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OpenStack Study: localfs.py**** CubicPower OpenStack Study ****
# Copyright 2012 Red Hat, Inc. # # 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. import os import tempfile from nova import exception from nova.openstack.common import excutils from nova.openstack.common.gettextutils import _ from nova.openstack.common import log as logging from nova import utils from nova.virt.disk.mount import loop from nova.virt.disk.mount import nbd from nova.virt.disk.vfs import api as vfs LOG = logging.getLogger(__name__)
**** CubicPower OpenStack Study **** class VFSLocalFS(vfs.VFS): """os.path.join() with safety check for injected file paths. Join the supplied path components and make sure that the resulting path we are injecting into is within the mounted guest fs. Trying to be clever and specifying a path with '..' in it will hit this safeguard. """
**** CubicPower OpenStack Study **** def _canonical_path(self, path): canonpath, _err = utils.execute( 'readlink', '-nm', os.path.join(self.imgdir, path.lstrip("/")), run_as_root=True) if not canonpath.startswith(os.path.realpath(self.imgdir) + '/'): raise exception.Invalid(_('File path %s not valid') % path) return canonpath """ This class implements a VFS module that is mapped to a virtual root directory present on the host filesystem. This implementation uses the nova.virt.disk.mount.Mount API to make virtual disk images visible in the host filesystem. If the disk format is raw, it will use the loopback mount impl, otherwise it will use the qemu-nbd impl. """
**** CubicPower OpenStack Study **** def __init__(self, imgfile, imgfmt="raw", partition=None, imgdir=None): super(VFSLocalFS, self).__init__(imgfile, imgfmt, partition) self.imgdir = imgdir self.mount = None
**** CubicPower OpenStack Study **** def setup(self): self.imgdir = tempfile.mkdtemp(prefix="openstack-vfs-localfs") try: if self.imgfmt == "raw": LOG.debug(_("Using LoopMount")) mount = loop.LoopMount(self.imgfile, self.imgdir, self.partition) else: LOG.debug(_("Using NbdMount")) mount = nbd.NbdMount(self.imgfile, self.imgdir, self.partition) if not mount.do_mount(): raise exception.NovaException(mount.error) self.mount = mount except Exception as e: with excutils.save_and_reraise_exception(): LOG.debug(_("Failed to mount image %(ex)s)"), {'ex': str(e)}) self.teardown()
**** CubicPower OpenStack Study **** def teardown(self): try: if self.mount: self.mount.do_teardown() except Exception as e: LOG.debug(_("Failed to unmount %(imgdir)s: %(ex)s") % {'imgdir': self.imgdir, 'ex': str(e)}) try: if self.imgdir: os.rmdir(self.imgdir) except Exception as e: LOG.debug(_("Failed to remove %(imgdir)s: %(ex)s") % {'imgdir': self.imgdir, 'ex': str(e)}) self.imgdir = None self.mount = None
**** CubicPower OpenStack Study **** def make_path(self, path): LOG.debug(_("Make directory path=%s"), path) canonpath = self._canonical_path(path) utils.execute('mkdir', '-p', canonpath, run_as_root=True)
**** CubicPower OpenStack Study **** def append_file(self, path, content): LOG.debug(_("Append file path=%s"), path) canonpath = self._canonical_path(path) args = ["-a", canonpath] kwargs = dict(process_input=content, run_as_root=True) utils.execute('tee', *args, **kwargs)
**** CubicPower OpenStack Study **** def replace_file(self, path, content): LOG.debug(_("Replace file path=%s"), path) canonpath = self._canonical_path(path) args = [canonpath] kwargs = dict(process_input=content, run_as_root=True) utils.execute('tee', *args, **kwargs)
**** CubicPower OpenStack Study **** def read_file(self, path): LOG.debug(_("Read file path=%s"), path) canonpath = self._canonical_path(path) return utils.read_file_as_root(canonpath)
**** CubicPower OpenStack Study **** def has_file(self, path): LOG.debug(_("Has file path=%s"), path) canonpath = self._canonical_path(path) exists, _err = utils.trycmd('readlink', '-e', canonpath, run_as_root=True) return exists
**** CubicPower OpenStack Study **** def set_permissions(self, path, mode): LOG.debug(_("Set permissions path=%(path)s mode=%(mode)o"), {'path': path, 'mode': mode}) canonpath = self._canonical_path(path) utils.execute('chmod', "%o" % mode, canonpath, run_as_root=True)
**** CubicPower OpenStack Study **** def set_ownership(self, path, user, group): LOG.debug(_("Set permissions path=%(path)s " "user=%(user)s group=%(group)s"), {'path': path, 'user': user, 'group': group}) canonpath = self._canonical_path(path) owner = None cmd = "chown" if group is not None and user is not None: owner = user + ":" + group elif user is not None: owner = user elif group is not None: owner = group cmd = "chgrp" if owner is not None: utils.execute(cmd, owner, canonpath, run_as_root=True)
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