Coverage for ipapython/ipautil : 47%

# Authors: Simo Sorce <ssorce@redhat.com> 

# 

# Copyright (C) 2007-2011  Red Hat 

# see file 'COPYING' for use and warranty information 

# 

# 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, either version 3 of the License, or 

# (at your option) any later version. 

# 

# 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, see <http://www.gnu.org/licenses/>. 

# 

SHARE_DIR = "/usr/share/ipa/" 

PLUGINS_SHARE_DIR = "/usr/share/ipa/plugins" 

GEN_PWD_LEN = 12 

IPA_BASEDN_INFO = 'ipa v2.0' 

import string 

import tempfile 

import subprocess 

import random 

import os, sys, traceback, readline 

import copy 

import stat 

import shutil 

import urllib2 

import socket 

import ldap 

import struct 

from types import * 

import re 

import xmlrpclib 

import datetime 

import netaddr 

from ipapython.ipa_log_manager import * 

from ipapython import ipavalidate 

from ipapython import config 

try: 

    from subprocess import CalledProcessError 

except ImportError: 

    # Python 2.4 doesn't implement CalledProcessError 

    class CalledProcessError(Exception): 

        """This exception is raised when a process run by check_call() returns 

        a non-zero exit status. The exit status will be stored in the 

        returncode attribute.""" 

        def __init__(self, returncode, cmd): 

            self.returncode = returncode 

            self.cmd = cmd 

        def __str__(self): 

            return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode) 

from ipapython.compat import sha1, md5 

def get_domain_name(): 

    try: 

        config.init_config() 

        domain_name = config.config.get_domain() 

    except Exception: 

        return None 

    return domain_name 

class CheckedIPAddress(netaddr.IPAddress): 

    # Use inet_pton() rather than inet_aton() for IP address parsing. We 

    # will use the same function in IPv4/IPv6 conversions + be stricter 

    # and don't allow IP addresses such as '1.1.1' in the same time 

    netaddr_ip_flags = netaddr.INET_PTON 

    def __init__(self, addr, match_local=False, parse_netmask=True, 

                 allow_network=False, allow_loopback=False, 

                 allow_broadcast=False, allow_multicast=False): 

        if isinstance(addr, CheckedIPAddress): 

            super(CheckedIPAddress, self).__init__(addr, flags=self.netaddr_ip_flags) 

            self.prefixlen = addr.prefixlen 

            self.defaultnet = addr.defaultnet 

            self.interface = addr.interface 

            return 

        net = None 

        iface = None 

        defnet = False 

        if isinstance(addr, netaddr.IPNetwork): 

            net = addr 

            addr = net.ip 

        elif isinstance(addr, netaddr.IPAddress): 

            pass 

        else: 

            try: 

                try: 

                    addr = netaddr.IPAddress(addr, flags=self.netaddr_ip_flags) 

                except netaddr.AddrFormatError: 

                    # netaddr.IPAddress doesn't handle zone indices in textual 

                    # IPv6 addresses. Try removing zone index and parse the 

                    # address again. 

                    if not isinstance(addr, basestring): 

                        raise 

                    addr, sep, foo = addr.partition('%') 

                    if sep != '%': 

                        raise 

                    addr = netaddr.IPAddress(addr, flags=self.netaddr_ip_flags) 

                    if addr.version != 6: 

                        raise 

            except ValueError: 

                net = netaddr.IPNetwork(addr, flags=self.netaddr_ip_flags) 

                if not parse_netmask: 

                    raise ValueError("netmask and prefix length not allowed here") 

                addr = net.ip 

        if addr.version not in (4, 6): 

            raise ValueError("unsupported IP version") 

        if not allow_loopback and addr.is_loopback(): 

            raise ValueError("cannot use loopback IP address") 

        if (not addr.is_loopback() and addr.is_reserved()) \ 

                or addr in netaddr.ip.IPV4_6TO4: 

            raise ValueError("cannot use IANA reserved IP address") 

