diskimage-builder/diskimage_builder/block_device/level1/partitioning.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.
from diskimage_builder.block_device.blockdevicesetupexception \
import BlockDeviceSetupException
from diskimage_builder.block_device.level1.mbr import MBR
from diskimage_builder.block_device.utils import parse_abs_size_spec
from diskimage_builder.block_device.utils import parse_rel_size_spec
from diskimage_builder.graph.digraph import Digraph
import logging
logger = logging.getLogger(__name__)
class Partition(Digraph.Node):
def __init__(self, name, flags, size, ptype, base, partitioning):
Digraph.Node.__init__(self, name)
self.flags = flags
self.size = size
self.ptype = ptype
self.base = base
self.partitioning = partitioning
def get_flags(self):
return self.flags
def get_size(self):
return self.size
def get_type(self):
return self.ptype
def insert_edges(self, dg):
bnode = dg.find(self.base)
assert bnode is not None
dg.create_edge(bnode, self)
def create(self, result, rollback):
self.partitioning.create(result, rollback)
def umount(self, state):
"""Partitioning does not need any umount task."""
pass
def cleanup(self, state):
"""Partitioning does not need any cleanup."""
pass
def delete(self, state):
"""Partitioning does not need any cleanup."""
pass
class Partitioning(object):
type_string = "partitioning"
flag_boot = 1
flag_primary = 2
def __init__(self, config, default_config):
logger.debug("Creating Partitioning object; config [%s]" % config)
# Because using multiple partitions of one base is done
# within one object, there is the need to store a flag if the
# creation of the partitions was already done.
self.already_created = False
# Parameter check
if 'base' not in config:
self._config_error("Partitioning config needs 'base'")
self.base = config['base']
if 'label' not in config:
self._config_error("Partitioning config needs 'label'")
self.label = config['label']
if self.label not in ("mbr", ):
self._config_error("Label must be 'mbr'")
# It is VERY important to get the alignment correct. If this
# is not correct, the disk performance might be very poor.
# Example: In some tests a 'off by one' leads to a write
# performance of 30% compared to a correctly aligned
# partition.
# The problem for DIB is, that it cannot assume that the host
# system uses the same IO sizes as the target system,
# therefore here a fixed approach (as used in all modern
# systems with large disks) is used. The partitions are
# aligned to 1MiB (which are about 2048 times 512 bytes
# blocks)
self.align = 1024 * 1024 # 1MiB as default
if 'align' in config:
self.align = parse_abs_size_spec(config['align'])
if 'partitions' not in config:
self._config_error("Partitioning config needs 'partitions'")
self.partitions = {}
for part_cfg in config['partitions']:
if 'name' not in part_cfg:
self.config_error("Missing 'name' in partition config")
part_name = part_cfg['name']
flags = set()
if 'flags' in part_cfg:
for f in part_cfg['flags']:
if f == 'boot':
flags.add(Partitioning.flag_boot)
elif f == 'primary':
flags.add(Partitioning.flag_primary)
else:
self._config_error("Unknown flag [%s] in "
"partitioning for [%s]"
% (f, part_name))
if 'size' not in part_cfg:
self._config_error("No 'size' in partition [%s]"
% part_name)
size = part_cfg['size']
ptype = int(part_cfg['type'], 16) if 'type' in part_cfg else 0x83
self.partitions[part_name] \
= Partition(part_name, flags, size, ptype, self.base, self)
logger.debug(part_cfg)
def _config_error(self, msg):
logger.error(msg)
raise BlockDeviceSetupException(msg)
def _size_of_block_dev(self, dev):
with open(dev, "r") as fd:
fd.seek(0, 2)
return fd.tell()
def insert_nodes(self, dg):
for _, part in self.partitions.items():
dg.add_node(part)
def create(self, result, rollback):
image_path = result[self.base]['image']
device_path = result[self.base]['device']
logger.info("Creating partition on [%s] [%s]" %
(self.base, image_path))
if self.already_created:
logger.info("Not creating the partitions a second time.")
return
assert self.label == 'mbr'
disk_size = self._size_of_block_dev(image_path)
with MBR(image_path, disk_size, self.align) as part_impl:
for part_name, part_cfg in self.partitions.items():
part_bootflag = Partitioning.flag_boot \
in part_cfg.get_flags()
part_primary = Partitioning.flag_primary \
in part_cfg.get_flags()
part_size = part_cfg.get_size()
part_free = part_impl.free()
part_type = part_cfg.get_type()
logger.debug("Not partitioned space [%d]" % part_free)
part_size = parse_rel_size_spec(part_size,
part_free)[1]
part_no \
= part_impl.add_partition(part_primary, part_bootflag,
part_size, part_type)
logger.debug("Create partition [%s] [%d]" %
(part_name, part_no))
result[part_name] = {'device': device_path + "p%d" % part_no}
self.already_created = True
return