Introduce a VFS implementation backed by the libguestfs APIs
This implements the VFS APIs using the libguestfs Python APIs. This removes the need to map the virtual disk image into the host filesystem, and thus avoids potential symlink attacks from the guest filesystem. It also performs better than the libguestfs FUSE module blueprint: virt-disk-api-refactoring Change-Id: I3202ec9479f22aa1ae461cab24968e54be1642c1 Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrange
parent
d23f6dc1c6
commit
74e38f1bae
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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#
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# Copyright 2012 Red Hat, Inc
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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class GuestFS(object):
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def __init__(self):
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self.drives = []
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self.running = False
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self.closed = False
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self.mounts = []
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self.files = {}
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self.auginit = False
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def launch(self):
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self.running = True
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def shutdown(self):
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self.running = False
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self.mounts = []
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self.drives = []
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def close(self):
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self.closed = True
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def add_drive_opts(self, file, *args, **kwargs):
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self.drives.append((file, kwargs['format']))
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def inspect_os(self):
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return ["/dev/guestvgf/lv_root"]
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def inspect_get_mountpoints(self, dev):
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return [["/", "/dev/mapper/guestvgf-lv_root"],
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["/boot", "/dev/vda1"]]
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def mount_options(self, options, device, mntpoint):
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self.mounts.append((options, device, mntpoint))
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def mkdir_p(self, path):
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if not path in self.files:
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self.files[path] = {
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"isdir": True,
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"gid": 100,
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"uid": 100,
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"mode": 0700
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}
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def read_file(self, path):
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if not path in self.files:
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self.files[path] = {
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"isdir": False,
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"content": "Hello World",
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"gid": 100,
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"uid": 100,
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"mode": 0700
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}
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return self.files[path]["content"]
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def write(self, path, content):
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if not path in self.files:
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self.files[path] = {
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"isdir": False,
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"content": "Hello World",
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"gid": 100,
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"uid": 100,
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"mode": 0700
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}
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self.files[path]["content"] = content
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def write_append(self, path, content):
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if not path in self.files:
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self.files[path] = {
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"isdir": False,
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"content": "Hello World",
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"gid": 100,
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"uid": 100,
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"mode": 0700
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}
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self.files[path]["content"] = self.files[path]["content"] + content
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def stat(self, path):
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if not path in self.files:
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raise Exception("No such file: " + path)
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return self.files[path]["mode"]
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def chown(self, uid, gid, path):
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if not path in self.files:
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raise Exception("No such file: " + path)
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if uid != -1:
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self.files[path]["uid"] = uid
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if gid != -1:
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self.files[path]["gid"] = gid
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def chmod(self, mode, path):
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if not path in self.files:
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raise Exception("No such file: " + path)
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self.files[path]["mode"] = mode
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def aug_init(self, root, flags):
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self.auginit = True
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def aug_close(self):
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self.auginit = False
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def aug_get(self, cfgpath):
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if not self.auginit:
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raise Exception("Augeus not initialized")
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if cfgpath == "/files/etc/passwd/root/uid":
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return 0
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elif cfgpath == "/files/etc/passwd/fred/uid":
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return 105
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elif cfgpath == "/files/etc/passwd/joe/uid":
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return 110
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elif cfgpath == "/files/etc/group/root/gid":
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return 0
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elif cfgpath == "/files/etc/group/users/gid":
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return 500
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elif cfgpath == "/files/etc/group/admins/gid":
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return 600
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raise Exception("Unknown path %s", cfgpath)
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@ -0,0 +1,176 @@
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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#
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# Copyright (C) 2012 Red Hat, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import sys
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from nova import test
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from nova.tests import fakeguestfs
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from nova.virt.disk.vfs import guestfs as vfsimpl
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class VirtDiskVFSGuestFSTest(test.TestCase):
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def setUp(self):
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super(VirtDiskVFSGuestFSTest, self).setUp()
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sys.modules['guestfs'] = fakeguestfs
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vfsimpl.guestfs = fakeguestfs
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def test_appliance_setup_inspect(self):
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vfs = vfsimpl.VFSGuestFS(imgfile="/dummy.qcow2",
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imgfmt="qcow2",
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partition=-1)
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vfs.setup()
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self.assertEqual(vfs.handle.running, True)
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self.assertEqual(len(vfs.handle.mounts), 2)
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self.assertEqual(vfs.handle.mounts[0][1],
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"/dev/mapper/guestvgf-lv_root")
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self.assertEqual(vfs.handle.mounts[1][1], "/dev/vda1")