        if addr.is_link_local(): 

            raise ValueError("cannot use link-local IP address") 

        if not allow_multicast and addr.is_multicast(): 

            raise ValueError("cannot use multicast IP address") 

        if match_local: 

            if addr.version == 4: 

                family = 'inet' 

            elif addr.version == 6: 

                family = 'inet6' 

            ipresult = run(['/sbin/ip', '-family', family, '-oneline', 'address', 'show']) 

            lines = ipresult[0].split('\n') 

            for line in lines: 

                fields = line.split() 

                if len(fields) < 4: 

                    continue 

                ifnet = netaddr.IPNetwork(fields[3]) 

                if ifnet == net or (net is None and ifnet.ip == addr): 

                    net = ifnet 

                    iface = fields[1] 

                    break 

            if iface is None: 

                raise ValueError('No network interface matches the provided IP address and netmask') 

        if net is None: 

            defnet = True 

            if addr.version == 4: 

                net = netaddr.IPNetwork(netaddr.cidr_abbrev_to_verbose(str(addr))) 

            elif addr.version == 6: 

                net = netaddr.IPNetwork(str(addr) + '/64') 

        if not allow_network and  addr == net.network: 

            raise ValueError("cannot use IP network address") 

        if not allow_broadcast and addr.version == 4 and addr == net.broadcast: 

            raise ValueError("cannot use broadcast IP address") 

        super(CheckedIPAddress, self).__init__(addr, flags=self.netaddr_ip_flags) 

        self.prefixlen = net.prefixlen 

        self.defaultnet = defnet 

        self.interface = iface 

    def is_local(self): 

        return self.interface is not None 

def valid_ip(addr): 

    return netaddr.valid_ipv4(addr) or netaddr.valid_ipv6(addr) 

def format_netloc(host, port=None): 

    """ 

    Format network location (host:port). 

    If the host part is a literal IPv6 address, it must be enclosed in square 

    brackets (RFC 2732). 

    """ 

    host = str(host) 

    try: 

        socket.inet_pton(socket.AF_INET6, host) 

        host = '[%s]' % host 

    except socket.error: 

        pass 

    if port is None: 

        return host 

    else: 

        return '%s:%s' % (host, str(port)) 

def realm_to_suffix(realm_name): 

    """Convert a kerberos realm into the IPA suffix.""" 

    s = realm_name.split(".") 

    terms = ["dc=" + x.lower() for x in s] 

    return ",".join(terms) 

def template_str(txt, vars): 

    val = string.Template(txt).substitute(vars) 

    # eval() is a special string one can insert into a template to have the 

    # Python interpreter evaluate the string. This is intended to allow 

    # math to be performed in templates. 

    pattern = re.compile('(eval\s*\(([^()]*)\))') 

    val = pattern.sub(lambda x: str(eval(x.group(2))), val) 

    return val 

def template_file(infilename, vars): 

    txt = open(infilename).read() 

    return template_str(txt, vars) 

def write_tmp_file(txt): 

    fd = tempfile.NamedTemporaryFile() 

    fd.write(txt) 

    fd.flush() 

    return fd 

def shell_quote(string): 

    return "'" + string.replace("'", "'\\''") + "'" 

def run(args, stdin=None, raiseonerr=True, 

        nolog=(), env=None, capture_output=True): 

    """ 

    Execute a command and return stdin, stdout and the process return code. 

    args is a list of arguments for the command 

    stdin is used if you want to pass input to the command 

    raiseonerr raises an exception if the return code is not zero 

    nolog is a tuple of strings that shouldn't be logged, like passwords. 

    Each tuple consists of a string to be replaced by XXXXXXXX. 

    For example, the command ['/usr/bin/setpasswd', '--password', 'Secret123', 'someuser'] 

    We don't want to log the password so nolog would be set to: 

    ('Secret123',) 

    The resulting log output would be: 

    /usr/bin/setpasswd --password XXXXXXXX someuser 

    If an value isn't found in the list it is silently ignored. 

