common/python/rift/downloader/local_file.py

#
#   Copyright 2016 RIFT.IO 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.
#
# Taken from http://stackoverflow.com/a/27786580


import logging
import requests
import os
from urllib.parse import urlparse


class LocalFileAdapter(requests.adapters.BaseAdapter):
    """Protocol Adapter to allow Requests to GET file:// URLs

    @todo: Properly handle non-empty hostname portions.
    """

    @staticmethod
    def _chkpath(method, path):
        """Return an HTTP status for the given filesystem path."""
        if method.lower() in ('put', 'delete'):
            return 501, "Not Implemented"  # TODO
        elif method.lower() not in ('get', 'head'):
            return 405, "Method Not Allowed"
        elif os.path.isdir(path):
            return 400, "Path Not A File"
        elif not os.path.isfile(path):
            return 404, "File Not Found"
        elif not os.access(path, os.R_OK):
            return 403, "Access Denied"
        else:
            return 200, "OK"

    def send(self, req, **kwargs):  # pylint: disable=unused-argument
        """Return the file specified by the given request

        @type req: C{PreparedRequest}
        @todo: Should I bother filling `response.headers` and processing
               If-Modified-Since and friends using `os.stat`?
        """

        log = logging.getLogger('rw-mano-log')
        log.debug("Request: {}".format(req))

        url = urlparse(req.path_url)
        path = os.path.normcase(os.path.normpath(url.path))
        response = requests.Response()

        response.status_code, response.reason = self._chkpath(req.method, path)
        log.debug("Response {}: {}".format(response.status_code, response.reason))
        if response.status_code == 200 and req.method.lower() != 'head':
            try:
                response.raw = open(path, 'rb')
            except (OSError, IOError) as err:
                response.status_code = 500
                response.reason = str(err)

        if isinstance(req.url, bytes):
            response.url = req.url.decode('utf-8')
        else:
            response.url = req.url

        response.request = req
        response.connection = self


        log.debug("Response {}: {}".format(response.status_code, response))
        return response

    def close(self):
        pass