Update _create_gnu_long_header to align with GNU Tar

Author: gdh1995

Lib/tarfile.py

@@ -1190,6 +1190,9 @@ def _create_gnu_long_header(cls, name, type, encoding, errors):
         info["type"] = type
         info["size"] = len(name)
         info["magic"] = GNU_MAGIC
+        info["mode"] = 0o100644
+        info["uname"] = "root"
+        info["gname"] = "root"
 
         # create extended header + name blocks.
         return cls._create_header(info, USTAR_FORMAT, encoding, errors) + \

Lib/test/test_tarfile.py

@@ -1875,6 +1875,34 @@ def test_longnamelink_1025(self):
         self._test(("longnam/" * 127) + "longname_",
                    ("longlnk/" * 127) + "longlink_")
 
+    def test_hidden_header_for_longname(self):
+        # Regression test for gh-130819.
+        memory_file = io.BytesIO()
+        tar = tarfile.open(mode="w", fileobj=memory_file, format=tarfile.GNU_FORMAT)
+        tar_info = tarfile.TarInfo("abcdef" * 20)
+        tar_info.type = tarfile.DIRTYPE
+        tar.addfile(tar_info, None)
+        tar.close()
+
+        class RawTabInfo(tarfile.TarInfo):
+
+            def _proc_member(self, tar_file):
+                if self.type in (tarfile.GNUTYPE_LONGNAME, tarfile.GNUTYPE_LONGLINK):
+                    tester.assertEqual(self.mode, 0o644)
+                    tester.assertEqual(self.uname, "root")
+                    tester.assertEqual(self.gname, "root")
+                return super()._proc_member(tar_file)  # type: ignore
+
+        tester = self
+        memory_file.seek(0)
+        tar = tarfile.open(fileobj=memory_file, mode="r", tarinfo=RawTabInfo)
+        try:
+            members = tar.getmembers()
+            self.assertEqual(len(members), 1)
+        finally:
+            tar.close()
+            memory_file.close()
+
 
 class DeviceHeaderTest(WriteTestBase, unittest.TestCase):
 

Misc/ACKS

@@ -663,6 +663,7 @@ Mikhail Golubev
 Marta Gómez Macías
 Guilherme Gonçalves
 Tiago Gonçalves
+Dahan Gong
 Chris Gonnerman
 Shelley Gooch
 David Goodger

Misc/NEWS.d/next/Library/2025-03-04-03-14-44.gh-issue-130819.Dphgb6.rst

@@ -0,0 +1,3 @@
+Emit ``mode``, ``uname`` and ``gname`` fields for long paths in
+:mod:`tarfile` archives, providing better bit-for-bit compatibility with GNU
+``tar(1)``.