fstab.py

# Copyright (C) 2011 Canonical
#
# Author:
#  Michael Vogt
#
# 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; version 3.
#
# 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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

from __future__ import print_function, unicode_literals

import os


class FstabEntry(object):
    """ a single fstab entry line """
    @classmethod
    def from_line(cls, line):
        # split up
        args = line.partition("#")[0].split()
        # use only the first 7 args and ignore anything after them, mount
        # seems to do the same, see bug #873411 comment #7
        return FstabEntry(*args[0:6])

    def __init__(self, fs_spec, mountpoint, fstype, options, dump=0, passno=0):
        # uuid or device
        self.fs_spec = fs_spec
        self.mountpoint = mountpoint
        self.fstype = fstype
        self.options = options
        self.dump = dump
        self.passno = passno

    def __repr__(self):
        return "<FstabEntry '%s' '%s' '%s' '%s' '%s' '%s'>" % (
            self.fs_spec, self.mountpoint, self.fstype,
            self.options, self.dump, self.passno)


class Fstab(list):
    """ a list of FstabEntry items """
    def __init__(self, fstab="/etc/fstab"):
        super(Fstab, self).__init__()

        with open(fstab) as fstab_file:
            for line in (l.strip() for l in fstab_file):
                if line == "" or line.startswith("#"):
                    continue
                try:
                    entry = FstabEntry.from_line(line)
                except ValueError:
                    continue
                self.append(entry)

    def get_supported_btrfs_root_fstab_entry(self):
        """ return the supported btrfs root FstabEntry or None """
        for entry in self:
            if (
                    entry.mountpoint == "/" and
                    entry.fstype == "btrfs" and
                    "subvol=@" in entry.options):
                return entry
        return None

    def uuid_for_mountpoint(self, mountpoint, fstab="/etc/fstab"):
        """ return the device or UUID for the given mountpoint """
        for entry in self:
            if entry.mountpoint == mountpoint:
                return entry.fs_spec
        return None