    """ 

    p_in = None 

    p_out = None 

    p_err = None 

    if isinstance(nolog, basestring): 

        # We expect a tuple (or list, or other iterable) of nolog strings. 

        # Passing just a single string is bad: strings are also, so this 

        # would result in every individual character of that string being 

        # replaced by XXXXXXXX. 

        # This is a sanity check to prevent that. 

        raise ValueError('nolog must be a tuple of strings.') 

    if env is None: 

        # copy default env 

        env = copy.deepcopy(os.environ) 

        env["PATH"] = "/bin:/sbin:/usr/kerberos/bin:/usr/kerberos/sbin:/usr/bin:/usr/sbin" 

    if stdin: 

        p_in = subprocess.PIPE 

    if capture_output: 

        p_out = subprocess.PIPE 

        p_err = subprocess.PIPE 

    try: 

        p = subprocess.Popen(args, stdin=p_in, stdout=p_out, stderr=p_err, 

                             close_fds=True, env=env) 

        stdout,stderr = p.communicate(stdin) 

        stdout,stderr = str(stdout), str(stderr)    # Make pylint happy 

    except KeyboardInterrupt: 

        p.wait() 

        raise 

    # The command and its output may include passwords that we don't want 

    # to log. Run through the nolog items. 

    args = ' '.join(args) 

    for value in nolog: 

        if not isinstance(value, basestring): 

            continue 

        quoted = urllib2.quote(value) 

        shquoted = shell_quote(value) 

        for nolog_value in (shquoted, value, quoted): 

            if capture_output: 

                stdout = stdout.replace(nolog_value, 'XXXXXXXX') 

                stderr = stderr.replace(nolog_value, 'XXXXXXXX') 

            args = args.replace(nolog_value, 'XXXXXXXX') 

    root_logger.debug('args=%s' % args) 

    if capture_output: 

        root_logger.debug('stdout=%s' % stdout) 

        root_logger.debug('stderr=%s' % stderr) 

    if p.returncode != 0 and raiseonerr: 

        raise CalledProcessError(p.returncode, args) 

    return (stdout, stderr, p.returncode) 

def file_exists(filename): 

    try: 

        mode = os.stat(filename)[stat.ST_MODE] 

        if stat.S_ISREG(mode): 

            return True 

        else: 

            return False 

    except: 

        return False 

def dir_exists(filename): 

    try: 

        mode = os.stat(filename)[stat.ST_MODE] 

        if stat.S_ISDIR(mode): 

            return True 

        else: 

            return False 

    except: 

        return False 

def install_file(fname, dest): 

    if file_exists(dest): 

        os.rename(dest, dest + ".orig") 

    shutil.move(fname, dest) 

def backup_file(fname): 

    if file_exists(fname): 

        os.rename(fname, fname + ".orig") 

# uses gpg to compress and encrypt a file 

def encrypt_file(source, dest, password, workdir = None): 

    if type(source) is not StringType or not len(source): 

        raise ValueError('Missing Source File') 

    #stat it so that we get back an exception if it does no t exist 

    os.stat(source) 

    if type(dest) is not StringType or not len(dest): 

        raise ValueError('Missing Destination File') 

    if type(password) is not StringType or not len(password): 

        raise ValueError('Missing Password') 

    #create a tempdir so that we can clean up with easily 

    tempdir = tempfile.mkdtemp('', 'ipa-', workdir) 

    gpgdir = tempdir+"/.gnupg" 

    try: 

        try: 

            #give gpg a fake dir so that we can leater remove all 

            #the cruft when we clean up the tempdir 

            os.mkdir(gpgdir) 

            args = ['/usr/bin/gpg', '--batch', '--homedir', gpgdir, '--passphrase-fd', '0', '--yes', '--no-tty', '-o', dest, '-c', source] 

            run(args, password) 

        except: 

            raise 

    finally: 