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self.assertEqual(vfs.handle.mounts[0][2], "/")
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self.assertEqual(vfs.handle.mounts[1][2], "/boot")
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handle = vfs.handle
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vfs.teardown()
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self.assertEqual(vfs.handle, None)
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self.assertEqual(handle.running, False)
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self.assertEqual(handle.closed, True)
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self.assertEqual(len(handle.mounts), 0)
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def test_appliance_setup_static_nopart(self):
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vfs = vfsimpl.VFSGuestFS(imgfile="/dummy.qcow2",
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imgfmt="qcow2",
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partition=None)
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vfs.setup()
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self.assertEqual(vfs.handle.running, True)
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self.assertEqual(len(vfs.handle.mounts), 1)
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self.assertEqual(vfs.handle.mounts[0][1], "/dev/sda")
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self.assertEqual(vfs.handle.mounts[0][2], "/")
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handle = vfs.handle
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vfs.teardown()
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self.assertEqual(vfs.handle, None)
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self.assertEqual(handle.running, False)
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self.assertEqual(handle.closed, True)
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self.assertEqual(len(handle.mounts), 0)
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def test_appliance_setup_static_part(self):
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vfs = vfsimpl.VFSGuestFS(imgfile="/dummy.qcow2",
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imgfmt="qcow2",
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partition=2)
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vfs.setup()
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self.assertEqual(vfs.handle.running, True)
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self.assertEqual(len(vfs.handle.mounts), 1)
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self.assertEqual(vfs.handle.mounts[0][1], "/dev/sda2")
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self.assertEqual(vfs.handle.mounts[0][2], "/")
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handle = vfs.handle
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vfs.teardown()
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self.assertEqual(vfs.handle, None)
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self.assertEqual(handle.running, False)
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self.assertEqual(handle.closed, True)
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self.assertEqual(len(handle.mounts), 0)
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def test_makepath(self):
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vfs = vfsimpl.VFSGuestFS(imgfile="/dummy.qcow2", imgfmt="qcow2")
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vfs.setup()
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vfs.make_path("/some/dir")
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vfs.make_path("/other/dir")
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self.assertTrue("/some/dir" in vfs.handle.files)
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self.assertTrue("/other/dir" in vfs.handle.files)
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self.assertTrue(vfs.handle.files["/some/dir"]["isdir"])
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self.assertTrue(vfs.handle.files["/other/dir"]["isdir"])
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vfs.teardown()
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def test_append_file(self):
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vfs = vfsimpl.VFSGuestFS(imgfile="/dummy.qcow2", imgfmt="qcow2")
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vfs.setup()
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vfs.append_file("/some/file", " Goodbye")
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self.assertTrue("/some/file" in vfs.handle.files)
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self.assertEqual(vfs.handle.files["/some/file"]["content"],
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"Hello World Goodbye")
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vfs.teardown()
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def test_replace_file(self):
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vfs = vfsimpl.VFSGuestFS(imgfile="/dummy.qcow2", imgfmt="qcow2")
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vfs.setup()
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vfs.replace_file("/some/file", "Goodbye")
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self.assertTrue("/some/file" in vfs.handle.files)
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self.assertEqual(vfs.handle.files["/some/file"]["content"],
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"Goodbye")
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vfs.teardown()
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def test_read_file(self):
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vfs = vfsimpl.VFSGuestFS(imgfile="/dummy.qcow2", imgfmt="qcow2")
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vfs.setup()
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self.assertEqual(vfs.read_file("/some/file"), "Hello World")
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vfs.teardown()
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def test_has_file(self):
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vfs = vfsimpl.VFSGuestFS(imgfile="/dummy.qcow2", imgfmt="qcow2")
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vfs.setup()
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vfs.read_file("/some/file")
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self.assertTrue(vfs.has_file("/some/file"))
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self.assertFalse(vfs.has_file("/other/file"))
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vfs.teardown()
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def test_set_permissions(self):
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vfs = vfsimpl.VFSGuestFS(imgfile="/dummy.qcow2", imgfmt="qcow2")
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vfs.setup()
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vfs.read_file("/some/file")
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self.assertEquals(vfs.handle.files["/some/file"]["mode"], 0700)
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vfs.set_permissions("/some/file", 0777)
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self.assertEquals(vfs.handle.files["/some/file"]["mode"], 0777)
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vfs.teardown()
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def test_set_ownership(self):
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vfs = vfsimpl.VFSGuestFS(imgfile="/dummy.qcow2", imgfmt="qcow2")
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vfs.setup()
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vfs.read_file("/some/file")
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self.assertEquals(vfs.handle.files["/some/file"]["uid"], 100)
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self.assertEquals(vfs.handle.files["/some/file"]["gid"], 100)
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vfs.set_ownership("/some/file", "fred", None)
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self.assertEquals(vfs.handle.files["/some/file"]["uid"], 105)
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self.assertEquals(vfs.handle.files["/some/file"]["gid"], 100)
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vfs.set_ownership("/some/file", None, "users")
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self.assertEquals(vfs.handle.files["/some/file"]["uid"], 105)
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self.assertEquals(vfs.handle.files["/some/file"]["gid"], 500)
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vfs.set_ownership("/some/file", "joe", "admins")
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self.assertEquals(vfs.handle.files["/some/file"]["uid"], 110)
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self.assertEquals(vfs.handle.files["/some/file"]["gid"], 600)
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vfs.teardown()
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2012 Red Hat, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import guestfs
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from nova import exception
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from nova.openstack.common import log as logging
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from nova.virt.disk.vfs import api as vfs
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LOG = logging.getLogger(__name__)
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guestfs = None
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class VFSGuestFS(vfs.VFS):
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"""
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This class implements a VFS module that uses the libguestfs APIs
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to access the disk image. The disk image is never mapped into
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the host filesystem, thus avoiding any potential for symlink
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attacks from the guest filesystem.
