backintime-common 1.1.12-2 / usr / share / backintime / common / encfstools.py

#    Copyright (C) 2012-2016 Germar Reitze
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License along
#    with this program; if not, write to the Free Software Foundation, Inc.,
#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

import os
import grp
import gettext
import subprocess
import re
import shutil
import tempfile
from datetime import datetime
from distutils.version import StrictVersion

import config
import mount
import password
import password_ipc
import tools
import sshtools
import logger
from exceptions import MountException, EncodeValueError
_=gettext.gettext

class EncFS_mount(mount.MountControl):
    """
    Mount encrypted paths with encfs.
    """

    CHECK_FUSE_GROUP = True

    def __init__(self, cfg = None, profile_id = None, hash_id = None, tmp_mount = False, parent = None, symlink = True, **kwargs):
        self.config = cfg
        if self.config is None:
            self.config = config.Config()

        self.profile_id = profile_id
        if self.profile_id is None:
            self.profile_id = self.config.get_current_profile()

        self.tmp_mount = tmp_mount
        self.hash_id = hash_id
        self.parent = parent
        self.symlink = symlink

        #init MountControl
        super(EncFS_mount, self).__init__()

        self.all_kwargs = {}

        self.setattr_kwargs('mode', self.config.get_snapshots_mode(self.profile_id), **kwargs)
        self.setattr_kwargs('hash_collision', self.config.get_hash_collision(), **kwargs)
        self.setattr_kwargs('path', self.config.get_local_encfs_path(self.profile_id), **kwargs)
        self.setattr_kwargs('reverse', False, **kwargs)
        self.setattr_kwargs('config_path', None, **kwargs)
        self.setattr_kwargs('password', None, store = False, **kwargs)
        self.setattr_kwargs('hash_id_1', None, **kwargs)
        self.setattr_kwargs('hash_id_2', None, **kwargs)

        self.set_default_args()

        self.symlink_subfolder = None
        self.log_command = '%s: %s' % (self.mode, self.path)

    def _mount(self):
        """mount the service"""
        if self.password is None:
            self.password = self.config.get_password(self.parent, self.profile_id, self.mode)
        logger.debug('Provide password through temp FIFO', self)
        thread = password_ipc.TempPasswordThread(self.password)
        env = self.get_env()
        env['ASKPASS_TEMP'] = thread.temp_file
        thread.start()

        encfs = ['encfs', '--extpass=backintime-askpass']
        if self.reverse:
            encfs += ['--reverse']
        if not self.is_configured():
            encfs += ['--standard']
        encfs += [self.path, self.mountpoint]
        logger.debug('Call mount command: %s'
                     %' '.join(encfs),
                     self)

        proc = subprocess.Popen(encfs, env = env,
                                stdout = subprocess.PIPE,
                                stderr = subprocess.STDOUT,
                                universal_newlines = True)
        output = proc.communicate()[0]
        self.backup_config()
        if proc.returncode:
            raise MountException( _('Can\'t mount \'%(command)s\':\n\n%(error)s') \
                                    % {'command': ' '.join(encfs), 'error': output} )

        thread.stop()

    def _umount(self):
        """umount the service"""
        try:
            subprocess.check_call(['fusermount', '-u', self.mountpoint])
        except subprocess.CalledProcessError:
            raise MountException( _('Can\'t unmount encfs %s') % self.mountpoint)

    def pre_mount_check(self, first_run = False):
        """check what ever conditions must be given for the mount"""
        self.check_fuse()
        if first_run:
            self.check_version()
        return True

    def post_mount_check(self):
        """check if mount was successful
           raise MountException( _('Error discription') ) if not"""
        return True

    def pre_umount_check(self):
        """check if service is safe to umount
           raise MountException( _('Error discription') ) if not"""
        return True

    def post_umount_check(self):
        """check if umount successful
           raise MountException( _('Error discription') ) if not"""
        return True

