| #!/usr/bin/env python |
| # |
| # Copyright 2007 Google Inc. |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| # |
| """A simple handler to serve static assets.""" |
| |
| |
| |
| import logging |
| import mimetypes |
| import os |
| import os.path |
| import threading |
| |
| import google |
| import webapp2 |
| |
| ASSETS_PATH = os.path.join(os.path.dirname(__file__), 'assets') |
| |
| |
| class StaticFileHandler(webapp2.RequestHandler): |
| """A request handler for returning static files.""" |
| |
| _asset_name_to_path = None |
| _asset_name_to_path_lock = threading.Lock() |
| |
| @classmethod |
| def _initialize_asset_map(cls): |
| # Generating a list of acceptable asset files reduces the possibility of |
| # path attacks. |
| cls._asset_name_to_path = {} |
| assets = os.listdir(ASSETS_PATH) |
| for asset in assets: |
| path = os.path.join(ASSETS_PATH, asset) |
| if os.path.isfile(path): |
| cls._asset_name_to_path[os.path.basename(path)] = path |
| |
| def get(self, asset_name): |
| """Serve out the contents of a file to self.response. |
| |
| Args: |
| asset_name: The name of the static asset to serve. Must be in ASSETS_PATH. |
| """ |
| with self._asset_name_to_path_lock: |
| if self._asset_name_to_path is None: |
| self._initialize_asset_map() |
| |
| if asset_name in self._asset_name_to_path: |
| asset_path = self._asset_name_to_path[asset_name] |
| try: |
| with open(asset_path, 'rb') as f: |
| data = f.read() |
| except (OSError, IOError): |
| logging.exception('Error reading file %s', asset_path) |
| self.response.set_status(500) |
| else: |
| content_type, _ = mimetypes.guess_type(asset_path) |
| assert content_type, ( |
| 'cannot determine content-type for %r' % asset_path |
| ) |
| self.response.headers['Content-Type'] = content_type |
| self.response.out.write(data) |
| else: |
| self.response.set_status(404) |
| |