        #job done, clean up 

        shutil.rmtree(tempdir, ignore_errors=True) 

def decrypt_file(source, dest, password, workdir = None): 

    if type(source) is not StringType or not len(source): 

        raise ValueError('Missing Source File') 

    #stat it so that we get back an exception if it does no t exist 

    os.stat(source) 

    if type(dest) is not StringType or not len(dest): 

        raise ValueError('Missing Destination File') 

    if type(password) is not StringType or not len(password): 

        raise ValueError('Missing Password') 

    #create a tempdir so that we can clean up with easily 

    tempdir = tempfile.mkdtemp('', 'ipa-', workdir) 

    gpgdir = tempdir+"/.gnupg" 

    try: 

        try: 

            #give gpg a fake dir so that we can leater remove all 

            #the cruft when we clean up the tempdir 

            os.mkdir(gpgdir) 

            args = ['/usr/bin/gpg', '--batch', '--homedir', gpgdir, '--passphrase-fd', '0', '--yes', '--no-tty', '-o', dest, '-d', source] 

            run(args, password) 

        except: 

            raise 

    finally: 

        #job done, clean up 

        shutil.rmtree(tempdir, ignore_errors=True) 

class CIDict(dict): 

    """ 

    Case-insensitive but case-respecting dictionary. 

    This code is derived from python-ldap's cidict.py module, 

    written by stroeder: http://python-ldap.sourceforge.net/ 

    This version extends 'dict' so it works properly with TurboGears. 

    If you extend UserDict, isinstance(foo, dict) returns false. 

    """ 

    def __init__(self, default=None): 

        super(CIDict, self).__init__() 

        self._keys = {} 

        self.update(default or {}) 

    def __getitem__(self, key): 

        return super(CIDict, self).__getitem__(key.lower()) 

    def __setitem__(self, key, value): 

        lower_key = key.lower() 

        self._keys[lower_key] = key 

        return super(CIDict, self).__setitem__(lower_key, value) 

    def __delitem__(self, key): 

        lower_key = key.lower() 

        del self._keys[lower_key] 

        return super(CIDict, self).__delitem__(key.lower()) 

    def update(self, dict): 

        for key in dict.keys(): 

            self[key] = dict[key] 

    def has_key(self, key): 

        return super(CIDict, self).has_key(key.lower()) 

    def get(self, key, failobj=None): 

        try: 

            return self[key] 

        except KeyError: 

            return failobj 

    def keys(self): 

        return self._keys.values() 

    def items(self): 

        result = [] 

        for k in self._keys.values(): 

            result.append((k, self[k])) 

        return result 

    def copy(self): 

        copy = {} 

        for k in self._keys.values(): 

            copy[k] = self[k] 

        return copy 

    def iteritems(self): 

        return self.copy().iteritems() 

    def iterkeys(self): 

        return self.copy().iterkeys() 

    def setdefault(self, key, value=None): 

        try: 

            return self[key] 

        except KeyError: 

            self[key] = value 

            return value 

    def pop(self, key, *args): 

        try: 

            value = self[key] 

            del self[key] 

            return value 

        except KeyError: 

            if len(args) == 1: 

                return args[0] 

            raise 

    def popitem(self): 

        (lower_key, value) = super(CIDict, self).popitem() 

        key = self._keys[lower_key] 

        del self._keys[lower_key] 

        return (key, value) 

class GeneralizedTimeZone(datetime.tzinfo): 

    """This class is a basic timezone wrapper for the offset specified 

       in a Generalized Time.  It is dst-ignorant.""" 

