Add sysupgrade state file

When IPA package is being updated, some of the configuration files
are also updated. Sometimes it may be useful to store upgrade meta
information for next package upgrades. For example an information
that some config file was already updated and we don't want to
update it again if user purposedly reverted the change.

This patch adds a new StateFile in /var/lib/ipa/sysupgrade which
is capable of holding this information. New sysupgrade.py module
was created to provide simple API to access the upgrade state
information.

ipaserver/install/sysupgrade.py

@@ -0,0 +1,47 @@
+# Authors: Martin Kosek <mkosek@redhat.com>
+#
+# Copyright (C) 2012  Red Hat
+# see file 'COPYING' for use and warranty information
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty 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, see <http://www.gnu.org/licenses/>.
+#
+
+import os
+import os.path
+
+from ipapython import sysrestore
+from ipapython.ipa_log_manager import *
+
+STATEFILE_DIR = '/var/lib/ipa/sysupgrade'
+STATEFILE_FILE = 'sysupgrade.state'
+
+_sstore = sysrestore.StateFile(STATEFILE_DIR, STATEFILE_FILE)
+
+def get_upgrade_state(module, state):
+    global _sstore
+    return _sstore.get_state(module, state)
+
+def set_upgrade_state(module, state, value):
+    global _sstore
+    _sstore.backup_state(module, state, value)
+
+def remove_upgrade_state(module, state):
+    global _sstore
+    _sstore.delete_state(module, state)
+
+def remove_upgrade_file():
+    try:
+        os.remove(os.path.join(STATEFILE_DIR, STATEFILE_FILE))
+    except Exception, e:
+        root_logger.debug('Cannot remove sysupgrade state file: %s', e)