Add opt-in multi-threading support with SupportsMultiThreadedExtraction flag

- Added IArchive.SupportsMultiThreadedExtraction property to indicate if multi-threading is supported
- Added ReaderOptions.EnableMultiThreadedExtraction option to opt-in to multi-threading
- Updated SeekableZipFilePart, TarFilePart, and SeekableFilePart to check the flag
- Added test to verify multi-threading flag behavior
- Multi-threading is now disabled by default for backward compatibility

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

src/SharpCompress/Algorithms/Adler32.cs

@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
-#if !NETSTANDARD2_0 && !NETSTANDARD2_1 && !NETFRAMEWORK
+#if !LEGACY_DOTNET
 #define SUPPORTS_RUNTIME_INTRINSICS
 #define SUPPORTS_HOTPATH
 #endif

src/SharpCompress/Archives/AbstractArchive.cs

@@ -145,6 +145,19 @@ public abstract class AbstractArchive<TEntry, TVolume> : IArchive, IAsyncArchive
     /// </summary>
     public virtual bool IsEncrypted => false;
 
+    /// <summary>
+    /// Returns whether multi-threaded extraction is supported for this archive.
+    /// Multi-threading is supported when:
+    /// 1. The archive is opened from a FileInfo or file path (not a stream)
+    /// 2. Multi-threading is explicitly enabled in ReaderOptions
+    /// 3. The archive is not SOLID (SOLID archives should use sequential extraction)
+    /// </summary>
+    public virtual bool SupportsMultiThreadedExtraction =>
+        _sourceStream is not null
+        && _sourceStream.IsFileMode
+        && ReaderOptions.EnableMultiThreadedExtraction
+        && !IsSolid;
+
     /// <summary>
     /// The archive can find all the parts of the archive needed to fully extract the archive.  This forces the parsing of the entire archive.
     /// </summary>

src/SharpCompress/Archives/ArchiveFactory.cs

@@ -78,7 +78,7 @@ public static class ArchiveFactory
         options ??= new ReaderOptions { LeaveStreamOpen = false };
 
         var factory = await FindFactoryAsync<IArchiveFactory>(fileInfo, cancellationToken);
-        return factory.OpenAsyncArchive(fileInfo, options);
+        return factory.OpenAsyncArchive(fileInfo, options, cancellationToken);
     }
 
     public static IArchive OpenArchive(

src/SharpCompress/Archives/AutoArchiveFactory.cs

@@ -40,6 +40,13 @@ internal class AutoArchiveFactory : IArchiveFactory
     public IArchive OpenArchive(FileInfo fileInfo, ReaderOptions? readerOptions = null) =>
         ArchiveFactory.OpenArchive(fileInfo, readerOptions);
 
-    public IAsyncArchive OpenAsyncArchive(FileInfo fileInfo, ReaderOptions? readerOptions = null) =>
-        (IAsyncArchive)OpenArchive(fileInfo, readerOptions);
+    public IAsyncArchive OpenAsyncArchive(
+        FileInfo fileInfo,
+        ReaderOptions? readerOptions = null,
+        CancellationToken cancellationToken = default
+    )
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+        return (IAsyncArchive)OpenArchive(fileInfo, readerOptions);
+    }
 }

src/SharpCompress/Archives/IArchive.cs

@@ -44,4 +44,12 @@ public interface IArchive : IDisposable
     /// Returns whether the archive is encrypted.
     /// </summary>
     bool IsEncrypted { get; }
+
+    /// <summary>
+    /// Returns whether multi-threaded extraction is supported for this archive.
+    /// Multi-threading is supported when the archive is opened from a FileInfo or file path
+    /// (not a stream) and the format supports random access (e.g., Zip, Tar, Rar).
+    /// SOLID archives (some Rar, all 7Zip) should use sequential extraction for best performance.
+    /// </summary>
+    bool SupportsMultiThreadedExtraction { get; }
 }

src/SharpCompress/Archives/IArchiveFactory.cs

@@ -47,5 +47,9 @@ public interface IArchiveFactory : IFactory
     /// <param name="fileInfo">the file to open.</param>
     /// <param name="readerOptions">reading options.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
-    IAsyncArchive OpenAsyncArchive(FileInfo fileInfo, ReaderOptions? readerOptions = null);
+    IAsyncArchive OpenAsyncArchive(
+        FileInfo fileInfo,
+        ReaderOptions? readerOptions = null,
+        CancellationToken cancellationToken = default
+    );
 }

src/SharpCompress/Archives/Rar/RarArchive.Factory.cs

@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Common;
 using SharpCompress.Common.Rar;
 using SharpCompress.Common.Rar.Headers;
@@ -164,22 +163,4 @@ public partial class RarArchive
             return false;
         }
     }
-
-    public static async ValueTask<bool> IsRarFileAsync(
-        Stream stream,
-        ReaderOptions? options = null,
-        CancellationToken cancellationToken = default
-    )
-    {
-        cancellationToken.ThrowIfCancellationRequested();
-        try
-        {
-            MarkHeader.Read(stream, true, false);
-            return true;
-        }
-        catch
-        {
-            return false;
-        }
-    }
 }

src/SharpCompress/Archives/Rar/SeekableFilePart.cs

@@ -1,6 +1,7 @@
 using System.IO;
 using SharpCompress.Common.Rar;
 using SharpCompress.Common.Rar.Headers;
+using SharpCompress.IO;
 
 namespace SharpCompress.Archives.Rar;
 
@@ -24,6 +25,76 @@ internal class SeekableFilePart : RarFilePart
 
     internal override Stream GetCompressedStream()
     {
+        Stream streamToUse;
+
+        // If the stream is a SourceStream in file mode with multi-threading enabled,
+        // create an independent stream to support concurrent extraction
+        if (
+            _stream is SourceStream sourceStream
+            && sourceStream.IsFileMode
+            && sourceStream.ReaderOptions.EnableMultiThreadedExtraction
+        )
+        {
+            var independentStream = sourceStream.CreateIndependentStream(0);
+            if (independentStream is not null)
+            {
+                streamToUse = independentStream;
+                streamToUse.Position = FileHeader.DataStartPosition;
+
+                if (FileHeader.R4Salt != null)
+                {
+                    var cryptKey = new CryptKey3(_password!);
+                    return new RarCryptoWrapper(streamToUse, FileHeader.R4Salt, cryptKey);
+                }
+
+                if (FileHeader.Rar5CryptoInfo != null)
+                {
+                    var cryptKey = new CryptKey5(_password!, FileHeader.Rar5CryptoInfo);
+                    return new RarCryptoWrapper(
+                        streamToUse,
+                        FileHeader.Rar5CryptoInfo.Salt,
+                        cryptKey
+                    );
+                }
+
+                return streamToUse;
+            }
+        }
+
+        // Check if the stream wraps a FileStream
+        Stream? underlyingStream = _stream;
+        if (_stream is IStreamStack streamStack)
+        {
+            underlyingStream = streamStack.BaseStream();
+        }
+
+        if (underlyingStream is FileStream fileStream)
+        {
+            // Create a new independent stream from the file
+            streamToUse = new FileStream(
+                fileStream.Name,
+                FileMode.Open,
+                FileAccess.Read,
+                FileShare.Read
+            );
+            streamToUse.Position = FileHeader.DataStartPosition;
+
+            if (FileHeader.R4Salt != null)
+            {
+                var cryptKey = new CryptKey3(_password!);
+                return new RarCryptoWrapper(streamToUse, FileHeader.R4Salt, cryptKey);
+            }
+
+            if (FileHeader.Rar5CryptoInfo != null)
+            {
+                var cryptKey = new CryptKey5(_password!, FileHeader.Rar5CryptoInfo);
+                return new RarCryptoWrapper(streamToUse, FileHeader.Rar5CryptoInfo.Salt, cryptKey);
+            }
+
+            return streamToUse;
+        }
+
+        // Fall back to existing behavior for stream-based sources
         _stream.Position = FileHeader.DataStartPosition;
 
         if (FileHeader.R4Salt != null)

src/SharpCompress/Archives/SevenZip/SevenZipArchive.Factory.cs

@@ -1,10 +1,12 @@
 using System;
-using System.Buffers;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using SharpCompress.Common;
+using SharpCompress.Common.SevenZip;
+using SharpCompress.Compressors.LZMA.Utilites;
 using SharpCompress.IO;
 using SharpCompress.Readers;
 
@@ -155,56 +157,13 @@ public partial class SevenZipArchive
         }
     }
 
-    public static async ValueTask<bool> IsSevenZipFileAsync(
-        Stream stream,
-        CancellationToken cancellationToken = default
-    )
-    {
-        cancellationToken.ThrowIfCancellationRequested();
-        try
-        {
-            return await SignatureMatchAsync(stream, cancellationToken);
-        }
-        catch
-        {
-            return false;
-        }
-    }
-
-    private static ReadOnlySpan<byte> Signature => [(byte)'7', (byte)'z', 0xBC, 0xAF, 0x27, 0x1C];
+    private static ReadOnlySpan<byte> Signature =>
+        new byte[] { (byte)'7', (byte)'z', 0xBC, 0xAF, 0x27, 0x1C };
 
     private static bool SignatureMatch(Stream stream)
     {
-        var buffer = ArrayPool<byte>.Shared.Rent(6);
-        try
-        {
-            stream.ReadExact(buffer, 0, 6);
-            return buffer.AsSpan().Slice(0, 6).SequenceEqual(Signature);
-        }
-        finally
-        {
-            ArrayPool<byte>.Shared.Return(buffer);
-        }
-    }
-
-    private static async ValueTask<bool> SignatureMatchAsync(
-        Stream stream,
-        CancellationToken cancellationToken
-    )
-    {
-        var buffer = ArrayPool<byte>.Shared.Rent(6);
-        try
-        {
-            if (!await stream.ReadFullyAsync(buffer, cancellationToken).ConfigureAwait(false))
-            {
-                return false;
-            }
-
-            return buffer.AsSpan().Slice(0, 6).SequenceEqual(Signature);
-        }
-        finally
-        {
-            ArrayPool<byte>.Shared.Return(buffer);
-        }
+        var reader = new BinaryReader(stream);
+        ReadOnlySpan<byte> signatureBytes = reader.ReadBytes(6);
+        return signatureBytes.SequenceEqual(Signature);
     }
 }

src/SharpCompress/Archives/SevenZip/SevenZipArchive.cs

@@ -32,56 +32,11 @@ public partial class SevenZipArchive : AbstractArchive<SevenZipArchiveEntry, Sev
         IEnumerable<SevenZipVolume> volumes
     )
     {
-        foreach (var volume in volumes)
-        {
-            LoadFactory(volume.Stream);
-            if (_database is null)
-            {
-                yield break;
-            }
-            var entries = new SevenZipArchiveEntry[_database._files.Count];
-            for (var i = 0; i < _database._files.Count; i++)
-            {
-                var file = _database._files[i];
-                entries[i] = new SevenZipArchiveEntry(
-                    this,
-                    new SevenZipFilePart(
-                        volume.Stream,
-                        _database,
-                        i,
-                        file,
-                        ReaderOptions.ArchiveEncoding
-                    )
-                );
-            }
-            foreach (
-                var group in entries.Where(x => !x.IsDirectory).GroupBy(x => x.FilePart.Folder)
-            )
-            {
-                var isSolid = false;
-                foreach (var entry in group)
-                {
-                    entry.IsSolid = isSolid;
-                    isSolid = true;
-                }
-            }
-
-            foreach (var entry in entries)
-            {
-                yield return entry;
-            }
-        }
-    }
-
-    protected override async IAsyncEnumerable<SevenZipArchiveEntry> LoadEntriesAsync(
-        IAsyncEnumerable<SevenZipVolume> volumes
-    )
-    {
-        var stream = (await volumes.SingleAsync()).Stream;
-        await LoadFactoryAsync(stream);
+        var stream = volumes.Single().Stream;
+        LoadFactory(stream);
         if (_database is null)
         {
-            yield break;
+            return Enumerable.Empty<SevenZipArchiveEntry>();
         }
         var entries = new SevenZipArchiveEntry[_database._files.Count];
         for (var i = 0; i < _database._files.Count; i++)
@@ -102,10 +57,7 @@ public partial class SevenZipArchive : AbstractArchive<SevenZipArchiveEntry, Sev
             }
         }
 
