/usr/share/backintime/common/mount.py is in backintime-common 1.0.34-0.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#
# 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 subprocess
import socket
import json
import gettext
from zlib import crc32
from time import sleep
import config
import logger
import tools
import password
_=gettext.gettext
class MountException(Exception):
pass
class HashCollision(Exception):
pass
class Mount(object):
def __init__(self, cfg = None, profile_id = None, tmp_mount = False, parent = None):
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.parent = parent
if self.config.get_password_use_cache(self.profile_id):
pw_cache = password.Password_Cache(self.config)
action = None
running = pw_cache.status()
if not running:
action = 'start'
if running and not pw_cache.check_version():
action = 'restart'
if not action is None:
try:
subprocess.check_call(['backintime', '--pw-cache', action], stdout=open(os.devnull, 'w'))
except subprocess.CalledProcessError:
pass
def mount(self, mode = None, check = True, **kwargs):
if mode is None:
mode = self.config.get_snapshots_mode(self.profile_id)
if self.config.SNAPSHOT_MODES[mode][0] is None:
#mode doesn't need to mount
return 'local'
else:
while True:
try:
mounttools = self.config.SNAPSHOT_MODES[mode][0]
tools = mounttools(cfg = self.config, profile_id = self.profile_id,
tmp_mount = self.tmp_mount, mode = mode,
parent = self.parent, **kwargs)
return tools.mount(check = check)
except HashCollision as ex:
logger.warning(str(ex))
del tools
check = False
continue
break
def umount(self, hash_id = None):
if hash_id is None:
hash_id = self.config.current_hash_id
if hash_id == 'local':
#mode doesn't need to umount
return
else:
umount_info = os.path.join(self.config.MOUNT_ROOT, self.config.get_user(), 'mnt', hash_id, 'umount')
with open(umount_info, 'r') as f:
data_string = f.read()
f.close()
kwargs = json.loads(data_string)
mode = kwargs.pop('mode')
mounttools = self.config.SNAPSHOT_MODES[mode][0]
tools = mounttools(cfg = self.config, profile_id = self.profile_id,
tmp_mount = self.tmp_mount, mode = mode,
hash_id = hash_id, parent = self.parent, **kwargs)
tools.umount()
def pre_mount_check(self, mode = None, first_run = False, **kwargs):
"""called by SettingsDialog.save_profile() to check
if settings are correct before saving"""
if mode is None:
mode = self.config.get_snapshots_mode(self.profile_id)
if self.config.SNAPSHOT_MODES[mode][0] is None:
#mode doesn't need to mount
return True
else:
mounttools = self.config.SNAPSHOT_MODES[mode][0]
tools = mounttools(cfg = self.config, profile_id = self.profile_id,
tmp_mount = self.tmp_mount, mode = mode,
parent = self.parent, **kwargs)
return tools.pre_mount_check(first_run)
def remount(self, new_profile_id, mode = None, hash_id = None, **kwargs):
"""mode <= new profile
kwargs <= new profile
hash_id <= old profile
self.profile_id <= old profile"""
if mode is None:
mode = self.config.get_snapshots_mode(new_profile_id)
if hash_id is None:
hash_id = self.config.current_hash_id
if self.config.SNAPSHOT_MODES[mode][0] is None:
#new profile don't need to mount.
self.umount(hash_id = hash_id)
return 'local'
if hash_id == 'local':
#old profile don't need to umount.
self.profile_id = new_profile_id
return self.mount(mode = mode, **kwargs)
mounttools = self.config.SNAPSHOT_MODES[mode][0]
tools = mounttools(cfg = self.config, profile_id = new_profile_id,
tmp_mount = self.tmp_mount, mode = mode,
parent = self.parent, **kwargs)
if tools.compare_remount(hash_id):
#profiles uses the same settings. just swap the symlinks
tools.remove_symlink(profile_id = self.profile_id)
tools.set_symlink(profile_id = new_profile_id, hash_id = hash_id)
return hash_id
else:
#profiles are different. we need to umount and mount again
self.umount(hash_id = hash_id)
self.profile_id = new_profile_id
return self.mount(mode = mode, **kwargs)
class MountControl(object):
def __init__(self):
self.local_host = self.config.get_host()
self.local_user = self.config.get_user()
self.pid = self.config.get_pid()
def set_default_args(self):
#self.destination should contain all arguments that are nessesary for mount.
