diskimage-builder/diskimage_builder/block_device/level0/localloop.py
Ian Wienand deb832d685 Create and use plugin/node abstract classes
This completes the transitions started in
Ic5a61365ef0132476b11bdbf1dd96885e91c3cb6

The new file plugin.py is the place to start with this change.  The
abstract base classes PluginBase and NodeBase are heavily documented.
NodeBase essentially replaces Digraph.Node

The changes in level?/*.py make no functional changes, but are just
refactoring to implement the plugin and node classes consistently.
Additionally we have added asserts during parsing & generation to
ensure plugins are implemented PluginBase, and get_nodes() is always
returning NodeBase objects for the graph.

Change-Id: Ie648e9224749491260dea65d7e8b8151a6824b9c
2017-05-26 11:48:11 +10:00

140 lines
5.0 KiB
Python

# Copyright 2016 Andreas Florath (andreas@florath.net)
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import logging
import os
import subprocess
from diskimage_builder.block_device.exception import \
BlockDeviceSetupException
from diskimage_builder.block_device.plugin import NodeBase
from diskimage_builder.block_device.plugin import PluginBase
from diskimage_builder.block_device.utils import parse_abs_size_spec
logger = logging.getLogger(__name__)
class LocalLoopNode(NodeBase):
"""Level0: Local loop image device handling.
This class handles local loop devices that can be used
for VM image installation.
"""
def __init__(self, config, default_config):
logger.debug("Creating LocalLoop object; config [%s] "
"default_config [%s]" % (config, default_config))
super(LocalLoopNode, self).__init__(config['name'])
if 'size' in config:
self.size = parse_abs_size_spec(config['size'])
logger.debug("Image size [%s]" % self.size)
else:
self.size = parse_abs_size_spec(default_config['image-size'])
logger.debug("Using default image size [%s]" % self.size)
if 'directory' in config:
self.image_dir = config['directory']
else:
self.image_dir = default_config['image-dir']
self.filename = os.path.join(self.image_dir, self.name + ".raw")
def get_edges(self):
"""Because this is created without base, there are no edges."""
return ([], [])
@staticmethod
def image_create(filename, size):
logger.info("Create image file [%s]" % filename)
with open(filename, "w") as fd:
fd.seek(size - 1)
fd.write("\0")
@staticmethod
def _image_delete(filename):
logger.info("Remove image file [%s]" % filename)
os.remove(filename)
@staticmethod
def _loopdev_attach(filename):
logger.info("loopdev attach")
logger.debug("Calling [sudo losetup --show -f %s]", filename)
subp = subprocess.Popen(["sudo", "losetup", "--show", "-f",
filename], stdout=subprocess.PIPE)
rval = subp.wait()
if rval == 0:
# [:-1]: Cut of the newline
block_device = subp.stdout.read()[:-1].decode("utf-8")
logger.info("New block device [%s]" % block_device)
return block_device
else:
logger.error("losetup failed")
raise BlockDeviceSetupException("losetup failed")
@staticmethod
def _loopdev_detach(loopdev):
logger.info("loopdev detach")
# loopback dev may be tied up a bit by udev events triggered
# by partition events
for try_cnt in range(10, 1, -1):
logger.debug("Calling [sudo losetup -d %s]", loopdev)
subp = subprocess.Popen(["sudo", "losetup", "-d",
loopdev])
rval = subp.wait()
if rval == 0:
logger.info("Successfully detached [%s]" % loopdev)
return 0
else:
logger.error("loopdev detach failed")
# Do not raise an error - maybe other cleanup methods
# can at least do some more work.
logger.debug("Gave up trying to detach [%s]" % loopdev)
return rval
def create(self, result, rollback):
logger.debug("[%s] Creating loop on [%s] with size [%d]" %
(self.name, self.filename, self.size))
rollback.append(lambda: self._image_delete(self.filename))
self.image_create(self.filename, self.size)
block_device = self._loopdev_attach(self.filename)
rollback.append(lambda: self._loopdev_detach(block_device))
if 'blockdev' not in result:
result['blockdev'] = {}
result['blockdev'][self.name] = {"device": block_device,
"image": self.filename}
logger.debug("Created loop name [%s] device [%s] image [%s]"
% (self.name, block_device, self.filename))
return
def umount(self, state):
self._loopdev_detach(state['blockdev'][self.name]['device'])
def cleanup(self, state):
pass
def delete(self, state):
self._image_delete(state['blockdev'][self.name]['image'])
class LocalLoop(PluginBase):
def __init__(self, config, defaults):
super(PluginBase, self).__init__()
self.node = LocalLoopNode(config, defaults)
def get_nodes(self):
return [self.node]