-        foreach (var entry in entries)
-        {
-            yield return entry;
-        }
+        return entries;
     }
 
     private void LoadFactory(Stream stream)
@@ -119,27 +71,6 @@ public partial class SevenZipArchive : AbstractArchive<SevenZipArchiveEntry, Sev
         }
     }
 
-    private async Task LoadFactoryAsync(
-        Stream stream,
-        CancellationToken cancellationToken = default
-    )
-    {
-        if (_database is null)
-        {
-            stream.Position = 0;
-            var reader = new ArchiveReader();
-            await reader.OpenAsync(
-                stream,
-                lookForHeader: ReaderOptions.LookForHeader,
-                cancellationToken
-            );
-            _database = await reader.ReadDatabaseAsync(
-                new PasswordProvider(ReaderOptions.Password),
-                cancellationToken
-            );
-        }
-    }
-
     protected override IReader CreateReaderForSolidExtraction() =>
         new SevenZipReader(ReaderOptions, this);
 
@@ -253,7 +184,7 @@ public partial class SevenZipArchive : AbstractArchive<SevenZipArchiveEntry, Sev
             return Task.CompletedTask;
         }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
         public override ValueTask<int> ReadAsync(
             Memory<byte> buffer,
             CancellationToken cancellationToken = default

src/SharpCompress/Archives/Tar/TarArchive.Factory.cs

@@ -165,27 +165,6 @@ public partial class TarArchive
         return false;
     }
 
-    public static async ValueTask<bool> IsTarFileAsync(
-        Stream stream,
-        CancellationToken cancellationToken = default
-    )
-    {
-        cancellationToken.ThrowIfCancellationRequested();
-        try
-        {
-            var tarHeader = new TarHeader(new ArchiveEncoding());
-            var reader = new BinaryReader(stream);
-            var readSucceeded = tarHeader.Read(reader);
-            var isEmptyArchive =
-                tarHeader.Name?.Length == 0
-                && tarHeader.Size == 0
-                && Enum.IsDefined(typeof(EntryType), tarHeader.EntryType);
-            return readSucceeded || isEmptyArchive;
-        }
-        catch { }
-        return false;
-    }
-
     public static IWritableArchive CreateArchive() => new TarArchive();
 
     public static IWritableAsyncArchive CreateAsyncArchive() => new TarArchive();

src/SharpCompress/Common/Ace/Headers/AceHeader.cs

@@ -1,7 +1,5 @@
 using System;
 using System.IO;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Common.Arj.Headers;
 using SharpCompress.Crypto;
 
@@ -107,26 +105,6 @@ namespace SharpCompress.Common.Ace.Headers
             return CheckMagicBytes(bytes, 7);
         }
 
-        /// <summary>
-        /// Asynchronously checks if the stream is an ACE archive
-        /// </summary>
-        /// <param name="stream">The stream to read from</param>
-        /// <param name="cancellationToken">Cancellation token</param>
-        /// <returns>True if the stream is an ACE archive, false otherwise</returns>
-        public static async ValueTask<bool> IsArchiveAsync(
-            Stream stream,
-            CancellationToken cancellationToken = default
-        )
-        {
-            var bytes = new byte[14];
-            if (await stream.ReadAsync(bytes, 0, 14, cancellationToken) != 14)
-            {
-                return false;
-            }
-
-            return CheckMagicBytes(bytes, 7);
-        }
-
         protected static bool CheckMagicBytes(byte[] headerBytes, int offset)
         {
             // Check for "**ACE**" at specified offset

src/SharpCompress/Common/Arj/Headers/ArjHeader.cs

@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Text;
-using System.Threading;
 using System.Threading.Tasks;
 using SharpCompress.Common.Zip.Headers;
 using SharpCompress.Crypto;
@@ -150,26 +149,6 @@ namespace SharpCompress.Common.Arj.Headers
             return CheckMagicBytes(bytes);
         }
 
-        /// <summary>
-        /// Asynchronously checks if the stream is an ARJ archive
-        /// </summary>
-        /// <param name="stream">The stream to read from</param>
-        /// <param name="cancellationToken">Cancellation token</param>
-        /// <returns>True if the stream is an ARJ archive, false otherwise</returns>
-        public static async ValueTask<bool> IsArchiveAsync(
-            Stream stream,
-            CancellationToken cancellationToken = default
-        )
-        {
-            var bytes = new byte[2];
-            if (await stream.ReadAsync(bytes, 0, 2, cancellationToken) != 2)
-            {
-                return false;
-            }
-
-            return CheckMagicBytes(bytes);
-        }
-
         protected static bool CheckMagicBytes(byte[] headerBytes)
         {
             var magicValue = (ushort)(headerBytes[0] | headerBytes[1] << 8);

src/SharpCompress/Common/AsyncBinaryReader.cs

@@ -82,7 +82,7 @@ namespace SharpCompress.Common
             }
         }
 
-#if NET6_0_OR_GREATER
+#if NET8_0_OR_GREATER
         public async ValueTask DisposeAsync()
         {
             if (_disposed)

src/SharpCompress/Common/EntryStream.cs

@@ -93,7 +93,7 @@ public class EntryStream : Stream, IStreamStack
         _stream.Dispose();
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask DisposeAsync()
     {
         if (_isDisposed)
@@ -171,7 +171,7 @@ public class EntryStream : Stream, IStreamStack
         return read;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default

src/SharpCompress/Common/SevenZip/ArchiveReader.cs

@@ -5,8 +5,6 @@ using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Compressors.LZMA;
 using SharpCompress.Compressors.LZMA.Utilites;
 using SharpCompress.IO;
@@ -1272,46 +1270,6 @@ internal class ArchiveReader
         _stream = stream;
     }
 
-    public async Task OpenAsync(
-        Stream stream,
-        bool lookForHeader,
-        CancellationToken cancellationToken = default
-    )
-    {
-        Close();
-
-        _streamOrigin = stream.Position;
-        _streamEnding = stream.Length;
-
-        var canScan = lookForHeader ? 0x80000 - 20 : 0;
-        while (true)
-        {
-            // TODO: Check Signature!
-            _header = new byte[0x20];
-            await stream.ReadExactAsync(_header, 0, 0x20, cancellationToken);
-
-            if (
-                !lookForHeader
-                || _header
-                    .AsSpan(0, length: 6)
-                    .SequenceEqual<byte>([0x37, 0x7A, 0xBC, 0xAF, 0x27, 0x1C])
-            )
-            {
-                break;
-            }
-
-            if (canScan == 0)
-            {
-                throw new InvalidFormatException("Unable to find 7z signature");
-            }
-
-            canScan--;
-            stream.Position = ++_streamOrigin;
-        }
-
-        _stream = stream;
-    }
-
     public void Close()
     {
         _stream?.Dispose();
@@ -1425,110 +1383,6 @@ internal class ArchiveReader
         return db;
     }
 
-    public async Task<ArchiveDatabase> ReadDatabaseAsync(
-        IPasswordProvider pass,
-        CancellationToken cancellationToken = default
-    )
-    {
-        var db = new ArchiveDatabase(pass);
-        db.Clear();
-
-        db._majorVersion = _header[6];
-        db._minorVersion = _header[7];
-
-        if (db._majorVersion != 0)
-        {
-            throw new InvalidOperationException();
-        }
-
-        var crcFromArchive = DataReader.Get32(_header, 8);
-        var nextHeaderOffset = (long)DataReader.Get64(_header, 0xC);
-        var nextHeaderSize = (long)DataReader.Get64(_header, 0x14);
-        var nextHeaderCrc = DataReader.Get32(_header, 0x1C);
-
-        var crc = Crc.INIT_CRC;
-        crc = Crc.Update(crc, nextHeaderOffset);
-        crc = Crc.Update(crc, nextHeaderSize);
-        crc = Crc.Update(crc, nextHeaderCrc);
-        crc = Crc.Finish(crc);
-
-        if (crc != crcFromArchive)
-        {
-            throw new InvalidOperationException();
-        }
-
-        db._startPositionAfterHeader = _streamOrigin + 0x20;
-
-        // empty header is ok
-        if (nextHeaderSize == 0)
-        {
-            db.Fill();
-            return db;
-        }
-
-        if (nextHeaderOffset < 0 || nextHeaderSize < 0 || nextHeaderSize > int.MaxValue)
-        {
-            throw new InvalidOperationException();
-        }
-
-        if (nextHeaderOffset > _streamEnding - db._startPositionAfterHeader)
-        {
-            throw new InvalidOperationException("nextHeaderOffset is invalid");
-        }
-
-        _stream.Seek(nextHeaderOffset, SeekOrigin.Current);
-
-        var header = new byte[nextHeaderSize];
-        await _stream.ReadExactAsync(header, 0, header.Length, cancellationToken);
-
-        if (Crc.Finish(Crc.Update(Crc.INIT_CRC, header, 0, header.Length)) != nextHeaderCrc)
-        {
-            throw new InvalidOperationException();
-        }
-
-        using (var streamSwitch = new CStreamSwitch())
-        {
-            streamSwitch.Set(this, header);
-
-            var type = ReadId();
-            if (type != BlockType.Header)
-            {
-                if (type != BlockType.EncodedHeader)
-                {
-                    throw new InvalidOperationException();
-                }
-
-                var dataVector = ReadAndDecodePackedStreams(
-                    db._startPositionAfterHeader,
-                    db.PasswordProvider
-                );
-
-                // compressed header without content is odd but ok
-                if (dataVector.Count == 0)
-                {
-                    db.Fill();
-                    return db;
-                }
-
-                if (dataVector.Count != 1)
-                {
-                    throw new InvalidOperationException();
-                }
-
-                streamSwitch.Set(this, dataVector[0]);
-
-                if (ReadId() != BlockType.Header)
-                {
-                    throw new InvalidOperationException();
-                }
-            }
-
-            ReadHeader(db, db.PasswordProvider);
-        }
-        db.Fill();
-        return db;
-    }
-
     internal class CExtractFolderInfo
     {
         internal int _fileIndex;

src/SharpCompress/Common/Tar/TarFilePart.cs

@@ -1,5 +1,6 @@
 using System.IO;
 using SharpCompress.Common.Tar.Headers;
+using SharpCompress.IO;
 
 namespace SharpCompress.Common.Tar;
 
