diskimage-builder/diskimage_builder/block_device/level0/localloop.py
Ian Wienand 75817ef205 Use networkx for digraph
This switches the code to use networkx for the digraph implementation.

Note that the old implementation specifically isn't removed in this
change -- for review clarity.  It will be replaced by a base class
that defines things properly to the API described below.

Plugins return a node object with three functions

 get_name() : return the unique name of this node

 get_nodes() : return a list of nodes for insertion into the graph.
  Usually this is just "self".  Some special things like partitioning
  add extra nodes at this point, however.

 get_edges() : return a tuple of two lists; edges_from and edges_to
  As you would expect the first is a list of node names that points to
  us, and the second is a list of node names we point to.  Usually
  this is only populated as ([self.base],[]) -- i.e. our "base" node
  points to us.  Some plugins, such as mounting, create links both to
  and from themselves, however.

Plugins have been updated, some test cases added (error cases
specifically)

Change-Id: Ic5a61365ef0132476b11bdbf1dd96885e91c3cb6
2017-05-26 11:42:10 +10:00

134 lines
4.8 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.utils import parse_abs_size_spec
from diskimage_builder.graph.digraph import Digraph
logger = logging.getLogger(__name__)
class LocalLoop(Digraph.Node):
"""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))
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 get_edges(self):
"""Because this is created without base, there are no edges."""
return ([], [])
def get_nodes(self):
"""Returns nodes for adding to the graph"""
return [self]
@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'])