Fix test failures for multi-threading support in file-based Zips

- Fix build errors in Tar tests by adding !NETFRAMEWORK condition to #if LINUX
- Fix split archive test failures by checking ss.Files.Count == 1 before opening independent file streams
- The multi-threading feature now correctly only applies to single-file ZIP archives, not split/multi-volume archives

Co-authored-by: adamhathcock <527620+adamhathcock@users.noreply.github.com>

src/SharpCompress/Archives/IArchiveEntryExtensions.cs

@@ -88,7 +88,7 @@ public static class IArchiveEntryExtensions
             entry,
             destinationDirectory,
             options,
-            (x, opt) => entry.WriteToFileAsync(x, opt, cancellationToken),
+            entry.WriteToFileAsync,
             cancellationToken
         );
 

src/SharpCompress/Archives/Zip/ZipArchiveEntry.cs

@@ -23,5 +23,7 @@ public class ZipArchiveEntry : ZipEntry, IArchiveEntry
 
     public bool IsComplete => true;
 
+    public override bool SupportsMultiThreading => Parts.Single().SupportsMultiThreading;
+
     #endregion
 }

src/SharpCompress/Common/Entry.cs

@@ -87,4 +87,5 @@ public abstract class Entry : IEntry
     /// Entry file attribute.
     /// </summary>
     public virtual int? Attrib => throw new NotImplementedException();
+    public virtual bool SupportsMultiThreading => false;
 }

src/SharpCompress/Common/ExtractionMethods.cs

@@ -128,7 +128,7 @@ internal static class ExtractionMethods
         IEntry entry,
         string destinationDirectory,
         ExtractionOptions? options,
-        Func<string, ExtractionOptions?, Task> writeAsync,
+        Func<string, ExtractionOptions?, CancellationToken, Task> writeAsync,
         CancellationToken cancellationToken = default
     )
     {
@@ -189,7 +189,7 @@ internal static class ExtractionMethods
                     "Entry is trying to write a file outside of the destination directory."
                 );
             }
-            await writeAsync(destinationFileName, options).ConfigureAwait(false);
+            await writeAsync(destinationFileName, options, cancellationToken).ConfigureAwait(false);
         }
         else if (options.ExtractFullPath && !Directory.Exists(destinationFileName))
         {

src/SharpCompress/Common/FilePart.cs

@@ -14,4 +14,6 @@ public abstract class FilePart
     internal abstract Stream? GetCompressedStream();
     internal abstract Stream? GetRawStream();
     internal bool Skipped { get; set; }
+
+    public virtual bool SupportsMultiThreading => false;
 }

src/SharpCompress/Common/IEntry.cs

@@ -21,4 +21,5 @@ public interface IEntry
     DateTime? LastModifiedTime { get; }
     long Size { get; }
     int? Attrib { get; }
+    public bool SupportsMultiThreading { get; }
 }

src/SharpCompress/Common/Zip/SeekableZipFilePart.cs

@@ -1,5 +1,7 @@
+using System;
 using System.IO;
 using SharpCompress.Common.Zip.Headers;
+using SharpCompress.IO;
 
 namespace SharpCompress.Common.Zip;
 
@@ -30,8 +32,17 @@ internal class SeekableZipFilePart : ZipFilePart
 
     protected override Stream CreateBaseStream()
     {
+        if (BaseStream is SourceStream ss && ss.IsFileMode && ss.Files.Count == 1)
+        {
+            var fileStream = ss.CurrentFile.OpenRead();
+            fileStream.Position = Header.DataStartPosition.NotNull();
+            return fileStream;
+        }
         BaseStream.Position = Header.DataStartPosition.NotNull();
 
         return BaseStream;
     }
+
+    public override bool SupportsMultiThreading =>
+        BaseStream is SourceStream ss && ss.IsFileMode && ss.Files.Count == 1;
 }

src/SharpCompress/IO/SourceStream.cs

@@ -15,7 +15,7 @@ public class SourceStream : Stream, IStreamStack
 #endif
     int IStreamStack.DefaultBufferSize { get; set; }
 
