Add an fsinfo class.

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

blivet/tasks/fsinfo.py

@@ -0,0 +1,127 @@
+# fsinfo.py
+# Filesystem information gathering classes.
+#
+# Copyright (C) 2015  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 FSInfo(task.Task):
+    """ An abstract class that represents an information gathering app. """
+
+    description = "filesystem info"
+
+    app_name = abc.abstractproperty(
+       doc="The name of the filesystem information gathering application.")
+
+    options = abc.abstractproperty(
+       doc="Options for invoking the 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 False
+
+    @property
+    def unready(self):
+        if not self.fs.exists:
+            return "filesystem has not been created"
+
+        if not os.path.exists(self.fs.device):
+            return "device does not exist"
+
+        return False
+
+    @property
+    def unable(self):
+        return False
+
+    def _infoCommand(self):
+        """ Returns the command for reading filesystem information.
+
+            :returns: a list of appropriate options
+            :rtype: list of str
+        """
+        return [str(self._app())] + self.options + [self.fs.device]
+
+    def doTask(self):
+        """ Returns information from the command.
+
+            :returns: a string representing the output of the command
+            :rtype: str
+            :raises FSError: if info cannot be obtained
+        """
+        error_msg = self.impossible
+        if error_msg:
+            raise FSError(error_msg)
+        try:
+            (rc, out) = util.run_program_and_capture_output(self._infoCommand())
+            if rc:
+                error_msg = "failed to gather fs info: %s" % rc
+        except OSError as e:
+            error_msg = "failed to gather fs info: %s" % e
+        if error_msg:
+            raise FSError(error_msg)
+        return out
+
+class Ext2FSInfo(FSInfo):
+    app_name = "dumpe2fs"
+    options = ["-h"]
+
+class JFSInfo(FSInfo):
+    app_name = "jfs_tune"
+    options = ["-l"]
+
+class NTFSInfo(FSInfo):
+    app_name = "ntfsinfo"
+    options = ["-m"]
+
+class ReiserFSInfo(FSInfo):
+    app_name = "debugreiserfs"
+    options = []
+
+class XFSInfo(FSInfo):
+    app_name = "xfs_db"
+    options = ["-c", "sb 0", "-c", "p dblocks", "-c", "p blocksize"]