From 3375aaa90c4c72347861f21bdf00a4498572f5ae Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 24 Jul 2026 07:18:02 +0000
Subject: [PATCH] fix: preserve transformed streams in reader detection

---
 .../IO/SharpCompressStream.Create.cs          | 14 +-----
 .../GZip/GZipArchiveTests.cs                  | 48 +++++++++++++++++++
 2 files changed, 50 insertions(+), 12 deletions(-)

diff --git a/src/SharpCompress/IO/SharpCompressStream.Create.cs b/src/SharpCompress/IO/SharpCompressStream.Create.cs
index 37d91ebf..645f5948 100644
--- a/src/SharpCompress/IO/SharpCompressStream.Create.cs
+++ b/src/SharpCompress/IO/SharpCompressStream.Create.cs
@@ -52,8 +52,8 @@ public partial class SharpCompressStream
     /// <paramref name="bufferSize"/> or <see cref="Common.Constants.RewindableBufferSize"/> to
     /// avoid this.</para>
     /// <para><b>Already-wrapped streams</b> — if <paramref name="stream"/> is already a
-    /// <see cref="SharpCompressStream"/> (or a stack that contains one), it is returned as-is to
-    /// prevent double-wrapping and double-buffering.</para>
+    /// <see cref="SharpCompressStream"/>, it is returned as-is to prevent double-wrapping and
+    /// double-buffering.</para>
     /// </remarks>
     /// <param name="stream">The underlying stream to wrap. Must not be <see langword="null"/>.</param>
     /// <param name="bufferSize">
@@ -90,16 +90,6 @@ public partial class SharpCompressStream
             return sharpCompressStream;
         }
 
-        // Check if stream is wrapping a SharpCompressStream (e.g., via IStreamStack)
-        if (stream is IStreamStack streamStack)
-        {
-            var underlying = streamStack.GetStream<SharpCompressStream>();
-            if (underlying is not null)
-            {
-                return underlying;
-            }
-        }
-
         if (stream.CanSeek)
         {
             return new SeekableSharpCompressStream(stream);
diff --git a/tests/SharpCompress.Test/GZip/GZipArchiveTests.cs b/tests/SharpCompress.Test/GZip/GZipArchiveTests.cs
index 5f9f5094..c3737e98 100644
--- a/tests/SharpCompress.Test/GZip/GZipArchiveTests.cs
+++ b/tests/SharpCompress.Test/GZip/GZipArchiveTests.cs
@@ -5,8 +5,13 @@ using SharpCompress.Archives;
 using SharpCompress.Archives.GZip;
 using SharpCompress.Archives.Tar;
 using SharpCompress.Common;
+using SharpCompress.Compressors;
+using SharpCompress.Compressors.Deflate;
+using SharpCompress.Readers;
 using SharpCompress.Test.Mocks;
+using SharpCompress.Writers;
 using SharpCompress.Writers.GZip;
+using SharpCompress.Writers.Tar;
 using Xunit;
 
 namespace SharpCompress.Test.GZip;
@@ -108,6 +113,49 @@ public class GZipArchiveTests : ArchiveTests
         Assert.Equal(size, tarStream.Length);
     }
 
+    [Fact]
+    public void GZip_Archive_EntryStream_Can_Be_Opened_As_Tar_Reader()
+    {
+        var sourceDirectory = Path.Combine(SCRATCH_FILES_PATH, "srcdir");
+        Directory.CreateDirectory(sourceDirectory);
+        File.WriteAllText(Path.Combine(sourceDirectory, "a.txt"), "i am a.txt");
+
+        var subDirectory = Path.Combine(sourceDirectory, "sub");
+        Directory.CreateDirectory(subDirectory);
+        File.WriteAllText(Path.Combine(subDirectory, "suba.txt"), "i am suba.txt");
+
+        var archivePath = Path.Combine(SCRATCH_FILES_PATH, "srcdir.tar.gz");
+        using (var fileStream = File.Create(archivePath))
+        using (var gzipStream = new GZipStream(fileStream, CompressionMode.Compress))
+        using (var tarArchive = TarArchive.CreateArchive())
+        {
+            tarArchive.AddAllFromDirectory(sourceDirectory, "*", SearchOption.AllDirectories);
+            tarArchive.SaveTo(gzipStream, new TarWriterOptions(CompressionType.None, false));
+        }
+
+        var destinationDirectory = Path.Combine(SCRATCH_FILES_PATH, "destdir");
+        Directory.CreateDirectory(destinationDirectory);
+        using var archive = GZipArchive.OpenArchive(archivePath);
+        using var entryStream = archive.Entries.First().OpenEntryStream();
+        using var reader = ReaderFactory.OpenReader(entryStream);
+        while (reader.MoveToNextEntry())
+        {
+            if (!reader.Entry.IsDirectory && reader.Entry.Size > 0)
+            {
+                reader.WriteEntryToDirectory(
+                    destinationDirectory,
+                    new ExtractionOptions { ExtractFullPath = true, Overwrite = true }
+                );
+            }
+        }
+
+        Assert.Equal("i am a.txt", File.ReadAllText(Path.Combine(destinationDirectory, "a.txt")));
+        Assert.Equal(
+            "i am suba.txt",
+            File.ReadAllText(Path.Combine(destinationDirectory, "sub", "suba.txt"))
+        );
+    }
+
     [Fact]
     public void TestGzCrcWithMostSignificantBitNotNegative()
     {