dak/daklib/dbconn.py

#!/usr/bin/python

""" DB access class

@contact: Debian FTPMaster <ftpmaster@debian.org>
@copyright: 2000, 2001, 2002, 2003, 2004, 2006  James Troup <james@nocrew.org>
@copyright: 2008-2009  Mark Hymers <mhy@debian.org>
@copyright: 2009, 2010  Joerg Jaspert <joerg@debian.org>
@copyright: 2009  Mike O'Connor <stew@debian.org>
@license: GNU General Public License version 2 or later
"""

# 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 2 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, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

################################################################################

# < mhy> I need a funny comment
# < sgran> two peanuts were walking down a dark street
# < sgran> one was a-salted
#  * mhy looks up the definition of "funny"

################################################################################

from __future__ import absolute_import, print_function

import apt_pkg
import daklib.daksubprocess
import functools
import os
from os.path import normpath
import re
import psycopg2
import subprocess
import traceback

from datetime import datetime, timedelta
from errno import ENOENT
from tempfile import mkstemp, mkdtemp
from tarfile import TarFile

from inspect import getargspec

import sqlalchemy
from sqlalchemy import create_engine, Table, MetaData, Column, Integer, desc, \
    Text, ForeignKey
from sqlalchemy.orm import sessionmaker, mapper, relation, object_session, \
    backref, MapperExtension, EXT_CONTINUE, object_mapper
import sqlalchemy.types
from sqlalchemy.orm.collections import attribute_mapped_collection
from sqlalchemy.ext.associationproxy import association_proxy

# Don't remove this, we re-export the exceptions to scripts which import us
from sqlalchemy.exc import *
from sqlalchemy.orm.exc import NoResultFound

from .aptversion import AptVersion
# Only import Config until Queue stuff is changed to store its config
# in the database
from .config import Config
from .textutils import fix_maintainer
from .dak_exceptions import DBUpdateError, NoSourceFieldError, FileExistsError

# suppress some deprecation warnings in squeeze related to sqlalchemy
import warnings
warnings.filterwarnings('ignore',
    "The SQLAlchemy PostgreSQL dialect has been renamed from 'postgres' to 'postgresql'.*",
    SADeprecationWarning)
warnings.filterwarnings('ignore',
    "Predicate of partial index .* ignored during reflection",
    SAWarning)

from .database.base import Base


################################################################################

# Patch in support for the debversion field type so that it works during
# reflection

class DebVersion(sqlalchemy.types.UserDefinedType):
    def get_col_spec(self):
        return "DEBVERSION"

    def bind_processor(self, dialect):
        return None

    def result_processor(self, dialect, coltype):
        return None

from sqlalchemy.databases import postgres
postgres.ischema_names['debversion'] = DebVersion

################################################################################

__all__ = ['IntegrityError', 'SQLAlchemyError', 'DebVersion']

################################################################################


def session_wrapper(fn):
    """
    Wrapper around common ".., session=None):" handling. If the wrapped
    function is called without passing 'session', we create a local one
    and destroy it when the function ends.

    Also attaches a commit_or_flush method to the session; if we created a
    local session, this is a synonym for session.commit(), otherwise it is a
    synonym for session.flush().
    """

    def wrapped(*args, **kwargs):
        private_transaction = False

        # Find the session object
        session = kwargs.get('session')

        if session is None:
            if len(args) <= len(getargspec(fn)[0]) - 1:
                # No session specified as last argument or in kwargs
                private_transaction = True
                session = kwargs['session'] = DBConn().session()
            else:
                # Session is last argument in args
                session = args[-1]
                if session is None:
                    args = list(args)
                    session = args[-1] = DBConn().session()
                    private_transaction = True

        if private_transaction:
            session.commit_or_flush = session.commit
        else:
            session.commit_or_flush = session.flush

        try:
            return fn(*args, **kwargs)
        finally:
            if private_transaction:
                # We created a session; close it.
                session.close()

    wrapped.__doc__ = fn.__doc__
    wrapped.__name__ = fn.__name__

    return wrapped

__all__.append('session_wrapper')

################################################################################


class ORMObject(object):
    """
    ORMObject is a base class for all ORM classes mapped by SQLalchemy. All
    derived classes must implement the properties() method.
    """