-    Stream IStreamStack.BaseStream() => _streams[_stream];
+    Stream IStreamStack.BaseStream() => _streams[_streamIndex];
 
     int IStreamStack.BufferSize
     {
@@ -35,7 +35,7 @@ public class SourceStream : Stream, IStreamStack
     private readonly List<Stream> _streams;
     private readonly Func<int, FileInfo?>? _getFilePart;
     private readonly Func<int, Stream?>? _getStreamPart;
-    private int _stream;
+    private int _streamIndex;
 
     public SourceStream(FileInfo file, Func<int, FileInfo?> getPart, ReaderOptions options)
         : this(null, null, file, getPart, options) { }
@@ -59,7 +59,7 @@ public class SourceStream : Stream, IStreamStack
 
         if (!IsFileMode)
         {
-            _streams.Add(stream!);
+            _streams.Add(stream.NotNull("stream is null"));
             _getStreamPart = getStreamPart;
             _getFilePart = _ => null;
             if (stream is FileStream fileStream)
@@ -69,12 +69,12 @@ public class SourceStream : Stream, IStreamStack
         }
         else
         {
-            _files.Add(file!);
+            _files.Add(file.NotNull("file is null"));
             _streams.Add(_files[0].OpenRead());
             _getFilePart = getFilePart;
             _getStreamPart = _ => null;
         }
-        _stream = 0;
+        _streamIndex = 0;
         _prevSize = 0;
 
 #if DEBUG_STREAMS
@@ -93,10 +93,12 @@ public class SourceStream : Stream, IStreamStack
     public ReaderOptions ReaderOptions { get; }
     public bool IsFileMode { get; }
 
-    public IEnumerable<FileInfo> Files => _files;
-    public IEnumerable<Stream> Streams => _streams;
+    public IReadOnlyList<FileInfo> Files => _files;
+    public IReadOnlyList<Stream> Streams => _streams;
 
-    private Stream Current => _streams[_stream];
+    private Stream Current => _streams[_streamIndex];
+
+    public FileInfo CurrentFile => _files[_streamIndex];
 
     public bool LoadStream(int index) //ensure all parts to id are loaded
     {
@@ -107,7 +109,7 @@ public class SourceStream : Stream, IStreamStack
                 var f = _getFilePart.NotNull("GetFilePart is null")(_streams.Count);
                 if (f == null)
                 {
-                    _stream = _streams.Count - 1;
+                    _streamIndex = _streams.Count - 1;
                     return false;
                 }
                 //throw new Exception($"File part {idx} not available.");
@@ -119,7 +121,7 @@ public class SourceStream : Stream, IStreamStack
                 var s = _getStreamPart.NotNull("GetStreamPart is null")(_streams.Count);
                 if (s == null)
                 {
-                    _stream = _streams.Count - 1;
+                    _streamIndex = _streams.Count - 1;
                     return false;
                 }
                 //throw new Exception($"Stream part {idx} not available.");
@@ -137,10 +139,10 @@ public class SourceStream : Stream, IStreamStack
     {
         if (LoadStream(idx))
         {
-            _stream = idx;
+            _streamIndex = idx;
         }
 
-        return _stream == idx;
+        return _streamIndex == idx;
     }
 
     public override bool CanRead => true;
@@ -184,7 +186,7 @@ public class SourceStream : Stream, IStreamStack
                 var length = Current.Length;
 
                 // Load next file if present
-                if (!SetStream(_stream + 1))
+                if (!SetStream(_streamIndex + 1))
                 {
                     break;
                 }
@@ -223,7 +225,7 @@ public class SourceStream : Stream, IStreamStack
             while (_prevSize + Current.Length < pos)
             {
                 _prevSize += Current.Length;
-                SetStream(_stream + 1);
+                SetStream(_streamIndex + 1);
             }
         }
 
@@ -273,7 +275,7 @@ public class SourceStream : Stream, IStreamStack
                 var length = Current.Length;
 
                 // Load next file if present
-                if (!SetStream(_stream + 1))
+                if (!SetStream(_streamIndex + 1))
                 {
                     break;
                 }
@@ -322,7 +324,7 @@ public class SourceStream : Stream, IStreamStack
                 var length = Current.Length;
 
                 // Load next file if present
-                if (!SetStream(_stream + 1))
+                if (!SetStream(_streamIndex + 1))
                 {
                     break;
                 }

src/SharpCompress/Readers/IReaderExtensions.cs

@@ -82,7 +82,7 @@ public static class IReaderExtensions
                 reader.Entry,
                 destinationDirectory,
                 options,
-                (fileName, opts) => reader.WriteEntryToFileAsync(fileName, opts, cancellationToken),
+                reader.WriteEntryToFileAsync,
                 cancellationToken
             )
             .ConfigureAwait(false);

tests/SharpCompress.Test/ArchiveTests.cs

@@ -134,6 +134,7 @@ public class ArchiveTests : ReaderTests
                 {
                     foreach (var entry in archive.Entries.Where(entry => !entry.IsDirectory))
                     {
+                        Assert.False(entry.SupportsMultiThreading);
                         entry.WriteToDirectory(
                             SCRATCH_FILES_PATH,
                             new ExtractionOptions { ExtractFullPath = true, Overwrite = true }
@@ -266,6 +267,34 @@ public class ArchiveTests : ReaderTests
         VerifyFiles();
     }
 
