diskimage-builder/diskimage_builder/block_device/level3/mount.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

146 lines
5.2 KiB
Python

# Copyright 2017 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
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 exec_sudo
from diskimage_builder.block_device.utils import sort_mount_points
logger = logging.getLogger(__name__)
# There is the need to collect all mount points to be able to
# sort them in a sensible way.
mount_points = {}
# The order of mounting and unmounting is important.
sorted_mount_points = None
class MountPointNode(NodeBase):
def __init__(self, mount_base, config):
super(MountPointNode, self).__init__(config['name'])
# Parameter check
self.mount_base = mount_base
for pname in ['base', 'mount_point']:
if pname not in config:
raise BlockDeviceSetupException(
"MountPoint config needs [%s]" % pname)
setattr(self, pname, config[pname])
logger.debug("MountPoint created [%s]" % self)
def get_node(self):
global mount_points
if self.mount_point in mount_points:
raise BlockDeviceSetupException(
"Mount point [%s] specified more than once"
% self.mount_point)
logger.debug("Insert node [%s]" % self)
mount_points[self.mount_point] = self
return self
def get_edges(self):
"""Insert all edges
After inserting all the nodes, the order of the mounting and
umounting can be computed. There is the need to mount
mount-points that contain other mount-points first.
Example: '/var' must be mounted before '/var/log'. If not the
second is not used for files at all.
The dependency edge is created in all cases from the base
element (typically a mkfs) and, if this is not the 'first'
mount-point, also depend on the mount point before. This
ensures that during mounting (and umounting) the correct
order is used.
"""
edge_from = []
edge_to = []
global mount_points
global sorted_mount_points
if sorted_mount_points is None:
logger.debug("Mount points [%s]" % mount_points)
sorted_mount_points = sort_mount_points(mount_points.keys())
logger.info("Sorted mount points [%s]" % (sorted_mount_points))
# Look for the occurance in the list
mpi = sorted_mount_points.index(self.mount_point)
if mpi > 0:
# If not the first: add also the dependency
dep = mount_points[sorted_mount_points[mpi - 1]]
edge_from.append(dep.name)
edge_from.append(self.base)
return (edge_from, edge_to)
def create(self, result, rollback):
logger.debug("mount called [%s]" % self.mount_point)
logger.debug("result [%s]" % result)
rel_mp = self.mount_point if self.mount_point[0] != '/' \
else self.mount_point[1:]
mount_point = os.path.join(self.mount_base, rel_mp)
if not os.path.exists(mount_point):
# Need to sudo this because of permissions in the new
# file system tree.
exec_sudo(['mkdir', '-p', mount_point])
logger.info("Mounting [%s] to [%s]" % (self.name, mount_point))
exec_sudo(["mount", result['filesys'][self.base]['device'],
mount_point])
if 'mount' not in result:
result['mount'] = {}
result['mount'][self.mount_point] \
= {'name': self.name, 'base': self.base, 'path': mount_point}
if 'mount_order' not in result:
result['mount_order'] = []
result['mount_order'].append(self.mount_point)
def umount(self, state):
logger.info("Called for [%s]" % self.name)
exec_sudo(["umount", state['mount'][self.mount_point]['path']])
def delete(self, state):
self.umount(state)
class Mount(PluginBase):
def __init__(self, config, defaults):
super(Mount, self).__init__()
self.mount_points = {}
if 'mount-base' not in defaults:
raise BlockDeviceSetupException(
"Mount default config needs 'mount-base'")
self.mount_base = defaults['mount-base']
mp = MountPointNode(self.mount_base, config)
self.mount_points[mp.get_name()] = mp
def get_nodes(self):
global sorted_mount_points
assert sorted_mount_points is None
nodes = []
for _, mp in self.mount_points.items():
nodes.append(mp.get_node())
return nodes