Personal Computer World 2009 February/PCWFEB09.iso/Software/Linux/Kubuntu 8.10/kubuntu-8.10-desktop-i386.iso/casper/filesystem.squashfs/usr/lib/python2.5/cookielib.pyc

Python Compiled Bytecode | 2008-10-29 | 53.8 KB | 1,826 lines

# Source Generated with Decompyle++
# File: in.pyc (Python 2.5)

"""HTTP cookie handling for web clients.

This module has (now fairly distant) origins in Gisle Aas' Perl module
HTTP::Cookies, from the libwww-perl library.

Docstrings, comments and debug strings in this code refer to the
attributes of the HTTP cookie system as cookie-attributes, to distinguish
them clearly from Python attributes.

Class diagram (note that BSDDBCookieJar and the MSIE* classes are not
distributed with the Python standard library, but are available from
http://wwwsearch.sf.net/):

                        CookieJar____
                        /     \\                  FileCookieJar      \\                   /    |   \\         \\       MozillaCookieJar | LWPCookieJar \\                        |               |                        |   ---MSIEBase |                         |  /      |     |                          | /   MSIEDBCookieJar BSDDBCookieJar
                  |/
               MSIECookieJar

"""
__all__ = [
    'Cookie',
    'CookieJar',
    'CookiePolicy',
    'DefaultCookiePolicy',
    'FileCookieJar',
    'LWPCookieJar',
    'LoadError',
    'MozillaCookieJar']
import re
import urlparse
import copy
import time
import urllib

try:
    import threading as _threading
except ImportError:
    import dummy_threading as _threading

import httplib
from calendar import timegm
debug = False
logger = None

def _debug(*args):
    global logger
    if not debug:
        return None

    if not logger:
        import logging
        logger = logging.getLogger('cookielib')

    return logger.debug(*args)

DEFAULT_HTTP_PORT = str(httplib.HTTP_PORT)
MISSING_FILENAME_TEXT = 'a filename was not supplied (nor was the CookieJar instance initialised with one)'

def _warn_unhandled_exception():
    import warnings
    import traceback
    import StringIO
    f = StringIO.StringIO()
    traceback.print_exc(None, f)
    msg = f.getvalue()
    warnings.warn('cookielib bug!\n%s' % msg, stacklevel = 2)

EPOCH_YEAR = 1970

def _timegm(tt):
    (year, month, mday, hour, min, sec) = tt[:6]
    if year >= EPOCH_YEAR:
        if month <= month:
            pass
        elif month <= 12:
            if mday <= mday:
                pass
            elif mday <= 31:
                if hour <= hour:
                    pass
                elif hour <= 24:
                    if min <= min:
                        pass
                    elif min <= 59:
                        if sec <= sec:
                            pass
                        elif sec <= 61:
                            return timegm(tt)
                        else:
                            return None

DAYS = [
    'Mon',
    'Tue',
    'Wed',
    'Thu',
    'Fri',
    'Sat',
    'Sun']
MONTHS = [
    'Jan',
    'Feb',
    'Mar',
    'Apr',
    'May',
    'Jun',
    'Jul',
    'Aug',
    'Sep',
    'Oct',
    'Nov',
    'Dec']
MONTHS_LOWER = []
for month in MONTHS:
    MONTHS_LOWER.append(month.lower())


def time2isoz(t = None):
    '''Return a string representing time in seconds since epoch, t.

    If the function is called without an argument, it will use the current
    time.

    The format of the returned string is like "YYYY-MM-DD hh:mm:ssZ",
    representing Universal Time (UTC, aka GMT).  An example of this format is:

    1994-11-24 08:49:37Z

    '''
    if t is None:
        t = time.time()

    (year, mon, mday, hour, min, sec) = time.gmtime(t)[:6]
    return '%04d-%02d-%02d %02d:%02d:%02dZ' % (year, mon, mday, hour, min, sec)


def time2netscape(t = None):
    '''Return a string representing time in seconds since epoch, t.

    If the function is called without an argument, it will use the current
    time.

    The format of the returned string is like this:

    Wed, DD-Mon-YYYY HH:MM:SS GMT

    '''
    if t is None:
        t = time.time()

    (year, mon, mday, hour, min, sec, wday) = time.gmtime(t)[:7]
    return '%s %02d-%s-%04d %02d:%02d:%02d GMT' % (DAYS[wday], mday, MONTHS[mon - 1], year, hour, min, sec)

UTC_ZONES = {
    'GMT': None,
    'UTC': None,
    'UT': None,
    'Z': None }
TIMEZONE_RE = re.compile('^([-+])?(\\d\\d?):?(\\d\\d)?$')

def offset_from_tz_string(tz):
    offset = None
    if tz in UTC_ZONES:
        offset = 0
    else:
        m = TIMEZONE_RE.search(tz)
        if m:
            offset = 3600 * int(m.group(2))
            if m.group(3):
                offset = offset + 60 * int(m.group(3))

            if m.group(1) == '-':
                offset = -offset


    return offset


def _str2time(day, mon, yr, hr, min, sec, tz):

    try:
        mon = MONTHS_LOWER.index(mon.lower()) + 1
    except ValueError:

        try:
            imon = int(mon)
        except ValueError:
            return None

        if imon <= imon:
            pass
        elif imon <= 12:
            mon = imon
        else:
            return None
    except:
        1

    if hr is None:
        hr = 0

    if min is None:
        min = 0

    if sec is None:
        sec = 0

    yr = int(yr)
    day = int(day)
    hr = int(hr)
    min = int(min)
    sec = int(sec)
    if yr < 1000:
        cur_yr = time.localtime(time.time())[0]
        m = cur_yr % 100
        tmp = yr
        yr = yr + cur_yr - m
        m = m - tmp
        if abs(m) > 50:
            if m > 0:
                yr = yr + 100
            else:
                yr = yr - 100


    t = _timegm((yr, mon, day, hr, min, sec, tz))
    if t is not None:
        if tz is None:
            tz = 'UTC'

        tz = tz.upper()
        offset = offset_from_tz_string(tz)
        if offset is None:
            return None

        t = t - offset

    return t

STRICT_DATE_RE = re.compile('^[SMTWF][a-z][a-z], (\\d\\d) ([JFMASOND][a-z][a-z]) (\\d\\d\\d\\d) (\\d\\d):(\\d\\d):(\\d\\d) GMT$')
WEEKDAY_RE = re.compile('^(?:Sun|Mon|Tue|Wed|Thu|Fri|Sat)[a-z]*,?\\s*', re.I)
LOOSE_HTTP_DATE_RE = re.compile('^\n    (\\d\\d?)            # day\n       (?:\\s+|[-\\/])\n    (\\w+)              # month\n        (?:\\s+|[-\\/])\n    (\\d+)              # year\n    (?:\n          (?:\\s+|:)    # separator before clock\n       (\\d\\d?):(\\d\\d)  # hour:min\n       (?::(\\d\\d))?    # optional seconds\n    )?                 # optional clock\n       \\s*\n    ([-+]?\\d{2,4}|(?![APap][Mm]\\b)[A-Za-z]+)? # timezone\n       \\s*\n    (?:\\(\\w+\\))?       # ASCII representation of timezone in parens.\n       \\s*$', re.X)

def http2time(text):
    '''Returns time in seconds since epoch of time represented by a string.

