bootstrap-vz/bootstrapvz/base/fs/partitionmaps/msdos.py
2018-02-25 04:12:24 +00:00

94 lines
4.3 KiB
Python

from .abstract import AbstractPartitionMap
from ..exceptions import PartitionError
from ..partitions.msdos import MSDOSPartition
from ..partitions.msdos_swap import MSDOSSwapPartition
from bootstrapvz.common.tools import log_check_call
class MSDOSPartitionMap(AbstractPartitionMap):
"""Represents a MS-DOS partition map
Sometimes also called MBR (but that confuses the hell out of me, so ms-dos it is)
"""
def __init__(self, data, sector_size, bootloader):
"""
:param dict data: volume.partitions part of the manifest
:param int sector_size: Sectorsize of the volume
:param str bootloader: Name of the bootloader we will use for bootstrapping
"""
from bootstrapvz.common.sectors import Sectors
# List of partitions
self.partitions = []
# Returns the last partition unless there is none
def last_partition():
return self.partitions[-1] if self.partitions else None
# The boot and swap partitions are optional
if 'boot' in data:
self.boot = MSDOSPartition(Sectors(data['boot']['size'], sector_size),
data['boot']['filesystem'], data['boot'].get('format_command', None),
data['boot'].get('mountopts', None), 'boot', last_partition())
self.partitions.append(self.boot)
# Offset all partitions by 1 sector.
# parted in jessie has changed and no longer allows
# partitions to be right next to each other.
partition_gap = Sectors(1, sector_size)
if 'swap' in data:
self.swap = MSDOSSwapPartition(Sectors(data['swap']['size'], sector_size), last_partition())
if self.swap.previous is not None:
# No need to pad if this is the first partition
self.swap.pad_start += partition_gap
self.swap.size -= partition_gap
self.partitions.append(self.swap)
self.root = MSDOSPartition(Sectors(data['root']['size'], sector_size),
data['root']['filesystem'], data['root'].get('format_command', None),
data['root'].get('mountopts', None), 'root', last_partition())
if self.root.previous is not None:
self.root.pad_start += partition_gap
self.root.size -= partition_gap
self.partitions.append(self.root)
# Raise exception while trying to create additional partitions
# as its hard to calculate the actual size of the extended partition ATM
# And anyhow - we should go with GPT...
for partition in data:
if partition not in ["boot", "swap", "root", "type"]:
raise PartitionError("If you want to have additional partitions please use GPT partition scheme")
# Mark boot as the boot partition, or root, if boot does not exist
getattr(self, 'boot', self.root).flags.append('boot')
# If we are using the grub bootloader, we will need to add a 2 MB offset
# at the beginning of the partitionmap and steal it from the first partition.
# The MBR offset is included in the grub offset, so if we don't use grub
# we should reduce the size of the first partition and move it by only 512 bytes.
if bootloader == 'grub':
mbr_offset = Sectors('2MiB', sector_size)
else:
mbr_offset = Sectors('512B', sector_size)
self.partitions[0].pad_start += mbr_offset
self.partitions[0].size -= mbr_offset
# Leave the last sector unformatted
# parted in jessie thinks that a partition 10 sectors in size
# goes from sector 0 to sector 9 (instead of 0 to 10)
self.partitions[-1].pad_end += 1
self.partitions[-1].size -= 1
super(MSDOSPartitionMap, self).__init__(bootloader)
def _before_create(self, event):
volume = event.volume
# Disk alignment still plays a role in virtualized environment,
# but I honestly have no clue as to what best practice is here, so we choose 'none'
log_check_call(['parted', '--script', '--align', 'none', volume.device_path,
'--', 'mklabel', 'msdos'])
# Create the partitions
for partition in self.partitions:
partition.create(volume)