args = self.all_kwargs.keys()
self.destination = '%s:' % self.all_kwargs['mode']
args.remove('mode')
args.sort()
for arg in args:
self.destination += ' %s' % self.all_kwargs[arg]
#unique id for every different mount settings. Similar settings even in
#different profiles will generate the same hash_id and so share the same
#mountpoint
if self.hash_id is None:
self.hash_id = self.hash(self.destination)
self.mount_root = self.config.MOUNT_ROOT
self.mount_user_path = os.path.join(self.mount_root, self.local_user)
self.snapshots_path = self.config.get_snapshots_path(profile_id = self.profile_id, mode = self.mode, tmp_mount = self.tmp_mount)
self.hash_id_path = self.get_hash_id_path()
self.mountpoint = self.get_mountpoint()
self.lock_path = self.get_lock_path()
self.umount_info = self.get_umount_info()
def mount(self, check = True):
self.create_mountstructure()
self.mountprocess_lock_acquire()
try:
if self.is_mounted():
if not self.compare_umount_info():
#We probably have a hash collision
self.config.increment_hash_collision()
raise HashCollision( _('Hash collision occurred in hash_id %s. Incrementing global value hash_collision and try again.') % self.hash_id)
logger.info('Mountpoint %s is already mounted' % self.mountpoint)
else:
if check:
self.pre_mount_check()
self._mount()
self.post_mount_check()
logger.info('mount %s on %s' % (self.log_command, self.mountpoint))
self.write_umount_info()
except Exception:
raise
else:
self.set_mount_lock()
self.set_symlink()
finally:
self.mountprocess_lock_release()
return self.hash_id
def umount(self):
self.mountprocess_lock_acquire()
try:
if not os.path.isdir(self.hash_id_path):
logger.info('Mountpoint %s does not exist.' % self.hash_id_path)
else:
if not self.is_mounted():
logger.info('Mountpoint %s is not mounted' % self.hash_id_path)
else:
if self.check_mount_lock():
logger.info('Mountpoint %s still in use. Keep mounted' % self.mountpoint)
else:
self.pre_umount_check()
self._umount()
self.post_umount_check()
if len(os.listdir(self.mountpoint)) > 0:
logger.warning('Mountpoint %s not empty after unmount' % self.mountpoint)
else:
logger.info('unmount %s from %s' % (self.log_command, self.mountpoint))
except Exception:
raise
else:
self.del_mount_lock()
self.remove_symlink()
finally:
self.mountprocess_lock_release()
def is_mounted(self):
"""return True if path is is already mounted"""
if tools.check_mountpoint(self.mountpoint):
return True
else:
if len(os.listdir(self.mountpoint)) > 0:
raise MountException( _('mountpoint %s not empty.') % self.mountpoint)
return False
def create_mountstructure(self):
""" folder structure in /tmp/backintime/<user>/:
mnt/ <= used for mount points
<pid>.lock <= mountprocess lock that will prevent different
processes modifying mountpoints at one time
<hash_id>/ <= will be shared by all profiles with the same mount settings
mountpoint/ <= real mountpoint
umount <= json file with all nessesary args for unmount
locks/ <= for each process you have a <pid>.lock file
<profile id>_<pid>/ <= sym-link to the right path. return by config.get_snapshots_path
(can be ../mnt/<hash_id>/mount_point for ssh or
../mnt/<hash_id>/<HOST>/<SHARE> for fusesmb ...)
tmp_<profile id>_<pid>/ <= sym-link for testing mountpoints in settingsdialog
"""
self.mkdir(self.mount_root, 0777, force_chmod = True)
self.mkdir(self.mount_user_path, 0700)
self.mkdir(os.path.join(self.mount_user_path, 'mnt'), 0700)
self.mkdir(self.hash_id_path, 0700)
self.mkdir(self.mountpoint, 0700)
self.mkdir(self.lock_path, 0700)
def mkdir(self, path, mode = 0777, force_chmod = False):
if not os.path.isdir(path):
os.mkdir(path, mode)
if force_chmod:
#hack: debian and ubuntu won't set go+w on mkdir in tmp
os.chmod(path, mode)
def mountprocess_lock_acquire(self, timeout = 60):
"""block while an other process is mounting or unmounting"""
lock_path = os.path.join(self.mount_user_path, 'mnt')
lock_suffix = '.lock'
lock = self.pid + lock_suffix
count = 0
while self.check_locks(lock_path, lock_suffix):
count += 1
if count == timeout:
raise MountException( _('Mountprocess lock timeout') )
sleep(1)
with open(os.path.join(lock_path, lock), 'w') as f:
f.write(self.pid)
f.close()
def mountprocess_lock_release(self):
lock_path = os.path.join(self.mount_user_path, 'mnt')
lock_suffix = '.lock'
lock = os.path.join(lock_path, self.pid + lock_suffix)
if os.path.exists(lock):
os.remove(lock)
def set_mount_lock(self):
"""lock mount for this process"""
if self.tmp_mount:
lock_suffix = '.tmp.lock'
else:
lock_suffix = '.lock'