    def get_env(self):
        """return environment with encfs configfile"""
        env = os.environ.copy()
        cfg = self.get_config_file()
        if os.path.isfile(cfg):
            env['ENCFS6_CONFIG'] = cfg
        return env

    def get_config_file(self):
        """return encfs config file"""
        f = '.encfs6.xml'
        if self.config_path is None:
            cfg = os.path.join(self.path, f)
        else:
            cfg = os.path.join(self.config_path, f)
        return cfg

    def is_configured(self):
        """check if encfs config file exist. If not and if we are in settingsdialog
           ask for password confirmation. _mount will then create a new config"""
        cfg = self.get_config_file()
        if os.path.isfile(cfg):
            logger.debug('Found encfs config in %s'
                         %cfg, self)
            return True
        else:
            logger.debug('No encfs config in %s'
                         %cfg, self)
            msg = _('Config for encrypted folder not found.')
            if not self.tmp_mount:
                raise MountException( msg )
            else:
                if not self.config.ask_question( msg + _('\nCreate a new encrypted folder?')):
                    raise MountException( _('Cancel') )
                else:
                    pw = password.Password(self.config)
                    password_confirm = pw._get_password_from_user(self.parent, prompt = _('Please confirm password'))
                    if self.password == password_confirm:
                        return False
                    else:
                        raise MountException( _('Password doesn\'t match') )

    def check_fuse(self):
        """check if encfs is installed and user is part of group fuse"""
        logger.debug('Check fuse', self)
        if not tools.check_command('encfs'):
            logger.debug('sshfs is missing', self)
            raise MountException( _('encfs not found. Please install e.g. \'apt-get install encfs\'') )
        if self.CHECK_FUSE_GROUP:
            user = self.config.get_user()
            try:
                fuse_grp_members = grp.getgrnam('fuse')[3]
            except KeyError:
                #group fuse doesn't exist. So most likely it isn't used by this distribution
                logger.debug("Group fuse doesn't exist. Skip test", self)
                return
            if not user in fuse_grp_members:
                logger.debug('User %s is not in group fuse' %user, self)
                raise MountException( _('%(user)s is not member of group \'fuse\'.\n Run \'sudo adduser %(user)s fuse\'. To apply changes logout and login again.\nLook at \'man backintime\' for further instructions.') % {'user': user})

    def check_version(self):
        """check encfs version.
           1.7.2 had a bug with --reverse that will create corrupt files"""
        logger.debug('Check version', self)
        if self.reverse:
            proc = subprocess.Popen(['encfs', '--version'],
                                    stdout = subprocess.PIPE,
                                    stderr = subprocess.STDOUT,
                                    universal_newlines = True)
            output = proc.communicate()[0]
            m = re.search(r'(\d\.\d\.\d)', output)
            if m and StrictVersion(m.group(1)) <= StrictVersion('1.7.2'):
                logger.debug('Wrong encfs version %s' %m.group(1), self)
                raise MountException( _('encfs version 1.7.2 and before has a bug with option --reverse. Please update encfs'))

    def backup_config(self):
        """create a backup of encfs config file into local config folder
        so in cases of the config file get deleted or corrupt user can restore
        it from there"""
        cfg = self.get_config_file()
        if not os.path.isfile(cfg):
            logger.warning('No encfs config in %s. Skip backup of config file.' %cfg, self)
            return
        backup_folder = self.config.get_encfsconfig_backup_folder(self.profile_id)
        tools.make_dirs(backup_folder)
        old_backups = tools.get_nonsnapshots_list_in_folder(backup_folder, True)
        if len(old_backups):
            last_backup = os.path.join(backup_folder, old_backups[-1])

