54c70766a4
It may make sense to create 'snapshot' volume out of already 'snapshot', not only 'origin'. In pracice it will exactly the same as 'snapshot connected directly to 'origin'. QubesOS/qubes-issues#866
518 lines
17 KiB
Python
518 lines
17 KiB
Python
#!/usr/bin/python2 -O
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# vim: fileencoding=utf-8
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#
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# The Qubes OS Project, https://www.qubes-os.org/
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#
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# Copyright (C) 2015 Joanna Rutkowska <joanna@invisiblethingslab.com>
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# Copyright (C) 2013-2015 Marek Marczykowski-Górecki
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# <marmarek@invisiblethingslab.com>
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# Copyright (C) 2015 Wojtek Porczyk <woju@invisiblethingslab.com>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along
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# with this program; if not, write to the Free Software Foundation, Inc.,
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# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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#
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from __future__ import absolute_import
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import os
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import os.path
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import re
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import subprocess
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from qubes.storage import Pool, StoragePoolException, Volume
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BLKSIZE = 512
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class FilePool(Pool):
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''' File based 'original' disk implementation '''
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driver = 'file'
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def __init__(self, name=None, dir_path=None):
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super(FilePool, self).__init__(name=name)
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assert dir_path, "No pool dir_path specified"
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self.dir_path = os.path.normpath(dir_path)
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def clone(self, source, target):
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''' Clones the volume if the `source.pool` if the source is a
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:py:class:`FileVolume`.
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'''
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if issubclass(FileVolume, source.__class__):
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raise StoragePoolException('Volumes %s and %s use different pools'
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% (source.__class__, target.__class__))
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if source.volume_type not in ['origin', 'read-write']:
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return target
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copy_file(source.vid, target.vid)
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return target
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def create(self, volume, source_volume=None):
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_type = volume.volume_type
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size = volume.size
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if _type == 'origin':
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create_sparse_file(volume.path_origin, size)
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create_sparse_file(volume.path_cow, size)
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elif _type in ['read-write'] and source_volume:
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copy_file(source_volume.path, volume.path)
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elif _type in ['read-write', 'volatile']:
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create_sparse_file(volume.path, size)
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return volume
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@property
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def config(self):
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return {
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'name': self.name,
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'dir_path': self.dir_path,
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'driver': FilePool.driver,
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}
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def resize(self, volume, size):
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''' Expands volume, throws
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:py:class:`qubst.storage.StoragePoolException` if given size is
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less than current_size
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'''
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_type = volume.volume_type
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if _type not in ['origin', 'read-write', 'volatile']:
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raise StoragePoolException('Can not resize a %s volume %s' %
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(_type, volume.vid))
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if size <= volume.size:
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raise StoragePoolException(
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'For your own safety, shrinking of %s is'
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' disabled. If you really know what you'
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' are doing, use `truncate` on %s manually.' %
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(volume.name, volume.vid))
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if _type == 'origin':
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path = volume.path_origin
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elif _type in ['read-write', 'volatile']:
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path = volume.path
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with open(path, 'a+b') as fd:
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fd.truncate(size)
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self._resize_loop_device(path)
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def remove(self, volume):
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if volume.volume_type in ['read-write', 'volatile']:
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_remove_if_exists(volume)
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elif volume.volume_type == 'origin':
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_remove_if_exists(volume)
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def rename(self, volume, old_name, new_name):
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assert issubclass(volume.__class__, FileVolume)
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old_dir = os.path.dirname(volume.path)
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new_dir = os.path.join(os.path.dirname(old_dir), new_name)
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if not os.path.exists(new_dir):
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os.makedirs(new_dir)
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if volume.volume_type == 'read-write':
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volume.rename_target_dir(new_name, new_dir)
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elif volume.volume_type == 'read-only':
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volume.rename_target_dir(old_name, new_dir)
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elif volume.volume_type in ['origin', 'volatile']:
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volume.rename_target_dir(new_dir)
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return volume
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def _resize_loop_device(self, path):
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# find loop device if any
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p = subprocess.Popen(
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['sudo', 'losetup', '--associated', path],
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stdout=subprocess.PIPE)