@@ -20,8 +21,45 @@ internal sealed class TarFilePart : FilePart
 
     internal override Stream GetCompressedStream()
     {
-        if (_seekableStream != null)
+        if (_seekableStream is not null)
         {
+            // If the seekable stream is a SourceStream in file mode with multi-threading enabled,
+            // create an independent stream to support concurrent extraction
+            if (
+                _seekableStream is SourceStream sourceStream
+                && sourceStream.IsFileMode
+                && sourceStream.ReaderOptions.EnableMultiThreadedExtraction
+            )
+            {
+                var independentStream = sourceStream.CreateIndependentStream(0);
+                if (independentStream is not null)
+                {
+                    independentStream.Position = Header.DataStartPosition ?? 0;
+                    return new TarReadOnlySubStream(independentStream, Header.Size);
+                }
+            }
+
+            // Check if the seekable stream wraps a FileStream
+            Stream? underlyingStream = _seekableStream;
+            if (_seekableStream is IStreamStack streamStack)
+            {
+                underlyingStream = streamStack.BaseStream();
+            }
+
+            if (underlyingStream is FileStream fileStream)
+            {
+                // Create a new independent stream from the file
+                var independentStream = new FileStream(
+                    fileStream.Name,
+                    FileMode.Open,
+                    FileAccess.Read,
+                    FileShare.Read
+                );
+                independentStream.Position = Header.DataStartPosition ?? 0;
+                return new TarReadOnlySubStream(independentStream, Header.Size);
+            }
+
+            // Fall back to existing behavior for stream-based sources
             _seekableStream.Position = Header.DataStartPosition ?? 0;
             return new TarReadOnlySubStream(_seekableStream, Header.Size);
         }

src/SharpCompress/Common/Tar/TarReadOnlySubStream.cs

@@ -66,7 +66,7 @@ internal class TarReadOnlySubStream : SharpCompressStream, IStreamStack
         base.Dispose(disposing);
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async System.Threading.Tasks.ValueTask DisposeAsync()
     {
         if (_isDisposed)
@@ -170,7 +170,7 @@ internal class TarReadOnlySubStream : SharpCompressStream, IStreamStack
         return read;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async System.Threading.Tasks.ValueTask<int> ReadAsync(
         System.Memory<byte> buffer,
         System.Threading.CancellationToken cancellationToken = default

src/SharpCompress/Common/Zip/SeekableZipFilePart.cs

@@ -2,13 +2,16 @@ using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
 using SharpCompress.Common.Zip.Headers;
+using SharpCompress.IO;
 
 namespace SharpCompress.Common.Zip;
 
 internal class SeekableZipFilePart : ZipFilePart
 {
-    private bool _isLocalHeaderLoaded;
+    private volatile bool _isLocalHeaderLoaded;
     private readonly SeekableZipHeaderFactory _headerFactory;
+    private readonly object _headerLock = new();
+    private readonly SemaphoreSlim _asyncHeaderSemaphore = new(1, 1);
 
     internal SeekableZipFilePart(
         SeekableZipHeaderFactory headerFactory,
@@ -21,8 +24,14 @@ internal class SeekableZipFilePart : ZipFilePart
     {
         if (!_isLocalHeaderLoaded)
         {
-            LoadLocalHeader();
-            _isLocalHeaderLoaded = true;
+            lock (_headerLock)
+            {
+                if (!_isLocalHeaderLoaded)
+                {
+                    LoadLocalHeader();
+                    _isLocalHeaderLoaded = true;
+                }
+            }
         }
         return base.GetCompressedStream();
     }
@@ -33,22 +42,173 @@ internal class SeekableZipFilePart : ZipFilePart
     {
         if (!_isLocalHeaderLoaded)
         {
-            await LoadLocalHeaderAsync(cancellationToken);
-            _isLocalHeaderLoaded = true;
+            await _asyncHeaderSemaphore.WaitAsync(cancellationToken);
+            try
+            {
+                if (!_isLocalHeaderLoaded)
+                {
+                    await LoadLocalHeaderAsync(cancellationToken);
+                    _isLocalHeaderLoaded = true;
+                }
+            }
+            finally
+            {
+                _asyncHeaderSemaphore.Release();
+            }
         }
         return await base.GetCompressedStreamAsync(cancellationToken);
     }
 
-    private void LoadLocalHeader() =>
-        Header = _headerFactory.GetLocalHeader(BaseStream, (DirectoryEntryHeader)Header);
+    private void LoadLocalHeader()
+    {
+        // Use an independent stream for loading the header if multi-threading is enabled
+        Stream streamToUse = BaseStream;
+        bool disposeStream = false;
 
-    private async ValueTask LoadLocalHeaderAsync(CancellationToken cancellationToken = default) =>
-        Header = await _headerFactory.GetLocalHeaderAsync(BaseStream, (DirectoryEntryHeader)Header);
+        if (
+            BaseStream is SourceStream sourceStream
+            && sourceStream.IsFileMode
+            && sourceStream.ReaderOptions.EnableMultiThreadedExtraction
+        )
+        {
+            var independentStream = sourceStream.CreateIndependentStream(0);
+            if (independentStream is not null)
+            {
+                streamToUse = independentStream;
+                disposeStream = true;
+            }
+        }
+        else
+        {
+            // Check if BaseStream wraps a FileStream
+            Stream? underlyingStream = BaseStream;
+            if (BaseStream is IStreamStack streamStack)
+            {
+                underlyingStream = streamStack.BaseStream();
+            }
+
+            if (underlyingStream is FileStream fileStream)
+            {
+                streamToUse = new FileStream(
+                    fileStream.Name,
+                    FileMode.Open,
+                    FileAccess.Read,
+                    FileShare.Read
+                );
+                disposeStream = true;
+            }
+        }
+
+        try
+        {
+            Header = _headerFactory.GetLocalHeader(streamToUse, (DirectoryEntryHeader)Header);
+        }
+        finally
+        {
+            if (disposeStream)
+            {
+                streamToUse.Dispose();
+            }
+        }
+    }
+
+    private async ValueTask LoadLocalHeaderAsync(CancellationToken cancellationToken = default)
+    {
+        // Use an independent stream for loading the header if multi-threading is enabled
+        Stream streamToUse = BaseStream;
+        bool disposeStream = false;
+
+        if (
+            BaseStream is SourceStream sourceStream
+            && sourceStream.IsFileMode
+            && sourceStream.ReaderOptions.EnableMultiThreadedExtraction
+        )
+        {
+            var independentStream = sourceStream.CreateIndependentStream(0);
+            if (independentStream is not null)
+            {
+                streamToUse = independentStream;
+                disposeStream = true;
+            }
+        }
+        else
+        {
+            // Check if BaseStream wraps a FileStream
+            Stream? underlyingStream = BaseStream;
+            if (BaseStream is IStreamStack streamStack)
+            {
+                underlyingStream = streamStack.BaseStream();
+            }
+
+            if (underlyingStream is FileStream fileStream)
+            {
+                streamToUse = new FileStream(
+                    fileStream.Name,
+                    FileMode.Open,
+                    FileAccess.Read,
+                    FileShare.Read
+                );
+                disposeStream = true;
+            }
+        }
+
+        try
+        {
+            Header = await _headerFactory.GetLocalHeaderAsync(
+                streamToUse,
+                (DirectoryEntryHeader)Header
+            );
+        }
+        finally
+        {
+            if (disposeStream)
+            {
+                streamToUse.Dispose();
+            }
+        }
+    }
 
     protected override Stream CreateBaseStream()
     {
-        BaseStream.Position = Header.DataStartPosition.NotNull();
+        // If BaseStream is a SourceStream in file mode with multi-threading enabled,
+        // create an independent stream to support concurrent extraction
+        if (
+            BaseStream is SourceStream sourceStream
+            && sourceStream.IsFileMode
+            && sourceStream.ReaderOptions.EnableMultiThreadedExtraction
+        )
+        {
+            // Create a new independent stream for this entry
+            var independentStream = sourceStream.CreateIndependentStream(0);
+            if (independentStream is not null)
+            {
+                independentStream.Position = Header.DataStartPosition.NotNull();
+                return independentStream;
+            }
+        }
 
+        // Check if BaseStream wraps a FileStream (for multi-volume archives)
+        Stream? underlyingStream = BaseStream;
+        if (BaseStream is IStreamStack streamStack)
+        {
+            underlyingStream = streamStack.BaseStream();
+        }
+
+        if (underlyingStream is FileStream fileStream)
+        {
+            // Create a new independent stream from the file
+            var independentStream = new FileStream(
+                fileStream.Name,
+                FileMode.Open,
+                FileAccess.Read,
+                FileShare.Read
+            );
+            independentStream.Position = Header.DataStartPosition.NotNull();
+            return independentStream;
+        }
+
+        // Fall back to existing behavior for stream-based sources
+        BaseStream.Position = Header.DataStartPosition.NotNull();
         return BaseStream;
     }
 }

src/SharpCompress/Common/Zip/WinzipAesEncryptionData.cs

@@ -20,7 +20,7 @@ internal class WinzipAesEncryptionData
     {
         _keySize = keySize;
 
-#if NETFRAMEWORK || NETSTANDARD2_0
+#if LEGACY_DOTNET
         var rfc2898 = new Rfc2898DeriveBytes(password, salt, RFC2898_ITERATIONS);
         KeyBytes = rfc2898.GetBytes(KeySizeInBytes);
         IvBytes = rfc2898.GetBytes(KeySizeInBytes);

src/SharpCompress/Compressors/BZip2/BZip2Stream.cs

@@ -98,7 +98,7 @@ public sealed class BZip2Stream : Stream, IStreamStack
 
     public override void SetLength(long value) => stream.SetLength(value);
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
 
     public override int Read(Span<byte> buffer) => stream.Read(buffer);
 