            #don't create a new backup if config hasn't changed
            if tools._get_md5sum_from_path(cfg) == \
               tools._get_md5sum_from_path(last_backup):
                logger.debug('Encfs config did not change. Skip backup', self)
                return

        new_backup_file = '.'.join((os.path.basename(cfg), datetime.now().strftime('%Y%m%d%H%M') ))
        new_backup = os.path.join(backup_folder, new_backup_file)
        logger.debug('Create backup of encfs config %s to %s'
                     %(cfg, new_backup), self)
        shutil.copy2(cfg, new_backup)

class EncFS_SSH(EncFS_mount):
    """Mount encrypted remote path with sshfs and encfs.
       Mount / with encfs --reverse.
       rsync will then sync the encrypted view on / to the remote path"""
    def __init__(self, cfg = None, profile_id = None, mode = None, parent = None,*args, **kwargs):
        self.config = cfg
        if self.config is None:
            self.config = config.Config()
        self.profile_id = profile_id
        if self.profile_id is None:
            self.profile_id = self.config.get_current_profile()
        self.mode = mode
        if self.mode is None:
            self.mode = self.config.get_snapshots_mode(self.profile_id)

        self.parent = parent
        self.args = args
        self.kwargs = kwargs

        self.ssh = sshtools.SSH(*self.args, symlink = False, **self.split_kwargs('ssh'))
        self.rev_root = EncFS_mount(*self.args, symlink = False, **self.split_kwargs('encfs_reverse'))
        super(EncFS_SSH, self).__init__(*self.args, **self.split_kwargs('encfs'))

    def mount(self, *args, **kwargs):
        """call mount for sshfs, encfs --reverse and encfs
           register 'encfsctl encode' in config.ENCODE"""
        logger.debug('Mount sshfs', self)
        self.ssh.mount(*args, **kwargs)
        #mount fsroot with encfs --reverse first.
        #If the config does not exist already this will make sure
        #the new created config works with --reverse
        if not os.path.isfile(self.get_config_file()):
            #encfs >= 1.8.0 changed behavior when ENCFS6_CONFIG environ variable
            #file does not exist. It will not create a new one anymore but just fail.
            #As encfs would create the config in /.encfs6.xml (which will most likly fail)
            #we need to mount a temp folder with reverse first and copy the config when done.
            logger.debug('Mount temp folder with encfs --reverse to create a new encfs config', self)
            with tempfile.TemporaryDirectory() as src:
                tmp_kwargs = self.split_kwargs('encfs_reverse')
                tmp_kwargs['path'] = src
                tmp_kwargs['config_path'] = src
                tmp_mount = EncFS_mount(*self.args, symlink = False, **tmp_kwargs)
                tmp_mount.mount(*args, **kwargs)
                tmp_mount.umount()
                cfg = tmp_mount.get_config_file()
                if os.path.isfile(cfg):
                    logger.debug('Copy new encfs config %s to its original place %s' %(cfg, self.ssh.mountpoint), self)
                    shutil.copy2(cfg, self.ssh.mountpoint)
                else:
                    logger.error('New encfs config %s not found' %cfg, self)
        logger.debug('Mount local filesystem root with encfs --reverse', self)
        self.rev_root.mount(*args, **kwargs)

        logger.debug('Mount encfs', self)
        kwargs['check'] = False
        ret = super(EncFS_SSH, self).mount(*args, **kwargs)
        self.config.ENCODE = Encode(self)
        return ret

    def umount(self, *args, **kwargs):
        """close 'encfsctl encode' process and set config.ENCODE back to the dummy class.
           call umount for encfs, encfs --reverse and sshfs"""
        self.config.ENCODE.close()
        self.config.ENCODE = Bounce()
        logger.debug('Unmount encfs', self)
        super(EncFS_SSH, self).umount(*args, **kwargs)
        logger.debug('Unmount local filesystem root mount encfs --reverse', self)
        self.rev_root.umount(*args, **kwargs)
        logger.debug('Unmount sshfs', self)
        self.ssh.umount(*args, **kwargs)