    Return value is an integer.

    None is returned if the format of str is unrecognized, the time is outside
    the representable range, or the timezone string is not recognized.  If the
    string contains no timezone, UTC is assumed.

    The timezone in the string may be numerical (like "-0800" or "+0100") or a
    string timezone (like "UTC", "GMT", "BST" or "EST").  Currently, only the
    timezone strings equivalent to UTC (zero offset) are known to the function.

    The function loosely parses the following formats:

    Wed, 09 Feb 1994 22:23:32 GMT       -- HTTP format
    Tuesday, 08-Feb-94 14:15:29 GMT     -- old rfc850 HTTP format
    Tuesday, 08-Feb-1994 14:15:29 GMT   -- broken rfc850 HTTP format
    09 Feb 1994 22:23:32 GMT            -- HTTP format (no weekday)
    08-Feb-94 14:15:29 GMT              -- rfc850 format (no weekday)
    08-Feb-1994 14:15:29 GMT            -- broken rfc850 format (no weekday)

    The parser ignores leading and trailing whitespace.  The time may be
    absent.

    If the year is given with only 2 digits, the function will select the
    century that makes the year closest to the current date.

    '''
    m = STRICT_DATE_RE.search(text)
    if m:
        g = m.groups()
        mon = MONTHS_LOWER.index(g[1].lower()) + 1
        tt = (int(g[2]), mon, int(g[0]), int(g[3]), int(g[4]), float(g[5]))
        return _timegm(tt)

    text = text.lstrip()
    text = WEEKDAY_RE.sub('', text, 1)
    (day, mon, yr, hr, min, sec, tz) = [
        None] * 7
    m = LOOSE_HTTP_DATE_RE.search(text)
    if m is not None:
        (day, mon, yr, hr, min, sec, tz) = m.groups()
    else:
        return None
    return _str2time(day, mon, yr, hr, min, sec, tz)

ISO_DATE_RE = re.compile('^\n    (\\d{4})              # year\n       [-\\/]?\n    (\\d\\d?)              # numerical month\n       [-\\/]?\n    (\\d\\d?)              # day\n   (?:\n         (?:\\s+|[-:Tt])  # separator before clock\n      (\\d\\d?):?(\\d\\d)    # hour:min\n      (?::?(\\d\\d(?:\\.\\d*)?))?  # optional seconds (and fractional)\n   )?                    # optional clock\n      \\s*\n   ([-+]?\\d\\d?:?(:?\\d\\d)?\n    |Z|z)?               # timezone  (Z is "zero meridian", i.e. GMT)\n      \\s*$', re.X)

def iso2time(text):
    '''
    As for http2time, but parses the ISO 8601 formats:

    1994-02-03 14:15:29 -0100    -- ISO 8601 format
    1994-02-03 14:15:29          -- zone is optional
    1994-02-03                   -- only date
    1994-02-03T14:15:29          -- Use T as separator
    19940203T141529Z             -- ISO 8601 compact format
    19940203                     -- only date

    '''
    text = text.lstrip()
    (day, mon, yr, hr, min, sec, tz) = [
        None] * 7
    m = ISO_DATE_RE.search(text)
    if m is not None:
        (yr, mon, day, hr, min, sec, tz, _) = m.groups()
    else:
        return None
    return _str2time(day, mon, yr, hr, min, sec, tz)


def unmatched(match):
    '''Return unmatched part of re.Match object.'''
    (start, end) = match.span(0)
    return match.string[:start] + match.string[end:]

HEADER_TOKEN_RE = re.compile('^\\s*([^=\\s;,]+)')
HEADER_QUOTED_VALUE_RE = re.compile('^\\s*=\\s*\\"([^\\"\\\\]*(?:\\\\.[^\\"\\\\]*)*)\\"')
HEADER_VALUE_RE = re.compile('^\\s*=\\s*([^\\s;,]*)')
HEADER_ESCAPE_RE = re.compile('\\\\(.)')

def split_header_words(header_values):
    '''Parse header values into a list of lists containing key,value pairs.

    The function knows how to deal with ",", ";" and "=" as well as quoted
    values after "=".  A list of space separated tokens are parsed as if they
    were separated by ";".

    If the header_values passed as argument contains multiple values, then they
    are treated as if they were a single value separated by comma ",".

    This means that this function is useful for parsing header fields that
    follow this syntax (BNF as from the HTTP/1.1 specification, but we relax
    the requirement for tokens).

      headers           = #header
      header            = (token | parameter) *( [";"] (token | parameter))

      token             = 1*<any CHAR except CTLs or separators>
      separators        = "(" | ")" | "<" | ">" | "@"
                        | "," | ";" | ":" | "\\" | <">
                        | "/" | "[" | "]" | "?" | "="
                        | "{" | "}" | SP | HT

      quoted-string     = ( <"> *(qdtext | quoted-pair ) <"> )
      qdtext            = <any TEXT except <">>
      quoted-pair       = "\\" CHAR

      parameter         = attribute "=" value
      attribute         = token
      value             = token | quoted-string

    Each header is represented by a list of key/value pairs.  The value for a
    simple token (not part of a parameter) is None.  Syntactically incorrect
    headers will not necessarily be parsed as you would want.