    def properties(self):
        '''
        This method should be implemented by all derived classes and returns a
        list of the important properties. The properties 'created' and
        'modified' will be added automatically. A suffix '_count' should be
        added to properties that are lists or query objects. The most important
        property name should be returned as the first element in the list
        because it is used by repr().
        '''
        return []

    def classname(self):
        '''
        Returns the name of the class.
        '''
        return type(self).__name__

    def __repr__(self):
        '''
        Returns a short string representation of the object using the first
        element from the properties() method.
        '''
        primary_property = self.properties()[0]
        value = getattr(self, primary_property)
        return '<%s %s>' % (self.classname(), str(value))

    def __str__(self):
        '''
        Returns a human readable form of the object using the properties()
        method.
        '''
        return '<%s(...)>' % (self.classname())

    @classmethod
    @session_wrapper
    def get(cls, primary_key,  session=None):
        '''
        This is a support function that allows getting an object by its primary
        key.

        Architecture.get(3[, session])

        instead of the more verbose

        session.query(Architecture).get(3)
        '''
        return session.query(cls).get(primary_key)

    def session(self, replace=False):
        '''
        Returns the current session that is associated with the object. May
        return None is object is in detached state.
        '''

        return object_session(self)

    def clone(self, session=None):
        """
        Clones the current object in a new session and returns the new clone. A
        fresh session is created if the optional session parameter is not
        provided. The function will fail if a session is provided and has
        unflushed changes.

        RATIONALE: SQLAlchemy's session is not thread safe. This method clones
        an existing object to allow several threads to work with their own
        instances of an ORMObject.

        WARNING: Only persistent (committed) objects can be cloned. Changes
        made to the original object that are not committed yet will get lost.
        The session of the new object will always be rolled back to avoid
        resource leaks.
        """

        if self.session() is None:
            raise RuntimeError(
                'Method clone() failed for detached object:\n%s' % self)
        self.session().flush()
        mapper = object_mapper(self)
        primary_key = mapper.primary_key_from_instance(self)
        object_class = self.__class__
        if session is None:
            session = DBConn().session()
        elif len(session.new) + len(session.dirty) + len(session.deleted) > 0:
            raise RuntimeError(
                'Method clone() failed due to unflushed changes in session.')
        new_object = session.query(object_class).get(primary_key)
        session.rollback()
        if new_object is None:
            raise RuntimeError(
                'Method clone() failed for non-persistent object:\n%s' % self)
        return new_object

__all__.append('ORMObject')

################################################################################


class ACL(ORMObject):
    def __repr__(self):
        return "<ACL {0}>".format(self.name)

__all__.append('ACL')


class ACLPerSource(ORMObject):
    def __repr__(self):
        return "<ACLPerSource acl={0} fingerprint={1} source={2} reason={3}>".format(self.acl.name, self.fingerprint.fingerprint, self.source, self.reason)

__all__.append('ACLPerSource')

################################################################################


from .database.architecture import Architecture

__all__.append('Architecture')


@session_wrapper
def get_architecture(architecture, session=None):
    """
    Returns database id for given C{architecture}.

    @type architecture: string
    @param architecture: The name of the architecture

    @type session: Session
    @param session: Optional SQLA session object (a temporary one will be
    generated if not supplied)

    @rtype: Architecture
    @return: Architecture object for the given arch (None if not present)
    """

    q = session.query(Architecture).filter_by(arch_string=architecture)

    try:
        return q.one()
    except NoResultFound:
        return None

__all__.append('get_architecture')

################################################################################


class Archive(object):
    def __init__(self, *args, **kwargs):
        pass

    def __repr__(self):
        return '<Archive %s>' % self.archive_name

__all__.append('Archive')


@session_wrapper
def get_archive(archive, session=None):
    """
    returns database id for given C{archive}.