    def __init__(self,offsetstr="Z"): 

        super(GeneralizedTimeZone, self).__init__() 

        self.name = offsetstr 

        self.houroffset = 0 

        self.minoffset = 0 

        if offsetstr == "Z": 

            self.houroffset = 0 

            self.minoffset = 0 

        else: 

            if (len(offsetstr) >= 3) and re.match(r'[-+]\d\d', offsetstr): 

                self.houroffset = int(offsetstr[0:3]) 

                offsetstr = offsetstr[3:] 

            if (len(offsetstr) >= 2) and re.match(r'\d\d', offsetstr): 

                self.minoffset = int(offsetstr[0:2]) 

                offsetstr = offsetstr[2:] 

            if len(offsetstr) > 0: 

                raise ValueError() 

        if self.houroffset < 0: 

            self.minoffset *= -1 

    def utcoffset(self, dt): 

        return datetime.timedelta(hours=self.houroffset, minutes=self.minoffset) 

    def dst(self): 

        return datetime.timedelta(0) 

    def tzname(self): 

        return self.name 

def parse_generalized_time(timestr): 

    """Parses are Generalized Time string (as specified in X.680), 

       returning a datetime object.  Generalized Times are stored inside 

       the krbPasswordExpiration attribute in LDAP. 

       This method doesn't attempt to be perfect wrt timezones.  If python 

       can't be bothered to implement them, how can we...""" 

    if len(timestr) < 8: 

        return None 

    try: 

        date = timestr[:8] 

        time = timestr[8:] 

        year = int(date[:4]) 

        month = int(date[4:6]) 

        day = int(date[6:8]) 

        hour = min = sec = msec = 0 

        tzone = None 

        if (len(time) >= 2) and re.match(r'\d', time[0]): 

            hour = int(time[:2]) 

            time = time[2:] 

            if len(time) >= 2 and (time[0] == "," or time[0] == "."): 

                hour_fraction = "." 

                time = time[1:] 

                while (len(time) > 0) and re.match(r'\d', time[0]): 

                    hour_fraction += time[0] 

                    time = time[1:] 

                total_secs = int(float(hour_fraction) * 3600) 

                min, sec = divmod(total_secs, 60) 

        if (len(time) >= 2) and re.match(r'\d', time[0]): 

            min = int(time[:2]) 

            time = time[2:] 

            if len(time) >= 2 and (time[0] == "," or time[0] == "."): 

                min_fraction = "." 

                time = time[1:] 

                while (len(time) > 0) and re.match(r'\d', time[0]): 

                    min_fraction += time[0] 

                    time = time[1:] 

                sec = int(float(min_fraction) * 60) 

        if (len(time) >= 2) and re.match(r'\d', time[0]): 

            sec = int(time[:2]) 

            time = time[2:] 

            if len(time) >= 2 and (time[0] == "," or time[0] == "."): 

                sec_fraction = "." 

                time = time[1:] 

                while (len(time) > 0) and re.match(r'\d', time[0]): 

                    sec_fraction += time[0] 

                    time = time[1:] 

                msec = int(float(sec_fraction) * 1000000) 

        if (len(time) > 0): 

            tzone = GeneralizedTimeZone(time) 

        return datetime.datetime(year, month, day, hour, min, sec, msec, tzone) 

    except ValueError: 

        return None 

def ipa_generate_password(characters=None,pwd_len=None): 

    ''' Generates password. Password cannot start or end with a whitespace 

    character. It also cannot be formed by whitespace characters only. 

    Length of password as well as string of characters to be used by 

    generator could be optionaly specified by characters and pwd_len 

    parameters, otherwise default values will be used: characters string 

    will be formed by all printable non-whitespace characters and space, 

    pwd_len will be equal to value of GEN_PWD_LEN. 

    ''' 

    if not characters: 

        characters=string.digits + string.ascii_letters + string.punctuation + ' ' 

    else: 

        if characters.isspace(): 

            raise ValueError("password cannot be formed by whitespaces only") 

    if not pwd_len: 

        pwd_len = GEN_PWD_LEN 

    upper_bound = len(characters) - 1 

    rndpwd = '' 

    r = random.SystemRandom() 

    for x in range(pwd_len): 

        rndchar = characters[r.randint(0,upper_bound)] 

        if (x == 0) or (x == pwd_len-1): 

            while rndchar.isspace(): 

                rndchar = characters[r.randint(0,upper_bound)] 

        rndpwd += rndchar 

    return rndpwd 

def parse_items(text): 

    '''Given text with items separated by whitespace or comma, return a list of those items 

    The returned list only contains non-empty items. 

