1 # -*- coding: UTF-8 -*-

     2 # Copyright (c) 2008 - 2012, Pascal Volk

     3 # See COPYING for distribution information.

     4 """

     5     VirtualMailManager.ext.postconf

     6     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

     7 

     8     Wrapper class for Postfix's postconf.

     9     Postconf instances can be used to read actual values of configuration

    10     parameters or edit the value of a configuration parameter.

    11 

    12     postconf.read(parameter) -> value

    13     postconf.edit(parameter, value)

    14 """

    15 

    16 import re

    17 from subprocess import Popen, PIPE

    18 

    19 from VirtualMailManager.errors import VMMError

    20 from VirtualMailManager.constants import VMM_ERROR

    21 

    22 _ = lambda msg: msg

    23 

    24 

    25 class Postconf(object):

    26     """Wrapper class for Postfix's postconf."""

    27     __slots__ = ('_bin', '_val')

    28     _parameter_re = re.compile(r'^\w+$')

    29     _variables_re = re.compile(r'\$\b\w+\b')

    30 

    31     def __init__(self, postconf_bin):

    32         """Creates a new Postconf instance.

    33 

    34         Argument:

    35 

    36         `postconf_bin` : str

    37           absolute path to the Postfix postconf binary.

    38         """

    39         self._bin = postconf_bin

    40         self._val = ''

    41 

    42     def edit(self, parameter, value):

    43         """Set the `parameter`'s value to `value`.

    44 

    45         Arguments:

    46 

    47         `parameter` : str

    48           the name of a Postfix configuration parameter

    49         `value` : str

    50           the parameter's new value.

    51         """

    52         self._check_parameter(parameter)

    53         stderr = Popen((self._bin, '-e', parameter + '=' + str(value)),

    54                        stderr=PIPE).communicate()[1]

    55         if stderr:

    56             raise VMMError(stderr.strip(), VMM_ERROR)

    57 

    58     def read(self, parameter, expand_vars=True):

    59         """Returns the parameters value.

    60 

    61         If expand_vars is True (default), all variables in the value will be

    62         expanded:

    63         e.g. mydestination: mail.example.com, localhost.example.com, localhost

    64         Otherwise the value may contain one or more variables.

    65         e.g. mydestination: $myhostname, localhost.$mydomain, localhost

    66 

    67         Arguments:

    68 

    69         `parameter` : str

    70           the name of a Postfix configuration parameter.

    71         `expand_vars` : bool

    72           indicates if variables should be expanded or not, default True

    73         """

    74         self._check_parameter(parameter)

    75         self._val = self._read(parameter)

    76         if expand_vars:

    77             self._expand_vars()

    78         return self._val

    79 

    80     def _check_parameter(self, parameter):

    81         """Check that the `parameter` looks like a configuration parameter.

    82         If not, a VMMError will be raised."""

    83         if not self.__class__._parameter_re.match(parameter):

    84             raise VMMError(_(u"The value '%s' does not look like a valid "

    85                              u"postfix configuration parameter name.") %

    86                            parameter, VMM_ERROR)

    87 

    88     def _expand_vars(self):

    89         """Expand the $variables in self._val to their values."""

    90         while True:

    91             pvars = set(self.__class__._variables_re.findall(self._val))

    92             if not pvars:

    93                 break

    94             if len(pvars) > 1:

    95                 self._expand_multi_vars(self._read_multi(pvars))

    96                 continue

    97             pvars = pvars.pop()

    98             self._val = self._val.replace(pvars, self._read(pvars[1:]))

    99 

   100     def _expand_multi_vars(self, old_new):

   101         """Replace all $vars in self._val with their values."""

   102         for old, new in old_new.iteritems():

   103             self._val = self._val.replace('$' + old, new)

   104 

   105     def _read(self, parameter):

   106         """Ask postconf for the value of a single configuration parameter."""

   107         stdout, stderr = Popen([self._bin, '-h', parameter], stdout=PIPE,

   108                                stderr=PIPE).communicate()

   109         if stderr:

   110             raise VMMError(stderr.strip(), VMM_ERROR)

   111         return stdout.strip()

   112 

   113     def _read_multi(self, parameters):

   114         """Ask postconf for multiple configuration parameters. Returns a dict

   115         parameter: value items."""

   116         cmd = [self._bin]

   117         cmd.extend(parameter[1:] for parameter in parameters)

   118         stdout, stderr = Popen(cmd, stdout=PIPE, stderr=PIPE).communicate()

   119         if stderr:

   120             raise VMMError(stderr.strip(), VMM_ERROR)

   121         par_val = {}

   122         for line in stdout.splitlines():

   123             par, val = line.split(' = ')

   124             par_val[par] = val

   125         return par_val

   126 

   127 del _