Use luci-config for infrequently changing settings, part 2.

appengine/components/tools/compile_proto.py

 #!/usr/bin/env python
 # Copyright 2014 The Swarming Authors. All rights reserved.
 # Use of this source code is governed by the Apache v2.0 license that can be
 # found in the LICENSE file.
 
 """Compiles all *.proto files it finds into *_pb2.py."""
 
 import logging
 import optparse
 import os
 import re
 import shutil
 import subprocess
 import sys
 import tempfile
 
 
+# Directory with this file.
+THIS_DIR = os.path.dirname(os.path.abspath(__file__))
+
+
 # Printed if protoc is missing or too old.
 PROTOC_INSTALL_HELP = r"""Could not find working protocol buffers compiler.
 
-To install it on Linux run install_protoc.py.
+To install it on Linux and Mac run %s.
 
-On Windows and Mac you are on your own.
-"""
+On Windows you are on your own.
+""" % (os.path.join(THIS_DIR, 'install_protoc.py'))
 
 
-# Directory with this file.
-THIS_DIR = os.path.dirname(os.path.abspath(__file__))
-
 # Where to look for 'protoc' first (before hitting PATH). install_protoc.py
 # installs protoc there.
 DEFAULT_PROTOC_DIR = os.path.join(THIS_DIR, 'protoc')
 
 # Minimally required protoc version.
 MIN_SUPPORTED_PROTOC_VERSION = (2, 5, 0)
+# Maximally supported protoc version.
+MAX_SUPPORTED_PROTOC_VERSION = (2, 5, 9)
 
 # Paths that should not be searched for *.proto.
 BLACKLISTED_PATHS = [
   re.compile(r'.*(/|\\)third_party(/|\\)?'),
 ]
 
 
 def is_blacklisted(path, blacklist):
   """True if |path| matches any regexp in |blacklist|."""
   return any(b.match(path) for b in blacklist)
@@ skipping 130 matching lines @@
   protoc_version = get_protoc_version()
   if protoc_version is None or protoc_version < MIN_SUPPORTED_PROTOC_VERSION:
     if protoc_version:
       existing = '.'.join(map(str, protoc_version))
       expected = '.'.join(map(str, MIN_SUPPORTED_PROTOC_VERSION))
       print >> sys.stderr, (
           'protoc version is too old (%s), expecting at least %s.\n' %
           (existing, expected))
     sys.stderr.write(PROTOC_INSTALL_HELP)
     return 1
+  # Make sure protoc produces code compatible with vendored libprotobuf.
+  if protoc_version > MAX_SUPPORTED_PROTOC_VERSION:
+    existing = '.'.join(map(str, protoc_version))
+    expected = '.'.join(map(str, MAX_SUPPORTED_PROTOC_VERSION))
+    print >> sys.stderr, (
+        'protoc version is too new (%s), expecting at most %s.\n' %
+        (existing, expected))
+    sys.stderr.write(PROTOC_INSTALL_HELP)
+    return 1
 
   # Include default blacklisted paths.
   blacklisted_paths = list(blacklisted_paths or [])
   blacklisted_paths.extend(BLACKLISTED_PATHS)
 
   if options.check:
     success = check_all_files(root_dir, import_paths, blacklisted_paths)
   else:
     success = compile_all_files(root_dir, import_paths, blacklisted_paths)
 
   return int(not success)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))