    This is easier to describe with some examples:

    >>> split_header_words([\'foo="bar"; port="80,81"; discard, bar=baz\'])
    [[(\'foo\', \'bar\'), (\'port\', \'80,81\'), (\'discard\', None)], [(\'bar\', \'baz\')]]
    >>> split_header_words([\'text/html; charset="iso-8859-1"\'])
    [[(\'text/html\', None), (\'charset\', \'iso-8859-1\')]]
    >>> split_header_words([r\'Basic realm="\\"foo\\bar\\""\'])
    [[(\'Basic\', None), (\'realm\', \'"foobar"\')]]

    '''
    if not not isinstance(header_values, basestring):
        raise AssertionError
    result = []
    for text in header_values:
        orig_text = text
        pairs = []
        while text:
            m = HEADER_TOKEN_RE.search(text)
            if m:
                text = unmatched(m)
                name = m.group(1)
                m = HEADER_QUOTED_VALUE_RE.search(text)
                if m:
                    text = unmatched(m)
                    value = m.group(1)
                    value = HEADER_ESCAPE_RE.sub('\\1', value)
                else:
                    m = HEADER_VALUE_RE.search(text)
                    if m:
                        text = unmatched(m)
                        value = m.group(1)
                        value = value.rstrip()
                    else:
                        value = None
                pairs.append((name, value))
                continue
            if text.lstrip().startswith(','):
                text = text.lstrip()[1:]
                if pairs:
                    result.append(pairs)

                pairs = []
                continue
            (non_junk, nr_junk_chars) = re.subn('^[=\\s;]*', '', text)
            if not nr_junk_chars > 0:
                raise AssertionError, "split_header_words bug: '%s', '%s', %s" % (orig_text, text, pairs)
            text = non_junk
        if pairs:
            result.append(pairs)
            continue

    return result

HEADER_JOIN_ESCAPE_RE = re.compile('([\\"\\\\])')

def join_header_words(lists):
    '''Do the inverse (almost) of the conversion done by split_header_words.

    Takes a list of lists of (key, value) pairs and produces a single header
    value.  Attribute values are quoted if needed.

    >>> join_header_words([[("text/plain", None), ("charset", "iso-8859/1")]])
    \'text/plain; charset="iso-8859/1"\'
    >>> join_header_words([[("text/plain", None)], [("charset", "iso-8859/1")]])
    \'text/plain, charset="iso-8859/1"\'

    '''
    headers = []
    for pairs in lists:
        attr = []
        for k, v in pairs:
            if v is not None:
                if not re.search('^\\w+$', v):
                    v = HEADER_JOIN_ESCAPE_RE.sub('\\\\\\1', v)
                    v = '"%s"' % v

                k = '%s=%s' % (k, v)

            attr.append(k)

        if attr:
            headers.append('; '.join(attr))
            continue

    return ', '.join(headers)


def parse_ns_headers(ns_headers):
    '''Ad-hoc parser for Netscape protocol cookie-attributes.

    The old Netscape cookie format for Set-Cookie can for instance contain
    an unquoted "," in the expires field, so we have to use this ad-hoc
    parser instead of split_header_words.

    XXX This may not make the best possible effort to parse all the crap
    that Netscape Cookie headers contain.  Ronald Tschalar\'s HTTPClient
    parser is probably better, so could do worse than following that if
    this ever gives any trouble.

    Currently, this is also used for parsing RFC 2109 cookies.

    '''
    known_attrs = ('expires', 'domain', 'path', 'secure', 'port', 'max-age')
    result = []
    for ns_header in ns_headers:
        pairs = []
        version_set = False
        for ii, param in enumerate(re.split(';\\s*', ns_header)):
            param = param.rstrip()
            if param == '':
                continue

            if '=' not in param:
                k = param
                v = None
            else:
                (k, v) = re.split('\\s*=\\s*', param, 1)
                k = k.lstrip()
            if ii != 0:
                lc = k.lower()
                if lc in known_attrs:
                    k = lc

                if k == 'version':
                    version_set = True

                if k == 'expires':
                    if v.startswith('"'):
                        v = v[1:]

                    if v.endswith('"'):
                        v = v[:-1]

                    v = http2time(v)


            pairs.append((k, v))

        if pairs:
            if not version_set:
                pairs.append(('version', '0'))

            result.append(pairs)
            continue

    return result

IPV4_RE = re.compile('\\.\\d+$')

def is_HDN(text):
    '''Return True if text is a host domain name.'''
    if IPV4_RE.search(text):
        return False

    if text == '':
        return False

    if text[0] == '.' or text[-1] == '.':
        return False

    return True


def domain_match(A, B):
    """Return True if domain A domain-matches domain B, according to RFC 2965.

    A and B may be host domain names or IP addresses.

    RFC 2965, section 1:

    Host names can be specified either as an IP address or a HDN string.
    Sometimes we compare one host name with another.  (Such comparisons SHALL
    be case-insensitive.)  Host A's name domain-matches host B's if

         *  their host name strings string-compare equal; or

         * A is a HDN string and has the form NB, where N is a non-empty
            name string, B has the form .B', and B' is a HDN string.  (So,
            x.y.com domain-matches .Y.com but not Y.com.)

    Note that domain-match is not a commutative operation: a.b.c.com
    domain-matches .c.com, but not the reverse.

    """
    A = A.lower()
    B = B.lower()
    if A == B:
        return True

    if not is_HDN(A):
        return False

    i = A.rfind(B)
    if i == -1 or i == 0:
        return False

    if not B.startswith('.'):
        return False

    if not is_HDN(B[1:]):
        return False

    return True


def liberal_is_HDN(text):
    '''Return True if text is a sort-of-like a host domain name.

    For accepting/blocking domains.

    '''
    if IPV4_RE.search(text):
        return False

    return True


def user_domain_match(A, B):
    '''For blocking/accepting domains.

    A and B may be host domain names or IP addresses.

    '''
    A = A.lower()
    B = B.lower()
    if not liberal_is_HDN(A) and liberal_is_HDN(B):
        if A == B:
            return True

        return False

    initial_dot = B.startswith('.')
    if initial_dot and A.endswith(B):
        return True

    if not initial_dot and A == B:
        return True

    return False

cut_port_re = re.compile(':\\d+$')

def request_host(request):
    '''Return request-host, as defined by RFC 2965.

    Variation from RFC: returned value is lowercased, for convenient
    comparison.

    '''
    url = request.get_full_url()
    host = urlparse.urlparse(url)[1]
    if host == '':
        host = request.get_header('Host', '')

    host = cut_port_re.sub('', host, 1)
    return host.lower()


def eff_request_host(request):
    '''Return a tuple (request-host, effective request-host name).

    As defined by RFC 2965, except both are lowercased.

