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Viewing changes to hooks/charmhelpers/core/fstab.py

charmhelpers resync [a=tribaal] [r=sparkiegeek,dpb]

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hooks/charmhelpers/core/fstab.py
 
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#!/usr/bin/env python
 
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# -*- coding: utf-8 -*-
 
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__author__ = 'Jorge Niedbalski R. <jorge.niedbalski@canonical.com>'
 
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import os
 
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class Fstab(file):
 
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    """This class extends file in order to implement a file reader/writer
 
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    for file `/etc/fstab`
 
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    """
 
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    class Entry(object):
 
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        """Entry class represents a non-comment line on the `/etc/fstab` file
 
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        """
 
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        def __init__(self, device, mountpoint, filesystem,
 
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                     options, d=0, p=0):
 
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            self.device = device
 
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            self.mountpoint = mountpoint
 
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            self.filesystem = filesystem
 
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            if not options:
 
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                options = "defaults"
 
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            self.options = options
 
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            self.d = d
 
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            self.p = p
 
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        def __eq__(self, o):
 
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            return str(self) == str(o)
 
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        def __str__(self):
 
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            return "{} {} {} {} {} {}".format(self.device,
 
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                                              self.mountpoint,
 
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                                              self.filesystem,
 
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                                              self.options,
 
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                                              self.d,
 
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                                              self.p)
 
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    DEFAULT_PATH = os.path.join(os.path.sep, 'etc', 'fstab')
 
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    def __init__(self, path=None):
 
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        if path:
 
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            self._path = path
 
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        else:
 
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            self._path = self.DEFAULT_PATH
 
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        file.__init__(self, self._path, 'r+')
 
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    def _hydrate_entry(self, line):
 
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        # NOTE: use split with no arguments to split on any
 
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        #       whitespace including tabs
 
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        return Fstab.Entry(*filter(
 
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            lambda x: x not in ('', None),
 
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            line.strip("\n").split()))
 
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    @property
 
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    def entries(self):
 
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        self.seek(0)
 
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        for line in self.readlines():
 
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            try:
 
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                if not line.startswith("#"):
 
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                    yield self._hydrate_entry(line)
 
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            except ValueError:
 
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                pass
 
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    def get_entry_by_attr(self, attr, value):
 
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        for entry in self.entries:
 
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            e_attr = getattr(entry, attr)
 
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            if e_attr == value:
 
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                return entry
 
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        return None
 
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    def add_entry(self, entry):
 
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        if self.get_entry_by_attr('device', entry.device):
 
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            return False
 
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        self.write(str(entry) + '\n')
 
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        self.truncate()
 
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        return entry
 
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    def remove_entry(self, entry):
 
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        self.seek(0)
 
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        lines = self.readlines()
 
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        found = False
 
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        for index, line in enumerate(lines):
 
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            if not line.startswith("#"):
 
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                if self._hydrate_entry(line) == entry:
 
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                    found = True
 
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                    break
 
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        if not found:
 
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            return False
 
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        lines.remove(line)
 
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        self.seek(0)
 
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        self.write(''.join(lines))
 
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        self.truncate()
 
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        return True
 
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    @classmethod
 
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    def remove_by_mountpoint(cls, mountpoint, path=None):
 
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        fstab = cls(path=path)
 
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        entry = fstab.get_entry_by_attr('mountpoint', mountpoint)
 
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        if entry:
 
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            return fstab.remove_entry(entry)
 
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        return False
 
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    @classmethod
 
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    def add(cls, device, mountpoint, filesystem, options=None, path=None):
 
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        return cls(path=path).add_entry(Fstab.Entry(device,
 
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                                                    mountpoint, filesystem,
 
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                                                    options=options))