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result = p.communicate()
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m = re.match(r'^(/dev/loop\d+):\s', result[0])
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if m is not None:
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loop_dev = m.group(1)
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# resize loop device
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subprocess.check_call(['sudo', 'losetup', '--set-capacity',
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loop_dev])
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def commit_template_changes(self, volume):
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if volume.volume_type != 'origin':
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return volume
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if os.path.exists(volume.path_cow):
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os.rename(volume.path_cow, volume.path_cow + '.old')
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old_umask = os.umask(002)
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with open(volume.path_cow, 'w') as f_cow:
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f_cow.truncate(volume.size)
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os.umask(old_umask)
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return volume
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def destroy(self):
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pass
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def setup(self):
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create_dir_if_not_exists(self.dir_path)
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appvms_path = os.path.join(self.dir_path, 'appvms')
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create_dir_if_not_exists(appvms_path)
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vm_templates_path = os.path.join(self.dir_path, 'vm-templates')
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create_dir_if_not_exists(vm_templates_path)
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def start(self, volume):
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if volume.volume_type == 'volatile':
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self._reset_volume(volume)
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if volume.volume_type in ['origin', 'snapshot']:
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_check_path(volume.path_origin)
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_check_path(volume.path_cow)
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else:
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_check_path(volume.path)
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return volume
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def stop(self, volume):
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pass
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def _reset_volume(self, volume):
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''' Remove and recreate a volatile volume '''
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assert volume.volume_type == 'volatile', "Not a volatile volume"
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assert volume.size
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_remove_if_exists(volume)
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with open(volume.path, "w") as f_volatile:
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f_volatile.truncate(volume.size)
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return volume
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def target_dir(self, vm):
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""" Returns the path to vmdir depending on the type of the VM.
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The default QubesOS file storage saves the vm images in three
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different directories depending on the ``QubesVM`` type:
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* ``appvms`` for ``QubesAppVm`` or ``QubesHvm``
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* ``vm-templates`` for ``QubesTemplateVm`` or ``QubesTemplateHvm``
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Args:
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vm: a QubesVM
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pool_dir: the root directory of the pool
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Returns:
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string (str) absolute path to the directory where the vm files
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are stored
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"""
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if vm.is_template():
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subdir = 'vm-templates'
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elif vm.is_disposablevm():
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subdir = 'appvms'
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return os.path.join(self.dir_path, subdir,
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vm.template.name + '-dvm')
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else:
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subdir = 'appvms'
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return os.path.join(self.dir_path, subdir, vm.name)
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def init_volume(self, vm, volume_config):
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assert 'volume_type' in volume_config, "Volume type missing " \
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+ str(volume_config)
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volume_type = volume_config['volume_type']
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known_types = {
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'read-write': ReadWriteFile,
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'read-only': ReadOnlyFile,
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'origin': OriginFile,
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'snapshot': SnapshotFile,
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'volatile': VolatileFile,
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}
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if volume_type not in known_types:
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raise StoragePoolException("Unknown volume type " + volume_type)
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if volume_type in ['snapshot', 'read-only']:
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name = volume_config['name']
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origin_vm = vm
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while hasattr(origin_vm, 'template') and \
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origin_vm.volume_config[name]['volume_type'] == \
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volume_type:
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origin_vm = origin_vm.template
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expected_origin_type = {
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'snapshot': 'origin',
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'read-only': 'read-write', # FIXME: really?
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}[volume_type]
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assert origin_vm.volume_config[name]['volume_type'] == \
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expected_origin_type
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origin_pool = vm.app.get_pool(origin_vm.volume_config[name]['pool'])
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assert isinstance(origin_pool,
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FilePool), 'Origin volume not a file volume'
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volume_config['target_dir'] = origin_pool.target_dir(origin_vm)
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volume_config['size'] = origin_vm.volume_config[name]['size']
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else:
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volume_config['target_dir'] = self.target_dir(vm)
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return known_types[volume_type](**volume_config)
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class FileVolume(Volume):
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''' Parent class for the xen volumes implementation which expects a
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`target_dir` param on initialization.
