diskimage-builder/diskimage_builder/block_device/level0/localloop.py

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# 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.blockdevice import \
BlockDeviceSetupException
from diskimage_builder.block_device.plugin_base import NodePluginBase
from diskimage_builder.block_device.tree_config import TreeConfig
from diskimage_builder.block_device.utils import parse_abs_size_spec
from diskimage_builder.graph.digraph import Digraph
logger = logging.getLogger(__name__)
class LocalLoop(NodePluginBase):
"""Level0: Local loop image device handling.
This class handles local loop devices that can be used
for VM image installation.
"""
tree_config = TreeConfig("local_loop")
def __init__(self, config, default_config):
logger.debug("Creating LocalLoop object; config [%s] "
"default_config [%s]" % (config, default_config))
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.name = config['name']
Digraph.Node.__init__(self, self.name)
self.filename = os.path.join(self.image_dir, self.name + ".raw")
def insert_edges(self, dg):
"""Because this is created without base, there are no edges."""
pass
@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'])