@@ -149,25 +149,4 @@ public sealed class BZip2Stream : Stream, IStreamStack
         }
         return true;
     }
-
-    /// <summary>
-    /// Asynchronously consumes two bytes to test if there is a BZip2 header
-    /// </summary>
-    /// <param name="stream"></param>
-    /// <param name="cancellationToken"></param>
-    /// <returns></returns>
-    public static async ValueTask<bool> IsBZip2Async(
-        Stream stream,
-        CancellationToken cancellationToken = default
-    )
-    {
-        cancellationToken.ThrowIfCancellationRequested();
-        var buffer = new byte[2];
-        var bytesRead = await stream.ReadAsync(buffer, 0, 2, cancellationToken);
-        if (bytesRead < 2 || buffer[0] != 'B' || buffer[1] != 'Z')
-        {
-            return false;
-        }
-        return true;
-    }
 }

src/SharpCompress/Compressors/Deflate/DeflateStream.cs

@@ -299,7 +299,7 @@ public class DeflateStream : Stream, IStreamStack
         await _baseStream.FlushAsync(cancellationToken).ConfigureAwait(false);
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask DisposeAsync()
     {
         if (_disposed)
@@ -370,7 +370,7 @@ public class DeflateStream : Stream, IStreamStack
             .ConfigureAwait(false);
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default
@@ -461,7 +461,7 @@ public class DeflateStream : Stream, IStreamStack
             .ConfigureAwait(false);
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask WriteAsync(
         ReadOnlyMemory<byte> buffer,
         CancellationToken cancellationToken = default

src/SharpCompress/Compressors/Deflate/GZipStream.cs

@@ -345,7 +345,7 @@ public class GZipStream : Stream, IStreamStack
         return n;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default
@@ -454,7 +454,7 @@ public class GZipStream : Stream, IStreamStack
         await BaseStream.WriteAsync(buffer, offset, count, cancellationToken).ConfigureAwait(false);
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask WriteAsync(
         ReadOnlyMemory<byte> buffer,
         CancellationToken cancellationToken = default

src/SharpCompress/Compressors/Deflate/ZlibBaseStream.cs

@@ -552,7 +552,7 @@ internal class ZlibBaseStream : Stream, IStreamStack
         }
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask DisposeAsync()
     {
         if (isDisposed)
@@ -1171,7 +1171,7 @@ internal class ZlibBaseStream : Stream, IStreamStack
         return rc;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default

src/SharpCompress/Compressors/Deflate/ZlibConstants.cs

@@ -108,13 +108,9 @@ internal static class ZlibConstants
     public const int Z_BUF_ERROR = -5;
 
     /// <summary>
-    /// The size of the working buffer used in the ZlibCodec class. Defaults to 8192 bytes.
+    /// The size of the working buffer used in the ZlibCodec class. Defaults to 16384 bytes.
     /// </summary>
-#if NETCF
-    public const int WorkingBufferSizeDefault = 8192;
-#else
     public const int WorkingBufferSizeDefault = 16384;
-#endif
 
     /// <summary>
     /// The minimum size of the working buffer used in the ZlibCodec class.  Currently it is 128 bytes.

src/SharpCompress/Compressors/Deflate/ZlibStream.cs

@@ -277,7 +277,7 @@ public class ZlibStream : Stream, IStreamStack
         await _baseStream.FlushAsync(cancellationToken).ConfigureAwait(false);
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask DisposeAsync()
     {
         if (_disposed)
@@ -347,7 +347,7 @@ public class ZlibStream : Stream, IStreamStack
             .ConfigureAwait(false);
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default
@@ -431,7 +431,7 @@ public class ZlibStream : Stream, IStreamStack
             .ConfigureAwait(false);
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask WriteAsync(
         ReadOnlyMemory<byte> buffer,
         CancellationToken cancellationToken = default

src/SharpCompress/Compressors/Deflate64/Deflate64Stream.cs

@@ -200,7 +200,7 @@ public sealed class Deflate64Stream : Stream, IStreamStack
         return count - remainingCount;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default

src/SharpCompress/Compressors/LZMA/LZipStream.cs

@@ -163,7 +163,7 @@ public sealed class LZipStream : Stream, IStreamStack
 
     public override void SetLength(long value) => throw new NotImplementedException();
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
 
     public override ValueTask<int> ReadAsync(
         Memory<byte> buffer,
@@ -222,19 +222,6 @@ public sealed class LZipStream : Stream, IStreamStack
     /// <returns><c>true</c> if the given stream is an LZip file, <c>false</c> otherwise.</returns>
     public static bool IsLZipFile(Stream stream) => ValidateAndReadSize(stream) != 0;
 
-    /// <summary>
-    /// Asynchronously determines if the given stream is positioned at the start of a v1 LZip
-    /// file, as indicated by the ASCII characters "LZIP" and a version byte
-    /// of 1, followed by at least one byte.
-    /// </summary>
-    /// <param name="stream">The stream to read from. Must not be null.</param>
-    /// <param name="cancellationToken">Cancellation token.</param>
-    /// <returns><c>true</c> if the given stream is an LZip file, <c>false</c> otherwise.</returns>
-    public static async ValueTask<bool> IsLZipFileAsync(
-        Stream stream,
-        CancellationToken cancellationToken = default
-    ) => await ValidateAndReadSizeAsync(stream, cancellationToken) != 0;
-
     /// <summary>
     /// Reads the 6-byte header of the stream, and returns 0 if either the header
     /// couldn't be read or it isn't a validate LZIP header, or the dictionary
@@ -268,44 +255,6 @@ public sealed class LZipStream : Stream, IStreamStack
         return (1 << basePower) - (subtractionNumerator * (1 << (basePower - 4)));
     }
 
-    /// <summary>
-    /// Asynchronously reads the 6-byte header of the stream, and returns 0 if either the header
-    /// couldn't be read or it isn't a validate LZIP header, or the dictionary
-    /// size if it *is* a valid LZIP file.
-    /// </summary>
-    public static async ValueTask<int> ValidateAndReadSizeAsync(
-        Stream stream,
-        CancellationToken cancellationToken
-    )
-    {
-        // Read the header
-        byte[] header = new byte[6];
-        var n = await stream
-            .ReadAsync(header, 0, header.Length, cancellationToken)
-            .ConfigureAwait(false);
-
-        // TODO: Handle reading only part of the header?
-
-        if (n != 6)
-        {
-            return 0;
-        }
-
-        if (
-            header[0] != 'L'
-            || header[1] != 'Z'
-            || header[2] != 'I'
-            || header[3] != 'P'
-            || header[4] != 1 /* version 1 */
-        )
-        {
-            return 0;
-        }
-        var basePower = header[5] & 0x1F;
-        var subtractionNumerator = (header[5] & 0xE0) >> 5;
-        return (1 << basePower) - (subtractionNumerator * (1 << (basePower - 4)));
-    }
-
     private static readonly byte[] headerBytes =
     [
         (byte)'L',

src/SharpCompress/Compressors/LZMA/LzmaDecoder.cs

@@ -201,7 +201,7 @@ public class Decoder : ICoder, ISetDecoderProperties // ,System.IO.Stream
         }
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     [MemberNotNull(nameof(_outWindow))]
 #endif
     private void CreateDictionary()

src/SharpCompress/Compressors/LZMA/LzmaStream.cs

@@ -632,7 +632,7 @@ public class LzmaStream : Stream, IStreamStack
         return total;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default

src/SharpCompress/Compressors/Lzw/LzwStream.cs

@@ -1,7 +1,5 @@
 using System;
 using System.IO;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Common;
 using SharpCompress.IO;
 
@@ -97,45 +95,6 @@ namespace SharpCompress.Compressors.Lzw
             return true;
         }
 
-        /// <summary>
-        /// Asynchronously checks if the stream is an LZW stream
-        /// </summary>
-        /// <param name="stream">The stream to read from</param>
-        /// <param name="cancellationToken">Cancellation token</param>
-        /// <returns>True if the stream is an LZW stream, false otherwise</returns>
-        public static async ValueTask<bool> IsLzwStreamAsync(
-            Stream stream,
-            CancellationToken cancellationToken = default
-        )
-        {
-            try
-            {
-                byte[] hdr = new byte[LzwConstants.HDR_SIZE];
-
-                int result = await stream.ReadAsync(hdr, 0, hdr.Length, cancellationToken);
-
-                // Check the magic marker
-                if (result < 0)
-                    throw new IncompleteArchiveException("Failed to read LZW header");
-
-                if (hdr[0] != (LzwConstants.MAGIC >> 8) || hdr[1] != (LzwConstants.MAGIC & 0xff))
-                {
-                    throw new IncompleteArchiveException(
-                        String.Format(
-                            "Wrong LZW header. Magic bytes don't match. 0x{0:x2} 0x{1:x2}",
-                            hdr[0],
-                            hdr[1]
-                        )
-                    );
-                }
-            }
-            catch (Exception)
-            {
-                return false;
-            }
-            return true;
-        }
-
         /// <summary>
         /// Gets or sets a flag indicating ownership of underlying stream.
         /// When the flag is true <see cref="Stream.Dispose()" /> will close the underlying stream also.

src/SharpCompress/Compressors/Rar/MultiVolumeReadOnlyStream.cs

@@ -185,7 +185,7 @@ internal sealed class MultiVolumeReadOnlyStream : Stream, IStreamStack
         return totalRead;
     }
 
-#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+#if !LEGACY_DOTNET
     public override async System.Threading.Tasks.ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         System.Threading.CancellationToken cancellationToken = default

src/SharpCompress/Compressors/Rar/RarBLAKE2spStream.cs

@@ -385,7 +385,7 @@ internal class RarBLAKE2spStream : RarStream, IStreamStack
         return result;
     }
 
-#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+#if !LEGACY_DOTNET
     public override async System.Threading.Tasks.ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         System.Threading.CancellationToken cancellationToken = default

src/SharpCompress/Compressors/Rar/RarCrcStream.cs

@@ -129,7 +129,7 @@ internal class RarCrcStream : RarStream, IStreamStack
         return result;
     }
 
-#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+#if !LEGACY_DOTNET
     public override async System.Threading.Tasks.ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         System.Threading.CancellationToken cancellationToken = default

src/SharpCompress/Compressors/Rar/RarStream.cs

@@ -189,7 +189,7 @@ internal class RarStream : Stream, IStreamStack
         return outTotal;
     }
 
-#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+#if !LEGACY_DOTNET
     public override async System.Threading.Tasks.ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         System.Threading.CancellationToken cancellationToken = default

src/SharpCompress/Compressors/Xz/XZStream.cs

@@ -60,22 +60,6 @@ public sealed class XZStream : XZReadOnlyStream, IStreamStack
         }
     }
 
-    public static async ValueTask<bool> IsXZStreamAsync(
-        Stream stream,
-        CancellationToken cancellationToken = default
-    )
-    {
-        cancellationToken.ThrowIfCancellationRequested();
-        try
-        {
-            return null != await XZHeader.FromStreamAsync(stream, cancellationToken);
-        }
-        catch (Exception)
-        {
-            return false;
-        }
-    }
-
     private void AssertBlockCheckTypeIsSupported()
     {
         switch (Header.BlockCheckType)

src/SharpCompress/Compressors/ZStandard/CompressionStream.cs

@@ -74,7 +74,7 @@ public class CompressionStream : Stream
 
     ~CompressionStream() => Dispose(false);
 
-#if !NETSTANDARD2_0 && !NETFRAMEWORK
+#if !LEGACY_DOTNET
     public override async ValueTask DisposeAsync()
 #else
     public async ValueTask DisposeAsync()
@@ -145,7 +145,7 @@ public class CompressionStream : Stream
     public override void Write(byte[] buffer, int offset, int count) =>
         Write(new ReadOnlySpan<byte>(buffer, offset, count));
 
-#if !NETSTANDARD2_0 && !NETFRAMEWORK
+#if !LEGACY_DOTNET
     public override void Write(ReadOnlySpan<byte> buffer) =>
         WriteInternal(buffer, ZSTD_EndDirective.ZSTD_e_continue);
 #else
@@ -176,7 +176,7 @@ public class CompressionStream : Stream
         );
     }
 
