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  # Copyright 2012 Michael Still and Canonical Inc
  # 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.
  
  """Config Drive v2 helper."""
  
  import os
  import shutil
  import tempfile
  
  from oslo.config import cfg
  
  from nova import exception
  from nova.openstack.common import fileutils
  from nova.openstack.common import log as logging
  from nova import utils
  from nova import version
  
  LOG = logging.getLogger(__name__)
  
  configdrive_opts = [
      cfg.StrOpt('config_drive_format',
                 default='iso9660',
                 help='Config drive format. One of iso9660 (default) or vfat'),
      cfg.StrOpt('config_drive_tempdir',
                 default=tempfile.tempdir,
                 help=('Where to put temporary files associated with '
                       'config drive creation')),
      # force_config_drive is a string option, to allow for future behaviors
      #  (e.g. use config_drive based on image properties)
      cfg.StrOpt('force_config_drive',
                 default=None,
                 help='Set to force injection to take place on a config drive '
                      '(if set, valid options are: always)'),
      cfg.StrOpt('mkisofs_cmd',
                 default='genisoimage',
                 help='Name and optionally path of the tool used for '
                      'ISO image creation')
      ]
  
  CONF = cfg.CONF
  CONF.register_opts(configdrive_opts)
  
  # Config drives are 64mb, if we can't size to the exact size of the data
  CONFIGDRIVESIZE_BYTES = 64 * 1024 * 1024
  
  
  class ConfigDriveBuilder(object):
      """Build config drives, optionally as a context manager."""
  
      def __init__(self, instance_md=None):
          self.imagefile = None
  
          # TODO(mikal): I don't think I can use utils.tempdir here, because
          # I need to have the directory last longer than the scope of this
          # method call
          self.tempdir = tempfile.mkdtemp(dir=CONF.config_drive_tempdir,
                                          prefix='cd_gen_')
  
          if instance_md is not None:
              self.add_instance_metadata(instance_md)
  
      def __enter__(self):
          return self
  
      def __exit__(self, exctype, excval, exctb):
          if exctype is not None:
              # NOTE(mikal): this means we're being cleaned up because an
              # exception was thrown. All bets are off now, and we should not
              # swallow the exception
              return False
          self.cleanup()
  
      def _add_file(self, path, data):
          filepath = os.path.join(self.tempdir, path)
          dirname = os.path.dirname(filepath)
          fileutils.ensure_tree(dirname)
          with open(filepath, 'w') as f:
              f.write(data)
  
      def add_instance_metadata(self, instance_md):
          for (path, value) in instance_md.metadata_for_config_drive():
              self._add_file(path, value)
              LOG.debug(_('Added %(filepath)s to config drive'),
                        {'filepath': path})
  
      def _make_iso9660(self, path):
          publisher = "%(product)s %(version)s" % {
              'product': version.product_string(),
              'version': version.version_string_with_package()
              }
  
          utils.execute(CONF.mkisofs_cmd,
                        '-o', path,
                        '-ldots',
                        '-allow-lowercase',
                        '-allow-multidot',
                        '-l',
                        '-publisher',
                        publisher,
                        '-quiet',
                        '-J',
                        '-r',
                        '-V', 'config-2',
                        self.tempdir,
                        attempts=1,
                        run_as_root=False)
  
      def _make_vfat(self, path):
          # NOTE(mikal): This is a little horrible, but I couldn't find an
          # equivalent to genisoimage for vfat filesystems.
          with open(path, 'w') as f:
              f.truncate(CONFIGDRIVESIZE_BYTES)
  
          utils.mkfs('vfat', path, label='config-2')
  
          mounted = False
          try:
              mountdir = tempfile.mkdtemp(dir=CONF.config_drive_tempdir,
                                          prefix='cd_mnt_')
              _out, err = utils.trycmd('mount', '-o',
                                       'loop,uid=%d,gid=%d' % (os.getuid(),
                                                               os.getgid()),
                                       path, mountdir,
                                       run_as_root=True)
              if err:
                  raise exception.ConfigDriveMountFailed(operation='mount',
                                                         error=err)
              mounted = True
  
              # NOTE(mikal): I can't just use shutils.copytree here, because the
              # destination directory already exists. This is annoying.
              for ent in os.listdir(self.tempdir):
                  shutil.copytree(os.path.join(self.tempdir, ent),
                                  os.path.join(mountdir, ent))
  
          finally:
              if mounted:
                  utils.execute('umount', mountdir, run_as_root=True)
              shutil.rmtree(mountdir)
  
      def make_drive(self, path):
          """Make the config drive.
  
          :param path: the path to place the config drive image at
  
          :raises ProcessExecuteError if a helper process has failed.
          """
          if CONF.config_drive_format == 'iso9660':
              self._make_iso9660(path)
          elif CONF.config_drive_format == 'vfat':
              self._make_vfat(path)
          else:
              raise exception.ConfigDriveUnknownFormat(
                  format=CONF.config_drive_format)
  
      def cleanup(self):
          if self.imagefile:
              utils.delete_if_exists(self.imagefile)
  
          try:
              shutil.rmtree(self.tempdir)
          except OSError as e:
              LOG.error(_('Could not remove tmpdir: %s'), str(e))
  
  
  def required_by(instance):
      return instance.get('config_drive') or CONF.force_config_drive
  
  
  def enabled_for(instance):
      return required_by(instance) or instance.get('config_drive_id')
  