    '''
    erhn = req_host = request_host(request)
    if req_host.find('.') == -1 and not IPV4_RE.search(req_host):
        erhn = req_host + '.local'

    return (req_host, erhn)


def request_path(request):
    '''request-URI, as defined by RFC 2965.'''
    url = request.get_full_url()
    (path, parameters, query, frag) = urlparse.urlparse(url)[2:]
    if parameters:
        path = '%s;%s' % (path, parameters)

    path = escape_path(path)
    req_path = urlparse.urlunparse(('', '', path, '', query, frag))
    if not req_path.startswith('/'):
        req_path = '/' + req_path

    return req_path


def request_port(request):
    host = request.get_host()
    i = host.find(':')
    if i >= 0:
        port = host[i + 1:]

        try:
            int(port)
        except ValueError:
            _debug("nonnumeric port: '%s'", port)
            return None
        except:
            None<EXCEPTION MATCH>ValueError


    None<EXCEPTION MATCH>ValueError
    port = DEFAULT_HTTP_PORT
    return port

HTTP_PATH_SAFE = "%/;:@&=+$,!~*'()"
ESCAPED_CHAR_RE = re.compile('%([0-9a-fA-F][0-9a-fA-F])')

def uppercase_escaped_char(match):
    return '%%%s' % match.group(1).upper()


def escape_path(path):
    '''Escape any invalid characters in HTTP URL, and uppercase all escapes.'''
    if isinstance(path, unicode):
        path = path.encode('utf-8')

    path = urllib.quote(path, HTTP_PATH_SAFE)
    path = ESCAPED_CHAR_RE.sub(uppercase_escaped_char, path)
    return path


def reach(h):
    '''Return reach of host h, as defined by RFC 2965, section 1.

    The reach R of a host name H is defined as follows:

       *  If

          -  H is the host domain name of a host; and,

          -  H has the form A.B; and

          -  A has no embedded (that is, interior) dots; and

          -  B has at least one embedded dot, or B is the string "local".
             then the reach of H is .B.

       *  Otherwise, the reach of H is H.

    >>> reach("www.acme.com")
    \'.acme.com\'
    >>> reach("acme.com")
    \'acme.com\'
    >>> reach("acme.local")
    \'.local\'

    '''
    i = h.find('.')
    if i >= 0:
        b = h[i + 1:]
        i = b.find('.')
        if is_HDN(h):
            pass
        None if i >= 0 or b == 'local' else b == 'local'

    return h


def is_third_party(request):
    '''

    RFC 2965, section 3.3.6:

        An unverifiable transaction is to a third-party host if its request-
        host U does not domain-match the reach R of the request-host O in the
        origin transaction.

    '''
    req_host = request_host(request)
    if not domain_match(req_host, reach(request.get_origin_req_host())):
        return True
    else:
        return False


class Cookie:
    '''HTTP Cookie.

    This class represents both Netscape and RFC 2965 cookies.

    This is deliberately a very simple class.  It just holds attributes.  It\'s
    possible to construct Cookie instances that don\'t comply with the cookie
    standards.  CookieJar.make_cookies is the factory function for Cookie
    objects -- it deals with cookie parsing, supplying defaults, and
    normalising to the representation used in this class.  CookiePolicy is
    responsible for checking them to see whether they should be accepted from
    and returned to the server.

    Note that the port may be present in the headers, but unspecified ("Port"
    rather than"Port=80", for example); if this is the case, port is None.

    '''

    def __init__(self, version, name, value, port, port_specified, domain, domain_specified, domain_initial_dot, path, path_specified, secure, expires, discard, comment, comment_url, rest, rfc2109 = False):
        if version is not None:
            version = int(version)

        if expires is not None:
            expires = int(expires)

        if port is None and port_specified is True:
            raise ValueError('if port is None, port_specified must be false')

        self.version = version
        self.name = name
        self.value = value
        self.port = port
        self.port_specified = port_specified
        self.domain = domain.lower()
        self.domain_specified = domain_specified
        self.domain_initial_dot = domain_initial_dot
        self.path = path
        self.path_specified = path_specified
        self.secure = secure
        self.expires = expires
        self.discard = discard
        self.comment = comment
        self.comment_url = comment_url
        self.rfc2109 = rfc2109
        self._rest = copy.copy(rest)


    def has_nonstandard_attr(self, name):
        return name in self._rest


    def get_nonstandard_attr(self, name, default = None):
        return self._rest.get(name, default)


    def set_nonstandard_attr(self, name, value):
        self._rest[name] = value


    def is_expired(self, now = None):
        if now is None:
            now = time.time()

        if self.expires is not None and self.expires <= now:
            return True

        return False


    def __str__(self):
        if self.port is None:
            p = ''
        else:
            p = ':' + self.port
        limit = self.domain + p + self.path
        if self.value is not None:
            namevalue = '%s=%s' % (self.name, self.value)
        else:
            namevalue = self.name
        return '<Cookie %s for %s>' % (namevalue, limit)


    def __repr__(self):
        args = []
        for name in ('version', 'name', 'value', 'port', 'port_specified', 'domain', 'domain_specified', 'domain_initial_dot', 'path', 'path_specified', 'secure', 'expires', 'discard', 'comment', 'comment_url'):
            attr = getattr(self, name)
            args.append('%s=%s' % (name, repr(attr)))

        args.append('rest=%s' % repr(self._rest))
        args.append('rfc2109=%s' % repr(self.rfc2109))
        return 'Cookie(%s)' % ', '.join(args)



class CookiePolicy:
    '''Defines which cookies get accepted from and returned to server.

    May also modify cookies, though this is probably a bad idea.

    The subclass DefaultCookiePolicy defines the standard rules for Netscape
    and RFC 2965 cookies -- override that if you want a customised policy.

    '''

    def set_ok(self, cookie, request):
        '''Return true if (and only if) cookie should be accepted from server.

        Currently, pre-expired cookies never get this far -- the CookieJar
        class deletes such cookies itself.

