447 lines
18 KiB
Python
447 lines
18 KiB
Python
#
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# The Qubes OS Project, https://www.qubes-os.org/
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#
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# Copyright (C) 2020 David Hobach <david@hobach.de>
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library 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 GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, see <https://www.gnu.org/licenses/>.
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#
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import logging
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import subprocess
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import json
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from shlex import quote
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import qubes.storage
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class CallbackPool(qubes.storage.Pool):
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''' Proxy storage pool driver adding callback functionality to other pool drivers.
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This way, users can extend storage pool drivers with custom functionality using the programming language of their choice.
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All configuration for this pool driver must be done in `/etc/qubes_callback.json`. Each configuration ID `conf_id` can be used
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to create a callback pool with e.g. `qvm-pool -o conf_id=your_conf_id -a pool_name callback`.
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Check the `qubes_callback.json.example` for an overview of the available options.
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Example applications of this driver:
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- custom pool mounts
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- encryption
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- debugging
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**Integration tests**:
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(all of these tests assume the `qubes_callback.json.example` configuration)
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Tests that should **fail**:
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```
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qvm-pool -a test callback
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qvm-pool -o conf_id=non-existing -a test callback
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qvm-pool -o conf_id=conf_id -a test callback
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qvm-pool -o conf_id=testing-fail-missing-all -a test callback
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qvm-pool -o conf_id=testing-fail-missing-bdriver-args -a test callback
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```
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Tests that should **work**:
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```
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qvm-pool -o conf_id=testing-succ-file-01 -a test callback
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qvm-pool
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ls /mnt/test01
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qvm-pool -r test && sudo rm -rf /mnt/test01
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echo '#!/bin/bash'$'\n''i=0 ; for arg in "$@" ; do echo "$i: $arg" >> /tmp/callback.log ; (( i++)) ; done ; exit 0' > /usr/bin/testCbLogArgs && chmod +x /usr/bin/testCbLogArgs
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rm -f /tmp/callback.log
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qvm-pool -o conf_id=testing-succ-file-02 -a test callback
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qvm-pool
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ls /mnt/test02
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less /tmp/callback.log (on_ctor & on_setup should be there and in that order)
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qvm-create -l red -P test test-vm
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cat /tmp/callback.log (2x on_volume_create should be added)
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qvm-start test-vm
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qvm-volume | grep test-vm
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grep test-vm /var/lib/qubes/qubes.xml
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ls /mnt/test02/appvms/
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cat /tmp/callback.log (2x on_volume_start should be added)
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qvm-shutdown test-vm
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cat /tmp/callback.log (2x on_volume_stop should be added)
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#reboot
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cat /tmp/callback.log (only (!) on_ctor should be there)
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qvm-start test-vm
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cat /tmp/callback.log (on_sinit & 2x on_volume_start should be added)
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qvm-shutdown --wait test-vm && qvm-remove test-vm
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qvm-pool -r test && sudo rm -rf /mnt/test02
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less /tmp/callback.log (2x on_volume_stop, 2x on_volume_remove, on_destroy should be added)
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qvm-pool -o conf_id=testing-succ-file-03 -a test callback
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qvm-pool
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ls /mnt/test03
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less /tmp/callback.log (on_ctor & on_setup should be there, no more arguments)
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qvm-pool -r test && sudo rm -rf /mnt/test03
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less /tmp/callback.log (nothing should have been added)
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#luks pool test:
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#(make sure /mnt/test.key & /mnt/test.luks don't exist)
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qvm-pool -o conf_id=testing-succ-file-luks -a tluks callback
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ls /mnt/
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qvm-pool
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sudo cryptsetup status test-luks
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sudo mount | grep test_luks
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ls /mnt/test_luks/
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qvm-create -l red -P tluks test-luks (journalctl -b0 should show two on_volume_create callbacks)
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ls /mnt/test_luks/appvms/test-luks/
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qvm-volume | grep test-luks
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qvm-start test-luks
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#reboot
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grep luks /var/lib/qubes/qubes.xml
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sudo cryptsetup status test-luks (should be inactive due to late on_sinit!)
