Expose ability to download network service impl in SDK.

mojo/public/tools/download_network_service.py

 #!/usr/bin/env python
 # Copyright 2015 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.
 
 import argparse
 import os
 import sys
 import tempfile
 import zipfile
 
 _PLATFORMS = ["linux-x64", "android-arm"]
 _APPS = ["network_service", "network_service_apptests"]
 
 if not sys.platform.startswith("linux"):
   print "Not supported for your platform"
   sys.exit(0)
 
 # Add //tools to the system path so that we can import the gs helper.
 script_dir = os.path.dirname(os.path.realpath(__file__))
+
+# TODO(blundell): Determine whether to move gs.py into the SDK or to inline the
+# contents of that function in this file as is done in download_shell_binary.py.
 tools_path = os.path.join(script_dir, os.pardir, os.pardir, os.pardir, "tools")
 sys.path.insert(0, tools_path)
 # pylint: disable=F0401
 import gs
 
 
-def download_app(app, version, platform, prebuilt_directory):
+def download_app(app, version):
+  prebuilt_directory = os.path.join(script_dir, "prebuilt/%s" % app)
+  stamp_path = os.path.join(prebuilt_directory, "VERSION")
+
+  try:
+    with open(stamp_path) as stamp_file:
+      current_version = stamp_file.read().strip()
+      if current_version == version:
+        return  # Already have the right version.
+  except IOError:
+    pass  # If the stamp file does not exist we need to download a new binary.
+
+  for platform in _PLATFORMS:
+    download_app_for_platform(app, version, platform)
+
+  with open(stamp_path, 'w') as stamp_file:
+    stamp_file.write(version)
+
+def download_app_for_platform(app, version, platform):
   binary_name = app + ".mojo"
   gs_path = "gs://mojo/%s/%s/%s/%s.zip" % (app, version, platform, binary_name)
-  output_directory = os.path.join(prebuilt_directory, platform)
+  output_directory = os.path.join(script_dir,
+                                  "prebuilt/%s/%s" % (app, platform))
 
   with tempfile.NamedTemporaryFile() as temp_zip_file:
     gs.download_from_public_bucket(gs_path, temp_zip_file.name)
     with zipfile.ZipFile(temp_zip_file.name) as z:
       zi = z.getinfo(binary_name)
       mode = zi.external_attr >> 16
       z.extract(zi, output_directory)
       os.chmod(os.path.join(output_directory, binary_name), mode)
 
-
 def main():
   parser = argparse.ArgumentParser(
       description="Download prebuilt network service binaries from google " +
                   "storage")
   parser.parse_args()
 
-  prebuilt_directory_path = os.path.join(script_dir, "prebuilt")
-  stamp_path = os.path.join(prebuilt_directory_path, "STAMP")
-  version_path = os.path.join(script_dir, "VERSION")
+  version_path = os.path.join(script_dir, "NETWORK_SERVICE_VERSION")
   with open(version_path) as version_file:
     version = version_file.read().strip()
 
-  try:
-    with open(stamp_path) as stamp_file:
-      current_version = stamp_file.read().strip()
-      if current_version == version:
-        return 0  # Already have the right version.
-  except IOError:
-    pass  # If the stamp file does not exist we need to download a new binary.
+  for app in _APPS:
+    download_app(app, version)
 
-  for platform in _PLATFORMS:
-    for app in _APPS:
-      download_app(app, version, platform, prebuilt_directory_path)
-
-  with open(stamp_path, 'w') as stamp_file:
-    stamp_file.write(version)
   return 0
 
 
 if __name__ == "__main__":
   sys.exit(main())