    def pre_mount_check(self, *args, **kwargs):
        """call pre_mount_check for sshfs, encfs --reverse and encfs"""
        if self.ssh.pre_mount_check(*args, **kwargs) and \
           self.rev_root.pre_mount_check(*args, **kwargs) and \
           super(EncFS_SSH, self).pre_mount_check(*args, **kwargs):
                return True

    def split_kwargs(self, mode):
        """split all given arguments for the desired mount class"""
        d = self.kwargs.copy()
        d['cfg']        = self.config
        d['profile_id'] = self.profile_id
        d['mode']       = self.mode
        d['parent']     = self.parent
        if mode == 'ssh':
            if 'path' in d:
                d.pop('path')
            if 'ssh_path' in d:
                d['path'] = d.pop('ssh_path')
            if 'ssh_password' in d:
                d['password'] = d.pop('ssh_password')
            else:
                d['password'] = self.config.get_password(parent = self.parent, profile_id = self.profile_id, mode = self.mode)
            if 'hash_id' in d:
                d.pop('hash_id')
            if 'hash_id_2' in d:
                d['hash_id'] = d['hash_id_2']
            return d

        elif mode == 'encfs':
            d['path'] = self.ssh.mountpoint
            d['hash_id_1'] = self.rev_root.hash_id
            d['hash_id_2'] = self.ssh.hash_id
            if 'encfs_password' in d:
                d['password'] = d.pop('encfs_password')
            else:
                d['password'] = self.config.get_password(parent = self.parent, profile_id = self.profile_id, mode = self.mode, pw_id = 2)
            return d

        elif mode == 'encfs_reverse':
            d['reverse'] = True
            d['path'] = '/'
            d['config_path'] = self.ssh.mountpoint
            if 'encfs_password' in d:
                d['password'] = d.pop('encfs_password')
            else:
                d['password'] = self.config.get_password(parent = self.parent, profile_id = self.profile_id, mode = self.mode, pw_id = 2)
            if 'hash_id' in d:
                d.pop('hash_id')
            if 'hash_id_1' in d:
                d['hash_id'] = d['hash_id_1']
            return d

class Encode(object):
    """encode path with encfsctl.
       ENCFS_SSH will replace config.ENCODE whit this"""
    def __init__(self, encfs):
        self.encfs = encfs
        self.password = self.encfs.password
        self.chroot = self.encfs.rev_root.mountpoint
        if not self.chroot[-1] == os.sep:
            self.chroot += os.sep
        self.remote_path = self.encfs.ssh.path
        if not self.remote_path[-1] == os.sep:
            self.remote_path += os.sep

        #precompile some regular expressions
        self.re_asterisk = re.compile(r'\*')
        self.re_separate_asterisk = re.compile(r'(.*?)(\*+)(.*)')

    def __del__(self):
        self.close()

    def start_process(self):
        """start 'encfsctl encode' process in pipe mode."""
        thread = password_ipc.TempPasswordThread(self.password)
        env = self.encfs.get_env()
        env['ASKPASS_TEMP'] = thread.temp_file
        thread.start()

        logger.debug('start \'encfsctl encode\' process', self)
        encfsctl = ['encfsctl', 'encode', '--extpass=backintime-askpass', '/']
        logger.debug('Call command: %s'
                     %' '.join(encfsctl),
                     self)
        self.p = subprocess.Popen(encfsctl, env = env, bufsize = 0,
                                stdin=subprocess.PIPE,
                                stdout=subprocess.PIPE,
                                universal_newlines = True)
        thread.stop()

    def path(self, path):
        """write plain path to encfsctl stdin and read encrypted path from stdout"""
        if not 'p' in vars(self):
            self.start_process()
        if not self.p.returncode is None:
            logger.warning('\'encfsctl encode\' process terminated. Restarting.', self)
            del self.p
            self.start_process()
        self.p.stdin.write(path + '\n')
        ret = self.p.stdout.readline().strip('\n')
        if not len(ret) and len(path):
            logger.debug('Failed to encode %s. Got empty string'
                         %path, self)
            raise EncodeValueError()
        return ret