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qvm-start test-luks
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sudo mount | grep test_luks
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qvm-shutdown --wait test-luks
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qvm-remove test-luks
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qvm-pool -r tluks
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sudo cryptsetup status test-luks
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ls -l /mnt/
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#ephemeral luks pool test (key in RAM / lost on reboot):
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qvm-pool -o conf_id=testing-succ-file-luks-eph -a teph callback (executes setup() twice due to signal_back)
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ls /mnt/
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ls /mnt/ram
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md5sum /mnt/ram/teph.key (1)
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sudo mount|grep -E 'ram|test'
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sudo cryptsetup status test-eph
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qvm-create -l red -P teph test-eph (should execute two on_volume_create callbacks)
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qvm-volume | grep test-eph
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ls /mnt/test_eph/appvms
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qvm-start test-eph
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#reboot
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ls /mnt/ram (should be empty)
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ls /mnt/
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sudo mount|grep -E 'ram|test' (should be empty)
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qvm-ls | grep eph (should still have test-eph)
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grep eph /var/lib/qubes/qubes.xml (should still have test-eph)
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qvm-remove test-eph (should create a new encrypted pool backend)
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sudo cryptsetup status test-eph
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grep eph /var/lib/qubes/qubes.xml (only the pool should be left)
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ls /mnt/test_eph/ (should have the appvms directory etc.)
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qvm-create -l red -P teph test-eph2
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ls /mnt/test_eph/appvms/
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ls /mnt/ram
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qvm-start test-eph2
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md5sum /mnt/ram/teph.key ((2), different than in (1))
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qvm-shutdown --wait test-eph2
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systemctl restart qubesd
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qvm-start test-eph2 (trigger storage re-init)
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md5sum /mnt/ram/teph.key (same as in (2))
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qvm-shutdown test-eph2
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sudo umount /mnt/test_eph
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qvm-create -l red -P teph test-eph-fail (must fail with error in journalctl)
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ls /mnt/test_eph/ (should be empty)
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systemctl restart qubesd
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qvm-remove test-eph2
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qvm-create -l red -P teph test-eph3
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md5sum /mnt/ram/teph.key (same as in (2))
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sudo mount|grep -E 'ram|test'
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ls /mnt/test_eph/appvms/test_eph3
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qvm-remove test-eph3
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qvm-ls | grep test-eph
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qvm-pool -r teph
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grep eph /var/lib/qubes/qubes.xml (nothing should be left)
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qvm-pool
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ls /mnt/
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ls /mnt/ram/ (should be empty)
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```
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'''
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driver = 'callback'
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config_path = '/etc/qubes_callback.json'
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def __init__(self, *, name, conf_id):
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'''Constructor.
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:param conf_id: Identifier as found inside the user-controlled configuration at `/etc/qubes_callback.json`.
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Non-ASCII, non-alphanumeric characters may be disallowed.
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**Security Note**: Depending on your RPC policy (admin.pool.Add) this constructor and its parameters
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may be called from an untrusted VM (not by default though). In those cases it may be security-relevant
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not to pick easily guessable `conf_id` values for your configuration as untrusted VMs may otherwise
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execute callbacks meant for other pools.
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'''
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#NOTE: attribute names **must** start with `_cb_` unless they are meant to be stored as self._cb_impl attributes
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self._cb_ctor_done = False #: Boolean to indicate whether or not `__init__` successfully ran through.
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self._cb_log = logging.getLogger('qubes.storage.callback') #: Logger instance.
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if not isinstance(conf_id, str):
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raise qubes.storage.StoragePoolException('conf_id is no String. VM attack?!')
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self._cb_conf_id = conf_id #: Configuration ID as passed to `__init__`.
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with open(CallbackPool.config_path) as json_file:
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conf_all = json.load(json_file)
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if not isinstance(conf_all, dict):
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raise qubes.storage.StoragePoolException('The file %s is supposed to define a dict.' % CallbackPool.config_path)
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try:
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self._cb_conf = conf_all[self._cb_conf_id] #: Dictionary holding all configuration for the given _cb_conf_id.
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except KeyError:
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#we cannot throw KeyErrors as we'll otherwise generate incorrect error messages @qubes.app._get_pool()
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raise qubes.storage.StoragePoolException('The specified conf_id %s could not be found inside %s.' % (self._cb_conf_id, CallbackPool.config_path))
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try:
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bdriver = self._cb_conf['bdriver']
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except KeyError:
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raise qubes.storage.StoragePoolException('Missing bdriver for the conf_id %s inside %s.' % (self._cb_conf_id, CallbackPool.config_path))
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self._cb_cmd_arg = json.dumps(self._cb_conf, sort_keys=True, indent=2) #: Full configuration as string in the format required by _callback().