    ''' 

    split_re = re.compile('[ ,\t\n]+') 

    items = split_re.split(text) 

    for item in items[:]: 

        if not item: items.remove(item) 

    return items 

def user_input(prompt, default = None, allow_empty = True): 

    if default == None: 

        while True: 

            ret = raw_input("%s: " % prompt) 

            if allow_empty or ret.strip(): 

                return ret 

    if isinstance(default, basestring): 

        while True: 

            ret = raw_input("%s [%s]: " % (prompt, default)) 

            if not ret and (allow_empty or default): 

                return default 

            elif ret.strip(): 

                return ret 

    if isinstance(default, bool): 

        if default: 

            choice = "yes" 

        else: 

            choice = "no" 

        while True: 

            ret = raw_input("%s [%s]: " % (prompt, choice)) 

            if not ret: 

                return default 

            elif ret.lower()[0] == "y": 

                return True 

            elif ret.lower()[0] == "n": 

                return False 

    if isinstance(default, int): 

        while True: 

            try: 

                ret = raw_input("%s [%s]: " % (prompt, default)) 

                if not ret: 

                    return default 

                ret = int(ret) 

            except ValueError: 

                pass 

            else: 

                return ret 

def get_gsserror(e): 

    """ 

    A GSSError exception looks differently in python 2.4 than it does 

    in python 2.5. Deal with it. 

    """ 

    try: 

       major = e[0] 

       minor = e[1] 

    except: 

       major = e[0][0] 

       minor = e[0][1] 

    return (major, minor) 

def host_port_open(host, port, socket_type=socket.SOCK_STREAM, socket_timeout=None): 

    families = (socket.AF_INET, socket.AF_INET6) 

    success = False 

    for family in families: 

        try: 

            try: 

                s = socket.socket(family, socket_type) 

            except socket.error: 

                continue 

            if socket_timeout is not None: 

                s.settimeout(socket_timeout) 

            s.connect((host, port)) 

            if socket_type == socket.SOCK_DGRAM: 

                s.send('') 

                s.recv(512) 

            success = True 

        except socket.error, e: 

            pass 

        finally: 

            s.close() 

        if success: 

            return True 

    return False 

def bind_port_responder(port, socket_type=socket.SOCK_STREAM, socket_timeout=None, responder_data=None): 

    families = (socket.AF_INET, socket.AF_INET6) 

    host = ''   # all available interfaces 

    for family in families: 

        try: 

            s = socket.socket(family, socket_type) 

        except socket.error, e: 

            if family == families[-1]:  # last available family 

                raise e 

    if socket_timeout is not None: 

        s.settimeout(socket_timeout) 

    if socket_type == socket.SOCK_STREAM: 

        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) 

    try: 

        s.bind((host, port)) 

        if socket_type == socket.SOCK_STREAM: 

            s.listen(1) 

            connection, client_address = s.accept() 

            try: 

                if responder_data: 

                    connection.sendall(responder_data) #pylint: disable=E1101 

            finally: 

                connection.close() 

        elif socket_type == socket.SOCK_DGRAM: 

            data, addr = s.recvfrom(1) 

            if responder_data: 

                s.sendto(responder_data, addr) 

    finally: 

        s.close() 

def get_ipa_basedn(conn): 

    """ 

    Get base DN of IPA suffix in given LDAP server. 