    @type archive: string
    @param archive: the name of the arhive

    @type session: Session
    @param session: Optional SQLA session object (a temporary one will be
    generated if not supplied)

    @rtype: Archive
    @return: Archive object for the given name (None if not present)

    """
    archive = archive.lower()

    q = session.query(Archive).filter_by(archive_name=archive)

    try:
        return q.one()
    except NoResultFound:
        return None

__all__.append('get_archive')

################################################################################


class ArchiveFile(object):
    def __init__(self, archive=None, component=None, file=None):
        self.archive = archive
        self.component = component
        self.file = file

    @property
    def path(self):
        return os.path.join(self.archive.path, 'pool', self.component.component_name, self.file.filename)

__all__.append('ArchiveFile')

################################################################################


class BinContents(ORMObject):
    def __init__(self, file=None, binary=None):
        self.file = file
        self.binary = binary

    def properties(self):
        return ['file', 'binary']

__all__.append('BinContents')

################################################################################


class DBBinary(ORMObject):
    def __init__(self, package=None, source=None, version=None,
        maintainer=None, architecture=None, poolfile=None,
        binarytype='deb', fingerprint=None):
        self.package = package
        self.source = source
        self.version = version
        self.maintainer = maintainer
        self.architecture = architecture
        self.poolfile = poolfile
        self.binarytype = binarytype
        self.fingerprint = fingerprint

    @property
    def pkid(self):
        return self.binary_id

    def properties(self):
        return ['package', 'version', 'maintainer', 'source', 'architecture',
            'poolfile', 'binarytype', 'fingerprint', 'install_date',
            'suites_count', 'binary_id', 'contents_count', 'extra_sources']

    metadata = association_proxy('key', 'value')

    def scan_contents(self):
        '''
        Yields the contents of the package. Only regular files are yielded and
        the path names are normalized after converting them from either utf-8
        or iso8859-1 encoding. It yields the string ' <EMPTY PACKAGE>' if the
        package does not contain any regular file.
        '''
        fullpath = self.poolfile.fullpath
        dpkg_cmd = ('dpkg-deb', '--fsys-tarfile', fullpath)
        dpkg = daklib.daksubprocess.Popen(dpkg_cmd, stdout=subprocess.PIPE)
        tar = TarFile.open(fileobj=dpkg.stdout, mode='r|')
        for member in tar.getmembers():
            if not member.isdir():
                name = normpath(member.name)
                # enforce proper utf-8 encoding
                try:
                    name.decode('utf-8')
                except UnicodeDecodeError:
                    name = name.decode('iso8859-1').encode('utf-8')
                yield name
        tar.close()
        dpkg.stdout.close()
        dpkg.wait()

    def read_control(self):
        '''
        Reads the control information from a binary.

        @rtype: text
        @return: stanza text of the control section.
        '''
        from . import utils
        fullpath = self.poolfile.fullpath
        with open(fullpath, 'r') as deb_file:
            return utils.deb_extract_control(deb_file)

    def read_control_fields(self):
        '''
        Reads the control information from a binary and return
        as a dictionary.

        @rtype: dict
        @return: fields of the control section as a dictionary.
        '''
        stanza = self.read_control()
        return apt_pkg.TagSection(stanza)

    @property
    def proxy(self):
        session = object_session(self)
        query = session.query(BinaryMetadata).filter_by(binary=self)
        return MetadataProxy(session, query)

__all__.append('DBBinary')


@session_wrapper
def get_suites_binary_in(package, session=None):
    """
    Returns list of Suite objects which given C{package} name is in

    @type package: str
    @param package: DBBinary package name to search for

    @rtype: list
    @return: list of Suite objects for the given package
    """

    return session.query(Suite).filter(Suite.binaries.any(DBBinary.package == package)).all()

__all__.append('get_suites_binary_in')


@session_wrapper
def get_component_by_package_suite(package, suite_list, arch_list=[], session=None):
    '''
    Returns the component name of the newest binary package in suite_list or
    None if no package is found. The result can be optionally filtered by a list
    of architecture names.

    @type package: str
    @param package: DBBinary package name to search for

    @type suite_list: list of str
    @param suite_list: list of suite_name items

    @type arch_list: list of str
    @param arch_list: optional list of arch_string items that defaults to []

    @rtype: str or NoneType
    @return: name of component or None
    '''

    q = session.query(DBBinary).filter_by(package=package). \
        join(DBBinary.suites).filter(Suite.suite_name.in_(suite_list))
    if len(arch_list) > 0:
        q = q.join(DBBinary.architecture). \
            filter(Architecture.arch_string.in_(arch_list))
    binary = q.order_by(desc(DBBinary.version)).first()
    if binary is None:
        return None
    else:
        return binary.poolfile.component.component_name

