sdk/platform-tools/systrace/catapult/devil/devil/android/device_temp_file.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 """A temp file that automatically gets pushed and deleted from a device."""
   6
   7 # pylint: disable=W0622
   8
   9 import posixpath
  10 import random
  11 import threading
  12
  13 from devil.android import device_errors
  14 from devil.utils import cmd_helper
  15
  16
  17 class DeviceTempFile(object):
  18
  19   def __init__(self, adb, suffix='', prefix='temp_file', dir='/data/local/tmp'):
  20     """Find an unused temporary file path on the device.
  21
  22     When this object is closed, the file will be deleted on the device.
  23
  24     Args:
  25       adb: An instance of AdbWrapper
  26       suffix: The suffix of the name of the temp file.
  27       prefix: The prefix of the name of the temp file.
  28       dir: The directory on the device where to place the temp file.
  29     Raises:
  30       ValueError if any of suffix, prefix, or dir are None.
  31     """
  32     if None in (dir, prefix, suffix):
  33       m = 'Provided None path component. (dir: %s, prefix: %s, suffix: %s)' % (
  34           dir, prefix, suffix)
  35       raise ValueError(m)
  36
  37     self._adb = adb
  38     # Python's random module use 52-bit numbers according to its docs.
  39     random_hex = hex(random.randint(0, 2 ** 52))[2:]
  40     self.name = posixpath.join(dir, '%s-%s%s' % (prefix, random_hex, suffix))
  41     self.name_quoted = cmd_helper.SingleQuote(self.name)
  42
  43   def close(self):
  44     """Deletes the temporary file from the device."""
  45     # ignore exception if the file is already gone.
  46     def delete_temporary_file():
  47       try:
  48         self._adb.Shell('rm -f %s' % self.name_quoted, expect_status=None)
  49       except device_errors.AdbCommandFailedError:
  50         # file does not exist on Android version without 'rm -f' support (ICS)
  51         pass
  52
  53     # It shouldn't matter when the temp file gets deleted, so do so
  54     # asynchronously.
  55     threading.Thread(
  56         target=delete_temporary_file,
  57         name='delete_temporary_file(%s)' % self._adb.GetDeviceSerial()).start()
  58
  59   def __enter__(self):
  60     return self
  61
  62   def __exit__(self, type, value, traceback):
  63     self.close()