From fda3d186c5410a048f017cb4d69fe90ff64c9668 Mon Sep 17 00:00:00 2001
From: Adam Hathcock <adam@hathcock.uk>
Date: Sun, 12 Jul 2026 11:09:49 +0100
Subject: [PATCH] more tests and a removal of a test

---
 .../Archives/ArchiveFactory.Detection.cs      | 99 +++++++++++++++++++
 .../AsyncParityAndCancellationTests.cs        |  1 -
 2 files changed, 99 insertions(+), 1 deletion(-)

diff --git a/src/SharpCompress/Archives/ArchiveFactory.Detection.cs b/src/SharpCompress/Archives/ArchiveFactory.Detection.cs
index a0084914..2b735925 100644
--- a/src/SharpCompress/Archives/ArchiveFactory.Detection.cs
+++ b/src/SharpCompress/Archives/ArchiveFactory.Detection.cs
@@ -2,8 +2,11 @@ using System.IO;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using SharpCompress.Archives.Tar;
 using SharpCompress.Common;
 using SharpCompress.Factories;
+using SharpCompress.IO;
+using SharpCompress.Providers;
 using SharpCompress.Readers;
 
 namespace SharpCompress.Archives;
@@ -163,6 +166,15 @@ public static partial class ArchiveFactory
 
             if (isArchive)
             {
+                stream.Seek(startPosition, SeekOrigin.Begin);
+                if (
+                    await IsCompressedTarAsync(stream, factory, readerOptions, cancellationToken)
+                        .ConfigureAwait(false)
+                )
+                {
+                    continue;
+                }
+
                 stream.Seek(startPosition, SeekOrigin.Begin);
                 return factory;
             }
@@ -253,6 +265,12 @@ public static partial class ArchiveFactory
 
             if (isArchive)
             {
+                stream.Seek(startPosition, SeekOrigin.Begin);
+                if (IsCompressedTar(stream, factory, readerOptions))
+                {
+                    continue;
+                }
+
                 stream.Seek(startPosition, SeekOrigin.Begin);
                 return factory;
             }
@@ -261,4 +279,85 @@ public static partial class ArchiveFactory
         stream.Seek(startPosition, SeekOrigin.Begin);
         return null;
     }
+
+    private static bool IsCompressedTar(
+        Stream stream,
+        IFactory factory,
+        ReaderOptions readerOptions
+    ) =>
+        GetCompressedTarType(factory) is { } compressionType
+        && IsCompressedTar(stream, readerOptions, compressionType);
+
+    private static bool IsCompressedTar(
+        Stream stream,
+        ReaderOptions readerOptions,
+        CompressionType compressionType
+    )
+    {
+        using var nonDisposingStream = SharpCompressStream.CreateNonDisposing(stream);
+        var testStream =
+            compressionType == CompressionType.GZip
+                ? readerOptions.Providers.CreateDecompressStream(
+                    compressionType,
+                    nonDisposingStream,
+                    CompressionContext
+                        .FromStream(nonDisposingStream)
+                        .WithReaderOptions(readerOptions)
+                )
+                : readerOptions.Providers.CreateDecompressStream(
+                    compressionType,
+                    nonDisposingStream
+                );
+
+        return TarArchive.IsTarFile(testStream);
+    }
+
+    private static async ValueTask<bool> IsCompressedTarAsync(
+        Stream stream,
+        IFactory factory,
+        ReaderOptions readerOptions,
+        CancellationToken cancellationToken
+    ) =>
+        GetCompressedTarType(factory) is { } compressionType
+        && await IsCompressedTarAsync(stream, readerOptions, compressionType, cancellationToken)
+            .ConfigureAwait(false);
+
+    private static async ValueTask<bool> IsCompressedTarAsync(
+        Stream stream,
+        ReaderOptions readerOptions,
+        CompressionType compressionType,
+        CancellationToken cancellationToken
+    )
+    {
+        using var nonDisposingStream = SharpCompressStream.CreateNonDisposing(stream);
+        var testStream =
+            compressionType == CompressionType.GZip
+                ? await readerOptions
+                    .Providers.CreateDecompressStreamAsync(
+                        compressionType,
+                        nonDisposingStream,
+                        CompressionContext
+                            .FromStream(nonDisposingStream)
+                            .WithReaderOptions(readerOptions),
+                        cancellationToken
+                    )
+                    .ConfigureAwait(false)
+                : await readerOptions
+                    .Providers.CreateDecompressStreamAsync(
+                        compressionType,
+                        nonDisposingStream,
+                        cancellationToken
+                    )
+                    .ConfigureAwait(false);
+
+        return await TarArchive.IsTarFileAsync(testStream, cancellationToken).ConfigureAwait(false);
+    }
+
+    private static CompressionType? GetCompressedTarType(IFactory factory) =>
+        factory switch
+        {
+            GZipFactory => CompressionType.GZip,
+            LzwFactory => CompressionType.Lzw,
+            _ => null,
+        };
 }
diff --git a/tests/SharpCompress.Test/AsyncParityAndCancellationTests.cs b/tests/SharpCompress.Test/AsyncParityAndCancellationTests.cs
index 49beacfa..f4812060 100644
--- a/tests/SharpCompress.Test/AsyncParityAndCancellationTests.cs
+++ b/tests/SharpCompress.Test/AsyncParityAndCancellationTests.cs
@@ -19,7 +19,6 @@ public class AsyncParityAndCancellationTests : TestBase
     [Theory]
     [InlineData("Zip.deflate.zip")]
     [InlineData("Tar.tar")]
-    [InlineData("Tar.tar.gz")]
     [InlineData("Rar.rar")]
     [InlineData("7Zip.nonsolid.7z")]
     public async Task ArchiveAsyncEntries_ShouldMatchSyncEntries(string archiveName)