__all__.append('get_component_by_package_suite')

################################################################################


class BuildQueue(object):
    def __init__(self, *args, **kwargs):
        pass

    def __repr__(self):
        return '<BuildQueue %s>' % self.queue_name

__all__.append('BuildQueue')

################################################################################


class Component(ORMObject):
    def __init__(self, component_name=None):
        self.component_name = component_name

    def __eq__(self, val):
        if isinstance(val, str):
            return (self.component_name == val)
        # This signals to use the normal comparison operator
        return NotImplemented

    def __ne__(self, val):
        if isinstance(val, str):
            return (self.component_name != val)
        # This signals to use the normal comparison operator
        return NotImplemented

    def properties(self):
        return ['component_name', 'component_id', 'description',
            'meets_dfsg', 'overrides_count']

__all__.append('Component')


@session_wrapper
def get_component(component, session=None):
    """
    Returns database id for given C{component}.

    @type component: string
    @param component: The name of the override type

    @rtype: int
    @return: the database id for the given component

    """
    component = component.lower()

    q = session.query(Component).filter_by(component_name=component)

    try:
        return q.one()
    except NoResultFound:
        return None

__all__.append('get_component')


def get_mapped_component_name(component_name):
    cnf = Config()
    for m in cnf.value_list("ComponentMappings"):
        (src, dst) = m.split()
        if component_name == src:
            component_name = dst
    return component_name

__all__.append('get_mapped_component_name')


@session_wrapper
def get_mapped_component(component_name, session=None):
    """get component after mappings

    Evaluate component mappings from ComponentMappings in dak.conf for the
    given component name.

    @todo: ansgar wants to get rid of this. It's currently only used for
           the security archive

    @type  component_name: str
    @param component_name: component name

    @param session: database session

    @rtype:  L{daklib.dbconn.Component} or C{None}
    @return: component after applying maps or C{None}
    """
    component_name = get_mapped_component_name(component_name)
    component = session.query(Component).filter_by(component_name=component_name).first()
    return component

__all__.append('get_mapped_component')


@session_wrapper
def get_component_names(session=None):
    """
    Returns list of strings of component names.

    @rtype: list
    @return: list of strings of component names
    """

    return [x.component_name for x in session.query(Component).all()]

__all__.append('get_component_names')

################################################################################


class DBConfig(object):
    def __init__(self, *args, **kwargs):
        pass

    def __repr__(self):
        return '<DBConfig %s>' % self.name

__all__.append('DBConfig')

################################################################################


class DSCFile(object):
    def __init__(self, *args, **kwargs):
        pass

    def __repr__(self):
        return '<DSCFile %s>' % self.dscfile_id

__all__.append('DSCFile')


@session_wrapper
def get_dscfiles(dscfile_id=None, source_id=None, poolfile_id=None, session=None):
    """
    Returns a list of DSCFiles which may be empty

    @type dscfile_id: int (optional)
    @param dscfile_id: the dscfile_id of the DSCFiles to find

    @type source_id: int (optional)
    @param source_id: the source id related to the DSCFiles to find

    @type poolfile_id: int (optional)
    @param poolfile_id: the poolfile id related to the DSCFiles to find

    @rtype: list
    @return: Possibly empty list of DSCFiles
    """

    q = session.query(DSCFile)

    if dscfile_id is not None:
        q = q.filter_by(dscfile_id=dscfile_id)

    if source_id is not None:
        q = q.filter_by(source_id=source_id)

    if poolfile_id is not None:
        q = q.filter_by(poolfile_id=poolfile_id)

    return q.all()

__all__.append('get_dscfiles')

################################################################################


class ExternalOverride(ORMObject):
    def __init__(self, *args, **kwargs):
        pass

    def __repr__(self):
        return '<ExternalOverride %s = %s: %s>' % (self.package, self.key, self.value)

__all__.append('ExternalOverride')

################################################################################


class PoolFile(ORMObject):
    def __init__(self, filename=None, filesize=-1,
        md5sum=None):
        self.filename = filename
        self.filesize = filesize
        self.md5sum = md5sum

    @property
    def fullpath(self):
        session = DBConn().session().object_session(self)
        af = session.query(ArchiveFile).join(Archive) \
                    .filter(ArchiveFile.file == self) \
                    .order_by(Archive.tainted.desc()).first()
        return af.path

