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#!/usr/bin/python
# Copyright (c) 2010 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.
"""Utilities for PyAuto."""
import logging
import os
import shutil
import tempfile
class ExistingPathReplacer(object):
"""Facilitates backing up a given path (file or dir)..
Often you want to manipulate a directory or file for testing but don't want to
meddle with the existing contents. This class lets you make a backup, and
reinstate the backup when done. A backup is made in an adjacent directory,
so you need to make sure you have write permissions to the parent directory.
Works seemlessly in cases where the requested path already exists, or not.
Automatically reinstates the backed up path (if any) when object is deleted.
"""
_path = ''
_backup_dir = None # dir to which existing content is backed up
_backup_basename = ''
def __init__(self, path, path_type='dir'):
"""Initialize the object, making backups if necessary.
Args:
path: the requested path to file or directory
path_type: path type. Options: 'file', 'dir'. Default: 'dir'
"""
assert path_type in ('file', 'dir'), 'Invalid path_type: %s' % path_type
self._path_type = path_type
self._path = path
if os.path.exists(self._path):
if 'dir' == self._path_type:
assert os.path.isdir(self._path), '%s is not a directory' % self._path
else:
assert os.path.isfile(self._path), '%s is not a file' % self._path
# take a backup
self._backup_basename = os.path.basename(self._path)
self._backup_dir = tempfile.mkdtemp(dir=os.path.dirname(self._path),
prefix='bkp-' + self._backup_basename)
logging.info('Backing up %s in %s' % (self._path, self._backup_dir))
shutil.move(self._path,
os.path.join(self._backup_dir, self._backup_basename))
self._CreateRequestedPath()
def __del__(self):
"""Cleanup. Reinstate backup."""
self._CleanupRequestedPath()
if self._backup_dir: # Reinstate, if backed up.
from_path = os.path.join(self._backup_dir, self._backup_basename)
logging.info('Reinstating backup from %s to %s' % (from_path, self._path))
shutil.move(from_path, self._path)
self._RemoveBackupDir()
def _CreateRequestedPath(self):
# Create intermediate dirs if needed.
if not os.path.exists(os.path.dirname(self._path)):
os.makedirs(os.path.dirname(self._path))
if 'dir' == self._path_type:
os.mkdir(self._path)
else:
open(self._path, 'w').close()
def _CleanupRequestedPath(self):
if os.path.exists(self._path):
if os.path.isdir(self._path):
shutil.rmtree(self._path, ignore_errors=True)
else:
os.remove(self._path)
def _RemoveBackupDir(self):
if self._backup_dir and os.path.isdir(self._backup_dir):
shutil.rmtree(self._backup_dir, ignore_errors=True)
def RemovePath(path):
"""Remove the given path (file or dir)."""
if os.path.isdir(path):
shutil.rmtree(path, ignore_errors=True)
return
try:
os.remove(path)
except OSError:
pass
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