cdbe5060ca
Change the LoopDevice class to be a context manager.
All code using LoopDevice was updated to the following
with statement:
with LoopDevice(...) as loop_provider:
loop_provider.some_member()
This is related to Issue #2412
112 lines
3.5 KiB
Python
112 lines
3.5 KiB
Python
# Copyright (c) 2015 SUSE Linux GmbH. All rights reserved.
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#
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# This file is part of kiwi.
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#
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# kiwi 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 3 of the License, or
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# (at your option) any later version.
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#
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# kiwi 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
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# along with kiwi. If not, see <http://www.gnu.org/licenses/>
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#
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import os
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import logging
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# project
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from kiwi.command import Command
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from kiwi.storage.device_provider import DeviceProvider
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from kiwi.utils.command_capabilities import CommandCapabilities
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from kiwi.exceptions import KiwiLoopSetupError
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log = logging.getLogger('kiwi')
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class LoopDevice(DeviceProvider):
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"""
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**Create and manage loop device file for block operations**
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:param string filename: loop file name to create
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:param int filesize_mbytes: size of the loop file
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:param int blocksize_bytes: blocksize used in loop driver
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"""
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def __init__(
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self, filename: str, filesize_mbytes: int = None,
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blocksize_bytes: int = None
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):
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self.node_name = ''
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if not os.path.exists(filename) and not filesize_mbytes:
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raise KiwiLoopSetupError(
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'Can not create loop file without a size'
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)
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self.filename = filename
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self.filesize_mbytes = filesize_mbytes
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self.blocksize_bytes = blocksize_bytes
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def __enter__(self):
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return self
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def get_device(self) -> str:
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"""
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Device node name
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:return: device node name
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:rtype: str
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"""
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return self.node_name
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def is_loop(self) -> bool:
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"""
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Always True
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:return: True
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:rtype: bool
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"""
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return True
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def create(self, overwrite: bool = True):
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"""
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Setup a loop device of the blocksize given in the constructor
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The file to loop is created with the size specified in the
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constructor unless an existing one should not be overwritten
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:param bool overwrite: overwrite existing file to loop
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"""
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if overwrite:
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qemu_img_size = format(self.filesize_mbytes) + 'M'
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Command.run(
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['qemu-img', 'create', self.filename, qemu_img_size]
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)
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loop_options = []
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if self.blocksize_bytes and self.blocksize_bytes != 512:
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if CommandCapabilities.has_option_in_help(
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'losetup', '--sector-size', raise_on_error=False
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):
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loop_options.append('--sector-size')
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else:
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loop_options.append('--logical-blocksize')
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loop_options.append(format(self.blocksize_bytes))
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loop_call = Command.run(
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['losetup'] + loop_options + ['-f', '--show', self.filename]
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)
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self.node_name = loop_call.output.rstrip(os.linesep)
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def __exit__(self, exc_type, exc_value, traceback):
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if self.node_name:
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try:
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Command.run(['losetup', '-d', self.node_name])
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except Exception as issue:
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log.error(
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'loop cleanup on {0} failed with: {1}'.format(
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self.node_name, issue
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)
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)
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