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from loopbackvolume import LoopbackVolume
from bootstrapvz.base.fs.exceptions import VolumeError
from ..tools import log_check_call
from . import get_partitions
class QEMUVolume(LoopbackVolume):
def _before_create(self, e):
self.image_path = e.image_path
vol_size = str(self.size.bytes.get_qty_in('MiB')) + 'M'
log_check_call(['qemu-img', 'create', '-f', self.qemu_format, self.image_path, vol_size])
def _check_nbd_module(self):
from bootstrapvz.base.fs.partitionmaps.none import NoPartitions
if isinstance(self.partition_map, NoPartitions):
if not self._module_loaded('nbd'):
msg = ('The kernel module `nbd\' must be loaded '
'(`modprobe nbd\') to attach .{extension} images'
.format(extension=self.extension))
raise VolumeError(msg)
else:
num_partitions = len(self.partition_map.partitions)
if not self._module_loaded('nbd'):
msg = ('The kernel module `nbd\' must be loaded '
'(run `modprobe nbd max_part={num_partitions}\') '
'to attach .{extension} images'
.format(num_partitions=num_partitions, extension=self.extension))
raise VolumeError(msg)
nbd_max_part = int(self._module_param('nbd', 'max_part'))
if nbd_max_part < num_partitions:
# Found here: http://bethesignal.org/blog/2011/01/05/how-to-mount-virtualbox-vdi-image/
msg = ('The kernel module `nbd\' was loaded with the max_part '
'parameter set to {max_part}, which is below '
'the amount of partitions for this volume ({num_partitions}). '
'Reload the nbd kernel module with max_part set to at least {num_partitions} '
'(`rmmod nbd; modprobe nbd max_part={num_partitions}\').'
.format(max_part=nbd_max_part, num_partitions=num_partitions))
raise VolumeError(msg)
def _before_attach(self, e):
self._check_nbd_module()
self.loop_device_path = self._find_free_nbd_device()
log_check_call(['qemu-nbd', '--connect', self.loop_device_path, self.image_path])
self.device_path = self.loop_device_path
def _before_detach(self, e):
log_check_call(['qemu-nbd', '--disconnect', self.loop_device_path])
del self.loop_device_path
self.device_path = None
def _module_loaded(self, module):
import re
regexp = re.compile('^{module} +'.format(module=module))
with open('/proc/modules') as loaded_modules:
for line in loaded_modules:
match = regexp.match(line)
if match is not None:
return True
return False
def _module_param(self, module, param):
import os.path
param_path = os.path.join('/sys/module', module, 'parameters', param)
with open(param_path) as param:
return param.read().strip()
# From http://lists.gnu.org/archive/html/qemu-devel/2011-11/msg02201.html
# Apparently it's not in the current qemu-nbd shipped with wheezy
def _is_nbd_used(self, device_name):
return device_name in get_partitions()
def _find_free_nbd_device(self):
import os.path
for i in xrange(0, 15):
device_name = 'nbd' + str(i)
if not self._is_nbd_used(device_name):
return os.path.join('/dev', device_name)
raise VolumeError('Unable to find free nbd device.')
def __setstate__(self, state):
for key in state:
self.__dict__[key] = state[key]
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