Source code for kiwi.storage.loop_device

# Copyright (c) 2015 SUSE Linux GmbH.  All rights reserved.
#
# This file is part of kiwi.
#
# kiwi 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 3 of the License, or
# (at your option) any later version.
#
# kiwi 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 kiwi.  If not, see <http://www.gnu.org/licenses/>
#
import os
import logging

# project
from kiwi.command import Command
from kiwi.storage.device_provider import DeviceProvider
from kiwi.utils.command_capabilities import CommandCapabilities

from kiwi.exceptions import (
    KiwiLoopSetupError
)

log = logging.getLogger('kiwi')


[docs]class LoopDevice(DeviceProvider): """ **Create and manage loop device file for block operations** :param string filename: loop file name to create :param int filesize_mbytes: size of the loop file :param int blocksize_bytes: blocksize used in loop driver """ def __init__(self, filename, filesize_mbytes=None, blocksize_bytes=None): self.node_name = None if not os.path.exists(filename) and not filesize_mbytes: raise KiwiLoopSetupError( 'Can not create loop file without a size' ) self.filename = filename self.filesize_mbytes = filesize_mbytes self.blocksize_bytes = blocksize_bytes
[docs] def get_device(self): """ Device node name :return: device node name :rtype: str """ return self.node_name
[docs] def is_loop(self): """ Always True :return: True :rtype: bool """ return True
[docs] def create(self, overwrite=True): """ Setup a loop device of the blocksize given in the constructor The file to loop is created with the size specified in the constructor unless an existing one should not be overwritten :param bool overwrite: overwrite existing file to loop """ if overwrite: qemu_img_size = format(self.filesize_mbytes) + 'M' Command.run( ['qemu-img', 'create', self.filename, qemu_img_size] ) loop_options = [] if self.blocksize_bytes and self.blocksize_bytes != 512: if CommandCapabilities.has_option_in_help( 'losetup', '--sector-size', raise_on_error=False ): loop_options.append('--sector-size') else: loop_options.append('--logical-blocksize') loop_options.append(format(self.blocksize_bytes)) loop_call = Command.run( ['losetup'] + loop_options + ['-f', '--show', self.filename] ) self.node_name = loop_call.output.rstrip('\n')
def __del__(self): if self.node_name: log.info('Cleaning up %s instance', type(self).__name__) try: Command.run(['losetup', '-d', self.node_name]) except Exception: log.warning( 'loop device %s still busy', self.node_name )