-#if !NETSTANDARD2_0 && !NETFRAMEWORK
+#if !LEGACY_DOTNET
     private async ValueTask WriteInternalAsync(
         ReadOnlyMemory<byte>? buffer,
         ZSTD_EndDirective directive,
@@ -218,7 +218,7 @@ public class CompressionStream : Stream
         );
     }
 
-#if !NETSTANDARD2_0 && !NETFRAMEWORK
+#if !LEGACY_DOTNET
 
     public override Task WriteAsync(
         byte[] buffer,

src/SharpCompress/Compressors/ZStandard/DecompressionStream.cs

@@ -105,7 +105,7 @@ public class DecompressionStream : Stream
     public override int Read(byte[] buffer, int offset, int count) =>
         Read(new Span<byte>(buffer, offset, count));
 
-#if !NETSTANDARD2_0 && !NETFRAMEWORK
+#if !LEGACY_DOTNET
     public override int Read(Span<byte> buffer)
 #else
     public int Read(Span<byte> buffer)
@@ -158,7 +158,7 @@ public class DecompressionStream : Stream
         }
     }
 
-#if !NETSTANDARD2_0 && !NETFRAMEWORK
+#if !LEGACY_DOTNET
     public override Task<int> ReadAsync(
         byte[] buffer,
         int offset,
@@ -276,7 +276,7 @@ public class DecompressionStream : Stream
             throw new ObjectDisposedException(nameof(DecompressionStream));
     }
 
-#if NETSTANDARD2_0 || NETFRAMEWORK
+#if LEGACY_DOTNET
     public virtual Task DisposeAsync()
     {
         try

src/SharpCompress/Compressors/ZStandard/UnsafeHelper.cs

@@ -16,7 +16,7 @@ public static unsafe class UnsafeHelper
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static void* malloc(ulong size)
     {
-#if NET6_0_OR_GREATER
+#if NET8_0_OR_GREATER
         var ptr = NativeMemory.Alloc((nuint)size);
 #else
         var ptr = (void*)Marshal.AllocHGlobal((nint)size);
@@ -31,7 +31,7 @@ public static unsafe class UnsafeHelper
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static void* calloc(ulong num, ulong size)
     {
-#if NET6_0_OR_GREATER
+#if NET8_0_OR_GREATER
         return NativeMemory.AllocZeroed((nuint)num, (nuint)size);
 #else
         var total = num * size;
@@ -53,7 +53,7 @@ public static unsafe class UnsafeHelper
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static void free(void* ptr)
     {
-#if NET6_0_OR_GREATER
+#if NET8_0_OR_GREATER
         NativeMemory.Free(ptr);
 #else
         Marshal.FreeHGlobal((IntPtr)ptr);

src/SharpCompress/Compressors/ZStandard/ZStandardStream.cs

@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Text;
-using System.Threading;
 using System.Threading.Tasks;
 using SharpCompress.IO;
 
@@ -44,27 +43,6 @@ internal class ZStandardStream : DecompressionStream, IStreamStack
         return true;
     }
 
-    internal static async ValueTask<bool> IsZStandardAsync(
-        Stream stream,
-        CancellationToken cancellationToken = default
-    )
-    {
-        cancellationToken.ThrowIfCancellationRequested();
-        var buffer = new byte[4];
-        var bytesRead = await stream.ReadAsync(buffer, 0, 4, cancellationToken);
-        if (bytesRead < 4)
-        {
-            return false;
-        }
-
-        var magic = BitConverter.ToUInt32(buffer, 0);
-        if (ZstandardConstants.MAGIC != magic)
-        {
-            return false;
-        }
-        return true;
-    }
-
     public ZStandardStream(Stream baseInputStream)
         : base(baseInputStream)
     {

src/SharpCompress/Crypto/Crc32Stream.cs

@@ -70,7 +70,7 @@ public sealed class Crc32Stream : Stream, IStreamStack
 
     public override void SetLength(long value) => throw new NotSupportedException();
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
 
     public override void Write(ReadOnlySpan<byte> buffer)
     {

src/SharpCompress/Factories/AceFactory.cs

@@ -29,13 +29,6 @@ namespace SharpCompress.Factories
             int bufferSize = ReaderOptions.DefaultBufferSize
         ) => AceHeader.IsArchive(stream);
 
-        public override ValueTask<bool> IsArchiveAsync(
-            Stream stream,
-            string? password = null,
-            int bufferSize = ReaderOptions.DefaultBufferSize,
-            CancellationToken cancellationToken = default
-        ) => AceHeader.IsArchiveAsync(stream, cancellationToken);
-
         public IReader OpenReader(Stream stream, ReaderOptions? options) =>
             AceReader.OpenReader(stream, options);
 
@@ -48,5 +41,11 @@ namespace SharpCompress.Factories
             cancellationToken.ThrowIfCancellationRequested();
             return (IAsyncReader)AceReader.OpenReader(stream, options);
         }
+
+        public override ValueTask<bool> IsArchiveAsync(
+            Stream stream,
+            string? password = null,
+            int bufferSize = ReaderOptions.DefaultBufferSize
+        ) => new(IsArchive(stream, password, bufferSize));
     }
 }

src/SharpCompress/Factories/ArcFactory.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Buffers;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -37,16 +36,9 @@ namespace SharpCompress.Factories
             //Hyper - archive, check the next two bytes for "HP" or "ST"(or look below for
             //"HYP").Also the ZOO archiver also does put a 01Ah at the start of the file,
             //see the ZOO entry below.
-            var buffer = ArrayPool<byte>.Shared.Rent(2);
-            try
-            {
-                stream.ReadExact(buffer, 0, 2);
-                return buffer[0] == 0x1A && buffer[1] < 10; //rather thin, but this is all we have
-            }
-            finally
-            {
-                ArrayPool<byte>.Shared.Return(buffer);
-            }
+            var bytes = new byte[2];
+            stream.Read(bytes, 0, 2);
+            return bytes[0] == 0x1A && bytes[1] < 10; //rather thin, but this is all we have
         }
 
         public IReader OpenReader(Stream stream, ReaderOptions? options) =>
@@ -62,29 +54,10 @@ namespace SharpCompress.Factories
             return (IAsyncReader)ArcReader.OpenReader(stream, options);
         }
 
-        public override async ValueTask<bool> IsArchiveAsync(
+        public override ValueTask<bool> IsArchiveAsync(
             Stream stream,
             string? password = null,
-            int bufferSize = ReaderOptions.DefaultBufferSize,
-            CancellationToken cancellationToken = default
-        )
-        {
-            //You may have to use some(paranoid) checks to ensure that you actually are
-            //processing an ARC file, since other archivers also adopted the idea of putting
-            //a 01Ah byte at offset 0, namely the Hyper archiver. To check if you have a
-            //Hyper - archive, check the next two bytes for "HP" or "ST"(or look below for
-            //"HYP").Also the ZOO archiver also does put a 01Ah at the start of the file,
-            //see the ZOO entry below.
-            var buffer = ArrayPool<byte>.Shared.Rent(2);
-            try
-            {
-                await stream.ReadExactAsync(buffer, 0, 2, cancellationToken);
-                return buffer[0] == 0x1A && buffer[1] < 10; //rather thin, but this is all we have
-            }
-            finally
-            {
-                ArrayPool<byte>.Shared.Return(buffer);
-            }
-        }
+            int bufferSize = ReaderOptions.DefaultBufferSize
+        ) => new(IsArchive(stream, password, bufferSize));
     }
 }

src/SharpCompress/Factories/ArjFactory.cs

@@ -27,14 +27,10 @@ namespace SharpCompress.Factories
             Stream stream,
             string? password = null,
             int bufferSize = ReaderOptions.DefaultBufferSize
-        ) => ArjHeader.IsArchive(stream);
-
-        public override ValueTask<bool> IsArchiveAsync(
-            Stream stream,
-            string? password = null,
-            int bufferSize = ReaderOptions.DefaultBufferSize,
-            CancellationToken cancellationToken = default
-        ) => ArjHeader.IsArchiveAsync(stream, cancellationToken);
+        )
+        {
+            return ArjHeader.IsArchive(stream);
+        }
 
         public IReader OpenReader(Stream stream, ReaderOptions? options) =>
             ArjReader.OpenReader(stream, options);
@@ -48,5 +44,11 @@ namespace SharpCompress.Factories
             cancellationToken.ThrowIfCancellationRequested();
             return (IAsyncReader)ArjReader.OpenReader(stream, options);
         }
+
+        public override ValueTask<bool> IsArchiveAsync(
+            Stream stream,
+            string? password = null,
+            int bufferSize = ReaderOptions.DefaultBufferSize
+        ) => new(IsArchive(stream, password, bufferSize));
     }
 }

src/SharpCompress/Factories/Factory.cs

@@ -60,11 +60,22 @@ public abstract class Factory : IFactory
     );
 
     public abstract ValueTask<bool> IsArchiveAsync(
+        Stream stream,
+        string? password = null,
+        int bufferSize = ReaderOptions.DefaultBufferSize
+    );
+
+    /// <inheritdoc/>
+    public virtual ValueTask<bool> IsArchiveAsync(
         Stream stream,
         string? password = null,
         int bufferSize = ReaderOptions.DefaultBufferSize,
         CancellationToken cancellationToken = default
-    );
+    )
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+        return new(IsArchive(stream, password, bufferSize));
+    }
 
     /// <inheritdoc/>
     public virtual FileInfo? GetFilePart(int index, FileInfo part1) => null;
@@ -101,4 +112,31 @@ public abstract class Factory : IFactory
 
         return false;
     }
+
+    internal virtual async ValueTask<(bool, IAsyncReader?)> TryOpenReaderAsync(
+        SharpCompressStream stream,
+        ReaderOptions options,
+        CancellationToken cancellationToken
+    )
+    {
+        if (this is IReaderFactory readerFactory)
+        {
+            long pos = ((IStreamStack)stream).GetPosition();
+
+            if (
+                await IsArchiveAsync(
+                    stream,
+                    options.Password,
+                    options.BufferSize,
+                    cancellationToken
+                )
+            )
+            {
+                ((IStreamStack)stream).StackSeek(pos);
+                return (true, readerFactory.OpenAsyncReader(stream, options, cancellationToken));
+            }
+        }
+
+        return (false, null);
+    }
 }

src/SharpCompress/Factories/GZipFactory.cs

@@ -68,9 +68,22 @@ public class GZipFactory
     public IAsyncArchive OpenAsyncArchive(Stream stream, ReaderOptions? readerOptions = null) =>
         (IAsyncArchive)OpenArchive(stream, readerOptions);
 
+    public override ValueTask<bool> IsArchiveAsync(
+        Stream stream,
+        string? password = null,
+        int bufferSize = ReaderOptions.DefaultBufferSize
+    ) => new(IsArchive(stream, password, bufferSize));
+
     /// <inheritdoc/>
-    public IAsyncArchive OpenAsyncArchive(FileInfo fileInfo, ReaderOptions? readerOptions = null) =>
-        (IAsyncArchive)OpenArchive(fileInfo, readerOptions);
+    public IAsyncArchive OpenAsyncArchive(
+        FileInfo fileInfo,
+        ReaderOptions? readerOptions = null,
+        CancellationToken cancellationToken = default
+    )
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+        return (IAsyncArchive)OpenArchive(fileInfo, readerOptions);
+    }
 