    None is returned if the suffix is not found 

    :param conn: Bound LDAP connection that will be used for searching 

    """ 

    entries = conn.search_ext_s( 

        '', scope=ldap.SCOPE_BASE, attrlist=['defaultnamingcontext', 'namingcontexts'] 

    ) 

    contexts = entries[0][1]['namingcontexts'] 

    if entries[0][1].get('defaultnamingcontext'): 

        # If there is a defaultNamingContext examine that one first 

        default = entries[0][1]['defaultnamingcontext'][0] 

        if default in contexts: 

            contexts.remove(default) 

        contexts.insert(0, entries[0][1]['defaultnamingcontext'][0]) 

    for context in contexts: 

        root_logger.debug("Check if naming context '%s' is for IPA" % context) 

        try: 

            entry = conn.search_s(context, ldap.SCOPE_BASE, "(info=IPA*)") 

        except ldap.NO_SUCH_OBJECT: 

            root_logger.debug("LDAP server did not return info attribute to check for IPA version") 

            continue 

        if len(entry) == 0: 

            root_logger.debug("Info attribute with IPA server version not found") 

            continue 

        info = entry[0][1]['info'][0].lower() 

        if info != IPA_BASEDN_INFO: 

            root_logger.debug("Detected IPA server version (%s) did not match the client (%s)" \ 

                % (info, IPA_BASEDN_INFO)) 

            continue 

        root_logger.debug("Naming context '%s' is a valid IPA context" % context) 

        return context 

    return None 

def config_replace_variables(filepath, replacevars=dict(), appendvars=dict()): 

    """ 

    Take a key=value based configuration file, and write new version 

    with certain values replaced or appended 

    All (key,value) pairs from replacevars and appendvars that were not found 

    in the configuration file, will be added there. 

    It is responsibility of a caller to ensure that replacevars and 

    appendvars do not overlap. 

    It is responsibility of a caller to back up file. 

    returns dictionary of affected keys and their previous values 

    One have to run restore_context(filepath) afterwards or 

    security context of the file will not be correct after modification 

    """ 

    pattern = re.compile(''' 

(^ 

                        \s* 

        (?P<option>     [^\#;]+?) 

                        (\s*=\s*) 

        (?P<value>      .+?)? 

                        (\s*((\#|;).*)?)? 

$)''', re.VERBOSE) 

    orig_stat = os.stat(filepath) 

    old_values = dict() 

    temp_filename = None 

    with tempfile.NamedTemporaryFile(delete=False) as new_config: 

        temp_filename = new_config.name 

        with open(filepath, 'r') as f: 

            for line in f: 

                new_line = line 

                m = pattern.match(line) 

                if m: 

                    option, value = m.group('option', 'value') 

                    if option is not None: 

                        if replacevars and option in replacevars: 

                            # replace value completely 

                            new_line = u"%s=%s\n" % (option, replacevars[option]) 

                            old_values[option] = value 

                        if appendvars and option in appendvars: 

                            # append new value unless it is already existing in the original one 

                            if not value: 

                                new_line = u"%s=%s\n" % (option, appendvars[option]) 

                            elif value.find(appendvars[option]) == -1: 

                                new_line = u"%s=%s %s\n" % (option, value, appendvars[option]) 

                            old_values[option] = value 

                new_config.write(new_line) 

        # Now add all options from replacevars and appendvars that were not found in the file 

        new_vars = replacevars.copy() 

        new_vars.update(appendvars) 

        newvars_view = set(new_vars.keys()) - set(old_values.keys()) 

        append_view = (set(appendvars.keys()) - newvars_view) 

        for item in newvars_view: 

            new_config.write("%s=%s\n" % (item,new_vars[item])) 

        for item in append_view: 

            new_config.write("%s=%s\n" % (item,appendvars[item])) 

        new_config.flush() 

        # Make sure the resulting file is readable by others before installing it 

        os.fchmod(new_config.fileno(), orig_stat.st_mode) 

        os.fchown(new_config.fileno(), orig_stat.st_uid, orig_stat.st_gid) 

    # At this point new_config is closed but not removed due to 'delete=False' above 

    # Now, install the temporary file as configuration and ensure old version is available as .orig