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'''
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def __init__(self, target_dir, **kwargs):
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self.target_dir = target_dir
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assert self.target_dir, "target_dir not specified"
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super(FileVolume, self).__init__(**kwargs)
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class SizeMixIn(FileVolume):
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''' A mix in which expects a `size` param to be > 0 on initialization and
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provides a usage property wrapper.
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'''
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def __init__(self, size=0, **kwargs):
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assert size, 'Empty size provided'
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assert size > 0, 'Size for volume ' + kwargs['name'] + ' is <=0'
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super(SizeMixIn, self).__init__(size=int(size), **kwargs)
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@property
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def usage(self):
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''' Returns the actualy used space '''
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return get_disk_usage(self.vid)
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@property
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def config(self):
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''' return config data for serialization to qubes.xml '''
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return {'name': self.name,
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'pool': self.pool,
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'size': str(self.size),
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'volume_type': self.volume_type}
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class ReadWriteFile(SizeMixIn):
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''' Represents a readable & writable file image based volume '''
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def __init__(self, **kwargs):
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super(ReadWriteFile, self).__init__(**kwargs)
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self.path = os.path.join(self.target_dir, self.name + '.img')
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self.vid = self.path
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def rename_target_dir(self, new_name, new_dir):
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''' Called by :py:class:`FilePool` when a domain changes it's name '''
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old_path = self.path
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file_name = os.path.basename(self.path)
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new_path = os.path.join(new_dir, file_name)
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os.rename(old_path, new_path)
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self.target_dir = new_dir
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self.path = new_path
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self.vid = self.path
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class ReadOnlyFile(FileVolume):
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''' Represents a readonly file image based volume '''
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usage = 0
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def __init__(self, size=0, **kwargs):
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super(ReadOnlyFile, self).__init__(size=int(size), **kwargs)
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self.path = self.vid
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def rename_target_dir(self, old_name, new_dir):
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""" Called by :py:class:`FilePool` when a domain changes it's name.
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Only copies the volume if it belongs to the domain being renamed.
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Currently if a volume is in a directory named the same as the domain,
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it's ”owned” by the domain.
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"""
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if os.path.basename(self.target_dir) == old_name:
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file_name = os.path.basename(self.path)
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new_path = os.path.join(new_dir, file_name)
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old_path = self.path
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os.rename(old_path, new_path)
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self.target_dir = new_dir
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self.path = new_path
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self.vid = self.path
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class OriginFile(SizeMixIn):
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''' Represents a readable, writeable & snapshotable file image based volume.
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This is used for TemplateVM's
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'''
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script = 'block-origin'
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def __init__(self, **kwargs):
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super(OriginFile, self).__init__(**kwargs)
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self.path_origin = os.path.join(self.target_dir, self.name + '.img')
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self.path_cow = os.path.join(self.target_dir, self.name + '-cow.img')
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self.path = '%s:%s' % (self.path_origin, self.path_cow)
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self.vid = self.path_origin
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def commit(self):
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''' Commit Template changes '''
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raise NotImplementedError
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def rename_target_dir(self, new_dir):
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''' Called by :py:class:`FilePool` when a domain changes it's name '''
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old_path_origin = self.path_origin
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old_path_cow = self.path_cow
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new_path_origin = os.path.join(new_dir, self.name + '.img')
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new_path_cow = os.path.join(new_dir, self.name + '-cow.img')
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os.rename(old_path_origin, new_path_origin)
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os.rename(old_path_cow, new_path_cow)
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self.target_dir = new_dir
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self.path_origin = new_path_origin
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self.path_cow = new_path_cow
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self.path = '%s:%s' % (self.path_origin, self.path_cow)
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self.vid = self.path_origin
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@property
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def usage(self):
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result = 0
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if os.path.exists(self.path_origin):
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result += get_disk_usage(self.path_origin)
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if os.path.exists(self.path_cow):
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result += get_disk_usage(self.path_cow)
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return result
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class SnapshotFile(FileVolume):
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''' Represents a readonly snapshot of an :py:class:`OriginFile` volume '''
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script = 'block-snapshot'
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rw = False
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usage = 0
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def __init__(self, name=None, size=None, **kwargs):
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assert size
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super(SnapshotFile, self).__init__(name=name, size=int(size), **kwargs)
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self.path_origin = os.path.join(self.target_dir, name + '.img')
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self.path_cow = os.path.join(self.target_dir, name + '-cow.img')
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self.path = '%s:%s' % (self.path_origin, self.path_cow)
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self.vid = self.path_origin
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class VolatileFile(SizeMixIn):
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''' Represents a readable & writeable file based volume, which will be
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discarded and recreated at each startup.
