Start moving users of parted to privsep.

This isn't all calls, but a step along the way. Note that I moved
a xenapi unit test to being the first unit test for privsep directly.
I'm not sure if I love this way of testing (having the "meat" of
the method undecorated and having a wrapper), but I've been unable
to come up with a way to mock away the entrypoint wrapper.

Change-Id: I35d4e7c6c43cbcbc1549aa28796ff97f447a4b03
blueprint: hurrah-for-privsep

nova/privsep/fs.py

@@ -153,3 +153,45 @@ def unprivileged_resize2fs(image, check_exit_code):
         processutils.execute('resize2fs',
                              image,
                              check_exit_code=check_exit_code)
+
+
+@nova.privsep.sys_admin_pctxt.entrypoint
+def create_partition_table(device, style, check_exit_code=True):
+    processutils.execute('parted', '--script', device, 'mklabel', style,
+                         check_exit_code=check_exit_code)
+
+
+@nova.privsep.sys_admin_pctxt.entrypoint
+def create_partition(device, style, start, end, check_exit_code=True):
+    processutils.execute('parted', '--script', device, '--',
+                         'mkpart', style, start, end,
+                         check_exit_code=check_exit_code)
+
+
+@nova.privsep.sys_admin_pctxt.entrypoint
+def list_partitions(device):
+    return unprivileged_list_partitions(device)
+
+
+# NOTE(mikal): this method is deliberately not wrapped in a privsep entrypoint
+def unprivileged_list_partitions(device):
+    """Return partition information (num, size, type) for a device."""
+
+    out, _err = processutils.execute('parted', '--script', '--machine',
+                                     device, 'unit s', 'print')
+    lines = [line for line in out.split('\n') if line]
+    partitions = []
+
+    LOG.debug('Partitions:')
+    for line in lines[2:]:
+        line = line.rstrip(';')
+        num, start, end, size, fstype, name, flags = line.split(':')
+        num = int(num)
+        start = int(start.rstrip('s'))
+        end = int(end.rstrip('s'))
+        size = int(size.rstrip('s'))
+        LOG.debug('  %(num)s: %(fstype)s %(size)d sectors',
+                  {'num': num, 'fstype': fstype, 'size': size})
+        partitions.append((num, start, size, fstype, name, flags))
+
+    return partitions

nova/tests/unit/privsep/test_fs.py

@@ -0,0 +1,34 @@
+# Copyright 2013 OpenStack Foundation
+# 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.
+
+import mock
+
+import nova.privsep.fs
+from nova import test
+
+
+class PrivsepFilesystemHelpersTestCase(test.NoDBTestCase):
+    @mock.patch('oslo_concurrency.processutils.execute')
+    def test_list_partitions(self, mock_execute):
+        parted_return = "BYT;\n...\n"
+        parted_return += "1:2s:11s:10s:ext3::boot;\n"
+        parted_return += "2:20s:11s:10s::bob:;\n"
+        mock_execute.return_value = (parted_return, None)
+
+        partitions = nova.privsep.fs.unprivileged_list_partitions("abc")
+
+        self.assertEqual(2, len(partitions))
+        self.assertEqual((1, 2, 10, "ext3", "", "boot"), partitions[0])
+        self.assertEqual((2, 20, 10, "", "bob", ""), partitions[1])

nova/tests/unit/virt/xenapi/test_vm_utils.py

@@ -451,19 +451,6 @@ class ResizeHelpersTestCase(VMUtilsTestBase):
     def test_auto_config_disk_returns_early_on_zero_size(self):
         vm_utils.try_auto_configure_disk("bad_session", "bad_vdi_ref", 0)
 
-    @mock.patch.object(utils, "execute")
-    def test_get_partitions(self, mock_execute):
-        parted_return = "BYT;\n...\n"
-        parted_return += "1:2s:11s:10s:ext3::boot;\n"
-        parted_return += "2:20s:11s:10s::bob:;\n"
-        mock_execute.return_value = (parted_return, None)
-
-        partitions = vm_utils._get_partitions("abc")
-
-        self.assertEqual(2, len(partitions))
-        self.assertEqual((1, 2, 10, "ext3", "", "boot"), partitions[0])
-        self.assertEqual((2, 20, 10, "", "bob", ""), partitions[1])
-
 
 class CheckVDISizeTestCase(VMUtilsTestBase):
     def setUp(self):

nova/virt/xenapi/vm_utils.py

@@ -973,16 +973,11 @@ def _make_partition(session, dev, partition_start, partition_end):
 
     # NOTE(bobball) If this runs in Dom0, parted will error trying
     # to re-read the partition table and return a generic error
-    utils.execute('parted', '--script', dev_path,
-                  'mklabel', 'msdos', run_as_root=True,
-                  check_exit_code=not session.is_local_connection)
-
-    utils.execute('parted', '--script', dev_path, '--',
-                  'mkpart', 'primary',
-                  partition_start,
-                  partition_end,
-                  run_as_root=True,
-                  check_exit_code=not session.is_local_connection)
+    nova.privsep.fs.create_partition_table(
+        dev_path, 'msdos', check_exit_code=not session.is_local_connection)
+    nova.privsep.fs.create_partition(
+        dev_path, 'primary', partition_start, partition_end,
+        check_exit_code=not session.is_local_connection)
 
     partition_path = utils.make_dev_path(dev, partition=1)
     if session.is_local_connection:
@@ -2253,27 +2248,7 @@ def _get_this_vm_ref(session):
 
 
 def _get_partitions(dev):
-    """Return partition information (num, size, type) for a device."""
-    dev_path = utils.make_dev_path(dev)
-    out, _err = utils.execute('parted', '--script', '--machine',
-                             dev_path, 'unit s', 'print',
-                             run_as_root=True)
-    lines = [line for line in out.split('\n') if line]
-    partitions = []
-
-    LOG.debug("Partitions:")
-    for line in lines[2:]:
-        line = line.rstrip(';')
-        num, start, end, size, fstype, name, flags = line.split(':')
-        num = int(num)
-        start = int(start.rstrip('s'))
-        end = int(end.rstrip('s'))
-        size = int(size.rstrip('s'))
-        LOG.debug("  %(num)s: %(fstype)s %(size)d sectors",
-                  {'num': num, 'fstype': fstype, 'size': size})
-        partitions.append((num, start, size, fstype, name, flags))
-
-    return partitions
+    return nova.privsep.fs.list_partitions(utils.make_dev_path(dev))
 
 
 def _stream_disk(session, image_service_func, image_type, virtual_size, dev):