Fix bug in merged tars with big file names on Python 3.8

pkg/archive.py

@@ -146,7 +146,7 @@ def __init__(self,
       # Instead, we manually re-implement gzopen from tarfile.py and set mtime.
       self.fileobj = gzip.GzipFile(
           filename=name, mode='w', compresslevel=9, mtime=self.default_mtime)
-    self.tar = tarfile.open(name=name, mode=mode, fileobj=self.fileobj)
+    self.tar = tarfile.open(name=name, mode=mode, fileobj=self.fileobj, format=tarfile.GNU_FORMAT)
     self.members = set([])
     self.directories = set([])
 

pkg/make_deb.py

@@ -146,7 +146,7 @@ def CreateDebControl(extrafiles=None, **kwargs):
   # Create the control.tar file
   tar = BytesIO()
   with gzip.GzipFile('control.tar.gz', mode='w', fileobj=tar, mtime=0) as gz:
-    with tarfile.open('control.tar.gz', mode='w', fileobj=gz) as f:
+    with tarfile.open('control.tar.gz', mode='w', fileobj=gz, format=tarfile.GNU_FORMAT) as f:
       tarinfo = tarfile.TarInfo('./control')
       control_file_data = controlfile.encode('utf-8')
       tarinfo.size = len(control_file_data)

pkg/tests/archive_test.py

@@ -227,6 +227,19 @@ def testMergeTarRelocated(self):
       f.add_tar(datafile, name_filter=lambda n: n != "./b", root="/foo")
     self.assertTarFileContent(self.tempfile, content)
 
+  def testMergeTarRelocatedBigNames(self):
+    content = [
+        {"name": ".", "mode": 0o755},
+        {"name": "./foo", "mode": 0o755},
+        {"name": "./foo/ninety-eight-characters-seems-to-be-the-maximum-limit-for-merged-tarballs-in-the-rules_pkg-for-bzl", "data": b"1"},
+        {"name": "./foo/ninety-eight-characters-seems-to-be-the-maximum-limit-for-merged-tarballs-in-the-rules_pkg-for-bzl-", "data": b"1"},
+        ]
+    with archive.TarFileWriter(self.tempfile) as f:
+      datafile = self.data_files.Rlocation(
+          os.path.join("rules_pkg", "tests", "testdata", "big-names.tar"))
+      f.add_tar(datafile, root="/foo")
+    self.assertTarFileContent(self.tempfile, content)
+
   def testDefaultMtimeNotProvided(self):
     with archive.TarFileWriter(self.tempfile) as f:
       self.assertEqual(f.default_mtime, 0)