1 files changed, 40 insertions, 3 deletions
diff --git a/tools/build_defs/pkg/build_tar.py b/tools/build_defs/pkg/build_tar.py
index e5428041a3..90d602d3d3 100644
--- a/tools/build_defs/pkg/build_tar.py
+++ b/tools/build_defs/pkg/build_tar.py
@@ -34,6 +34,11 @@ gflags.DEFINE_multistring('empty_file', [], 'An empty file to add to the layer')
 
 gflags.DEFINE_multistring('empty_dir', [], 'An empty dir to add to the layer')
 
+gflags.DEFINE_multistring(
+    'empty_root_dir',
+    [],
+    'An empty dir to add to the layer')
+
 gflags.DEFINE_multistring('tar', [], 'A tar file to add to the layer')
 
 gflags.DEFINE_multistring('deb', [], 'A debian package to add to the layer')
@@ -72,6 +77,9 @@ gflags.DEFINE_multistring('owner_names', None,
                           'Specify the owner names of individual files, e.g. '
                           'path/to/file=root.root.')
 
+gflags.DEFINE_string(
+    'root_directory', './', 'Default root directory is named "."')
+
 FLAGS = gflags.FLAGS
 
 
@@ -81,13 +89,18 @@ class TarFile(object):
   class DebError(Exception):
     pass
 
-  def __init__(self, output, directory, compression):
+  def __init__(self, output, directory, compression, root_directory):
     self.directory = directory
     self.output = output
     self.compression = compression
+    self.root_directory = root_directory
 
   def __enter__(self):
-    self.tarfile = archive.TarFileWriter(self.output, self.compression)
+    self.tarfile = archive.TarFileWriter(
+        self.output,
+        self.compression,
+        self.root_directory
+    )
     return self
 
   def __exit__(self, t, v, traceback):
@@ -175,6 +188,23 @@ class TarFile(object):
     self.add_empty_file(
         destpath, mode=mode, ids=ids, names=names, kind=tarfile.DIRTYPE)
 
+  def add_empty_root_dir(self, destpath, mode=None, ids=None, names=None):
+    """Add a directory to the root of the tar file.
+
+    Args:
+       destpath: the name of the directory in the layer
+       mode: force to set the specified mode, defaults to 644
+       ids: (uid, gid) for the file to set ownership
+       names: (username, groupname) for the file to set ownership.
+
+    An empty directory will be created as `destfile` in the root layer.
+    """
+    original_root_directory = self.tarfile.root_directory
+    self.tarfile.root_directory = destpath
+    self.add_empty_dir(
+        destpath, mode=mode, ids=ids, names=names)
+    self.tarfile.root_directory = original_root_directory
+
   def add_tar(self, tar):
     """Merge a tar file into the destination tar file.
 
@@ -265,7 +295,12 @@ def main(unused_argv):
       ids_map[f] = (int(user), int(group))
 
   # Add objects to the tar file
-  with TarFile(FLAGS.output, FLAGS.directory, FLAGS.compression) as output:
+  with TarFile(
+      FLAGS.output,
+      FLAGS.directory,
+      FLAGS.compression,
+      FLAGS.root_directory
+  ) as output:
 
     def file_attributes(filename):
       if filename[0] == '/':
@@ -283,6 +318,8 @@ def main(unused_argv):
       output.add_empty_file(f, **file_attributes(f))
     for f in FLAGS.empty_dir:
       output.add_empty_dir(f, **file_attributes(f))
+    for f in FLAGS.empty_root_dir:
+      output.add_empty_root_dir(f, **file_attributes(f))
     for tar in FLAGS.tar:
       output.add_tar(tar)
     for deb in FLAGS.deb: