Added method for loading of the gatekeeper_trees.json config.

scripts/slave/gatekeeper_ng_config.py

 #!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Loads gatekeeper configuration files for use with gatekeeper_ng.py.
 
 The gatekeeper json configuration file has two main sections: 'masters'
 and 'categories.' The following shows the breakdown of a possible config,
 but note that all nodes are optional (including the root 'masters' and
@@ skipping 229 matching lines @@
           gatekeeper_builder['forgiving_steps'] |= gatekeeper_builder[
               'closing_steps']
           gatekeeper_builder['forgiving_optional'] |= gatekeeper_builder[
               'closing_optional']
           gatekeeper_builder['closing_steps'] = set([])
           gatekeeper_builder['closing_optional'] = set([])
 
   return gatekeeper_config
 
 
+def load_gatekeeper_tree_config(filename):
+  """Loads and verifies tree config json, returned loaded config json."""
+  with open(filename) as f:
+    trees_config = json.load(f)
+
+  tree_config_keys = ['masters',
+                      'build-db',
+                      'open-tree',
+                      'password-file',
+                      'revision-properties',
+                      'set-status',
+                      'status-url',
+                      'track-revisions']
+
+  for tree_name, tree_config in trees_config.iteritems():
+    allowed_keys(tree_config, *tree_config_keys)
+    assert isinstance(tree_name, basestring)
+
+    masters = tree_config.get('masters', [])
+    assert isinstance(masters, list)
+    assert all(isinstance(master, basestring) for master in masters)
+
+    assert isinstance(tree_config.get('build-db', ''), basestring)
+    assert isinstance(tree_config.get('open-tree', True), bool)
+    assert isinstance(tree_config.get('password-file', ''), basestring)
+    assert isinstance(tree_config.get('revision-properties', ''), basestring)
+    assert isinstance(tree_config.get('set-status', True), bool)
+    assert isinstance(tree_config.get('status-url', ''), basestring)
+    assert isinstance(tree_config.get('track-revisions', True), bool)
+
+  return trees_config
+
 def gatekeeper_section_hash(gatekeeper_section):
   st = cStringIO.StringIO()
   flatten_to_json(gatekeeper_section, st)
   return hashlib.sha256(st.getvalue()).hexdigest()
 
 
 def inject_hashes(gatekeeper_config):
   new_config = copy.deepcopy(gatekeeper_config)
   for master in new_config.values():
     for section in master:
@@ skipping 30 matching lines @@
     gatekeeper_config = inject_hashes(gatekeeper_config)
 
   flatten_to_json(gatekeeper_config, sys.stdout)
   print
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())