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OpenStack Study: vhdutils.py**** CubicPower OpenStack Study ****
# Copyright 2013 Cloudbase Solutions Srl # All Rights Reserved. # # 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. """ Utility class for VHD related operations. Official VHD format specs can be retrieved at: http://technet.microsoft.com/en-us/library/bb676673.aspx See "Download the Specifications Without Registering" Official VHDX format specs can be retrieved at: http://www.microsoft.com/en-us/download/details.aspx?id=34750 """ import struct import sys if sys.platform == 'win32': import wmi from nova.openstack.common.gettextutils import _ from nova.virt.hyperv import constants from nova.virt.hyperv import vmutils from xml.etree import ElementTree VHD_HEADER_SIZE_FIX = 512 VHD_BAT_ENTRY_SIZE = 4 VHD_DYNAMIC_DISK_HEADER_SIZE = 1024 VHD_HEADER_SIZE_DYNAMIC = 512 VHD_FOOTER_SIZE_DYNAMIC = 512 VHD_BLK_SIZE_OFFSET = 544 VHD_SIGNATURE = 'conectix' VHDX_SIGNATURE = 'vhdxfile'
**** CubicPower OpenStack Study **** class VHDUtils(object):
**** CubicPower OpenStack Study **** def __init__(self): self._vmutils = vmutils.VMUtils() if sys.platform == 'win32': self._conn = wmi.WMI(moniker='//./root/virtualization')
**** CubicPower OpenStack Study **** def validate_vhd(self, vhd_path): image_man_svc = self._conn.Msvm_ImageManagementService()[0] (job_path, ret_val) = image_man_svc.ValidateVirtualHardDisk( Path=vhd_path) self._vmutils.check_ret_val(ret_val, job_path)
**** CubicPower OpenStack Study **** def create_dynamic_vhd(self, path, max_internal_size, format): if format != constants.DISK_FORMAT_VHD: raise vmutils.HyperVException(_("Unsupported disk format: %s") % format) image_man_svc = self._conn.Msvm_ImageManagementService()[0] (job_path, ret_val) = image_man_svc.CreateDynamicVirtualHardDisk( Path=path, MaxInternalSize=max_internal_size) self._vmutils.check_ret_val(ret_val, job_path)
**** CubicPower OpenStack Study **** def create_differencing_vhd(self, path, parent_path): image_man_svc = self._conn.Msvm_ImageManagementService()[0] (job_path, ret_val) = image_man_svc.CreateDifferencingVirtualHardDisk( Path=path, ParentPath=parent_path) self._vmutils.check_ret_val(ret_val, job_path)
**** CubicPower OpenStack Study **** def reconnect_parent_vhd(self, child_vhd_path, parent_vhd_path): image_man_svc = self._conn.Msvm_ImageManagementService()[0] (job_path, ret_val) = image_man_svc.ReconnectParentVirtualHardDisk( ChildPath=child_vhd_path, ParentPath=parent_vhd_path, Force=True) self._vmutils.check_ret_val(ret_val, job_path)
**** CubicPower OpenStack Study **** def merge_vhd(self, src_vhd_path, dest_vhd_path): image_man_svc = self._conn.Msvm_ImageManagementService()[0] (job_path, ret_val) = image_man_svc.MergeVirtualHardDisk( SourcePath=src_vhd_path, DestinationPath=dest_vhd_path) self._vmutils.check_ret_val(ret_val, job_path)
**** CubicPower OpenStack Study **** def _get_resize_method(self): image_man_svc = self._conn.Msvm_ImageManagementService()[0] return image_man_svc.ExpandVirtualHardDisk
**** CubicPower OpenStack Study **** def resize_vhd(self, vhd_path, new_max_size, is_file_max_size=True): if is_file_max_size: new_internal_max_size = self.get_internal_vhd_size_by_file_size( vhd_path, new_max_size) else: new_internal_max_size = new_max_size resize = self._get_resize_method() (job_path, ret_val) = resize( Path=vhd_path, MaxInternalSize=new_internal_max_size) self._vmutils.check_ret_val(ret_val, job_path)
**** CubicPower OpenStack Study **** def get_internal_vhd_size_by_file_size(self, vhd_path, new_vhd_file_size): """Fixed VHD size = Data Block size + 512 bytes Dynamic_VHD_size = Dynamic Disk Header + Copy of hard disk footer + Hard Disk Footer + Data Block + BAT Dynamic Disk header fields Copy of hard disk footer (512 bytes) Dynamic Disk Header (1024 bytes) BAT (Block Allocation table) Data Block 1 Data Block 2 Data Block n Hard Disk Footer (512 bytes) Default block size is 2M BAT entry size is 4byte """ base_vhd_info = self.get_vhd_info(vhd_path) vhd_type = base_vhd_info['Type'] if vhd_type == constants.VHD_TYPE_FIXED: vhd_header_size = VHD_HEADER_SIZE_FIX return new_vhd_file_size - vhd_header_size elif vhd_type == constants.VHD_TYPE_DYNAMIC: bs = self._get_vhd_dynamic_blk_size(vhd_path) bes = VHD_BAT_ENTRY_SIZE ddhs = VHD_DYNAMIC_DISK_HEADER_SIZE hs = VHD_HEADER_SIZE_DYNAMIC fs = VHD_FOOTER_SIZE_DYNAMIC max_internal_size = (new_vhd_file_size - (hs + ddhs + fs)) * bs / (bes + bs) return max_internal_size else: raise vmutils.HyperVException(_("The %(vhd_type)s type VHD " "is not supported") % {"vhd_type": vhd_type})
**** CubicPower OpenStack Study **** def _get_vhd_dynamic_blk_size(self, vhd_path): blk_size_offset = VHD_BLK_SIZE_OFFSET try: with open(vhd_path, "rb") as f: f.seek(blk_size_offset) version = f.read(4) except IOError: raise vmutils.HyperVException(_("Unable to obtain block size from" " VHD %(vhd_path)s") % {"vhd_path": vhd_path}) return struct.unpack('>i', version)[0]
**** CubicPower OpenStack Study **** def get_vhd_parent_path(self, vhd_path): return self.get_vhd_info(vhd_path).get("ParentPath")
**** CubicPower OpenStack Study **** def get_vhd_info(self, vhd_path): image_man_svc = self._conn.Msvm_ImageManagementService()[0] (vhd_info, job_path, ret_val) = image_man_svc.GetVirtualHardDiskInfo(vhd_path) self._vmutils.check_ret_val(ret_val, job_path) vhd_info_dict = {} et = ElementTree.fromstring(vhd_info) for item in et.findall("PROPERTY"): name = item.attrib["NAME"] value_text = item.find("VALUE").text if name == "ParentPath": vhd_info_dict[name] = value_text elif name in ["FileSize", "MaxInternalSize"]: vhd_info_dict[name] = long(value_text) elif name in ["InSavedState", "InUse"]: vhd_info_dict[name] = bool(value_text) elif name == "Type": vhd_info_dict[name] = int(value_text) return vhd_info_dict
**** CubicPower OpenStack Study **** def get_vhd_format(self, path): with open(path, 'rb') as f: # Read header if f.read(8) == VHDX_SIGNATURE: return constants.DISK_FORMAT_VHDX # Read footer f.seek(0, 2) file_size = f.tell() if file_size >= 512: f.seek(-512, 2) if f.read(8) == VHD_SIGNATURE: return constants.DISK_FORMAT_VHD raise vmutils.HyperVException(_('Unsupported virtual disk format'))
**** CubicPower OpenStack Study **** def get_best_supported_vhd_format(self): return constants.DISK_FORMAT_VHD
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