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'''
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def __init__(self, **kwargs):
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super(VolatileFile, self).__init__(**kwargs)
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self.path = os.path.join(self.target_dir, self.name + '.img')
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self.vid = self.path
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def rename_target_dir(self, new_dir):
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''' Called by :py:class:`FilePool` when a domain changes it's name '''
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_remove_if_exists(self)
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file_name = os.path.basename(self.path)
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self.target_dir = new_dir
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new_path = os.path.join(new_dir, file_name)
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self.path = new_path
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self.vid = self.path
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def create_sparse_file(path, size):
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''' Create an empty sparse file '''
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if os.path.exists(path):
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raise IOError("Volume %s already exists", path)
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parent_dir = os.path.dirname(path)
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if not os.path.exists(parent_dir):
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os.makedirs(parent_dir)
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with open(path, 'a+b') as fh:
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fh.truncate(size)
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def get_disk_usage_one(st):
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'''Extract disk usage of one inode from its stat_result struct.
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If known, get real disk usage, as written to device by filesystem, not
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logical file size. Those values may be different for sparse files.
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:param os.stat_result st: stat result
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:returns: disk usage
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'''
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try:
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return st.st_blocks * BLKSIZE
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except AttributeError:
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return st.st_size
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def get_disk_usage(path):
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'''Get real disk usage of given path (file or directory).
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When *path* points to directory, then it is evaluated recursively.
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This function tries estiate real disk usage. See documentation of
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:py:func:`get_disk_usage_one`.
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:param str path: path to evaluate
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:returns: disk usage
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'''
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try:
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st = os.lstat(path)
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except OSError:
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return 0
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ret = get_disk_usage_one(st)
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# if path is not a directory, this is skipped
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for dirpath, dirnames, filenames in os.walk(path):
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for name in dirnames + filenames:
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ret += get_disk_usage_one(os.lstat(os.path.join(dirpath, name)))
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return ret
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def create_dir_if_not_exists(path):
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""" Check if a directory exists in if not create it.
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This method does not create any parent directories.
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"""
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if not os.path.exists(path):
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os.mkdir(path)
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def copy_file(source, destination):
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'''Effective file copy, preserving sparse files etc.
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'''
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# TODO: Windows support
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# We prefer to use Linux's cp, because it nicely handles sparse files
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assert os.path.exists(source), \
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"Missing the source %s to copy from" % source
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assert not os.path.exists(destination), \
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"Destination %s already exists" % destination
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parent_dir = os.path.dirname(destination)
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if not os.path.exists(parent_dir):
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os.makedirs(parent_dir)
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try:
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subprocess.check_call(['cp', '--reflink=auto', source, destination])
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except subprocess.CalledProcessError:
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raise IOError('Error while copying {!r} to {!r}'.format(source,
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destination))
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def _remove_if_exists(volume):
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if os.path.exists(volume.path):
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os.remove(volume.path)
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if volume.volume_type == 'origin':
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|
os.remove(volume.path_cow)
|
|
|
|
|
|
def _check_path(path):
|
|
''' Raise an StoragePoolException if ``path`` does not exist'''
|
|
if not os.path.exists(path):
|
|
raise StoragePoolException('Missing image file: %s' % path)
|