From 918747fd876e276d6a6e9476ee9e19c7d0bb469b Mon Sep 17 00:00:00 2001
From: dannysullivan <danielalexandersullivan@gmail.com>
Date: Thu, 26 Mar 2020 13:30:34 -0400
Subject: [PATCH] Add option to preserve input tar mtimes in TarFileWriter

Also backfill unit tests of default mtime functionality
---
 tools/build_defs/pkg/archive.py      | 10 ++++++++--
 tools/build_defs/pkg/archive_test.py | 28 ++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/tools/build_defs/pkg/archive.py b/tools/build_defs/pkg/archive.py
index 52c26912de255b..b497a219bca070 100644
--- a/tools/build_defs/pkg/archive.py
+++ b/tools/build_defs/pkg/archive.py
@@ -115,7 +115,8 @@ def __init__(self,
                name,
                compression='',
                root_directory='./',
-               default_mtime=None):
+               default_mtime=None,
+               preserve_tar_mtimes=False):
     """TarFileWriter wraps tarfile.open().
 
     Args:
@@ -125,6 +126,7 @@ def __init__(self,
       default_mtime: default mtime to use for elements in the archive.
           May be an integer or the value 'portable' to use the date
           2000-01-01, which is compatible with non *nix OSes'.
+      preserve_tar_mtimes: if true, keep file mtimes from input tar file.
     """
     if compression in ['bzip2', 'bz2']:
       mode = 'w:bz2'
@@ -135,6 +137,9 @@ def __init__(self,
     self.xz = compression in ['xz', 'lzma']
     self.name = name
     self.root_directory = six.ensure_str(root_directory).rstrip('/')
+
+    self.preserve_mtime = preserve_tar_mtimes
+
     if default_mtime is None:
       self.default_mtime = 0
     elif default_mtime == 'portable':
@@ -385,7 +390,8 @@ def add_tar(self,
       intar = tarfile.open(name=tar, mode=inmode)
     for tarinfo in intar:
       if name_filter is None or name_filter(tarinfo.name):
-        tarinfo.mtime = self.default_mtime
+        if not self.preserve_mtime:
+          tarinfo.mtime = self.default_mtime
         if rootuid is not None and tarinfo.uid == rootuid:
           tarinfo.uid = 0
           tarinfo.uname = 'root'
diff --git a/tools/build_defs/pkg/archive_test.py b/tools/build_defs/pkg/archive_test.py
index a2e0df401a12fe..f5696c6207f8ab 100644
--- a/tools/build_defs/pkg/archive_test.py
+++ b/tools/build_defs/pkg/archive_test.py
@@ -161,6 +161,34 @@ def assertSimpleFileContent(self, names):
     } for n in names])
     self.assertTarFileContent(self.tempfile, content)
 
+  def testDefaultMtimeNotProvided(self):
+    with archive.TarFileWriter(self.tempfile) as f:
+      self.assertEqual(f.default_mtime, 0)
+
+  def testDefaultMtimeProvided(self):
+    with archive.TarFileWriter(self.tempfile, default_mtime=1234) as f:
+      self.assertEqual(f.default_mtime, 1234)
+
+  def testPortableMtime(self):
+    with archive.TarFileWriter(self.tempfile, default_mtime="portable") as f:
+      self.assertEqual(f.default_mtime, 946684800)
+
+  def testPreserveTarMtimesTrue(self):
+    with archive.TarFileWriter(self.tempfile, preserve_tar_mtimes=True) as f:
+      input_tar_path = os.path.join(testenv.TESTDATA_PATH, "tar_test.tar")
+      f.add_tar(input_tar_path)
+      input_tar = tarfile.open(input_tar_path, "r")
+      for file_name in f.members:
+        input_file = input_tar.getmember(file_name)
+        output_file = f.tar.getmember(file_name)
+        self.assertEqual(input_file.mtime, output_file.mtime)
+
+  def testPreserveTarMtimesFalse(self):
+    with archive.TarFileWriter(self.tempfile, preserve_tar_mtimes=False) as f:
+      f.add_tar(os.path.join(testenv.TESTDATA_PATH, "tar_test.tar"))
+      for output_file in f.tar:
+        self.assertEqual(output_file.mtime, 0)
+
   def testAddFile(self):
     self.assertSimpleFileContent(["./a"])
     self.assertSimpleFileContent(["./b"])