    def exclude(self, path):
        """encrypt paths for snapshots.take_snapshot exclude list.
           After encoding the path a wildcard would not match anymore
           so all paths with wildcards are ignored. Only single and double asterisk
           that will match a full file or folder name will work.
        """
        if tools.patternHasNotEncryptableWildcard(path):
            return None

        enc = ''
        m = self.re_asterisk.search(path)
        if not m is None:
            path_ = path[:]
            while True:
                #search for foo/*, foo/*/bar, */bar or **/bar
                #but not foo* or foo/*bar
                m = self.re_separate_asterisk.search(path_)
                if m is None:
                    return None
                if m.group(1):
                    if not m.group(1).endswith(os.sep):
                        return None
                    enc = os.path.join(enc, self.path(m.group(1)) )
                enc = os.path.join(enc, m.group(2) )
                if m.group(3):
                    if not m.group(3).startswith(os.sep):
                        return None
                    m1 = self.re_asterisk.search(m.group(3))
                    if m1 is None:
                        enc = os.path.join(enc, self.path(m.group(3)) )
                        break
                    else:
                        path_ = m.group(3)
                        continue
                else:
                    break
        else:
            enc = self.path(path)
        if os.path.isabs(path):
            return os.path.join(os.sep, enc)
        return enc

    def include(self, path):
        """encrypt paths for snapshots.take_snapshot include list."""
        return os.path.join(os.sep, self.path(path))

    def remote(self, path):
        """encode the path on remote host starting from backintime/host/user/..."""
        enc_path = self.path( path[len(self.remote_path):] )
        return os.path.join(self.remote_path, enc_path)

    def close(self):
        """stop encfsctl process"""
        if 'p' in vars(self) and self.p.returncode is None:
            logger.debug('stop \'encfsctl encode\' process', self)
            self.p.communicate()

class Bounce(object):
    """Dummy class that will simply return all input.
       This is the standard for config.ENCODE"""
    def __init__(self):
        self.chroot = os.sep

    def path(self, path):
        return path

    def exclude(self, path):
        return path

    def include(self, path):
        return path

    def remote(self, path):
        return path

    def close(self):
        pass

class Decode(object):
    """decode path with encfsctl."""
    def __init__(self, cfg, string = True):
        self.mode = cfg.get_snapshots_mode()
        if self.mode == 'local_encfs':
            self.password = cfg.get_password(pw_id = 1)
        elif self.mode == 'ssh_encfs':
            self.password = cfg.get_password(pw_id = 2)
        self.encfs = cfg.SNAPSHOT_MODES[self.mode][0](cfg)
        self.remote_path = cfg.get_snapshots_path_ssh()
        if not self.remote_path:
            self.remote_path = './'
        if not self.remote_path[-1] == os.sep:
            self.remote_path += os.sep

        #german translation changed from Snapshot to Schnappschuss.
        #catch both variants otherwise old logs wouldn't get decoded.
        _take_snapshot = _('Take snapshot').replace('Schnappschuss', '(?:Schnappschuss|Snapshot)')

        #precompile some regular expressions
        host, port, user, path, cipher = cfg.get_ssh_host_port_user_path_cipher()
        #replace: --exclude"<crypted_path>" or --include"<crypted_path>"
        self.re_include_exclude = re.compile(r'(--(?:ex|in)clude=")(.*?)(")')

        #replace: 'USER@HOST:"PATH<crypted_path>"'
        self.re_remote_path =     re.compile(r'(\'%s@%s:"%s)(.*?)("\')' %(user, host, path) )

        #replace: --link-dest="../../<crypted_path>"
        self.re_link_dest =       re.compile(r'(--link-dest="\.\./\.\./)(.*?)(")')