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"""
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def __init__(self, imgfile, imgfmt='raw', partition=None):
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super(VFSGuestFS, self).__init__(imgfile, imgfmt, partition)
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global guestfs
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if guestfs is None:
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guestfs = __import__('guestfs')
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self.handle = None
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def setup_os(self):
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if self.partition == -1:
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self.setup_os_inspect()
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else:
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self.setup_os_static()
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def setup_os_static(self):
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LOG.debug(_("Mount guest OS image %(imgfile)s partition %(part)s"),
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{'imgfile': self.imgfile, 'part': str(self.partition)})
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if self.partition:
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self.handle.mount_options("", "/dev/sda%d" % self.partition, "/")
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else:
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self.handle.mount_options("", "/dev/sda", "/")
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def setup_os_inspect(self):
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LOG.debug(_("Inspecting guest OS image %s"), self.imgfile)
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roots = self.handle.inspect_os()
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if len(roots) == 0:
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raise exception.NovaException(_("No operating system found in %s"),
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self.imgfile)
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if len(roots) != 1:
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LOG.debug(_("Multi-boot OS %(roots)s") % {'roots': str(roots)})
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raise exception.NovaException(
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_("Multi-boot operating system found in %s"),
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self.imgfile)
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self.setup_os_root(roots[0])
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def setup_os_root(self, root):
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LOG.debug(_("Inspecting guest OS root filesystem %s"), root)
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mounts = self.handle.inspect_get_mountpoints(root)
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if len(mounts) == 0:
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raise exception.NovaException(
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_("No mount points found in %(root)s of %(imgfile)s") %
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{'root': root, 'imgfile': self.imgfile})
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mounts.sort(key=lambda mount: mount[1])
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for mount in mounts:
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LOG.debug(_("Mounting %(dev)s at %(dir)s") %
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{'dev': mount[1], 'dir': mount[0]})
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self.handle.mount_options("", mount[1], mount[0])
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def setup(self):
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try:
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LOG.debug(_("Setting up appliance for %(imgfile)s %(imgfmt)s") %
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{'imgfile': self.imgfile, 'imgfmt': self.imgfmt})
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self.handle = guestfs.GuestFS()
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self.handle.add_drive_opts(self.imgfile, format=self.imgfmt)
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self.handle.launch()
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self.setup_os()
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self.handle.aug_init("/", 0)
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except Exception, e:
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self.handle = None
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raise
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def teardown(self):
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LOG.debug(_("Tearing down appliance"))
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try:
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self.handle.aug_close()
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except Exception, e:
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LOG.debug(_("Failed to close augeas %s"), str(e))
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try:
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self.handle.shutdown()
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except Exception, e:
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LOG.debug(_("Failed to shutdown appliance %s"), str(e))
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try:
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self.handle.close()
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except Exception, e:
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LOG.debug(_("Failed to close guest handle %s"), str(e))
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self.handle = None
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@staticmethod
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def _canonicalize_path(path):
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if path[0] != '/':
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return '/' + path
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return path
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def make_path(self, path):
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LOG.debug(_("Make directory path=%(path)s") % locals())
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path = self._canonicalize_path(path)
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self.handle.mkdir_p(path)
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def append_file(self, path, content):
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LOG.debug(_("Append file path=%(path)s") % locals())
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path = self._canonicalize_path(path)
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self.handle.write_append(path, content)
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def replace_file(self, path, content):
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LOG.debug(_("Replace file path=%(path)s") % locals())
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path = self._canonicalize_path(path)
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self.handle.write(path, content)
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def read_file(self, path):
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LOG.debug(_("Read file path=%(path)s") % locals())
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path = self._canonicalize_path(path)
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return self.handle.read_file(path)
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def has_file(self, path):
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LOG.debug(_("Has file path=%(path)s") % locals())
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path = self._canonicalize_path(path)
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try:
|
||||
self.handle.stat(path)
|
||||
return True
|
||||
except Exception, e:
|
||||
return False
|
||||
|
||||
def set_permissions(self, path, mode):
|
||||
LOG.debug(_("Set permissions path=%(path)s mode=%(mode)s") % locals())
|
||||
path = self._canonicalize_path(path)
|
||||
self.handle.chmod(mode, path)
|
||||
|
||||
def set_ownership(self, path, user, group):
|
||||
LOG.debug(_("Set ownership path=%(path)s "
|
||||
"user=%(user)s group=%(group)s") % locals())
|
||||
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") % locals())
|
||||
self.handle.chown(uid, gid, path)
|
||||
Loading…
Reference in New Issue