add synchronize_owners utility

This helper synchronizes OWNERS directives between a main branch and a
tracking branch. In the directories in which the main branch has an
OWNERS file, the tracking branch's equivalent OWNERS file will have a
directive to include the main branch file. Existing OWNERS file contents
are preserved by prepending the include directive if absent.

Example usage (executed in an common-android-multi repo checkout):
 $  build/synchronize_owners common-mainline/ android-mainline common12-5.10/

Bug: 184248201
Signed-off-by: Matthias Maennich <maennich@google.com>
Change-Id: I41b0e0e8ff20b45ef1f1e8641e1107af95bc7c85

1 files changed, 75 insertions, 0 deletions

diff --git a/synchronize_owners b/synchronize_owners
new file mode 100755
index 00000000..2fffe3ee
--- /dev/null
+++ b/synchronize_owners
@@ -0,0 +1,75 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2021 The Android Open main Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import argparse
+import os
+import pathlib
+import sys
+
+
+def process_owners(main_dir, main_branch, tracking_dir):
+  # walk the tree ...
+  for subdir, _, files in os.walk(main_dir):
+    for file in files:
+      # ... and for each OWNERS file in the main ...
+      if file == 'OWNERS':
+        rel_dir = pathlib.Path(subdir[len(main_dir.name) + 1:])
+        owners = rel_dir / file
+
+        target = tracking_dir / owners
+        comment_line = (f'# include OWNERS from the authoritative '
+                        f'{main_branch} branch\n')
+        include_line = f'include kernel/common:{main_branch}:/{owners}\n'
+
+        # ... either add a new file with include directive ...
+        if not target.is_file():
+          with open(target, 'w') as file:
+            file.writelines([comment_line, include_line])
+
+        # ... or ensure the include directive is in the file
+        else:
+          with open(target) as file:
+            contents = file.readlines()
+          if include_line not in contents:
+            with open(target, 'w') as file:
+              file.writelines([comment_line, include_line, '\n'] + contents)
+
+
+def is_dir(dirname):
+  result = pathlib.Path(dirname)
+  if not result.is_dir():
+    raise argparse.ArgumentTypeError(f'{dirname} is not a directory')
+  else:
+    return result
+
+
+def main():
+  parser = argparse.ArgumentParser()
+
+  parser.add_argument(
+      'main_dir', type=is_dir, help='main directory to synchronize from')
+  parser.add_argument('main_branch', help='main branch name'),
+  parser.add_argument(
+      'tracking_dir', type=is_dir, help='tracking directory to synchronize to')
+
+  args = parser.parse_args()
+
+  process_owners(args.main_dir, args.main_branch, args.tracking_dir)
+
+
+if __name__ == '__main__':
+  sys.exit(main())