        #search for: [C] <f+++++++++ <crypted_path>
        self.re_change = re.compile(r'(^\[C\] .{11} )(.*)')

        #search for: [I] Take snapshot (rsync: BACKINTIME: <f+++++++++ <crypted_path>)
        #            [I] Take snapshot (rsync: deleting <crypted_path>)
        #            [I] Take snapshot (rsync: rsync: readlink_stat("...mountpoint/<crypted_path>")
        #            [I] Take snapshot (rsync: rsync: send_files failed to open "...mountpoint/<crypted_path>": Permission denied (13))
        #            [I] Take snapshot (rsync: file has vanished: "...mountpoint/<crypted_path>")
        #            [I] Take snapshot (rsync: <crypted_path>)
        pattern = []
        pattern.append(r' BACKINTIME: .{11} ')
        pattern.append(r' deleting ')
        pattern.append(r' rsync: readlink_stat\(".*?mountpoint/')
        pattern.append(r' rsync: send_files failed to open ".*?mountpoint/')
        pattern.append(r' file has vanished: ".*?mountpoint/')
        pattern.append(r' ')
        self.re_info = re.compile(r'(^\[I\] %s \(rsync:(?:%s))(.*?)(\).*|".*)' % (_take_snapshot, '|'.join(pattern)) )

        #search for: [E] Error: rsync readlink_stat("...mountpoint/<crypted_path>")
        #            [E] Error: rsync: send_files failed to open "...mountpoint/<crypted_path>": Permission denied (13)
        #            [E] Error: rsync: recv_generator: failed to stat "...mountpoint/<crypted_path>": File name too long (36)
        pattern = []
        pattern.append(r' rsync: readlink_stat\(".*?mountpoint/')
        pattern.append(r' rsync: send_files failed to open ".*?mountpoint/')
        pattern.append(r' rsync: recv_generator: failed to stat ".*?mountpoint/')
        pattern.append(r' rsync: .*?".*?mountpoint/')
        self.re_error = re.compile(r'(^\[E\] Error:(?:%s))(.*?)(".*)' % '|'.join(pattern))

        #search for: [I] ssh USER@HOST cp -aRl "PATH<crypted_path>"* "PATH<crypted_path>"
        self.re_info_cp= re.compile(r'(^\[I\] .*? cp -aRl "%s/)(.*?)("\* "%s/)(.*?)(")' % (path, path) )

        #search for all chars except *
        self.re_all_except_asterisk = re.compile(r'[^\*]+')

        #search for: <crypted_path> -> <crypted_path>
        self.re_all_except_arrow = re.compile(r'(.*?)((?: [-=]> )+)(.*)')

        #skip: [I] Take snapshot (rsync: sending incremental file list)
        #      [I] Take snapshot (rsync: building file list ... done)
        #      [I] Take snapshot (rsync: sent 26569703 bytes  received 239616 bytes  85244.26 bytes/sec)
        #      [I] Take snapshot (rsync: total size is 9130263449  speedup is 340.56)
        #      [I] Take snapshot (rsync: rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1070) [sender=3.0.9])
        #      [I] Take snapshot (rsync: rsync warning: some files vanished before they could be transferred (code 24) at main.c(1070) [sender=3.0.9])
        pattern = []
        pattern.append(r'sending incremental file list')
        pattern.append(r'building file list ... done')
        pattern.append(r'sent .*? received')
        pattern.append(r'total size is .*? speedup is')
        pattern.append(r'rsync error: some files/attrs were not transferred')
        pattern.append(r'rsync warning: some files vanished before they could be transferred')
        self.re_skip = re.compile(r'^\[I\] %s \(rsync: (%s)' % (_take_snapshot, '|'.join(pattern)) )

        self.string = string
        if string:
            self.newline = '\n'
        else:
            self.newline = b'\n'

    def __del__(self):
        self.close()