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try:
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cls = qubes.utils.get_entry_point_one(qubes.storage.STORAGE_ENTRY_POINT, bdriver)
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except KeyError:
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raise qubes.storage.StoragePoolException('The driver %s was not found on your system.' % bdriver)
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if not issubclass(cls, qubes.storage.Pool):
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raise qubes.storage.StoragePoolException('The class %s must be a subclass of qubes.storage.Pool.' % cls)
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self._cb_requires_init = self._check_init() #: Boolean indicating whether late storage initialization yet has to be done or not.
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bdriver_args = self._cb_conf.get('bdriver_args', {})
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self._cb_impl = cls(name=name, **bdriver_args) #: Instance of the backend pool driver.
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super().__init__(name=name, revisions_to_keep=int(bdriver_args.get('revisions_to_keep', 1)))
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self._cb_ctor_done = True
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self._callback('on_ctor')
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def _check_init(self):
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''' Whether or not this object requires late storage initialization via callback. '''
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cmd = self._cb_conf.get('on_sinit')
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if not cmd:
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cmd = self._cb_conf.get('cmd')
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return bool(cmd and cmd != '-')
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def _init(self, callback=True):
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''' Late storage initialization on first use for e.g. decryption on first usage request.
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:param callback: Whether to trigger the `on_sinit` callback or not.
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'''
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#maybe TODO: if this function is meant to be run in parallel (are Pool operations asynchronous?), a function lock is required!
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if callback:
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self._callback('on_sinit')
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self._cb_requires_init = False
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def _assert_initialized(self, **kwargs):
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if self._cb_requires_init:
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self._init(**kwargs)
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def _callback(self, cb, cb_args=None):
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'''Run a callback.
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:param cb: Callback identifier string.
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:param cb_args: Optional list of arguments to pass to the command as last arguments.
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Only passed on for the generic command specified as `cmd`, not for `on_xyz` callbacks.
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'''
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if self._cb_ctor_done:
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cmd = self._cb_conf.get(cb)
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args = [] #on_xyz callbacks should never receive arguments
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if not cmd:
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if cb_args is None:
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cb_args = []
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cmd = self._cb_conf.get('cmd')
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args = [self.name, self._cb_conf['bdriver'], cb, self._cb_cmd_arg, *cb_args]
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if cmd and cmd != '-':
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args = filter(None, args)
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args = ' '.join(quote(str(a)) for a in args)
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cmd = ' '.join(filter(None, [cmd, args]))
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self._cb_log.info('callback driver executing (%s, %s %s): %s', self._cb_conf_id, cb, cb_args, cmd)
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res = subprocess.run(['/bin/bash', '-c', cmd], check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
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#stdout & stderr are reported if the exit code check fails
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self._cb_log.debug('callback driver stdout (%s, %s %s): %s', self._cb_conf_id, cb, cb_args, res.stdout)
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self._cb_log.debug('callback driver stderr (%s, %s %s): %s', self._cb_conf_id, cb, cb_args, res.stderr)
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if self._cb_conf.get('signal_back', False) is True:
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self._process_signals(res.stdout)
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def _process_signals(self, out):
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'''Process any signals found inside a string.
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:param out: String to check for signals. Each signal must be on a dedicated line.
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They are executed in the order they are found. Callbacks are not triggered.
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'''
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for line in out.splitlines():
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if line == 'SIGNAL_setup':
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self._cb_log.info('callback driver processing SIGNAL_setup for %s', self._cb_conf_id)
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self._setup_cb(callback=False)
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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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'driver': CallbackPool.driver,
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'conf_id': self._cb_conf_id,
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}
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def destroy(self):
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self._assert_initialized()
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ret = self._cb_impl.destroy()
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self._callback('on_destroy')
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return ret
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def init_volume(self, vm, volume_config):
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return CallbackVolume(self, self._cb_impl.init_volume(vm, volume_config))
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def _setup_cb(self, callback=True):
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if callback:
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self._callback('on_setup')
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self._assert_initialized(callback=False) #setup is assumed to include storage initialization
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return self._cb_impl.setup()
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def setup(self):
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return self._setup_cb()
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@property
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def volumes(self):
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for vol in self._cb_impl.volumes:
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yield CallbackVolume(self, vol)
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def list_volumes(self):
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for vol in self._cb_impl.list_volumes():
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yield CallbackVolume(self, vol)
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def get_volume(self, vid):
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return CallbackVolume(self, self._cb_impl.get_volume(vid))
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def included_in(self, app):
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if self._cb_requires_init:
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return None
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return self._cb_impl.included_in(app)
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@property
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def size(self):
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if self._cb_requires_init:
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return None
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return self._cb_impl.size
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@property
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def usage(self):
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if self._cb_requires_init:
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return None
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return self._cb_impl.usage
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#remaining method & attribute delegation ("delegation pattern")
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#Convention: The methods of this object have priority over the delegated object's methods. All attributes are
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# passed to the delegated object unless their name starts with '_cb_'.
