heron/shell/src/python/handlers/filedatahandler.py

#!/usr/bin/env python3
# -*- encoding: utf-8 -*-

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#  or more contributor license agreements.  See the NOTICE file
#  distributed with this work for additional information
#  regarding copyright ownership.  The ASF licenses this file
#  to you 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
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#  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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#  under the License.


''' filedatahandler.py '''
import json
import os
import tornado.web

from heron.shell.src.python import utils

class FileDataHandler(tornado.web.RequestHandler):
  """
  Responsible for reading and returning the file data given the offset
  and length of file to be read.
  """
  @tornado.web.asynchronous
  def get(self, path):
    """ get method """
    if path is None:
      return {}

    if not utils.check_path(path):
      self.write("Only relative paths are allowed")
      self.set_status(403)
      self.finish()
      return

    offset = self.get_argument("offset", default=-1)
    length = self.get_argument("length", default=-1)
    if not os.path.isfile(path):
      return {}
    data = utils.read_chunk(path, offset=offset, length=length, escape_data=True)
    self.write(json.dumps(data))
    self.finish()