        '''
        raise NotImplementedError()


    def return_ok(self, cookie, request):
        '''Return true if (and only if) cookie should be returned to server.'''
        raise NotImplementedError()


    def domain_return_ok(self, domain, request):
        '''Return false if cookies should not be returned, given cookie domain.
        '''
        return True


    def path_return_ok(self, path, request):
        '''Return false if cookies should not be returned, given cookie path.
        '''
        return True



class DefaultCookiePolicy(CookiePolicy):
    '''Implements the standard rules for accepting and returning cookies.'''
    DomainStrictNoDots = 1
    DomainStrictNonDomain = 2
    DomainRFC2965Match = 4
    DomainLiberal = 0
    DomainStrict = DomainStrictNoDots | DomainStrictNonDomain

    def __init__(self, blocked_domains = None, allowed_domains = None, netscape = True, rfc2965 = False, rfc2109_as_netscape = None, hide_cookie2 = False, strict_domain = False, strict_rfc2965_unverifiable = True, strict_ns_unverifiable = False, strict_ns_domain = DomainLiberal, strict_ns_set_initial_dollar = False, strict_ns_set_path = False):
        '''Constructor arguments should be passed as keyword arguments only.'''
        self.netscape = netscape
        self.rfc2965 = rfc2965
        self.rfc2109_as_netscape = rfc2109_as_netscape
        self.hide_cookie2 = hide_cookie2
        self.strict_domain = strict_domain
        self.strict_rfc2965_unverifiable = strict_rfc2965_unverifiable
        self.strict_ns_unverifiable = strict_ns_unverifiable
        self.strict_ns_domain = strict_ns_domain
        self.strict_ns_set_initial_dollar = strict_ns_set_initial_dollar
        self.strict_ns_set_path = strict_ns_set_path
        if blocked_domains is not None:
            self._blocked_domains = tuple(blocked_domains)
        else:
            self._blocked_domains = ()
        if allowed_domains is not None:
            allowed_domains = tuple(allowed_domains)

        self._allowed_domains = allowed_domains


    def blocked_domains(self):
        '''Return the sequence of blocked domains (as a tuple).'''
        return self._blocked_domains


    def set_blocked_domains(self, blocked_domains):
        '''Set the sequence of blocked domains.'''
        self._blocked_domains = tuple(blocked_domains)


    def is_blocked(self, domain):
        for blocked_domain in self._blocked_domains:
            if user_domain_match(domain, blocked_domain):
                return True
                continue

        return False


    def allowed_domains(self):
        '''Return None, or the sequence of allowed domains (as a tuple).'''
        return self._allowed_domains


    def set_allowed_domains(self, allowed_domains):
        '''Set the sequence of allowed domains, or None.'''
        if allowed_domains is not None:
            allowed_domains = tuple(allowed_domains)

        self._allowed_domains = allowed_domains


    def is_not_allowed(self, domain):
        if self._allowed_domains is None:
            return False

        for allowed_domain in self._allowed_domains:
            if user_domain_match(domain, allowed_domain):
                return False
                continue

        return True


    def set_ok(self, cookie, request):
        '''
        If you override .set_ok(), be sure to call this method.  If it returns
        false, so should your subclass (assuming your subclass wants to be more
        strict about which cookies to accept).

        '''
        _debug(' - checking cookie %s=%s', cookie.name, cookie.value)
        if not cookie.name is not None:
            raise AssertionError
        for n in ('version', 'verifiability', 'name', 'path', 'domain', 'port'):
            fn_name = 'set_ok_' + n
            fn = getattr(self, fn_name)
            if not fn(cookie, request):
                return False
                continue

        return True


    def set_ok_version(self, cookie, request):
        if cookie.version is None:
            _debug('   Set-Cookie2 without version attribute (%s=%s)', cookie.name, cookie.value)
            return False

        if cookie.version > 0 and not (self.rfc2965):
            _debug('   RFC 2965 cookies are switched off')
            return False
        elif cookie.version == 0 and not (self.netscape):
            _debug('   Netscape cookies are switched off')
            return False

        return True


    def set_ok_verifiability(self, cookie, request):
        if request.is_unverifiable() and is_third_party(request):
            if cookie.version > 0 and self.strict_rfc2965_unverifiable:
                _debug('   third-party RFC 2965 cookie during unverifiable transaction')
                return False
            elif cookie.version == 0 and self.strict_ns_unverifiable:
                _debug('   third-party Netscape cookie during unverifiable transaction')
                return False


        return True


    def set_ok_name(self, cookie, request):
        if cookie.version == 0 and self.strict_ns_set_initial_dollar and cookie.name.startswith('$'):
            _debug("   illegal name (starts with '$'): '%s'", cookie.name)
            return False

        return True


    def set_ok_path(self, cookie, request):
        if cookie.path_specified:
            req_path = request_path(request)
            if (cookie.version > 0 or cookie.version == 0 or self.strict_ns_set_path) and not req_path.startswith(cookie.path):
                _debug('   path attribute %s is not a prefix of request path %s', cookie.path, req_path)
                return False


        return True


    def set_ok_domain(self, cookie, request):
        if self.is_blocked(cookie.domain):
            _debug('   domain %s is in user block-list', cookie.domain)
            return False

        if self.is_not_allowed(cookie.domain):
            _debug('   domain %s is not in user allow-list', cookie.domain)
            return False

        if cookie.domain_specified:
            (req_host, erhn) = eff_request_host(request)
            domain = cookie.domain
            if self.strict_domain and domain.count('.') >= 2:
                i = domain.rfind('.')
                j = domain.rfind('.', 0, i)
                if j == 0:
                    tld = domain[i + 1:]
                    sld = domain[j + 1:i]
                    if sld.lower() in ('co', 'ac', 'com', 'edu', 'org', 'net', 'gov', 'mil', 'int', 'aero', 'biz', 'cat', 'coop', 'info', 'jobs', 'mobi', 'museum', 'name', 'pro', 'travel', 'eu') and len(tld) == 2:
                        _debug('   country-code second level domain %s', domain)
                        return False



            if domain.startswith('.'):
                undotted_domain = domain[1:]
            else:
                undotted_domain = domain
            embedded_dots = undotted_domain.find('.') >= 0
            if not embedded_dots and domain != '.local':
                _debug('   non-local domain %s contains no embedded dot', domain)
                return False

            if cookie.version == 0:
                if not erhn.endswith(domain) and not erhn.startswith('.') and not ('.' + erhn).endswith(domain):
                    _debug('   effective request-host %s (even with added initial dot) does not end end with %s', erhn, domain)
                    return False


            if cookie.version > 0 or self.strict_ns_domain & self.DomainRFC2965Match:
                if not domain_match(erhn, domain):
                    _debug('   effective request-host %s does not domain-match %s', erhn, domain)
                    return False


            if cookie.version > 0 or self.strict_ns_domain & self.DomainStrictNoDots:
                host_prefix = req_host[:-len(domain)]
                if host_prefix.find('.') >= 0 and not IPV4_RE.search(req_host):
                    _debug('   host prefix %s for domain %s contains a dot', host_prefix, domain)
                    return False



        return True


    def set_ok_port(self, cookie, request):
        if cookie.port_specified:
            req_port = request_port(request)
            if req_port is None:
                req_port = '80'
            else:
                req_port = str(req_port)
            for p in cookie.port.split(','):

                try:
                    int(p)
                except ValueError:
                    _debug('   bad port %s (not numeric)', p)
                    return False

                if p == req_port:
                    break
                    continue
            else:
                return False

        return True


    def return_ok(self, cookie, request):
        '''
        If you override .return_ok(), be sure to call this method.  If it
        returns false, so should your subclass (assuming your subclass wants to
        be more strict about which cookies to return).

