Add input content checking to some build scripts

build/android/gyp/push_libraries.py

 #!/usr/bin/env python
 #
 # Copyright 2013 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.
 
 """Pushes native libraries to a device.
 
 """
 
 import json
 import optparse
 import os
 import sys
 
+from util import md5_check
+
 BUILD_ANDROID_DIR = os.path.join(os.path.dirname(__file__), '..')
 sys.path.append(BUILD_ANDROID_DIR)
 
 from pylib import android_commands
 from pylib import build_utils
 
 
 def DoPush(options):
   libraries = build_utils.ReadJson(options.libraries_json)
 
   adb = android_commands.AndroidCommands()
-  adb.RunShellCommand('mkdir ' + options.device_dir)
+  needs_directory = True
   for lib in libraries:
     device_path = os.path.join(options.device_dir, lib)
     host_path = os.path.join(options.libraries_dir, lib)
-    adb.PushIfNeeded(host_path, device_path)
+
+    md5_stamp = '%s.%s.md5' % (host_path, adb.Adb().GetSerialNumber())
+    md5_checker = md5_check.Md5Checker(stamp=md5_stamp, inputs=[host_path])
+    if md5_checker.IsStale():
+      if needs_directory:
+        adb.RunShellCommand('mkdir ' + options.device_dir)
+        needs_directory = False
+      adb.PushIfNeeded(host_path, device_path)
+    md5_checker.Write()
 
 
 def main(argv):
   parser = optparse.OptionParser()
   parser.add_option('--libraries-dir',
       help='Directory that contains stripped libraries.')
   parser.add_option('--device-dir',
       help='Device directory to push the libraries to.')
   parser.add_option('--libraries-json',
       help='Path to the json list of native libraries.')
   parser.add_option('--stamp', help='Path to touch on success.')
   options, _ = parser.parse_args()
 
   required_options = ['libraries_dir', 'device_dir', 'libraries_json']
   build_utils.CheckOptions(options, parser, required=required_options)
 
   DoPush(options)
 
   if options.stamp:
     build_utils.Touch(options.stamp)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))