intermediate commit

.agents/skills/tar-format/references/tar-format.md

@@ -280,7 +280,7 @@ Archive API:
 
 - `TarArchive.OpenArchive(Stream)` and `TarArchive.OpenAsyncArchive(Stream)` require seekable raw tar streams.
 - File/path overloads own the opened file stream.
-- Compressed tar wrappers are supported through `TarReader`, not `TarArchive`.
+- Compressed tar wrappers are supported through `TarReader`, not `TarArchive` or `ArchiveFactory`; archive detection blocks them instead of opening the outer compression wrapper as a standalone archive.
 
 Parsed metadata surfaced through entries includes:
 

docs/API.md

@@ -73,7 +73,7 @@ using (var archive = ArchiveFactory.OpenArchive(parts))
 }
 ```
 
-`ArchiveInformation.SupportsRandomAccess` is `true` when the detected format supports `IArchive` random access. It is `false` for reader-only formats such as Ace, Arc, Arj, and standalone LZW, where `ReaderFactory.OpenReader` should be used instead. Compressed tar wrappers such as `.tar.gz` and `.tar.xz` are also reader-only; use `ReaderFactory.OpenReader` or `TarReader.OpenReader` for those files.
+`ArchiveInformation.SupportsRandomAccess` is `true` when the detected format supports `IArchive` random access. It is `false` for reader-only formats such as Ace, Arc, Arj, and standalone LZW, where `ReaderFactory.OpenReader` should be used instead. Compressed tar wrappers such as `.tar.gz` and `.tar.xz` are also reader-only; `ArchiveFactory.GetArchiveInformation` returns `null` for them and `ArchiveFactory.OpenArchive` does not open them as the outer compression wrapper. Use `ReaderFactory.OpenReader` or `TarReader.OpenReader` for those files.
 
 ### Creating Archives
 

docs/FORMATS.md

@@ -31,7 +31,7 @@
 4. The 7Zip format doesn't allow for reading as a forward-only stream, so 7Zip read support is only through the Archive API. Writing is supported through SevenZipWriter for non-solid archives with LZMA/LZMA2 and requires a seekable output stream. See [7Zip Format Notes](#7zip-format-notes) for details on async extraction behavior.
 5. LZip has no support for extra data like the file name or timestamp. There is a default filename used when looking at the entry Key on the archive.
 
-`ArchiveFactory.GetArchiveInformation(...).SupportsRandomAccess` is `true` when the detected format has an Archive API in this table. It is `false` for reader-only formats such as Ace, Arc, Arj, and standalone LZW. Compressed tar wrappers are supported by `ReaderFactory`/`TarReader`, not by `ArchiveFactory`/`TarArchive`.
+`ArchiveFactory.GetArchiveInformation(...).SupportsRandomAccess` is `true` when the detected format has an Archive API in this table. It is `false` for reader-only formats such as Ace, Arc, Arj, and standalone LZW. Compressed tar wrappers are supported by `ReaderFactory`/`TarReader`, not by `ArchiveFactory`/`TarArchive`; ArchiveFactory detection blocks them instead of opening the outer compression wrapper as a standalone archive.
 
 ### Zip Format Notes
 

docs/TAR_SPEC.md

@@ -84,7 +84,7 @@ Implications:
 - Tar detection is content-based, not extension-based.
 - Wrapper detection is not sufficient by itself. The decompressed payload must also parse as tar.
 - Non-seekable wrapper detection is supported through the recording and rewind mechanism on the reader path.
-- `ArchiveFactory`/`TarArchive` do not open compressed tar wrappers; use `ReaderFactory`/`TarReader` for `.tar.gz`, `.tar.bz2`, `.tar.xz`, `.tar.zst`, `.tar.lz`, and `.tar.Z`.
+- `ArchiveFactory`/`TarArchive` do not open compressed tar wrappers and do not fall through to the outer compression wrapper archive; use `ReaderFactory`/`TarReader` for `.tar.gz`, `.tar.bz2`, `.tar.xz`, `.tar.zst`, `.tar.lz`, and `.tar.Z`.
 - The largest rewind requirement currently comes from BZip2, which declares a larger minimum probe buffer in `TarWrapper`.
 
 `TarArchive.IsTarFile` and `TarArchive.IsTarFileAsync` attempt to read a single tar header and return `false` on any exception. They also treat an all-zero empty archive block as a valid empty tar archive when the entry type is defined.

tests/SharpCompress.Test/ArchiveFactoryTests.cs

@@ -409,7 +409,6 @@ public class ArchiveFactoryTests : TestBase
     [InlineData("Tar.noEmptyDirs.tar", ArchiveType.Tar, true)]
     [InlineData("Tar.tar", ArchiveType.Tar, true)]
     [InlineData("TarCorrupted.tar", ArchiveType.Tar, true)]
-    [InlineData("TarWithSymlink.tar.gz", ArchiveType.GZip, true)]
     [InlineData("WinZip26.zip", ArchiveType.Zip, true)]
     [InlineData("WinZip26_BZip2.zipx", ArchiveType.Zip, true)]
     [InlineData("WinZip26_LZMA.zipx", ArchiveType.Zip, true)]
@@ -567,7 +566,6 @@ public class ArchiveFactoryTests : TestBase
     [InlineData("Tar.noEmptyDirs.tar", ArchiveType.Tar, true)]
     [InlineData("Tar.tar", ArchiveType.Tar, true)]
