,7 @@ namespace ICSharpCode.SharpZipLib.Zip.Compression.Streams
 	/// <remarks>
 	/// The buffer supports decryption of incoming data.
 	/// </remarks>
-	public class InflaterInputBuffer
+	public class InflaterInputBuffer : IDisposable
 	{
 		#region Constructors
 
@@ -36,7 +37,16 @@ public InflaterInputBuffer(Stream stream, int bufferSize)
 			{
 				bufferSize = 1024;
 			}
-			rawData = new byte[bufferSize];
+
+			if(ArrayPool<bool>.Shared != null)
+			{
+				rawData = ArrayPool<byte>.Shared.Rent(bufferSize);
+				isRawDataOwnedByArrayPool = true;
+			}
+			else
+			{
+				rawData = new byte[bufferSize];
+			}
 			clearText = rawData;
 		}
 
@@ -269,6 +279,20 @@ public long ReadLeLong()
 			return (uint)ReadLeInt() | ((long)ReadLeInt() << 32);
 		}
 
+		/// <summary>
+		/// Implements the dispose method of the <see cref="IDisposable"/> interface.
+		/// </summary>
+		public void Dispose()
+		{
+			if(isRawDataOwnedByArrayPool)
+			{
+				ArrayPool<byte>.Shared.Return(rawData);
+			}
+			rawData = null;
+			clearText = null;
+			internalClearText = null;
+		}
+
 		/// <summary>
 		/// Get/set the <see cref="ICryptoTransform"/> to apply to any data.
 		/// </summary>
@@ -306,6 +330,7 @@ public ICryptoTransform CryptoTransform
 
 		private int rawLength;
 		private byte[] rawData;
+		private bool isRawDataOwnedByArrayPool = false;
 
 		private int clearTextLength;
 		private byte[] clearText;
@@ -637,6 +662,11 @@ protected override void Dispose(bool disposing)
 				InflaterPool.Instance.Return(inflater);
 			}
 			inf = null;
+
+			if(inputBuffer != null)
+			{
+				inputBuffer.Dispose();
+			}
 		}
 
 		/// <summary>