Mark for 0.42.0

Fix DivideByZeroException when compressing empty files with BZip2

src/SharpCompress/Compressors/BZip2/CBZip2OutputStream.cs

@@ -544,6 +544,12 @@ internal sealed class CBZip2OutputStream : Stream, IStreamStack
 
     private void EndBlock()
     {
+        // Skip block processing for empty input (no data written)
+        if (last < 0)
+        {
+            return;
+        }
+
         blockCRC = mCrc.GetFinalCRC();
         combinedCRC = (combinedCRC << 1) | (int)(((uint)combinedCRC) >> 31);
         combinedCRC ^= blockCRC;

src/SharpCompress/SharpCompress.csproj

@@ -2,9 +2,9 @@
   <PropertyGroup>
     <AssemblyTitle>SharpCompress - Pure C# Decompression/Compression</AssemblyTitle>
     <NeutralLanguage>en-US</NeutralLanguage>
-    <VersionPrefix>0.41.0</VersionPrefix>
-    <AssemblyVersion>0.41.0</AssemblyVersion>
-    <FileVersion>0.41.0</FileVersion>
+    <VersionPrefix>0.42.0</VersionPrefix>
+    <AssemblyVersion>0.42.0</AssemblyVersion>
+    <FileVersion>0.42.0</FileVersion>
     <Authors>Adam Hathcock</Authors>
     <TargetFrameworks>net48;net481;netstandard2.0;net6.0;net8.0</TargetFrameworks>
     <AssemblyName>SharpCompress</AssemblyName>

tests/SharpCompress.Test/Zip/ZipWriterTests.cs

@@ -1,5 +1,7 @@
+using System.IO;
 using System.Text;
 using SharpCompress.Common;
+using SharpCompress.Writers;
 using Xunit;
 
 namespace SharpCompress.Test.Zip;
@@ -9,6 +11,42 @@ public class ZipWriterTests : WriterTests
     public ZipWriterTests()
         : base(ArchiveType.Zip) { }
 
+    [Fact]
+    public void Zip_BZip2_Write_EmptyFile()
+    {
+        // Test that writing an empty file with BZip2 compression doesn't throw DivideByZeroException
+        using var memoryStream = new MemoryStream();
+        var options = new WriterOptions(CompressionType.BZip2)
+        {
+            ArchiveEncoding = new ArchiveEncoding { Default = new UTF8Encoding(false) },
+        };
+
+        using (var writer = WriterFactory.Open(memoryStream, ArchiveType.Zip, options))
+        {
+            writer.Write("test-folder/zero-byte-file.txt", Stream.Null);
+        }
+
+        Assert.True(memoryStream.Length > 0);
+    }
+
+    [Fact]
+    public void Zip_BZip2_Write_EmptyFolder()
+    {
+        // Test that writing an empty folder entry with BZip2 compression doesn't throw DivideByZeroException
+        using var memoryStream = new MemoryStream();
+        var options = new WriterOptions(CompressionType.BZip2)
+        {
+            ArchiveEncoding = new ArchiveEncoding { Default = new UTF8Encoding(false) },
+        };
+
+        using (var writer = WriterFactory.Open(memoryStream, ArchiveType.Zip, options))
+        {
+            writer.Write("test-empty-folder/", Stream.Null);
+        }
+
+        Assert.True(memoryStream.Length > 0);
+    }
+
     [Fact]
     public void Zip_Deflate_Write() =>
         Write(