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def __getattr__(self, name):
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#NOTE: This method is only called when an attribute cannot be resolved locally (not part of the instance,
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# not part of the class tree). It is also called for methods that cannot be resolved.
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return getattr(self._cb_impl, name)
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def __setattr__(self, name, value):
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#NOTE: This method is called on every attribute assignment.
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if name.startswith('_cb_'):
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super().__setattr__(name, value)
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else:
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setattr(self._cb_impl, name, value)
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def __delattr__(self, name):
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if name.startswith('_cb_'):
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super().__delattr__(name)
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else:
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delattr(self._cb_impl, name)
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class CallbackVolume:
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''' Proxy volume adding callback functionality to other volumes.
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Required to support the `on_sinit` callback for late storage initialization.
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**Important for Developers**: Even though instances of this class behave exactly as `qubes.storage.Volume` instances,
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they are no such instances (e.g. `assert isinstance(obj, qubes.storage.Volume)` will fail).
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'''
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def __init__(self, pool, impl):
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'''Constructor.
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:param pool: `CallbackPool` of this volume
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:param impl: `qubes.storage.Volume` object to wrap
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'''
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assert isinstance(impl, qubes.storage.Volume), 'impl must be a qubes.storage.Volume instance. Found a %s instance.' % impl.__class__
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assert isinstance(pool, CallbackPool), 'pool must use a qubes.storage.CallbackPool instance. Found a %s instance.' % pool.__class__
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self._cb_pool = pool #: CallbackPool instance the Volume belongs to.
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self._cb_impl = impl #: Backend volume implementation instance.
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def _assert_initialized(self, **kwargs):
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return self._cb_pool._assert_initialized(**kwargs) # pylint: disable=protected-access
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def _callback(self, cb, cb_args=None, **kwargs):
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if cb_args is None:
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cb_args = []
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vol_args = [self.name, self.vid, *cb_args]
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return self._cb_pool._callback(cb, cb_args=vol_args, **kwargs) # pylint: disable=protected-access
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def create(self):
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self._assert_initialized()
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self._callback('on_volume_create')
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return self._cb_impl.create()
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def remove(self):
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self._assert_initialized()
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ret = self._cb_impl.remove()
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self._callback('on_volume_remove')
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return ret
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def resize(self, size):
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self._assert_initialized()
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self._callback('on_volume_resize', cb_args=[size])
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return self._cb_impl.resize(size)
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def start(self):
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self._assert_initialized()
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self._callback('on_volume_start')
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return self._cb_impl.start()
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def stop(self):
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self._assert_initialized()
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ret = self._cb_impl.stop()
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self._callback('on_volume_stop')
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return ret
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def import_data(self):
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self._assert_initialized()
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self._callback('on_volume_import_data')
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return self._cb_impl.import_data()
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def import_data_end(self, success):
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self._assert_initialized()
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ret = self._cb_impl.import_data_end(success)
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self._callback('on_volume_import_data_end', cb_args=[success])
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return ret
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def import_volume(self, src_volume):
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self._assert_initialized()
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self._callback('on_volume_import', cb_args=[src_volume.vid])
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return self._cb_impl.import_volume(src_volume)
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def is_dirty(self):
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if self._cb_pool._cb_requires_init: # pylint: disable=protected-access
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return False
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return self._cb_impl.is_dirty()
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def is_outdated(self):
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if self._cb_pool._cb_requires_init: # pylint: disable=protected-access
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return False
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return self._cb_impl.is_outdated()
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#remaining method & attribute delegation
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def __getattr__(self, name):
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if name in ['block_device', 'verify', 'revert', 'export']:
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self._assert_initialized()
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return getattr(self._cb_impl, name)
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def __setattr__(self, name, value):
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if name.startswith('_cb_'):
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super().__setattr__(name, value)
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|
else:
|
|
setattr(self._cb_impl, name, value)
|
|
|
|
def __delattr__(self, name):
|
|
if name.startswith('_cb_'):
|
|
super().__delattr__(name)
|
|
else:
|
|
delattr(self._cb_impl, name)
|