build/android/pylib/system_properties.py

   1 # Copyright 2013 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
   6 class SystemProperties(dict):
   7
   8   """A dict interface to interact with device system properties.
   9
  10   System properties are key/value pairs as exposed by adb shell getprop/setprop.
  11
  12   This implementation minimizes interaction with the physical device. It is
  13   valid for the lifetime of a boot.
  14   """
  15
  16   def __init__(self, android_commands):
  17     super(SystemProperties, self).__init__()
  18     self._adb = android_commands
  19     self._cached_static_properties = {}
  20
  21   def __getitem__(self, key):
  22     if self._IsStatic(key):
  23       if key not in self._cached_static_properties:
  24         self._cached_static_properties[key] = self._GetProperty(key)
  25       return self._cached_static_properties[key]
  26     return self._GetProperty(key)
  27
  28   def __setitem__(self, key, value):
  29     # TODO(tonyg): This can fail with no root. Verify that it succeeds.
  30     self._adb.SendShellCommand('setprop %s "%s"' % (key, value), retry_count=3)
  31
  32   @staticmethod
  33   def _IsStatic(key):
  34     # TODO(tonyg): This list is conservative and could be expanded as needed.
  35     return (key.startswith('ro.boot.') or
  36             key.startswith('ro.build.') or
  37             key.startswith('ro.product.'))
  38
  39   def _GetProperty(self, key):
  40     return self._adb.SendShellCommand('getprop %s' % key, retry_count=3).strip()