Add a filesystem syncing task.

Signed-off-by: mulhern <amulhern@redhat.com>

blivet/tasks/fssync.py

@@ -0,0 +1,111 @@
+# fssync.py
+# Filesystem syncing classes.
+#
+# Copyright (C) 2014  Red Hat, Inc.
+#
+# This copyrighted material is made available to anyone wishing to use,
+# modify, copy, or redistribute it subject to the terms and conditions of
+# the GNU General Public License v.2, or (at your option) any later version.
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY expressed or implied, including the implied warranties of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
+# Public License for more details.  You should have received a copy of the
+# GNU General Public License along with this program; if not, write to the
+# Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301, USA.  Any Red Hat trademarks that are incorporated in the
+# source code or documentation are not subject to the GNU General Public
+# License and may only be used or replicated with the express permission of
+# Red Hat, Inc.
+#
+# Red Hat Author(s): Anne Mulhern <amulhern@redhat.com>
+
+import abc
+import os
+
+from six import add_metaclass
+
+from ..errors import FSError
+from .. import util
+
+from . import availability
+from . import task
+
+@add_metaclass(abc.ABCMeta)
+class FSSync(task.Task):
+    """ An abstract class that represents syncing a filesystem. """
+
+    description = "filesystem syncing"
+
+    app_name = abc.abstractproperty(doc="The name of the syncing application.")
+
+    @classmethod
+    def _app(cls):
+        return availability.Application(availability.Path(), cls.app_name)
+
+    def __init__(self, an_fs):
+        """ Initializer.
+
+            :param FS an_fs: a filesystem object
+        """
+        self.fs = an_fs
+
+    @classmethod
+    def available(cls):
+        return cls._app().available
+
+    @property
+    def unavailable(self):
+        if not self._app().available:
+            return "application %s not available" % self._app()
+        return None
+
+    @property
+    def unready(self):
+        if not self.fs.status:
+            return "filesystem has not been mounted"
+
+        if not os.path.exists(self.fs.device):
+            return "device does not exist"
+
+        return False
+
+    @property
+    def unable(self):
+        return False
+
+    @abc.abstractmethod
+    def doTask(self):
+        raise NotImplementedError()
+
+class XFSSync(FSSync):
+    """ Info application for XFS. """
+
+    app_name = "xfs_freeze"
+
+    def _freezeCommand(self):
+        return [str(self._app()), "-f", self.fs.systemMountpoint]
+
+    def _unfreezeCommand(self):
+        return [str(self._app()), "-u", self.fs.systemMountpoint]
+
+    def doTask(self, root="/"):
+        # pylint: disable=arguments-differ
+        error_msg = self.impossible
+        if error_msg:
+            raise FSError(error_msg)
+
+        error_msg = None
+        try:
+            rc = util.run_program(self._freezeCommand(), root=root)
+        except OSError as e:
+            error_msg = "failed to sync filesytem: %s" % e
+        error_msg = error_msg or rc
+
+        try:
+            rc = util.run_program(self._unfreezeCommand(), root=root)
+        except OSError as e:
+            error_msg = error_msg or "failed to sync filesystem: %s" % e
+        error_msg = error_msg or rc
+
+        if error_msg:
+            raise FSError(error_msg)