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      1 # Copyright 2014 The Chromium Authors. All rights reserved.
      2 # Use of this source code is governed by a BSD-style license that can be
      3 # found in the LICENSE file.
      4 
      5 import json
      6 import logging
      7 import os
      8 import threading
      9 import time
     10 
     11 logger = logging.getLogger(__name__)
     12 
     13 
     14 class Blacklist(object):
     15 
     16   def __init__(self, path):
     17     self._blacklist_lock = threading.RLock()
     18     self._path = path
     19 
     20   def Read(self):
     21     """Reads the blacklist from the blacklist file.
     22 
     23     Returns:
     24       A dict containing bad devices.
     25     """
     26     with self._blacklist_lock:
     27       blacklist = dict()
     28       if not os.path.exists(self._path):
     29         return blacklist
     30 
     31       try:
     32         with open(self._path, 'r') as f:
     33           blacklist = json.load(f)
     34       except (IOError, ValueError) as e:
     35         logger.warning('Unable to read blacklist: %s', str(e))
     36         os.remove(self._path)
     37 
     38       if not isinstance(blacklist, dict):
     39         logger.warning('Ignoring %s: %s (a dict was expected instead)',
     40                         self._path, blacklist)
     41         blacklist = dict()
     42 
     43       return blacklist
     44 
     45   def Write(self, blacklist):
     46     """Writes the provided blacklist to the blacklist file.
     47 
     48     Args:
     49       blacklist: list of bad devices to write to the blacklist file.
     50     """
     51     with self._blacklist_lock:
     52       with open(self._path, 'w') as f:
     53         json.dump(blacklist, f)
     54 
     55   def Extend(self, devices, reason='unknown'):
     56     """Adds devices to blacklist file.
     57 
     58     Args:
     59       devices: list of bad devices to be added to the blacklist file.
     60       reason: string specifying the reason for blacklist (eg: 'unauthorized')
     61     """
     62     timestamp = time.time()
     63     event_info = {
     64         'timestamp': timestamp,
     65         'reason': reason,
     66     }
     67     device_dicts = {device: event_info for device in devices}
     68     logger.info('Adding %s to blacklist %s for reason: %s',
     69                  ','.join(devices), self._path, reason)
     70     with self._blacklist_lock:
     71       blacklist = self.Read()
     72       blacklist.update(device_dicts)
     73       self.Write(blacklist)
     74 
     75   def Reset(self):
     76     """Erases the blacklist file if it exists."""
     77     logger.info('Resetting blacklist %s', self._path)
     78     with self._blacklist_lock:
     79       if os.path.exists(self._path):
     80         os.remove(self._path)
     81