lock = self.pid + lock_suffix
with open(os.path.join(self.lock_path, lock), 'w') as f:
f.write(self.pid)
f.close()
def check_mount_lock(self):
"""return True if mount is locked by other processes"""
lock_suffix = '.lock'
return self.check_locks(self.lock_path, lock_suffix)
def del_mount_lock(self):
"""remove mount lock for this process"""
if self.tmp_mount:
lock_suffix = '.tmp.lock'
else:
lock_suffix = '.lock'
lock = os.path.join(self.lock_path, self.pid + lock_suffix)
if os.path.exists(lock):
os.remove(lock)
def check_process_alive(self, pid):
"""check if process is still alive"""
if os.path.exists(os.path.join('/proc', pid)):
return True
return False
def check_locks(self, path, lock_suffix):
"""return True if there are active locks"""
for file in os.listdir(path):
if not file[-len(lock_suffix):] == lock_suffix:
continue
is_tmp = False
if os.path.basename(file)[-len(lock_suffix)-len('.tmp'):-len(lock_suffix)] == '.tmp':
is_tmp = True
if is_tmp:
lock_pid = os.path.basename(file)[:-len('.tmp')-len(lock_suffix)]
else:
lock_pid = os.path.basename(file)[:-len(lock_suffix)]
if lock_pid == self.pid:
if is_tmp == self.tmp_mount:
continue
if self.check_process_alive(lock_pid):
return True
else:
#clean up
os.remove(os.path.join(path, file))
for symlink in os.listdir(self.mount_user_path):
if symlink.endswith('_%s' % lock_pid):
os.remove(os.path.join(self.mount_user_path, symlink))
return False
def setattr_kwargs(self, arg, default, store = True, **kwargs):
"""if kwargs[arg] exist set self.<arg> to kwargs[arg]
else set self.<arg> to default which should be the value from config"""
if arg in kwargs:
value = kwargs[arg]
else:
value = default
setattr(self, arg, value)
if store:
#make dictionary with all used args for umount
self.all_kwargs[arg] = value
def write_umount_info(self):
"""dump dictionary self.all_kwargs to umount_info file"""
data_string = json.dumps(self.all_kwargs)
with open(self.umount_info, 'w') as f:
f.write(data_string)
f.close
def read_umount_info(self, umount_info = None):
"""load dictionary kwargs from umount_info file"""
if umount_info is None:
umount_info = self.umount_info
with open(umount_info, 'r') as f:
data_string = f.read()
f.close()
return json.loads(data_string)
def compare_umount_info(self, umount_info = None):
"""just in case of hash collisions in <hash_id> we compare self.all_kwargs
with the old saved in umount_info file.
return True if both are identical"""
#run self.all_kwargs through json first
current_kwargs = json.loads(json.dumps(self.all_kwargs))
saved_kwargs = self.read_umount_info(umount_info)
if not len(current_kwargs) == len(saved_kwargs):
return False
for arg in current_kwargs.keys():
if not arg in saved_kwargs.keys():
return False
if not current_kwargs[arg] == saved_kwargs[arg]:
return False
return True
def compare_remount(self, old_hash_id):
"""return True if profiles are identiacal and we don't need to remount"""
if old_hash_id == self.hash_id:
return self.compare_umount_info(self.get_umount_info(old_hash_id))
return False
def set_symlink(self, profile_id = None, hash_id = None, tmp_mount = None):
if not self.symlink:
return
if profile_id is None:
profile_id = self.profile_id
if hash_id is None:
hash_id = self.hash_id
if tmp_mount is None:
tmp_mount = self.tmp_mount
dst = self.config.get_snapshots_path(profile_id = profile_id, mode = self.mode, tmp_mount = tmp_mount)
mountpoint = self.get_mountpoint(hash_id)
if self.symlink_subfolder is None:
src = mountpoint
else:
src = os.path.join(mountpoint, self.symlink_subfolder)
if os.path.exists(dst):
os.remove(dst)
os.symlink(src, dst)
def remove_symlink(self, profile_id = None, tmp_mount = None):
if not self.symlink:
return
if profile_id is None:
profile_id = self.profile_id
if tmp_mount is None:
tmp_mount = self.tmp_mount
os.remove(self.config.get_snapshots_path(profile_id = profile_id, mode = self.mode, tmp_mount = tmp_mount))
def hash(self, str):
"""return a hex crc32 hash of str"""
return('%X' % (crc32(str) & 0xFFFFFFFF))
def get_hash_id_path(self, hash_id = None):
if hash_id is None:
hash_id = self.hash_id
return os.path.join(self.mount_user_path, 'mnt', self.hash_id)
def get_mountpoint(self, hash_id = None):
return os.path.join(self.get_hash_id_path(hash_id), 'mountpoint')
def get_lock_path(self, hash_id = None):
return os.path.join(self.get_hash_id_path(hash_id), 'locks')
def get_umount_info(self, hash_id = None):
return os.path.join(self.get_hash_id_path(hash_id), 'umount')
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