+    protected async Task ArchiveFileRead_Multithreaded(
+        IArchiveFactory archiveFactory,
+        string testArchive,
+        ReaderOptions? readerOptions = null
+    )
+    {
+        testArchive = Path.Combine(TEST_ARCHIVES_PATH, testArchive);
+        var tasks = new List<Task>();
+        using (var archive = archiveFactory.Open(new FileInfo(testArchive), readerOptions))
+        {
+            foreach (var entry in archive.Entries.Where(entry => !entry.IsDirectory))
+            {
+                if (archiveFactory.KnownArchiveType == ArchiveType.Zip)
+                {
+                    Assert.True(entry.SupportsMultiThreading);
+                }
+
+                var t = entry.WriteToDirectoryAsync(
+                    SCRATCH_FILES_PATH,
+                    new ExtractionOptions { ExtractFullPath = true, Overwrite = true }
+                );
+                tasks.Add(t);
+            }
+        }
+        await Task.WhenAll(tasks);
+        VerifyFiles();
+    }
+
     protected void ArchiveFileRead(
         IArchiveFactory archiveFactory,
         string testArchive,
@@ -277,6 +306,11 @@ public class ArchiveTests : ReaderTests
         {
             foreach (var entry in archive.Entries.Where(entry => !entry.IsDirectory))
             {
+                if (archiveFactory.KnownArchiveType == ArchiveType.Zip)
+                {
+                    Assert.True(entry.SupportsMultiThreading);
+                }
+
                 entry.WriteToDirectory(
                     SCRATCH_FILES_PATH,
                     new ExtractionOptions { ExtractFullPath = true, Overwrite = true }
@@ -289,6 +323,11 @@ public class ArchiveTests : ReaderTests
     protected void ArchiveFileRead(string testArchive, ReaderOptions? readerOptions = null) =>
         ArchiveFileRead(ArchiveFactory.AutoFactory, testArchive, readerOptions);
 
+    protected Task ArchiveFileRead_Multithreaded(
+        string testArchive,
+        ReaderOptions? readerOptions = null
+    ) => ArchiveFileRead_Multithreaded(ArchiveFactory.AutoFactory, testArchive, readerOptions);
+
     protected void ArchiveFileSkip(
         string testArchive,
         string fileOrder,

tests/SharpCompress.Test/Tar/TarReaderAsyncTests.cs

@@ -207,7 +207,7 @@ public class TarReaderAsyncTests : ReaderTests
         Assert.Throws<IncompleteArchiveException>(() => reader.MoveToNextEntry());
     }
 
-#if LINUX
+#if LINUX && !NETFRAMEWORK
     [Fact]
     public async Task Tar_GZip_With_Symlink_Entries_Async()
     {

tests/SharpCompress.Test/Tar/TarReaderTests.cs

@@ -201,7 +201,7 @@ public class TarReaderTests : ReaderTests
         Assert.Throws<IncompleteArchiveException>(() => reader.MoveToNextEntry());
     }
 
-#if LINUX
+#if LINUX && !NETFRAMEWORK
     [Fact]
     public void Tar_GZip_With_Symlink_Entries()
     {

tests/SharpCompress.Test/Zip/ZipArchiveTests.cs

@@ -2,6 +2,7 @@ using System;
 using System.IO;
 using System.Linq;
 using System.Text;
+using System.Threading.Tasks;
 using SharpCompress.Archives;
 using SharpCompress.Archives.Zip;
 using SharpCompress.Common;
@@ -88,6 +89,10 @@ public class ZipArchiveTests : ArchiveTests
     [Fact]
     public void Zip_Deflate_ArchiveFileRead() => ArchiveFileRead("Zip.deflate.zip");
 
+    [Fact]
+    public Task Zip_Deflate_ArchiveFileRead_Multithreaded() =>
+        ArchiveFileRead_Multithreaded("Zip.deflate.zip");
+
     [Fact]
     public void Zip_Deflate_ArchiveExtractToDirectory() =>
         ArchiveExtractToDirectory("Zip.deflate.zip");