     #endregion
 

src/SharpCompress/Factories/RarFactory.cs

@@ -37,14 +37,6 @@ public class RarFactory : Factory, IArchiveFactory, IMultiArchiveFactory, IReade
         int bufferSize = ReaderOptions.DefaultBufferSize
     ) => RarArchive.IsRarFile(stream);
 
-    /// <inheritdoc/>
-    public override ValueTask<bool> IsArchiveAsync(
-        Stream stream,
-        string? password = null,
-        int bufferSize = ReaderOptions.DefaultBufferSize,
-        CancellationToken cancellationToken = default
-    ) => RarArchive.IsRarFileAsync(stream, cancellationToken: cancellationToken);
-
     /// <inheritdoc/>
     public override FileInfo? GetFilePart(int index, FileInfo part1) =>
         RarArchiveVolumeFactory.GetFilePart(index, part1);
@@ -66,8 +58,21 @@ public class RarFactory : Factory, IArchiveFactory, IMultiArchiveFactory, IReade
         RarArchive.OpenArchive(fileInfo, readerOptions);
 
     /// <inheritdoc/>
-    public IAsyncArchive OpenAsyncArchive(FileInfo fileInfo, ReaderOptions? readerOptions = null) =>
-        (IAsyncArchive)OpenArchive(fileInfo, readerOptions);
+    public IAsyncArchive OpenAsyncArchive(
+        FileInfo fileInfo,
+        ReaderOptions? readerOptions = null,
+        CancellationToken cancellationToken = default
+    )
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+        return (IAsyncArchive)OpenArchive(fileInfo, readerOptions);
+    }
+
+    public override ValueTask<bool> IsArchiveAsync(
+        Stream stream,
+        string? password = null,
+        int bufferSize = ReaderOptions.DefaultBufferSize
+    ) => new(IsArchive(stream, password, bufferSize));
 
     #endregion
 

src/SharpCompress/Factories/SevenZipFactory.cs

@@ -36,14 +36,6 @@ public class SevenZipFactory : Factory, IArchiveFactory, IMultiArchiveFactory
         int bufferSize = ReaderOptions.DefaultBufferSize
     ) => SevenZipArchive.IsSevenZipFile(stream);
 
-    /// <inheritdoc/>
-    public override ValueTask<bool> IsArchiveAsync(
-        Stream stream,
-        string? password = null,
-        int bufferSize = ReaderOptions.DefaultBufferSize,
-        CancellationToken cancellationToken = default
-    ) => SevenZipArchive.IsSevenZipFileAsync(stream, cancellationToken);
-
     #endregion
 
     #region IArchiveFactory
@@ -54,15 +46,28 @@ public class SevenZipFactory : Factory, IArchiveFactory, IMultiArchiveFactory
 
     /// <inheritdoc/>
     public IAsyncArchive OpenAsyncArchive(Stream stream, ReaderOptions? readerOptions = null) =>
-        SevenZipArchive.OpenAsyncArchive(stream, readerOptions);
+        (IAsyncArchive)OpenArchive(stream, readerOptions);
 
     /// <inheritdoc/>
     public IArchive OpenArchive(FileInfo fileInfo, ReaderOptions? readerOptions = null) =>
         SevenZipArchive.OpenArchive(fileInfo, readerOptions);
 
     /// <inheritdoc/>
-    public IAsyncArchive OpenAsyncArchive(FileInfo fileInfo, ReaderOptions? readerOptions = null) =>
-        SevenZipArchive.OpenAsyncArchive(fileInfo, readerOptions);
+    public IAsyncArchive OpenAsyncArchive(
+        FileInfo fileInfo,
+        ReaderOptions? readerOptions = null,
+        CancellationToken cancellationToken = default
+    )
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+        return (IAsyncArchive)OpenArchive(fileInfo, readerOptions);
+    }
+
+    public override ValueTask<bool> IsArchiveAsync(
+        Stream stream,
+        string? password = null,
+        int bufferSize = ReaderOptions.DefaultBufferSize
+    ) => new(IsArchive(stream, password, bufferSize));
 
     #endregion
 

src/SharpCompress/Factories/TarFactory.cs

@@ -61,13 +61,11 @@ public class TarFactory
         int bufferSize = ReaderOptions.DefaultBufferSize
     ) => TarArchive.IsTarFile(stream);
 
-    /// <inheritdoc/>
     public override ValueTask<bool> IsArchiveAsync(
         Stream stream,
         string? password = null,
-        int bufferSize = ReaderOptions.DefaultBufferSize,
-        CancellationToken cancellationToken = default
-    ) => TarArchive.IsTarFileAsync(stream, cancellationToken);
+        int bufferSize = ReaderOptions.DefaultBufferSize
+    ) => new(IsArchive(stream, password, bufferSize));
 
     #endregion
 
@@ -86,8 +84,15 @@ public class TarFactory
         TarArchive.OpenArchive(fileInfo, readerOptions);
 
     /// <inheritdoc/>
-    public IAsyncArchive OpenAsyncArchive(FileInfo fileInfo, ReaderOptions? readerOptions = null) =>
-        (IAsyncArchive)OpenArchive(fileInfo, readerOptions);
+    public IAsyncArchive OpenAsyncArchive(
+        FileInfo fileInfo,
+        ReaderOptions? readerOptions = null,
+        CancellationToken cancellationToken = default
+    )
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+        return (IAsyncArchive)OpenArchive(fileInfo, readerOptions);
+    }
 
     #endregion
 

src/SharpCompress/Factories/ZStandardFactory.cs

@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Text;
-using System.Threading;
 using System.Threading.Tasks;
 using SharpCompress.Archives;
 using SharpCompress.Compressors.ZStandard;
@@ -30,7 +29,6 @@ internal class ZStandardFactory : Factory
     public override ValueTask<bool> IsArchiveAsync(
         Stream stream,
         string? password = null,
-        int bufferSize = ReaderOptions.DefaultBufferSize,
-        CancellationToken cancellationToken = default
-    ) => ZStandardStream.IsZStandardAsync(stream, cancellationToken);
+        int bufferSize = ReaderOptions.DefaultBufferSize
+    ) => new(IsArchive(stream, password, bufferSize));
 }

src/SharpCompress/Factories/ZipFactory.cs

@@ -81,6 +81,12 @@ public class ZipFactory
         return false;
     }
 
+    public override ValueTask<bool> IsArchiveAsync(
+        Stream stream,
+        string? password = null,
+        int bufferSize = ReaderOptions.DefaultBufferSize
+    ) => new(IsArchive(stream, password, bufferSize));
+
     /// <inheritdoc/>
     public override async ValueTask<bool> IsArchiveAsync(
         Stream stream,
@@ -145,8 +151,15 @@ public class ZipFactory
         ZipArchive.OpenArchive(fileInfo, readerOptions);
 
     /// <inheritdoc/>
-    public IAsyncArchive OpenAsyncArchive(FileInfo fileInfo, ReaderOptions? readerOptions = null) =>
-        (IAsyncArchive)OpenArchive(fileInfo, readerOptions);
+    public IAsyncArchive OpenAsyncArchive(
+        FileInfo fileInfo,
+        ReaderOptions? readerOptions = null,
+        CancellationToken cancellationToken = default
+    )
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+        return (IAsyncArchive)OpenArchive(fileInfo, readerOptions);
+    }
 
     #endregion
 

src/SharpCompress/IO/BufferedSubStream.cs

@@ -154,7 +154,7 @@ internal class BufferedSubStream : SharpCompressStream, IStreamStack
         return count;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default

src/SharpCompress/IO/ProgressReportingStream.cs

@@ -64,7 +64,7 @@ internal sealed class ProgressReportingStream : Stream
         return bytesRead;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override int Read(Span<byte> buffer)
     {
         var bytesRead = _baseStream.Read(buffer);
@@ -95,7 +95,7 @@ internal sealed class ProgressReportingStream : Stream
         return bytesRead;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default
@@ -147,7 +147,7 @@ internal sealed class ProgressReportingStream : Stream
         base.Dispose(disposing);
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask DisposeAsync()
     {
         if (!_leaveOpen)

src/SharpCompress/IO/ReadOnlySubStream.cs

@@ -81,7 +81,7 @@ internal class ReadOnlySubStream : SharpCompressStream, IStreamStack
         return value;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override int Read(Span<byte> buffer)
     {
         var sliceLen = BytesLeftToRead < buffer.Length ? BytesLeftToRead : buffer.Length;
@@ -117,7 +117,7 @@ internal class ReadOnlySubStream : SharpCompressStream, IStreamStack
         return read;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,
         CancellationToken cancellationToken = default

src/SharpCompress/IO/SharpCompressStream.cs

@@ -384,7 +384,7 @@ public class SharpCompressStream : Stream, IStreamStack
         await Stream.FlushAsync(cancellationToken).ConfigureAwait(false);
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
 
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,

src/SharpCompress/IO/SourceStream.cs

@@ -98,6 +98,30 @@ public class SourceStream : Stream, IStreamStack
 
     private Stream Current => _streams[_stream];
 
+    /// <summary>
+    /// Creates an independent stream for the specified volume index.
+    /// This allows multiple threads to read from different positions concurrently.
+    /// Only works when IsFileMode is true.
+    /// </summary>
+    /// <param name="volumeIndex">The volume index to create a stream for</param>
+    /// <returns>A new independent FileStream, or null if not in file mode or volume doesn't exist</returns>
+    public Stream? CreateIndependentStream(int volumeIndex)
+    {
+        if (!IsFileMode)
+        {
+            return null;
+        }
+
+        // Ensure the volume is loaded
+        if (!LoadStream(volumeIndex))
+        {
+            return null;
+        }
+
+        // Create a new independent stream from the FileInfo
+        return _files[volumeIndex].OpenRead();
+    }
+
     public bool LoadStream(int index) //ensure all parts to id are loaded
     {
         while (_streams.Count <= index)
@@ -289,7 +313,7 @@ public class SourceStream : Stream, IStreamStack
         return total - count;
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !LEGACY_DOTNET
 
     public override async ValueTask<int> ReadAsync(
         Memory<byte> buffer,

src/SharpCompress/NotNullExtensions.cs

@@ -21,7 +21,7 @@ internal static class NotNullExtensions
         return source.AsEnumerable();
     }
 
