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128 lines
3.9 KiB
Python
128 lines
3.9 KiB
Python
from abc import ABCMeta
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from abc import abstractmethod
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from bootstrapvz.common.tools import log_check_call
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from bootstrapvz.common.fsm_proxy import FSMProxy
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from ..exceptions import PartitionError
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class AbstractPartitionMap(FSMProxy):
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"""Abstract representation of a partiton map
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This class is a finite state machine and represents the state of the real partition map
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"""
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__metaclass__ = ABCMeta
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# States the partition map can be in
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events = [{'name': 'create', 'src': 'nonexistent', 'dst': 'unmapped'},
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{'name': 'map', 'src': 'unmapped', 'dst': 'mapped'},
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{'name': 'unmap', 'src': 'mapped', 'dst': 'unmapped'},
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]
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def __init__(self, bootloader):
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"""
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Args:
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bootloader (str): Name of the bootloader we will use for bootstrapping
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"""
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# Create the configuration for the state machine
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cfg = {'initial': 'nonexistent', 'events': self.events, 'callbacks': {}}
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super(AbstractPartitionMap, self).__init__(cfg)
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def is_blocking(self):
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"""Returns whether the partition map is blocking volume detach operations
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Returns:
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bool.
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"""
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return self.fsm.current == 'mapped'
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def get_total_size(self):
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"""Returns the total size the partitions occupy
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Returns:
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Bytes. The size of all the partitions
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"""
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# We just need the endpoint of the last partition
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return self.partitions[-1].get_end()
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def create(self, volume):
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"""Creates the partition map
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Args:
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volume (Volume): The volume to create the partition map on
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"""
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self.fsm.create(volume=volume)
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@abstractmethod
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def _before_create(self, event):
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pass
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def map(self, volume):
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"""Maps the partition map to device nodes
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Args:
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volume (Volume): The volume the partition map resides on
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"""
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self.fsm.map(volume=volume)
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def _before_map(self, event):
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"""
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Raises:
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PartitionError
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"""
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volume = event.volume
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try:
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# Ask kpartx how the partitions will be mapped before actually attaching them.
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mappings = log_check_call(['kpartx', '-l', volume.device_path])
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import re
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regexp = re.compile('^(?P<name>.+[^\d](?P<p_idx>\d+)) : '
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'(?P<start_blk>\d) (?P<num_blks>\d+) '
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'{device_path} (?P<blk_offset>\d+)$'
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.format(device_path=volume.device_path))
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log_check_call(['kpartx', '-a', volume.device_path])
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import os.path
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# Run through the kpartx output and map the paths to the partitions
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for mapping in mappings:
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match = regexp.match(mapping)
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if match is None:
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raise PartitionError('Unable to parse kpartx output: {line}'.format(line=mapping))
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partition_path = os.path.join('/dev/mapper', match.group('name'))
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p_idx = int(match.group('p_idx')) - 1
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self.partitions[p_idx].map(partition_path)
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# Check if any partition was not mapped
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for idx, partition in enumerate(self.partitions):
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if partition.fsm.current not in ['mapped', 'formatted']:
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raise PartitionError('kpartx did not map partition #{idx}'.format(idx=idx + 1))
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except PartitionError as e:
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# Revert any mapping and reraise the error
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for partition in self.partitions:
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if not partition.fsm.can('unmap'):
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partition.unmap()
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log_check_call(['kpartx', '-d', volume.device_path])
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raise e
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def unmap(self, volume):
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"""Unmaps the partition
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Args:
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volume (Volume): The volume to unmap the partition map from
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"""
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self.fsm.unmap(volume=volume)
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def _before_unmap(self, event):
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"""
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Raises:
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PartitionError
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"""
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volume = event.volume
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# Run through all partitions before unmapping and make sure they can all be unmapped
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for partition in self.partitions:
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if partition.fsm.cannot('unmap'):
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msg = 'The partition {partition} prevents the unmap procedure'.format(partition=partition)
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raise PartitionError(msg)
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# Actually unmap the partitions
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log_check_call(['kpartx', '-d', volume.device_path])
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# Call unmap on all partitions
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for partition in self.partitions:
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partition.unmap()
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