Merge pull request #717 from ds5678/lzma-improvements

Several improvements to the LZMA Compressor

src/SharpCompress/Compressors/LZMA/ICoder.cs

@@ -150,7 +150,7 @@ internal enum CoderPropId
 
 internal interface ISetCoderProperties
 {
-    void SetCoderProperties(CoderPropId[] propIDs, object[] properties);
+    void SetCoderProperties(ReadOnlySpan<CoderPropId> propIDs, ReadOnlySpan<object> properties);
 }
 
 internal interface IWriteCoderProperties

src/SharpCompress/Compressors/LZMA/LzmaEncoder.cs

@@ -1725,9 +1725,9 @@ internal class Encoder : ICoder, ISetCoderProperties, IWriteCoderProperties
         return -1;
     }
 
-    public void SetCoderProperties(CoderPropId[] propIDs, object[] properties)
+    public void SetCoderProperties(ReadOnlySpan<CoderPropId> propIDs, ReadOnlySpan<object> properties)
     {
-        for (uint i = 0; i < properties.Length; i++)
+        for (int i = 0; i < properties.Length; i++)
         {
             var prop = properties[i];
             switch (propIDs[i])

src/SharpCompress/Compressors/LZMA/LzmaEncoderProperties.cs

@@ -1,9 +1,16 @@
+using System;
+
 namespace SharpCompress.Compressors.LZMA;
 
 public class LzmaEncoderProperties
 {
-    internal CoderPropId[] _propIDs;
-    internal object[] _properties;
+    public static LzmaEncoderProperties Default { get; } = new();
+
+    internal ReadOnlySpan<CoderPropId> PropIDs => _propIDs;
+    private readonly CoderPropId[] _propIDs;
+
+    internal ReadOnlySpan<object> Properties => _properties;
+    private readonly object[] _properties;
 
     public LzmaEncoderProperties() : this(false) { }
 

src/SharpCompress/Compressors/LZMA/LzmaStream.cs

@@ -1,4 +1,4 @@
-#nullable disable
+#nullable disable
 
 using System;
 using System.Buffers.Binary;
@@ -111,7 +111,7 @@ public class LzmaStream : Stream
         }
 
         _encoder = new Encoder();
-        _encoder.SetCoderProperties(properties._propIDs, properties._properties);
+        _encoder.SetCoderProperties(properties.PropIDs, properties.Properties);
         var prop = new byte[5];
         _encoder.WriteCoderProperties(prop);
         Properties = prop;

tests/SharpCompress.Test/Streams/LzmaStreamTests.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Buffers;
+using System.Buffers.Binary;
 using System.IO;
 using SharpCompress.Compressors.LZMA;
 using Xunit;
@@ -177,6 +179,9 @@ public class LzmaStreamTests
             0x90
         };
 
+    /// <summary>
+    /// The decoded data for <see cref="lzmaData"/>.
+    /// </summary>
     private static byte[] lzmaResultData { get; } =
         new byte[]
         {
@@ -528,4 +533,54 @@ public class LzmaStreamTests
 
         Assert.Equal(output.ToArray(), lzmaResultData);
     }
+
+    [Fact]
+    public void TestLzmaStreamEncodingWritesData()
+    {
+        using MemoryStream inputStream = new MemoryStream(lzmaResultData);
+        using MemoryStream outputStream = new();
+        using LzmaStream lzmaStream = new LzmaStream(LzmaEncoderProperties.Default, false, outputStream);
+        inputStream.CopyTo(lzmaStream);
+        lzmaStream.Close();
+        Assert.NotEqual(0, outputStream.Length);
+    }
+
+    [Fact]
+    public void TestLzmaEncodingAccuracy()
+    {
+        var input = new MemoryStream(lzmaResultData);
+        var compressed = new MemoryStream();
+        LzmaStream lzmaEncodingStream = new LzmaStream(LzmaEncoderProperties.Default, false, compressed);
+        input.CopyTo(lzmaEncodingStream);
+        lzmaEncodingStream.Close();
+        compressed.Position = 0;
+
+        var output = new MemoryStream();
+        DecompressLzmaStream(lzmaEncodingStream.Properties, compressed, compressed.Length, output, lzmaResultData.LongLength);
+
+        Assert.Equal(output.ToArray(), lzmaResultData);
+    }
+
+    private static void DecompressLzmaStream(byte[] properties, Stream compressedStream, long compressedSize, Stream decompressedStream, long decompressedSize)
+    {
+        LzmaStream lzmaStream = new LzmaStream(properties, compressedStream, compressedSize, -1, null, false);
+
+        byte[] buffer = ArrayPool<byte>.Shared.Rent(1024);
+        long totalRead = 0;
+        while (totalRead < decompressedSize)
+        {
+            int toRead = (int)Math.Min(buffer.Length, decompressedSize - totalRead);
+            int read = lzmaStream.Read(buffer, 0, toRead);
+            if (read > 0)
+            {
+                decompressedStream.Write(buffer, 0, read);
+                totalRead += read;
+            }
+            else
+            {
+                break;
+            }
+        }
+        ArrayPool<byte>.Shared.Return(buffer);
+    }
 }