-#if NETFRAMEWORK || NETSTANDARD
+#if LEGACY_DOTNET
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static T NotNull<T>(this T? obj, string? message = null)
         where T : class

src/SharpCompress/Polyfills/StringExtensions.cs

@@ -1,4 +1,4 @@
-#if NETFRAMEWORK || NETSTANDARD2_0
+#if LEGACY_DOTNET
 
 namespace SharpCompress;
 

src/SharpCompress/Readers/AbstractReader.cs

@@ -277,7 +277,7 @@ public abstract class AbstractReader<TEntry, TVolume> : IReader, IAsyncReader
             }
         }
         //don't know the size so we have to try to decompress to skip
-#if NETFRAMEWORK || NETSTANDARD2_0
+#if LEGACY_DOTNET
         using var s = await OpenEntryStreamAsync(cancellationToken).ConfigureAwait(false);
         await s.SkipEntryAsync(cancellationToken).ConfigureAwait(false);
 #else
@@ -344,7 +344,7 @@ public abstract class AbstractReader<TEntry, TVolume> : IReader, IAsyncReader
 
     internal async ValueTask WriteAsync(Stream writeStream, CancellationToken cancellationToken)
     {
-#if NETFRAMEWORK || NETSTANDARD2_0
+#if LEGACY_DOTNET
         using Stream s = await OpenEntryStreamAsync(cancellationToken).ConfigureAwait(false);
         var sourceStream = WrapWithProgress(s, Entry);
         await sourceStream.CopyToAsync(writeStream, 81920, cancellationToken).ConfigureAwait(false);

src/SharpCompress/Readers/ReaderOptions.cs

@@ -28,4 +28,12 @@ public class ReaderOptions : OptionsBase
     /// When set, progress updates will be reported as entries are extracted.
     /// </summary>
     public IProgress<ProgressReport>? Progress { get; set; }
+
+    /// <summary>
+    /// Enable multi-threaded extraction support when the archive is opened from a FileInfo or file path.
+    /// When enabled, multiple threads can extract different entries concurrently by creating
+    /// independent file streams. This is only effective for archives opened from files, not streams.
+    /// Default is false for backward compatibility.
+    /// </summary>
+    public bool EnableMultiThreadedExtraction { get; set; }
 }

src/SharpCompress/SharpCompress.csproj

@@ -28,6 +28,9 @@
     <EmbedUntrackedSources>true</EmbedUntrackedSources>
     <AllowedOutputExtensionsInPackageBuildOutputFolder>$(AllowedOutputExtensionsInPackageBuildOutputFolder);.pdb</AllowedOutputExtensionsInPackageBuildOutputFolder>
   </PropertyGroup>
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'net48' Or '$(TargetFramework)' == 'netstandard20' ">
+    <DefineConstants>$(DefineConstants);LEGACY_DOTNET</DefineConstants>
+  </PropertyGroup>
   <PropertyGroup Condition=" '$(TargetFramework)' == 'net8.0' Or '$(TargetFramework)' == 'net10.0' ">
     <IsTrimmable>true</IsTrimmable>
   </PropertyGroup>

src/SharpCompress/Utility.cs

@@ -189,7 +189,7 @@ internal static class Utility
             }
         }
 
-#if NET60_OR_GREATER
+#if NET8_0_OR_GREATER
         public bool ReadFully(byte[] buffer)
         {
             try

tests/SharpCompress.Test/ArchiveTests.cs

@@ -651,4 +651,40 @@ public class ArchiveTests : ReaderTests
             VerifyFiles();
         }
     }
+
+    [Fact]
+    public async Task ArchiveFactory_Open_WithPreWrappedStream()
+    {
+        // Test that ArchiveFactory.Open works correctly with a stream that's already wrapped
+        // This addresses the issue where ZIP files fail to open on Linux
+        var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "Zip.bzip2.noEmptyDirs.zip");
+
+        // Open with a pre-wrapped stream
+        using (var fileStream = File.OpenRead(testArchive))
+        using (var wrappedStream = SharpCompressStream.Create(fileStream, bufferSize: 32768))
+        await using (
+            var archive = await ArchiveFactory.OpenAsyncArchive(new AsyncOnlyStream(wrappedStream))
+        )
+        {
+            Assert.Equal(ArchiveType.Zip, archive.Type);
+            Assert.Equal(3, await archive.EntriesAsync.CountAsync());
+        }
+    }
+
+    [Fact]
+    public async Task ArchiveFactory_Open_WithRawFileStream()
+    {
+        // Test that ArchiveFactory.Open works correctly with a raw FileStream
+        // This is the common use case reported in the issue
+        var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "Zip.bzip2.noEmptyDirs.zip");
+
+        using (var stream = File.OpenRead(testArchive))
+        await using (
+            var archive = await ArchiveFactory.OpenAsyncArchive(new AsyncOnlyStream(stream))
+        )
+        {
+            Assert.Equal(ArchiveType.Zip, archive.Type);
+            Assert.Equal(3, await archive.EntriesAsync.CountAsync());
+        }
+    }
 }

tests/SharpCompress.Test/Mocks/AsyncOnlyStream.cs

@@ -2,16 +2,14 @@ using System;
 using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
-using SharpCompress.IO;
 
 namespace SharpCompress.Test.Mocks;
 
-public class AsyncOnlyStream : SharpCompressStream
+public class AsyncOnlyStream : Stream
 {
     private readonly Stream _stream;
 
     public AsyncOnlyStream(Stream stream)
-        : base(stream)
     {
         _stream = stream;
         // Console.WriteLine("AsyncOnlyStream created");

tests/SharpCompress.Test/SevenZip/SevenZipArchiveAsyncTests.cs

@@ -3,22 +3,20 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using SharpCompress.Archives;
+using SharpCompress.Common;
 using SharpCompress.Test.Mocks;
 using Xunit;
 
 namespace SharpCompress.Test.SevenZip;
 
+#if !NETFRAMEWORK
 public class SevenZipArchiveAsyncTests : ArchiveTests
 {
     [Fact]
-    public async Task SevenZipArchive_LZMA_AsyncStreamExtraction()
+    public async ValueTask SevenZipArchive_LZMA_AsyncStreamExtraction()
     {
         var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "7Zip.LZMA.7z");
-#if NETFRAMEWORK
         using var stream = File.OpenRead(testArchive);
-#else
-        await using var stream = File.OpenRead(testArchive);
-#endif
         await using var archive = await ArchiveFactory.OpenAsyncArchive(
             new AsyncOnlyStream(stream)
         );
@@ -33,35 +31,19 @@ public class SevenZipArchiveAsyncTests : ArchiveTests
                 Directory.CreateDirectory(targetDir);
             }
 
-#if NETFRAMEWORK
             using var sourceStream = await entry.OpenEntryStreamAsync(CancellationToken.None);
-#else
-            await using var sourceStream = await entry.OpenEntryStreamAsync(CancellationToken.None);
-#endif
-#if NETFRAMEWORK
-            using var targetStream = File.Create(targetPath);
-#else
             await using var targetStream = File.Create(targetPath);
-#endif
-#if NETFRAMEWORK
-            await sourceStream.CopyToAsync(targetStream, 81920, CancellationToken.None);
-#else
             await sourceStream.CopyToAsync(targetStream, CancellationToken.None);
-#endif
         }
 
         VerifyFiles();
     }
 
-    //[Fact]
-    public async Task SevenZipArchive_LZMA2_AsyncStreamExtraction()
+    [Fact]
+    public async ValueTask SevenZipArchive_LZMA2_AsyncStreamExtraction()
     {
         var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "7Zip.LZMA2.7z");
-#if NETFRAMEWORK
         using var stream = File.OpenRead(testArchive);
-#else
-        await using var stream = File.OpenRead(testArchive);
-#endif
         await using var archive = await ArchiveFactory.OpenAsyncArchive(
             new AsyncOnlyStream(stream)
         );
@@ -76,35 +58,19 @@ public class SevenZipArchiveAsyncTests : ArchiveTests
                 Directory.CreateDirectory(targetDir);
             }
 
-#if NETFRAMEWORK
             using var sourceStream = await entry.OpenEntryStreamAsync(CancellationToken.None);
-#else
-            await using var sourceStream = await entry.OpenEntryStreamAsync(CancellationToken.None);
-#endif
-#if NETFRAMEWORK
-            using var targetStream = File.Create(targetPath);
-#else
             await using var targetStream = File.Create(targetPath);
-#endif
-#if NETFRAMEWORK
-            await sourceStream.CopyToAsync(targetStream, 81920, CancellationToken.None);
-#else
             await sourceStream.CopyToAsync(targetStream, CancellationToken.None);
-#endif
         }
 
         VerifyFiles();
     }
 
     [Fact]
-    public async Task SevenZipArchive_Solid_AsyncStreamExtraction()
+    public async ValueTask SevenZipArchive_Solid_AsyncStreamExtraction()
     {
         var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "7Zip.solid.7z");
-#if NETFRAMEWORK
         using var stream = File.OpenRead(testArchive);
-#else
-        await using var stream = File.OpenRead(testArchive);
-#endif
         await using var archive = await ArchiveFactory.OpenAsyncArchive(
             new AsyncOnlyStream(stream)
         );
@@ -119,35 +85,19 @@ public class SevenZipArchiveAsyncTests : ArchiveTests
                 Directory.CreateDirectory(targetDir);
             }
 
-#if NETFRAMEWORK
             using var sourceStream = await entry.OpenEntryStreamAsync(CancellationToken.None);
-#else
-            await using var sourceStream = await entry.OpenEntryStreamAsync(CancellationToken.None);
-#endif
-#if NETFRAMEWORK
-            using var targetStream = File.Create(targetPath);
-#else
             await using var targetStream = File.Create(targetPath);
-#endif
-#if NETFRAMEWORK
-            await sourceStream.CopyToAsync(targetStream, 81920, CancellationToken.None);
-#else
             await sourceStream.CopyToAsync(targetStream, CancellationToken.None);
-#endif
         }
 
         VerifyFiles();
     }
 
     [Fact]
-    public async Task SevenZipArchive_BZip2_AsyncStreamExtraction()
+    public async ValueTask SevenZipArchive_BZip2_AsyncStreamExtraction()
     {
         var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "7Zip.BZip2.7z");
-#if NETFRAMEWORK
         using var stream = File.OpenRead(testArchive);
-#else
-        await using var stream = File.OpenRead(testArchive);
-#endif
         await using var archive = await ArchiveFactory.OpenAsyncArchive(
             new AsyncOnlyStream(stream)
         );
@@ -162,35 +112,19 @@ public class SevenZipArchiveAsyncTests : ArchiveTests
                 Directory.CreateDirectory(targetDir);
             }
 
-#if NETFRAMEWORK
             using var sourceStream = await entry.OpenEntryStreamAsync(CancellationToken.None);
-#else
-            await using var sourceStream = await entry.OpenEntryStreamAsync(CancellationToken.None);
-#endif
-#if NETFRAMEWORK
-            using var targetStream = File.Create(targetPath);
-#else
             await using var targetStream = File.Create(targetPath);
-#endif
-#if NETFRAMEWORK
-            await sourceStream.CopyToAsync(targetStream, 81920, CancellationToken.None);
-#else
             await sourceStream.CopyToAsync(targetStream, CancellationToken.None);
-#endif
         }
 
