From 7332ed892677723e0c62259ca7eff02f8cefcc27 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Mon, 6 Jul 2026 02:02:37 +0000
Subject: [PATCH] Accept UnauthorizedAccessException or IOException in Tar
 chained-symlink test on Windows

The ExtractToDirectory_RejectsChainedSymlinkDirectoryTraversal_WithNestedFile
test intermittently fails on Windows (~0.25%) because the colliding directory
creation during a rejected traversal can surface as IOException instead of
UnauthorizedAccessException depending on extraction ordering. Both exceptions
mean the traversal was rejected; the post-extraction assertions still verify
nothing escaped the destination.

Refs #130177

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../TarFile/TarFile.ExtractToDirectory.File.Tests.cs     | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/libraries/System.Formats.Tar/tests/TarFile/TarFile.ExtractToDirectory.File.Tests.cs b/src/libraries/System.Formats.Tar/tests/TarFile/TarFile.ExtractToDirectory.File.Tests.cs
index d8d4e46d005da1..04e1c0088c1012 100644
--- a/src/libraries/System.Formats.Tar/tests/TarFile/TarFile.ExtractToDirectory.File.Tests.cs
+++ b/src/libraries/System.Formats.Tar/tests/TarFile/TarFile.ExtractToDirectory.File.Tests.cs
@@ -544,8 +544,13 @@ public void ExtractToDirectory_RejectsChainedSymlinkDirectoryTraversal_WithNeste
 
             if (OperatingSystem.IsWindows())
             {
-                // Windows only creates file symlinks and trying to process a directory symlink will throw UnauthorizedAccessException instead of IOException
-                Assert.Throws<UnauthorizedAccessException>(() => TarFile.ExtractToDirectory(tarPath, destDir, overwriteFiles: true));
+                // Windows only creates file symlinks. Processing the chained directory symlink usually
+                // surfaces as UnauthorizedAccessException, but depending on the order in which the entries
+                // are extracted the colliding directory creation can instead surface as IOException
+                // ("a file or directory with the same name already exists"). Either way the traversal is
+                // rejected before anything escapes the destination, which the assertions below verify.
+                Exception ex = Assert.ThrowsAny<Exception>(() => TarFile.ExtractToDirectory(tarPath, destDir, overwriteFiles: true));
+                Assert.True(ex is UnauthorizedAccessException or IOException, $"Unexpected exception type: {ex.GetType()}");
             }
             else
             {