    def start_process(self):
        """start 'encfsctl decode' process in pipe mode."""
        thread = password_ipc.TempPasswordThread(self.password)
        env = os.environ.copy()
        env['ASKPASS_TEMP'] = thread.temp_file
        thread.start()

        logger.debug('start \'encfsctl decode\' process', self)
        encfsctl = ['encfsctl', 'decode', '--extpass=backintime-askpass', self.encfs.path]
        logger.debug('Call command: %s'
                     %' '.join(encfsctl),
                     self)
        self.p = subprocess.Popen(encfsctl, env = env,
                                  stdin=subprocess.PIPE,
                                  stdout=subprocess.PIPE,
                                  universal_newlines = self.string,   #return string (if True) or bytes
                                  bufsize = 0)
        thread.stop()

    def path(self, path):
        """write crypted path to encfsctl stdin and read plain path from stdout
           if stdout is empty (most likly because there was an error) return crypt path"""
        if self.string:
            assert isinstance(path, str), 'path is not str type: %s' % path
        else:
            assert isinstance(path, bytes), 'path is not bytes type: %s' % path
        if not 'p' in vars(self):
            self.start_process()
        if not self.p.returncode is None:
            logger.warning('\'encfsctl decode\' process terminated. Restarting.', self)
            del self.p
            self.start_process()
        self.p.stdin.write(path + self.newline)
        ret = self.p.stdout.readline()
        ret = ret.strip(self.newline)
        if ret:
            return ret
        return path

    def list(self, list_):
        """decode a list of paths"""
        output = []
        for path in list_:
            output.append(self.path(path))
        return output

    def log(self, line):
        """decode paths in takesnapshot.log"""
        #rsync cmd
        if line.startswith('[I] rsync') or line.startswith('[I] nocache rsync'):
            line = self.re_include_exclude.sub(self.replace, line)
            line = self.re_remote_path.sub(self.replace, line)
            line = self.re_link_dest.sub(self.replace, line)
            return line
        #[C] Change lines
        m = self.re_change.match(line)
        if not m is None:
            return m.group(1) + self.path_with_arrow(m.group(2))
        #[I] Information lines
        m = self.re_skip.match(line)
        if not m is None:
            return line
        m = self.re_info.match(line)
        if not m is None:
            return m.group(1) + self.path_with_arrow(m.group(2)) + m.group(3)
        #[E] Error lines
        m = self.re_error.match(line)
        if not m is None:
            return m.group(1) + self.path(m.group(2)) + m.group(3)
        #cp cmd
        m = self.re_info_cp.match(line)
        if not m is None:
            return m.group(1) + self.path(m.group(2)) + m.group(3) + self.path(m.group(4)) + m.group(5)
        return line

    def replace(self, m):
        """return decoded string for re.sub"""
        decrypt = self.re_all_except_asterisk.sub(self.path_m, m.group(2))
        if os.path.isabs(m.group(2)):
            decrypt = os.path.join(os.sep, decrypt)
        return m.group(1) + decrypt + m.group(3)

    def path_m(self, m):
        """return decoded path of a match object"""
        return self.path(m.group(0))

    def path_with_arrow(self, path):
        """rsync print symlinks like 'dest -> src'. This will decode both and also normal paths"""
        m = self.re_all_except_arrow.match(path)
        if not m is None:
            return self.path(m.group(1)) + m.group(2) + self.path(m.group(3))
        else:
            return self.path(path)

    def remote(self, path):
        """decode the path on remote host starting from backintime/host/user/..."""
        assert isinstance(path, bytes), 'path is not bytes type: %s' % path

        remote_path = self.remote_path.encode()
        dec_path = self.path( path[len(remote_path):] )
        return os.path.join(remote_path, dec_path)

    def close(self):
        """stop encfsctl process"""
        if 'p' in vars(self) and self.p.returncode is None:
            logger.debug('stop \'encfsctl decode\' process', self)
            self.p.communicate()