+
−# -*- coding: UTF-8 -*-
+
−# Copyright (c) 2008 - 2011, Pascal Volk
+
−# See COPYING for distribution information.
+
−"""
+
−    VirtualMailManager.ext.postconf
+
−    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
−
+
−    Wrapper class for Postfix's postconf.
+
−    Postconf instances can be used to read actual values of configuration
+
−    parameters or edit the value of a configuration parameter.
+
−
+
−    postconf.read(parameter) -> value
+
−    postconf.edit(parameter, value)
+
−"""
+
−
+
−import re
+
−from subprocess import Popen, PIPE
+
−
+
−from VirtualMailManager.errors import VMMError
+
−from VirtualMailManager.constants import VMM_ERROR
+
−
+
−_ = lambda msg: msg
+
−
+
−
+
−class Postconf(object):
+
−    """Wrapper class for Postfix's postconf."""
+
−    __slots__ = ('_bin', '_val')
+
−    _parameter_re = re.compile(r'^\w+$')
+
−    _variables_re = re.compile(r'\$\b\w+\b')
+
−
+
−    def __init__(self, postconf_bin):
+
−        """Creates a new Postconf instance.
+
−
+
−        Argument:
+
−
+
−        `postconf_bin` : str
+
−          absolute path to the Postfix postconf binary.
+
−        """
+
−        self._bin = postconf_bin
+
−        self._val = ''
+
−
+
−    def edit(self, parameter, value):
+
−        """Set the `parameter`'s value to `value`.
+
−
+
−        Arguments:
+
−
+
−        `parameter` : str
+
−          the name of a Postfix configuration parameter
+
−        `value` : str
+
−          the parameter's new value.
+
−        """
+
−        self._check_parameter(parameter)
+
−        stderr = Popen((self._bin, '-e', parameter + '=' + str(value)),
+
−                       stderr=PIPE).communicate()[1]
+
−        if stderr:
+
−            raise VMMError(stderr.strip(), VMM_ERROR)
+
−
+
−    def read(self, parameter, expand_vars=True):
+
−        """Returns the parameters value.
+
−
+
−        If expand_vars is True (default), all variables in the value will be
+
−        expanded:
+
−        e.g. mydestination: mail.example.com, localhost.example.com, localhost
+
−        Otherwise the value may contain one or more variables.
+
−        e.g. mydestination: $myhostname, localhost.$mydomain, localhost
+
−
+
−        Arguments:
+
−
+
−        `parameter` : str
+
−          the name of a Postfix configuration parameter.
+
−        `expand_vars` : bool
+
−          indicates if variables should be expanded or not, default True
+
−        """
+
−        self._check_parameter(parameter)
+
−        self._val = self._read(parameter)
+
−        if expand_vars:
+
−            self._expand_vars()
+
−        return self._val
+
−
+
−    def _check_parameter(self, parameter):
+
−        """Check that the `parameter` looks like a configuration parameter.
+
−        If not, a VMMError will be raised."""
+
−        if not self.__class__._parameter_re.match(parameter):
+
−            raise VMMError(_(u"The value '%s' does not look like a valid "
+
−                             u"postfix configuration parameter name.") %
+
−                           parameter, VMM_ERROR)
+
−
+
−    def _expand_vars(self):
+
−        """Expand the $variables in self._val to their values."""
+
−        while True:
+
−            pvars = set(self.__class__._variables_re.findall(self._val))
+
−            if not pvars:
+
−                break
+
−            if len(pvars) > 1:
+
−                self._expand_multi_vars(self._read_multi(pvars))
+
−                continue
+
−            pvars = pvars.pop()
+
−            self._val = self._val.replace(pvars, self._read(pvars[1:]))
+
−
+
−    def _expand_multi_vars(self, old_new):
+
−        """Replace all $vars in self._val with their values."""
+
−        for old, new in old_new.iteritems():
+
−            self._val = self._val.replace('$' + old, new)
+
−
+
−    def _read(self, parameter):
+
−        """Ask postconf for the value of a single configuration parameter."""
+
−        stdout, stderr = Popen([self._bin, '-h', parameter], stdout=PIPE,
+
−                               stderr=PIPE).communicate()
+
−        if stderr:
+
−            raise VMMError(stderr.strip(), VMM_ERROR)
+
−        return stdout.strip()
+
−
+
−    def _read_multi(self, parameters):
+
−        """Ask postconf for multiple configuration parameters. Returns a dict
+
−        parameter: value items."""
+
−        cmd = [self._bin]
+
−        cmd.extend(parameter[1:] for parameter in parameters)
+
−        stdout, stderr = Popen(cmd, stdout=PIPE, stderr=PIPE).communicate()
+
−        if stderr:
+
−            raise VMMError(stderr.strip(), VMM_ERROR)
+
−        par_val = {}
+
−        for line in stdout.splitlines():
+
−            par, val = line.split(' = ')
+
−            par_val[par] = val
+
−        return par_val
+
−
+
−del _