core-admin/qubes/tests/storage_reflink.py

#
# The Qubes OS Project, https://www.qubes-os.org
#
# Copyright (C) 2018 Rusty Bird <rustybird@net-c.com>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, see <https://www.gnu.org/licenses/>.
#

''' Tests for the file-reflink storage driver '''

# pylint: disable=protected-access
# pylint: disable=invalid-name

import os
import shutil
import subprocess
import sys

import qubes.tests
from qubes.storage import reflink


class ReflinkMixin:
    def setUp(self, fs_type='btrfs'):  # pylint: disable=arguments-differ
        super().setUp()
        self.test_dir = '/var/tmp/test-reflink-units-on-' + fs_type
        mkdir_fs(self.test_dir, fs_type, cleanup_via=self.addCleanup)

    def test_000_copy_file(self):
        source = os.path.join(self.test_dir, 'source-file')
        dest = os.path.join(self.test_dir, 'new-directory', 'dest-file')
        content = os.urandom(1024**2)

        with open(source, 'wb') as source_io:
            source_io.write(content)

        ficlone_succeeded = reflink._copy_file(source, dest)
        self.assertEqual(ficlone_succeeded, self.ficlone_supported)

        self.assertNotEqual(os.stat(source).st_ino, os.stat(dest).st_ino)
        with open(source, 'rb') as source_io:
            self.assertEqual(source_io.read(), content)
        with open(dest, 'rb') as dest_io:
            self.assertEqual(dest_io.read(), content)

    def test_001_create_and_resize_files_and_update_loopdevs(self):
        img_real = os.path.join(self.test_dir, 'img-real')
        img_sym = os.path.join(self.test_dir, 'img-sym')
        size_initial = 111 * 1024**2
        size_resized = 222 * 1024**2

        os.symlink(img_real, img_sym)
        reflink._create_sparse_file(img_real, size_initial)
        self.assertEqual(reflink._get_file_disk_usage(img_real), 0)
        self.assertEqual(os.stat(img_real).st_size, size_initial)

        dev_from_real = setup_loopdev(img_real, cleanup_via=self.addCleanup)
        dev_from_sym = setup_loopdev(img_sym, cleanup_via=self.addCleanup)

        reflink._resize_file(img_real, size_resized)
        self.assertEqual(reflink._get_file_disk_usage(img_real), 0)
        self.assertEqual(os.stat(img_real).st_size, size_resized)

        reflink_update_loopdev_sizes(os.path.join(self.test_dir, 'unrelated'))

        for dev in (dev_from_real, dev_from_sym):
            self.assertEqual(get_blockdev_size(dev), size_initial)

        reflink_update_loopdev_sizes(img_sym)

        for dev in (dev_from_real, dev_from_sym):
            self.assertEqual(get_blockdev_size(dev), size_resized)

class TC_00_ReflinkOnBtrfs(ReflinkMixin, qubes.tests.QubesTestCase):
    def setUp(self):  # pylint: disable=arguments-differ
        super().setUp('btrfs')
        self.ficlone_supported = True

class TC_01_ReflinkOnExt4(ReflinkMixin, qubes.tests.QubesTestCase):
    def setUp(self):  # pylint: disable=arguments-differ
        super().setUp('ext4')
        self.ficlone_supported = False


def setup_loopdev(img, cleanup_via=None):
    dev = str.strip(cmd('sudo', 'losetup', '-f', '--show', img).decode())
    if cleanup_via is not None:
        cleanup_via(detach_loopdev, dev)
    return dev

def detach_loopdev(dev):
    cmd('sudo', 'losetup', '-d', dev)

def get_fs_type(directory):
    # 'stat -f -c %T' would identify ext4 as 'ext2/ext3'
    return cmd('df', '--output=fstype', directory).decode().splitlines()[1]

def mkdir_fs(directory, fs_type,
             accessible=True, max_size=100*1024**3, cleanup_via=None):
    os.mkdir(directory)

    if get_fs_type(directory) != fs_type:
        img = os.path.join(directory, 'img')
        with open(img, 'xb') as img_io:
            img_io.truncate(max_size)
        cmd('mkfs.' + fs_type, img)
        dev = setup_loopdev(img)
        os.remove(img)
        cmd('sudo', 'mount', dev, directory)
        detach_loopdev(dev)

    if accessible:
        cmd('sudo', 'chmod', '777', directory)
    else:
        cmd('sudo', 'chmod', '000', directory)
        cmd('sudo', 'chattr', '+i', directory)  # cause EPERM on write as root

    if cleanup_via is not None:
        cleanup_via(rmtree_fs, directory)

def rmtree_fs(directory):
    cmd('sudo', 'chattr', '-i', directory)
    cmd('sudo', 'chmod', '777', directory)
    if os.path.ismount(directory):
        try:
            cmd('sudo', 'umount', directory)
        except:
            cmd('sudo', 'fuser', '-vm', directory)
            raise
        # loop device and backing file are garbage collected automatically
    shutil.rmtree(directory)

def get_blockdev_size(dev):
    return int(cmd('sudo', 'blockdev', '--getsize64', dev))

def reflink_update_loopdev_sizes(img):
    env = [k + '=' + v for k, v in os.environ.items()  # 'sudo -E' alone would
           if k.startswith('PYTHON')]                  # drop some of these
    code = ('from qubes.storage import reflink\n'
            'reflink._update_loopdev_sizes(%r)' % img)
    cmd('sudo', '-E', 'env', *env, sys.executable, '-c', code)

def cmd(*argv):
    p = subprocess.run(argv, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    if p.returncode != 0:
        raise Exception(str(p))  # this will show stdout and stderr
    return p.stdout