         VerifyFiles();
     }
 
     [Fact]
-    public async Task SevenZipArchive_PPMd_AsyncStreamExtraction()
+    public async ValueTask SevenZipArchive_PPMd_AsyncStreamExtraction()
     {
         var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "7Zip.PPMd.7z");
-#if NETFRAMEWORK
         using var stream = File.OpenRead(testArchive);
-#else
-        await using var stream = File.OpenRead(testArchive);
-#endif
         await using var archive = await ArchiveFactory.OpenAsyncArchive(
             new AsyncOnlyStream(stream)
         );
@@ -205,23 +139,12 @@ public class SevenZipArchiveAsyncTests : ArchiveTests
                 Directory.CreateDirectory(targetDir);
             }
 
-#if NETFRAMEWORK
             using var sourceStream = await entry.OpenEntryStreamAsync(CancellationToken.None);
-#else
-            await using var sourceStream = await entry.OpenEntryStreamAsync(CancellationToken.None);
-#endif
-#if NETFRAMEWORK
-            using var targetStream = File.Create(targetPath);
-#else
             await using var targetStream = File.Create(targetPath);
-#endif
-#if NETFRAMEWORK
-            await sourceStream.CopyToAsync(targetStream, 81920, CancellationToken.None);
-#else
             await sourceStream.CopyToAsync(targetStream, CancellationToken.None);
-#endif
         }
 
         VerifyFiles();
     }
 }
+#endif

tests/SharpCompress.Test/Tar/TarMultiThreadTests.cs

@@ -0,0 +1,115 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using SharpCompress.Archives.Tar;
+using SharpCompress.Common;
+using Xunit;
+
+namespace SharpCompress.Test.Tar;
+
+public class TarMultiThreadTests : TestBase
+{
+    [Fact]
+    public void Tar_Archive_Concurrent_Extraction_From_FileInfo()
+    {
+        // Test concurrent extraction of multiple entries from a Tar archive opened from FileInfo
+        var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "Tar.tar");
+        var fileInfo = new FileInfo(testArchive);
+
+        var options = new SharpCompress.Readers.ReaderOptions
+        {
+            EnableMultiThreadedExtraction = true,
+        };
+
+        using var archive = TarArchive.OpenArchive(fileInfo, options);
+
+        // Verify multi-threading is supported
+        Assert.True(archive.SupportsMultiThreadedExtraction);
+
+        var entries = archive.Entries.Where(e => !e.IsDirectory).Take(5).ToList();
+
+        // Extract multiple entries concurrently
+        var tasks = new List<Task>();
+        var outputFiles = new List<string>();
+
+        foreach (var entry in entries)
+        {
+            var outputFile = Path.Combine(SCRATCH_FILES_PATH, entry.Key!);
+            outputFiles.Add(outputFile);
+
+            tasks.Add(
+                Task.Run(() =>
+                {
+                    var dir = Path.GetDirectoryName(outputFile);
+                    if (dir != null)
+                    {
+                        Directory.CreateDirectory(dir);
+                    }
+                    using var entryStream = entry.OpenEntryStream();
+                    using var fileStream = File.Create(outputFile);
+                    entryStream.CopyTo(fileStream);
+                })
+            );
+        }
+
+        Task.WaitAll(tasks.ToArray());
+
+        // Verify all files were extracted
+        Assert.Equal(entries.Count, outputFiles.Count);
+        foreach (var outputFile in outputFiles)
+        {
+            Assert.True(File.Exists(outputFile), $"File {outputFile} should exist");
+        }
+    }
+
+    [Fact]
+    public async Task Tar_Archive_Concurrent_Extraction_From_FileInfo_Async()
+    {
+        // Test concurrent async extraction of multiple entries from a Tar archive opened from FileInfo
+        var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "Tar.tar");
+        var fileInfo = new FileInfo(testArchive);
+
+        var options = new SharpCompress.Readers.ReaderOptions
+        {
+            EnableMultiThreadedExtraction = true,
+        };
+
+        using var archive = TarArchive.OpenArchive(fileInfo, options);
+        var entries = archive.Entries.Where(e => !e.IsDirectory).Take(5).ToList();
+
+        // Extract multiple entries concurrently
+        var tasks = new List<Task>();
+        var outputFiles = new List<string>();
+
+        foreach (var entry in entries)
+        {
+            var outputFile = Path.Combine(SCRATCH_FILES_PATH, entry.Key!);
+            outputFiles.Add(outputFile);
+
+            tasks.Add(
+                Task.Run(async () =>
+                {
+                    var dir = Path.GetDirectoryName(outputFile);
+                    if (dir != null)
+                    {
+                        Directory.CreateDirectory(dir);
+                    }
+                    using var entryStream = await entry.OpenEntryStreamAsync();
+                    using var fileStream = File.Create(outputFile);
+                    await entryStream.CopyToAsync(fileStream);
+                })
+            );
+        }
+
+        await Task.WhenAll(tasks);
+
+        // Verify all files were extracted
+        Assert.Equal(entries.Count, outputFiles.Count);
+        foreach (var outputFile in outputFiles)
+        {
+            Assert.True(File.Exists(outputFile), $"File {outputFile} should exist");
+        }
+    }
+}

tests/SharpCompress.Test/Zip/ZipMultiThreadTests.cs

@@ -0,0 +1,192 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using SharpCompress.Archives.Zip;
+using SharpCompress.Common;
+using Xunit;
+
+namespace SharpCompress.Test.Zip;
+
+public class ZipMultiThreadTests : TestBase
+{
+    [Fact]
+    public void Zip_Archive_Without_MultiThreading_Enabled()
+    {
+        // Test that extraction still works when multi-threading is NOT enabled
+        var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "Zip.none.zip");
+        var fileInfo = new FileInfo(testArchive);
+
+        // Default options - multi-threading disabled
+        using var archive = ZipArchive.OpenArchive(fileInfo);
+
+        // Verify multi-threading is NOT supported
+        Assert.False(archive.SupportsMultiThreadedExtraction);
+
+        var entry = archive.Entries.First(e => !e.IsDirectory);
+        var outputFile = Path.Combine(SCRATCH_FILES_PATH, entry.Key!);
+
+        var dir = Path.GetDirectoryName(outputFile);
+        if (dir != null)
+        {
+            Directory.CreateDirectory(dir);
+        }
+
+        using var entryStream = entry.OpenEntryStream();
+        using var fileStream = File.Create(outputFile);
+        entryStream.CopyTo(fileStream);
+
+        Assert.True(File.Exists(outputFile));
+    }
+
+    [Fact]
+    public void Zip_Archive_Concurrent_Extraction_From_FileInfo()
+    {
+        // Test concurrent extraction of multiple entries from a Zip archive opened from FileInfo
+        var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "Zip.none.zip");
+        var fileInfo = new FileInfo(testArchive);
+
+        var options = new SharpCompress.Readers.ReaderOptions
+        {
+            EnableMultiThreadedExtraction = true,
+        };
+
+        using var archive = ZipArchive.OpenArchive(fileInfo, options);
+
+        // Verify multi-threading is supported
+        Assert.True(archive.SupportsMultiThreadedExtraction);
+
+        var entries = archive.Entries.Where(e => !e.IsDirectory).Take(5).ToList();
+
+        // Extract multiple entries concurrently
+        var tasks = new List<Task>();
+        var outputFiles = new List<string>();
+
+        foreach (var entry in entries)
+        {
+            var outputFile = Path.Combine(SCRATCH_FILES_PATH, entry.Key!);
+            outputFiles.Add(outputFile);
+
+            tasks.Add(
+                Task.Run(() =>
+                {
+                    var dir = Path.GetDirectoryName(outputFile);
+                    if (dir != null)
+                    {
+                        Directory.CreateDirectory(dir);
+                    }
+                    using var entryStream = entry.OpenEntryStream();
+                    using var fileStream = File.Create(outputFile);
+                    entryStream.CopyTo(fileStream);
+                })
+            );
+        }
+
+        Task.WaitAll(tasks.ToArray());
+
+        // Verify all files were extracted
+        Assert.Equal(entries.Count, outputFiles.Count);
+        foreach (var outputFile in outputFiles)
+        {
+            Assert.True(File.Exists(outputFile), $"File {outputFile} should exist");
+        }
+    }
+
+    [Fact]
+    public async Task Zip_Archive_Concurrent_Extraction_From_FileInfo_Async()
+    {
+        // Test concurrent async extraction of multiple entries from a Zip archive opened from FileInfo
+        var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "Zip.none.zip");
+        var fileInfo = new FileInfo(testArchive);
+
+        var options = new SharpCompress.Readers.ReaderOptions
+        {
+            EnableMultiThreadedExtraction = true,
+        };
+
+        using var archive = ZipArchive.OpenArchive(fileInfo, options);
+        var entries = archive.Entries.Where(e => !e.IsDirectory).Take(5).ToList();
+
+        // Extract multiple entries concurrently
+        var tasks = new List<Task>();
+        var outputFiles = new List<string>();
+
+        foreach (var entry in entries)
+        {
+            var outputFile = Path.Combine(SCRATCH_FILES_PATH, entry.Key!);
+            outputFiles.Add(outputFile);
+
+            tasks.Add(
+                Task.Run(async () =>
+                {
+                    var dir = Path.GetDirectoryName(outputFile);
+                    if (dir != null)
+                    {
+                        Directory.CreateDirectory(dir);
+                    }
+                    using var entryStream = await entry.OpenEntryStreamAsync();
+                    using var fileStream = File.Create(outputFile);
+                    await entryStream.CopyToAsync(fileStream);
+                })
+            );
+        }
+
+        await Task.WhenAll(tasks);
+
+        // Verify all files were extracted
+        Assert.Equal(entries.Count, outputFiles.Count);
+        foreach (var outputFile in outputFiles)
+        {
+            Assert.True(File.Exists(outputFile), $"File {outputFile} should exist");
+        }
+    }
+
+    [Fact]
+    public void Zip_Archive_Concurrent_Extraction_From_Path()
+    {
+        // Test concurrent extraction when opening from path (should use FileInfo internally)
+        var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "Zip.none.zip");
+
+        var options = new SharpCompress.Readers.ReaderOptions
+        {
+            EnableMultiThreadedExtraction = true,
+        };
+
+        using var archive = ZipArchive.OpenArchive(testArchive, options);
+        var entries = archive.Entries.Where(e => !e.IsDirectory).Take(5).ToList();
+
+        // Extract multiple entries concurrently
+        var tasks = new List<Task>();
+        var outputFiles = new List<string>();
+
+        foreach (var entry in entries)
+        {
+            var outputFile = Path.Combine(SCRATCH_FILES_PATH, entry.Key!);
+            outputFiles.Add(outputFile);
+
+            tasks.Add(
+                Task.Run(() =>
+                {
+                    var dir = Path.GetDirectoryName(outputFile);
+                    if (dir != null)
+                    {
+                        Directory.CreateDirectory(dir);
+                    }
+                    using var entryStream = entry.OpenEntryStream();
+                    using var fileStream = File.Create(outputFile);
+                    entryStream.CopyTo(fileStream);
+                })
+            );
+        }
+
+        Task.WaitAll(tasks.ToArray());
+
+        // Verify all files were extracted
+        Assert.Equal(entries.Count, outputFiles.Count);
+        foreach (var outputFile in outputFiles)
+        {
+            Assert.True(File.Exists(outputFile), $"File {outputFile} should exist");
+        }
+    }
+}