        '''
        _debug(' - checking cookie %s=%s', cookie.name, cookie.value)
        for n in ('version', 'verifiability', 'secure', 'expires', 'port', 'domain'):
            fn_name = 'return_ok_' + n
            fn = getattr(self, fn_name)
            if not fn(cookie, request):
                return False
                continue

        return True


    def return_ok_version(self, cookie, request):
        if cookie.version > 0 and not (self.rfc2965):
            _debug('   RFC 2965 cookies are switched off')
            return False
        elif cookie.version == 0 and not (self.netscape):
            _debug('   Netscape cookies are switched off')
            return False

        return True


    def return_ok_verifiability(self, cookie, request):
        if request.is_unverifiable() and is_third_party(request):
            if cookie.version > 0 and self.strict_rfc2965_unverifiable:
                _debug('   third-party RFC 2965 cookie during unverifiable transaction')
                return False
            elif cookie.version == 0 and self.strict_ns_unverifiable:
                _debug('   third-party Netscape cookie during unverifiable transaction')
                return False


        return True


    def return_ok_secure(self, cookie, request):
        if cookie.secure and request.get_type() != 'https':
            _debug('   secure cookie with non-secure request')
            return False

        return True


    def return_ok_expires(self, cookie, request):
        if cookie.is_expired(self._now):
            _debug('   cookie expired')
            return False

        return True


    def return_ok_port(self, cookie, request):
        if cookie.port:
            req_port = request_port(request)
            if req_port is None:
                req_port = '80'

            for p in cookie.port.split(','):
                if p == req_port:
                    break
                    continue
            else:
                return False

        return True


    def return_ok_domain(self, cookie, request):
        (req_host, erhn) = eff_request_host(request)
        domain = cookie.domain
        if cookie.version == 0 and self.strict_ns_domain & self.DomainStrictNonDomain and not (cookie.domain_specified) and domain != erhn:
            _debug('   cookie with unspecified domain does not string-compare equal to request domain')
            return False

        if cookie.version > 0 and not domain_match(erhn, domain):
            _debug('   effective request-host name %s does not domain-match RFC 2965 cookie domain %s', erhn, domain)
            return False

        if cookie.version == 0 and not ('.' + erhn).endswith(domain):
            _debug('   request-host %s does not match Netscape cookie domain %s', req_host, domain)
            return False

        return True


    def domain_return_ok(self, domain, request):
        (req_host, erhn) = eff_request_host(request)
        if not req_host.startswith('.'):
            req_host = '.' + req_host

        if not erhn.startswith('.'):
            erhn = '.' + erhn

        if not req_host.endswith(domain) or erhn.endswith(domain):
            return False

        if self.is_blocked(domain):
            _debug('   domain %s is in user block-list', domain)
            return False

        if self.is_not_allowed(domain):
            _debug('   domain %s is not in user allow-list', domain)
            return False

        return True


    def path_return_ok(self, path, request):
        _debug('- checking cookie path=%s', path)
        req_path = request_path(request)
        if not req_path.startswith(path):
            _debug('  %s does not path-match %s', req_path, path)
            return False

        return True



def vals_sorted_by_key(adict):
    keys = adict.keys()
    keys.sort()
    return map(adict.get, keys)


def deepvalues(mapping):
    '''Iterates over nested mapping, depth-first, in sorted order by key.'''
    values = vals_sorted_by_key(mapping)
    for obj in values:
        mapping = False

        try:
            obj.items
        except AttributeError:
            pass

        mapping = True
        for subobj in deepvalues(obj):
            yield subobj

        if not mapping:
            yield obj
            continue



class Absent:
    pass


class CookieJar:
    '''Collection of HTTP cookies.

    You may not need to know about this class: try
    urllib2.build_opener(HTTPCookieProcessor).open(url).

    '''
    non_word_re = re.compile('\\W')
    quote_re = re.compile('([\\"\\\\])')
    strict_domain_re = re.compile('\\.?[^.]*')
    domain_re = re.compile('[^.]*')
    dots_re = re.compile('^\\.+')
    magic_re = '^\\#LWP-Cookies-(\\d+\\.\\d+)'

    def __init__(self, policy = None):
        if policy is None:
            policy = DefaultCookiePolicy()

        self._policy = policy
        self._cookies_lock = _threading.RLock()
        self._cookies = { }


    def set_policy(self, policy):
        self._policy = policy


    def _cookies_for_domain(self, domain, request):
        cookies = []
        if not self._policy.domain_return_ok(domain, request):
            return []

        _debug('Checking %s for cookies to return', domain)
        cookies_by_path = self._cookies[domain]
        for path in cookies_by_path.keys():
            if not self._policy.path_return_ok(path, request):
                continue

            cookies_by_name = cookies_by_path[path]
            for cookie in cookies_by_name.values():
                if not self._policy.return_ok(cookie, request):
                    _debug('   not returning cookie')
                    continue

                _debug("   it's a match")
                cookies.append(cookie)


        return cookies


    def _cookies_for_request(self, request):
        '''Return a list of cookies to be returned to server.'''
        cookies = []
        for domain in self._cookies.keys():
            cookies.extend(self._cookies_for_domain(domain, request))

        return cookies


    def _cookie_attrs(self, cookies):
        '''Return a list of cookie-attributes to be returned to server.

        like [\'foo="bar"; $Path="/"\', ...]

        The $Version attribute is also added when appropriate (currently only
        once per request).

