sdk/platform-tools/systrace/catapult/devil/devil/android/device_temp_file.py

# Copyright 2013 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""A temp file that automatically gets pushed and deleted from a device."""

# pylint: disable=W0622

import logging
import posixpath
import random
import threading

from devil import base_error
from devil.android import device_errors
from devil.utils import cmd_helper

logger = logging.getLogger(__name__)


def _GenerateName(prefix, suffix, dir):
  random_hex = hex(random.randint(0, 2 ** 52))[2:]
  return posixpath.join(dir, '%s-%s%s' % (prefix, random_hex, suffix))


class DeviceTempFile(object):
  """A named temporary file on a device.

  Behaves like tempfile.NamedTemporaryFile.
  """

  def __init__(self, adb, suffix='', prefix='temp_file', dir='/data/local/tmp'):
    """Find an unused temporary file path on the device.

    When this object is closed, the file will be deleted on the device.

    Args:
      adb: An instance of AdbWrapper
      suffix: The suffix of the name of the temporary file.
      prefix: The prefix of the name of the temporary file.
      dir: The directory on the device in which the temporary file should be
        placed.
    Raises:
      ValueError if any of suffix, prefix, or dir are None.
    """
    if None in (dir, prefix, suffix):
      m = 'Provided None path component. (dir: %s, prefix: %s, suffix: %s)' % (
          dir, prefix, suffix)
      raise ValueError(m)

    self._adb = adb
    # Python's random module use 52-bit numbers according to its docs.
    self.name = _GenerateName(prefix, suffix, dir)
    self.name_quoted = cmd_helper.SingleQuote(self.name)

  def close(self):
    """Deletes the temporary file from the device."""
    # ignore exception if the file is already gone.
    def delete_temporary_file():
      try:
        self._adb.Shell('rm -f %s' % self.name_quoted, expect_status=None)
      except base_error.BaseError as e:
        # We don't really care, and stack traces clog up the log.
        # Log a warning and move on.
        logger.warning('Failed to delete temporary file %s: %s',
                        self.name, str(e))

    # It shouldn't matter when the temp file gets deleted, so do so
    # asynchronously.
    threading.Thread(
        target=delete_temporary_file,
        name='delete_temporary_file(%s)' % self._adb.GetDeviceSerial()).start()

  def __enter__(self):
    return self

  def __exit__(self, type, value, traceback):
    self.close()


class NamedDeviceTemporaryDirectory(object):
  """A named temporary directory on a device."""

  def __init__(self, adb, suffix='', prefix='tmp', dir='/data/local/tmp'):
    """Find an unused temporary directory path on the device. The directory is
    not created until it is used with a 'with' statement.

    When this object is closed, the directory will be deleted on the device.

    Args:
      adb: An instance of AdbWrapper
      suffix: The suffix of the name of the temporary directory.
      prefix: The prefix of the name of the temporary directory.
      dir: The directory on the device where to place the temporary directory.
    Raises:
      ValueError if any of suffix, prefix, or dir are None.
    """
    self._adb = adb
    self.name = _GenerateName(prefix, suffix, dir)
    self.name_quoted = cmd_helper.SingleQuote(self.name)

  def close(self):
    """Deletes the temporary directory from the device."""
    def delete_temporary_dir():
      try:
        self._adb.Shell('rm -rf %s' % self.name, expect_status=None)
      except device_errors.AdbCommandFailedError:
        pass

    threading.Thread(
        target=delete_temporary_dir,
        name='delete_temporary_dir(%s)' % self._adb.GetDeviceSerial()).start()

  def __enter__(self):
    self._adb.Shell('mkdir -p %s' % self.name)
    return self

  def __exit__(self, exc_type, exc_val, exc_tb):
    self.close()