diskimage-builder/diskimage_builder/block_device/level0/localloop.py
Ian Wienand 00da1982ce Add a more generic tree->graph parser
This moves to a more generic config parser that doesn't have plugins
parsing part of the tree.

I understand why it ended up that way; we have "partitions" key which
has special semantics compared to others keys and there was a desire
to keep it isolated from core tree->graph code.  But this isn't really
isolated; you have to reverse-engineer several module-crossing
boundaries, extras classes and repetitive recursive functions.

Ultimately, plugins should have access to the node graph, but not
participate in configuration parsing.  This way we ensure that plugins
can't invent new methods of configuration parsing.

Note: unit tests produce the same tree -> graph conversion as the old
method.  i.e. this is not intended to have a functional change.

Change-Id: I8a5d62a076a5a50597f2f1df3a8615afba6dadb2
2017-05-26 10:13:14 +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 insert_edges(self, dg):
"""Because this is created without base, there are no edges."""
pass
def insert_nodes(self, dg):
"""Adds self as a node to the given digraph"""
dg.add_node(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'])