Handle missing required arg in build/mac/find_sdk.py

build/mac/find_sdk.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """Prints the lowest locally available SDK version greater than or equal to a
 given minimum sdk version to standard output.
 
 Usage:
   python find_sdk.py 10.6  # Ignores SDKs < 10.6
@@ skipping 17 matching lines @@
   parser = OptionParser()
   parser.add_option("--verify",
                     action="store_true", dest="verify", default=False,
                     help="return the sdk argument and warn if it doesn't exist")
   parser.add_option("--sdk_path",
                     action="store", type="string", dest="sdk_path", default="",
                     help="user-specified SDK path; bypasses verification")
   parser.add_option("--print_sdk_path",
                     action="store_true", dest="print_sdk_path", default=False,
                     help="Additionaly print the path the SDK (appears first).")
-  (options, args) = parser.parse_args()
+  options, args = parser.parse_args()
+  if len(args) != 1:
+    parser.error('Please specify a minimum SDK version')
   min_sdk_version = args[0]
 
   job = subprocess.Popen(['xcode-select', '-print-path'],
                          stdout=subprocess.PIPE,
                          stderr=subprocess.STDOUT)
   out, err = job.communicate()
   if job.returncode != 0:
     print >> sys.stderr, out
     print >> sys.stderr, err
     raise Exception(('Error %d running xcode-select, you might have to run '
@@ skipping 32 matching lines @@
     print subprocess.check_output(['xcodebuild', '-version', '-sdk',
                                    'macosx' + best_sdk, 'Path']).strip()
 
   return best_sdk
 
 
 if __name__ == '__main__':
   if sys.platform != 'darwin':
     raise Exception("This script only runs on Mac")
   print main()
+  sys.exit(0)