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OpenStack Study: guestfs.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. from eventlet import tpool from nova import exception from nova.openstack.common.gettextutils import _ from nova.openstack.common import log as logging from nova.virt.disk.vfs import api as vfs LOG = logging.getLogger(__name__) guestfs = None
**** CubicPower OpenStack Study **** class VFSGuestFS(vfs.VFS): """This class implements a VFS module that uses the libguestfs APIs to access the disk image. The disk image is never mapped into the host filesystem, thus avoiding any potential for symlink attacks from the guest filesystem. """
**** CubicPower OpenStack Study **** def __init__(self, imgfile, imgfmt='raw', partition=None): super(VFSGuestFS, self).__init__(imgfile, imgfmt, partition) global guestfs if guestfs is None: guestfs = __import__('guestfs') self.handle = None
**** CubicPower OpenStack Study **** def setup_os(self): if self.partition == -1: self.setup_os_inspect() else: self.setup_os_static()
**** CubicPower OpenStack Study **** def setup_os_static(self): LOG.debug(_("Mount guest OS image %(imgfile)s partition %(part)s"), {'imgfile': self.imgfile, 'part': str(self.partition)}) if self.partition: self.handle.mount_options("", "/dev/sda%d" % self.partition, "/") else: self.handle.mount_options("", "/dev/sda", "/")
**** CubicPower OpenStack Study **** def setup_os_inspect(self): LOG.debug(_("Inspecting guest OS image %s"), self.imgfile) roots = self.handle.inspect_os() if len(roots) == 0: raise exception.NovaException(_("No operating system found in %s") % self.imgfile) if len(roots) != 1: LOG.debug(_("Multi-boot OS %(roots)s") % {'roots': str(roots)}) raise exception.NovaException( _("Multi-boot operating system found in %s") % self.imgfile) self.setup_os_root(roots[0])
**** CubicPower OpenStack Study **** def setup_os_root(self, root): LOG.debug(_("Inspecting guest OS root filesystem %s"), root) mounts = self.handle.inspect_get_mountpoints(root) if len(mounts) == 0: raise exception.NovaException( _("No mount points found in %(root)s of %(imgfile)s") % {'root': root, 'imgfile': self.imgfile}) # the root directory must be mounted first mounts.sort(key=lambda mount: mount[0]) root_mounted = False for mount in mounts: LOG.debug(_("Mounting %(dev)s at %(dir)s") % {'dev': mount[1], 'dir': mount[0]}) try: self.handle.mount_options("", mount[1], mount[0]) root_mounted = True except RuntimeError as e: msg = _("Error mounting %(device)s to %(dir)s in image" " %(imgfile)s with libguestfs (%(e)s)") % \ {'imgfile': self.imgfile, 'device': mount[1], 'dir': mount[0], 'e': e} if root_mounted: LOG.debug(msg) else: raise exception.NovaException(msg)
**** CubicPower OpenStack Study **** def setup(self): LOG.debug(_("Setting up appliance for %(imgfile)s %(imgfmt)s") % {'imgfile': self.imgfile, 'imgfmt': self.imgfmt}) try: self.handle = tpool.Proxy(guestfs.GuestFS(close_on_exit=False)) except TypeError as e: if 'close_on_exit' in str(e): # NOTE(russellb) In case we're not using a version of # libguestfs new enough to support the close_on_exit paramater, # which was added in libguestfs 1.20. self.handle = tpool.Proxy(guestfs.GuestFS()) else: raise try: self.handle.add_drive_opts(self.imgfile, format=self.imgfmt) self.handle.launch() self.setup_os() self.handle.aug_init("/", 0) except RuntimeError as e: # explicitly teardown instead of implicit close() # to prevent orphaned VMs in cases when an implicit # close() is not enough self.teardown() raise exception.NovaException( _("Error mounting %(imgfile)s with libguestfs (%(e)s)") % {'imgfile': self.imgfile, 'e': e}) except Exception: # explicitly teardown instead of implicit close() # to prevent orphaned VMs in cases when an implicit # close() is not enough self.teardown() raise
**** CubicPower OpenStack Study **** def teardown(self): LOG.debug(_("Tearing down appliance")) try: try: self.handle.aug_close() except RuntimeError as e: LOG.warn(_("Failed to close augeas %s"), e) try: self.handle.shutdown() except AttributeError: # Older libguestfs versions haven't an explicit shutdown pass except RuntimeError as e: LOG.warn(_("Failed to shutdown appliance %s"), e) try: self.handle.close() except AttributeError: # Older libguestfs versions haven't an explicit close pass except RuntimeError as e: LOG.warn(_("Failed to close guest handle %s"), e) finally: # dereference object and implicitly close() self.handle = None @staticmethod
**** CubicPower OpenStack Study **** def _canonicalize_path(path): if path[0] != '/': return '/' + path return path
**** CubicPower OpenStack Study **** def make_path(self, path): LOG.debug(_("Make directory path=%s"), path) path = self._canonicalize_path(path) self.handle.mkdir_p(path)
**** CubicPower OpenStack Study **** def append_file(self, path, content): LOG.debug(_("Append file path=%s"), path) path = self._canonicalize_path(path) self.handle.write_append(path, content)
**** CubicPower OpenStack Study **** def replace_file(self, path, content): LOG.debug(_("Replace file path=%s"), path) path = self._canonicalize_path(path) self.handle.write(path, content)
**** CubicPower OpenStack Study **** def read_file(self, path): LOG.debug(_("Read file path=%s"), path) path = self._canonicalize_path(path) return self.handle.read_file(path)
**** CubicPower OpenStack Study **** def has_file(self, path): LOG.debug(_("Has file path=%s"), path) path = self._canonicalize_path(path) try: self.handle.stat(path) return True except RuntimeError: return False
**** CubicPower OpenStack Study **** def set_permissions(self, path, mode): LOG.debug(_("Set permissions path=%(path)s mode=%(mode)s"), {'path': path, 'mode': mode}) path = self._canonicalize_path(path) self.handle.chmod(mode, path)
**** CubicPower OpenStack Study **** def set_ownership(self, path, user, group): LOG.debug(_("Set ownership path=%(path)s " "user=%(user)s group=%(group)s"), {'path': path, 'user': user, 'group': group}) path = self._canonicalize_path(path) uid = -1 gid = -1 if user is not None: uid = int(self.handle.aug_get( "/files/etc/passwd/" + user + "/uid")) if group is not None: gid = int(self.handle.aug_get( "/files/etc/group/" + group + "/gid")) LOG.debug(_("chown uid=%(uid)d gid=%(gid)s"), {'uid': uid, 'gid': gid}) self.handle.chown(uid, gid, path)
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