        '''

        def decreasing_size(a, b):
            return cmp(len(b.path), len(a.path))

        cookies.sort(decreasing_size)
        version_set = False
        attrs = []
        for cookie in cookies:
            version = cookie.version
            if not version_set:
                version_set = True
                if version > 0:
                    attrs.append('$Version=%s' % version)


            if cookie.value is not None and self.non_word_re.search(cookie.value) and version > 0:
                value = self.quote_re.sub('\\\\\\1', cookie.value)
            else:
                value = cookie.value
            if cookie.value is None:
                attrs.append(cookie.name)
            else:
                attrs.append('%s=%s' % (cookie.name, value))
            if version > 0:
                if cookie.path_specified:
                    attrs.append('$Path="%s"' % cookie.path)

                if cookie.domain.startswith('.'):
                    domain = cookie.domain
                    if not (cookie.domain_initial_dot) and domain.startswith('.'):
                        domain = domain[1:]

                    attrs.append('$Domain="%s"' % domain)

                if cookie.port is not None:
                    p = '$Port'
                    if cookie.port_specified:
                        p = p + '="%s"' % cookie.port

                    attrs.append(p)

            cookie.port is not None

        return attrs


    def add_cookie_header(self, request):
        '''Add correct Cookie: header to request (urllib2.Request object).

        The Cookie2 header is also added unless policy.hide_cookie2 is true.

        '''
        _debug('add_cookie_header')
        self._cookies_lock.acquire()
        self._policy._now = self._now = int(time.time())
        cookies = self._cookies_for_request(request)
        attrs = self._cookie_attrs(cookies)
        if attrs:
            if not request.has_header('Cookie'):
                request.add_unredirected_header('Cookie', '; '.join(attrs))


        if self._policy.rfc2965 and not (self._policy.hide_cookie2) and not request.has_header('Cookie2'):
            for cookie in cookies:
                if cookie.version != 1:
                    request.add_unredirected_header('Cookie2', '$Version="1"')
                    break
                    continue


        self._cookies_lock.release()
        self.clear_expired_cookies()


    def _normalized_cookie_tuples(self, attrs_set):
        '''Return list of tuples containing normalised cookie information.

        attrs_set is the list of lists of key,value pairs extracted from
        the Set-Cookie or Set-Cookie2 headers.

        Tuples are name, value, standard, rest, where name and value are the
        cookie name and value, standard is a dictionary containing the standard
        cookie-attributes (discard, secure, version, expires or max-age,
        domain, path and port) and rest is a dictionary containing the rest of
        the cookie-attributes.

        '''
        cookie_tuples = []
        boolean_attrs = ('discard', 'secure')
        value_attrs = ('version', 'expires', 'max-age', 'domain', 'path', 'port', 'comment', 'commenturl')
        for cookie_attrs in attrs_set:
            (name, value) = cookie_attrs[0]
            max_age_set = False
            bad_cookie = False
            standard = { }
            rest = { }
            for k, v in cookie_attrs[1:]:
                lc = k.lower()
                if lc in value_attrs or lc in boolean_attrs:
                    k = lc

                if k in boolean_attrs and v is None:
                    v = True

                if k in standard:
                    continue

                if k == 'domain':
                    if v is None:
                        _debug('   missing value for domain attribute')
                        bad_cookie = True
                        break

                    v = v.lower()

                if k == 'expires':
                    if max_age_set:
                        continue

                    if v is None:
                        _debug('   missing or invalid value for expires attribute: treating as session cookie')
                        continue


                if k == 'max-age':
                    max_age_set = True

                    try:
                        v = int(v)
                    except ValueError:
                        _debug('   missing or invalid (non-numeric) value for max-age attribute')
                        bad_cookie = True
                        break

                    k = 'expires'
                    v = self._now + v

                if k in value_attrs or k in boolean_attrs:
                    if v is None and k not in ('port', 'comment', 'commenturl'):
                        _debug('   missing value for %s attribute' % k)
                        bad_cookie = True
                        break

                    standard[k] = v
                    continue
                rest[k] = v

            if bad_cookie:
                continue

            cookie_tuples.append((name, value, standard, rest))

        return cookie_tuples


    def _cookie_from_cookie_tuple(self, tup, request):
        (name, value, standard, rest) = tup
        domain = standard.get('domain', Absent)
        path = standard.get('path', Absent)
        port = standard.get('port', Absent)
        expires = standard.get('expires', Absent)
        version = standard.get('version', None)
        if version is not None:
            version = int(version)

        secure = standard.get('secure', False)
        discard = standard.get('discard', False)
        comment = standard.get('comment', None)
        comment_url = standard.get('commenturl', None)
        if path is not Absent and path != '':
            path_specified = True
            path = escape_path(path)
        else:
            path_specified = False
            path = request_path(request)
            i = path.rfind('/')
            if i != -1:
                if version == 0:
                    path = path[:i]
                else:
                    path = path[:i + 1]

            if len(path) == 0:
                path = '/'

        domain_specified = domain is not Absent
        domain_initial_dot = False
        if domain_specified:
            domain_initial_dot = bool(domain.startswith('.'))

        if domain is Absent:
            (req_host, erhn) = eff_request_host(request)
            domain = erhn
        elif not domain.startswith('.'):
            domain = '.' + domain

        port_specified = False
        if port is not Absent:
            if port is None:
                port = request_port(request)
            else:
                port_specified = True
                port = re.sub('\\s+', '', port)
        else:
            port = None
        if expires is Absent:
            expires = None
            discard = True
        elif expires <= self._now:

            try:
                self.clear(domain, path, name)
            except KeyError:
                pass

            _debug("Expiring cookie, domain='%s', path='%s', name='%s'", domain, path, name)
            return None

        return Cookie(version, name, value, port, port_specified, domain, domain_specified, domain_initial_dot, path, path_specified, secure, expires, discard, comment, comment_url, rest)


    def _cookies_from_attrs_set(self, attrs_set, request):
        cookie_tuples = self._normalized_cookie_tuples(attrs_set)
        cookies = []
        for tup in cookie_tuples:
            cookie = self._cookie_from_cookie_tuple(tup, request)
            if cookie:
                cookies.append(cookie)
                continue

        return cookies


    def _process_rfc2109_cookies(self, cookies):
        rfc2109_as_ns = getattr(self._policy, 'rfc2109_as_netscape', None)
        if rfc2109_as_ns is None:
            rfc2109_as_ns = not (self._policy.rfc2965)

        for cookie in cookies:
            if cookie.version == 1:
                cookie.rfc2109 = True
                if rfc2109_as_ns:
                    cookie.version = 0

            rfc2109_as_ns



    def make_cookies(self, response, request):
        '''Return sequence of Cookie objects extracted from response object.'''
        headers = response.info()
        rfc2965_hdrs = headers.getheaders('Set-Cookie2')
        ns_hdrs = headers.getheaders('Set-Cookie')
        rfc2965 = self._policy.rfc2965
        netscape = self._policy.netscape
        if not not rfc2965_hdrs or not ns_hdrs:
            if not not ns_hdrs or not rfc2965:
                if (not rfc2965_hdrs or not netscape or not netscape) and not rfc2965:
                    return []


