'Returns the provided temporary URL parameters (sig, expires, prefix),
if given and syntactically valid. Either sig, expires or prefix could
be None if not provided. If provided, expires is also
converted to an int if possible or 0 if not, and checked for
expiration (returns 0 if expired).
:param env: The WSGI environment for the request.
:returns: (sig, expires, prefix, filename, inline) as described above.'

def _get_temp_url_info(self, env):

    temp_url_sig = temp_url_expires = temp_url_prefix = filename = inline = None
    qs = parse_qs(env.get('QUERY_STRING', ''), keep_blank_values=True)
    if ('temp_url_sig' in qs):
        temp_url_sig = qs['temp_url_sig'][0]
    if ('temp_url_expires' in qs):
        try:
            temp_url_expires = int(qs['temp_url_expires'][0])
        except ValueError:
            try:
                temp_url_expires = timegm(strptime(qs['temp_url_expires'][0], EXPIRES_ISO8601_FORMAT))
            except ValueError:
                temp_url_expires = 0
        if (temp_url_expires < time()):
            temp_url_expires = 0
    if ('temp_url_prefix' in qs):
        temp_url_prefix = qs['temp_url_prefix'][0]
    if ('filename' in qs):
        filename = qs['filename'][0]
    if ('inline' in qs):
        inline = True
    return (temp_url_sig, temp_url_expires, temp_url_prefix, filename, inline)