     [InlineData("TarCorrupted.tar", ArchiveType.Tar, true)]
-    [InlineData("TarWithSymlink.tar.gz", ArchiveType.GZip, true)]
     [InlineData("WinZip26.zip", ArchiveType.Zip, true)]
     [InlineData("WinZip26_BZip2.zipx", ArchiveType.Zip, true)]
     [InlineData("WinZip26_LZMA.zipx", ArchiveType.Zip, true)]
@@ -658,6 +656,58 @@ public class ArchiveFactoryTests : TestBase
         Assert.Null(info);
     }
 
+    [Theory]
+    [InlineData("Tar.tar.gz")]
+    [InlineData("Tar.tar.Z")]
+    public void IsArchive_ReturnsFalse_ForCompressedTar(string archiveName)
+    {
+        using var stream = File.OpenRead(GetTestArchivePath(archiveName));
+
+        var isArchive = ArchiveFactory.IsArchive(stream, out var archiveType);
+
+        Assert.False(isArchive);
+        Assert.Null(archiveType);
+    }
+
+    [Theory]
+    [InlineData("Tar.tar.gz")]
+    [InlineData("Tar.tar.Z")]
+    public async ValueTask IsArchiveAsync_ReturnsFalse_ForCompressedTar(string archiveName)
+    {
+        using var stream = File.OpenRead(GetTestArchivePath(archiveName));
+
+        var (isArchive, archiveType) = await ArchiveFactory.IsArchiveAsync(stream);
+
+        Assert.False(isArchive);
+        Assert.Null(archiveType);
+    }
+
+    [Theory]
+    [InlineData("Tar.tar.gz")]
+    [InlineData("Tar.tar.Z")]
+    public void GetArchiveInformation_ReturnsNull_ForCompressedTar(string archiveName)
+    {
+        using var stream = File.OpenRead(GetTestArchivePath(archiveName));
+
+        var info = ArchiveFactory.GetArchiveInformation(stream);
+
+        Assert.Null(info);
+    }
+
+    [Theory]
+    [InlineData("Tar.tar.gz")]
+    [InlineData("Tar.tar.Z")]
+    public async ValueTask GetArchiveInformationAsync_ReturnsNull_ForCompressedTar(
+        string archiveName
+    )
+    {
+        using var stream = File.OpenRead(GetTestArchivePath(archiveName));
+
+        var info = await ArchiveFactory.GetArchiveInformationAsync(stream);
+
+        Assert.Null(info);
+    }
+
     [Theory]
     [InlineData("Zip.deflate.zip", ArchiveType.Zip)]
     [InlineData("Tar.noEmptyDirs.tar", ArchiveType.Tar)]

tests/SharpCompress.Test/Tar/TarArchiveAsyncTests.cs

@@ -35,16 +35,30 @@ public class TarArchiveAsyncTests : ArchiveTests
         );
     }
 
-    [Fact]
-    public async ValueTask TarArchiveOpenAsyncArchive_RejectsCompressedTar()
+    [Theory]
+    [InlineData("Tar.tar.gz")]
+    [InlineData("Tar.tar.Z")]
+    public async ValueTask TarArchiveOpenAsyncArchive_RejectsCompressedTar(string archiveName)
     {
-        using Stream stream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, "Tar.tar.gz"));
+        using Stream stream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, archiveName));
 
         await Assert.ThrowsAsync<InvalidFormatException>(async () =>
             await TarArchive.OpenAsyncArchive(stream)
         );
     }
 
+    [Theory]
+    [InlineData("Tar.tar.gz")]
+    [InlineData("Tar.tar.Z")]
+    public async ValueTask ArchiveFactoryOpenAsyncArchive_RejectsCompressedTar(string archiveName)
+    {
+        using Stream stream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, archiveName));
+
+        await Assert.ThrowsAsync<ArchiveOperationException>(async () =>
+            await ArchiveFactory.OpenAsyncArchive(stream)
+        );
+    }
+
     [Fact]
     public async ValueTask TarArchiveOpenAsyncStream_Throws_On_Unreadable_Stream()
     {

tests/SharpCompress.Test/Tar/TarArchiveTests.cs

@@ -486,19 +486,22 @@ public class TarArchiveTests : ArchiveTests
         Assert.False(isTar);
     }
 
-    [Fact]
-    public void ArchiveFactoryStreamRead_Autodetect_CompressedTar_AsGZip()
+    [Theory]
+    [InlineData("Tar.tar.gz")]
+    [InlineData("Tar.tar.Z")]
+    public void ArchiveFactoryStreamRead_Autodetect_RejectsCompressedTar(string archiveName)
     {
-        using Stream stream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, "Tar.tar.gz"));
-        using var archive = ArchiveFactory.OpenArchive(stream);
+        using Stream stream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, archiveName));
 
-        Assert.Equal(ArchiveType.GZip, archive.Type);
+        Assert.Throws<ArchiveOperationException>(() => ArchiveFactory.OpenArchive(stream));
     }
 
-    [Fact]
-    public void TarArchiveOpenArchive_RejectsCompressedTar()
+    [Theory]
+    [InlineData("Tar.tar.gz")]
+    [InlineData("Tar.tar.Z")]
+    public void TarArchiveOpenArchive_RejectsCompressedTar(string archiveName)
     {
-        using Stream stream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, "Tar.tar.gz"));
+        using Stream stream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, archiveName));
 
         Assert.Throws<InvalidFormatException>(() => TarArchive.OpenArchive(stream));
     }