        try:
            cookies = self._cookies_from_attrs_set(split_header_words(rfc2965_hdrs), request)
        except Exception:
            _warn_unhandled_exception()
            cookies = []

        if ns_hdrs and netscape:

            try:
                ns_cookies = self._cookies_from_attrs_set(parse_ns_headers(ns_hdrs), request)
            except Exception:
                _warn_unhandled_exception()
                ns_cookies = []

            self._process_rfc2109_cookies(ns_cookies)
            if rfc2965:
                lookup = { }
                for cookie in cookies:
                    lookup[(cookie.domain, cookie.path, cookie.name)] = None


                def no_matching_rfc2965(ns_cookie, lookup = lookup):
                    key = (ns_cookie.domain, ns_cookie.path, ns_cookie.name)
                    return key not in lookup

                ns_cookies = filter(no_matching_rfc2965, ns_cookies)

            if ns_cookies:
                cookies.extend(ns_cookies)


        return cookies


    def set_cookie_if_ok(self, cookie, request):
        """Set a cookie if policy says it's OK to do so."""
        self._cookies_lock.acquire()
        self._policy._now = self._now = int(time.time())
        if self._policy.set_ok(cookie, request):
            self.set_cookie(cookie)

        self._cookies_lock.release()


    def set_cookie(self, cookie):
        '''Set a cookie, without checking whether or not it should be set.'''
        c = self._cookies
        self._cookies_lock.acquire()

        try:
            if cookie.domain not in c:
                c[cookie.domain] = { }

            c2 = c[cookie.domain]
            if cookie.path not in c2:
                c2[cookie.path] = { }

            c3 = c2[cookie.path]
            c3[cookie.name] = cookie
        finally:
            self._cookies_lock.release()



    def extract_cookies(self, response, request):
        '''Extract cookies from response, where allowable given the request.'''
        _debug('extract_cookies: %s', response.info())
        self._cookies_lock.acquire()
        self._policy._now = self._now = int(time.time())
        for cookie in self.make_cookies(response, request):
            if self._policy.set_ok(cookie, request):
                _debug(' setting cookie: %s', cookie)
                self.set_cookie(cookie)
                continue

        self._cookies_lock.release()


    def clear(self, domain = None, path = None, name = None):
        '''Clear some cookies.

        Invoking this method without arguments will clear all cookies.  If
        given a single argument, only cookies belonging to that domain will be
        removed.  If given two arguments, cookies belonging to the specified
        path within that domain are removed.  If given three arguments, then
        the cookie with the specified name, path and domain is removed.

        Raises KeyError if no matching cookie exists.

        '''
        if name is not None:
            if domain is None or path is None:
                raise ValueError('domain and path must be given to remove a cookie by name')

            del self._cookies[domain][path][name]
        elif path is not None:
            if domain is None:
                raise ValueError('domain must be given to remove cookies by path')

            del self._cookies[domain][path]
        elif domain is not None:
            del self._cookies[domain]
        else:
            self._cookies = { }


    def clear_session_cookies(self):
        """Discard all session cookies.

        Note that the .save() method won't save session cookies anyway, unless
        you ask otherwise by passing a true ignore_discard argument.

        """
        self._cookies_lock.acquire()
        for cookie in self:
            if cookie.discard:
                self.clear(cookie.domain, cookie.path, cookie.name)
                continue

        self._cookies_lock.release()


    def clear_expired_cookies(self):
        """Discard all expired cookies.

        You probably don't need to call this method: expired cookies are never
        sent back to the server (provided you're using DefaultCookiePolicy),
        this method is called by CookieJar itself every so often, and the
        .save() method won't save expired cookies anyway (unless you ask
        otherwise by passing a true ignore_expires argument).

        """
        self._cookies_lock.acquire()
        now = time.time()
        for cookie in self:
            if cookie.is_expired(now):
                self.clear(cookie.domain, cookie.path, cookie.name)
                continue

        self._cookies_lock.release()


    def __iter__(self):
        return deepvalues(self._cookies)


    def __len__(self):
        '''Return number of contained cookies.'''
        i = 0
        for cookie in self:
            i = i + 1

        return i


    def __repr__(self):
        r = []
        for cookie in self:
            r.append(repr(cookie))

        return '<%s[%s]>' % (self.__class__, ', '.join(r))


    def __str__(self):
        r = []
        for cookie in self:
            r.append(str(cookie))

        return '<%s[%s]>' % (self.__class__, ', '.join(r))



class LoadError(IOError):
    pass


class FileCookieJar(CookieJar):
    '''CookieJar that can be loaded from and saved to a file.'''

    def __init__(self, filename = None, delayload = False, policy = None):
        '''
        Cookies are NOT loaded from the named file until either the .load() or
        .revert() method is called.

        '''
        CookieJar.__init__(self, policy)
        if filename is not None:

            try:
                filename + ''
            raise ValueError('filename must be string-like')


        self.filename = filename
        self.delayload = bool(delayload)


    def save(self, filename = None, ignore_discard = False, ignore_expires = False):
        '''Save cookies to a file.'''
        raise NotImplementedError()


    def load(self, filename = None, ignore_discard = False, ignore_expires = False):
        '''Load cookies from a file.'''
        if filename is None:
            if self.filename is not None:
                filename = self.filename
            else:
                raise ValueError(MISSING_FILENAME_TEXT)

        f = open(filename)

        try:
            self._really_load(f, filename, ignore_discard, ignore_expires)
        finally:
            f.close()



    def revert(self, filename = None, ignore_discard = False, ignore_expires = False):
        """Clear all cookies and reload cookies from a saved file.

        Raises LoadError (or IOError) if reversion is not successful; the
        object's state will not be altered if this happens.

        """
        if filename is None:
            if self.filename is not None:
                filename = self.filename
            else:
                raise ValueError(MISSING_FILENAME_TEXT)

        self._cookies_lock.acquire()
        old_state = copy.deepcopy(self._cookies)
        self._cookies = { }

        try:
            self.load(filename, ignore_discard, ignore_expires)
        except (LoadError, IOError):
            self._cookies = old_state
            raise

        self._cookies_lock.release()


from _LWPCookieJar import LWPCookieJar, lwp_cookie_str
from _MozillaCookieJar import MozillaCookieJar