    @property
    def component(self):
        session = DBConn().session().object_session(self)
        component_id = session.query(ArchiveFile.component_id).filter(ArchiveFile.file == self) \
                              .group_by(ArchiveFile.component_id).one()
        return session.query(Component).get(component_id)

    @property
    def basename(self):
        return os.path.basename(self.filename)

    def is_valid(self, filesize=-1, md5sum=None):
        return self.filesize == long(filesize) and self.md5sum == md5sum

    def properties(self):
        return ['filename', 'file_id', 'filesize', 'md5sum', 'sha1sum',
            'sha256sum', 'source', 'binary', 'last_used']

    def identical_to(self, filename):
        """
        compare size and hash with the given file

        @rtype: bool
        @return: true if the given file has the same size and hash as this object; false otherwise
        """
        st = os.stat(filename)
        if self.filesize != st.st_size:
            return False

        f = open(filename, "r")
        sha256sum = apt_pkg.sha256sum(f)
        if sha256sum != self.sha256sum:
            return False

        return True

__all__.append('PoolFile')

################################################################################


class Fingerprint(ORMObject):
    def __init__(self, fingerprint=None):
        self.fingerprint = fingerprint

    def properties(self):
        return ['fingerprint', 'fingerprint_id', 'keyring', 'uid',
            'binary_reject']

__all__.append('Fingerprint')


@session_wrapper
def get_fingerprint(fpr, session=None):
    """
    Returns Fingerprint object for given fpr.

    @type fpr: string
    @param fpr: The fpr to find / add

    @type session: SQLAlchemy
    @param session: Optional SQL session object (a temporary one will be
    generated if not supplied).

    @rtype: Fingerprint
    @return: the Fingerprint object for the given fpr or None
    """

    q = session.query(Fingerprint).filter_by(fingerprint=fpr)

    try:
        ret = q.one()
    except NoResultFound:
        ret = None

    return ret

__all__.append('get_fingerprint')


@session_wrapper
def get_or_set_fingerprint(fpr, session=None):
    """
    Returns Fingerprint object for given fpr.

    If no matching fpr is found, a row is inserted.

    @type fpr: string
    @param fpr: The fpr to find / add

    @type session: SQLAlchemy
    @param session: Optional SQL session object (a temporary one will be
    generated if not supplied).  If not passed, a commit will be performed at
    the end of the function, otherwise the caller is responsible for commiting.
    A flush will be performed either way.

    @rtype: Fingerprint
    @return: the Fingerprint object for the given fpr
    """

    q = session.query(Fingerprint).filter_by(fingerprint=fpr)

    try:
        ret = q.one()
    except NoResultFound:
        fingerprint = Fingerprint()
        fingerprint.fingerprint = fpr
        session.add(fingerprint)
        session.commit_or_flush()
        ret = fingerprint

    return ret

__all__.append('get_or_set_fingerprint')

################################################################################

# Helper routine for Keyring class


def get_ldap_name(entry):
    name = []
    for k in ["cn", "mn", "sn"]:
        ret = entry.get(k)
        if ret and ret[0] != "" and ret[0] != "-":
            name.append(ret[0])
    return " ".join(name)

################################################################################


class Keyring(object):
    keys = {}
    fpr_lookup = {}

    def __init__(self, *args, **kwargs):
        pass

    def __repr__(self):
        return '<Keyring %s>' % self.keyring_name

    def de_escape_gpg_str(self, txt):
        esclist = re.split(r'(\\x..)', txt)
        for x in range(1, len(esclist), 2):
            esclist[x] = "%c" % (int(esclist[x][2:], 16))
        return "".join(esclist)

    def parse_address(self, uid):
        """parses uid and returns a tuple of real name and email address"""
        import email.Utils
        (name, address) = email.Utils.parseaddr(uid)
        name = re.sub(r"\s*[(].*[)]", "", name)
        name = self.de_escape_gpg_str(name)
        if name == "":
            name = uid
        return (name, address)

    def load_keys(self, keyring):
        if not self.keyring_id:
            raise Exception('Must be initialized with database information')

        cmd = ["gpg", "--no-default-keyring", "--keyring", keyring,
               "--with-colons", "--fingerprint", "--fingerprint"]
        p = daklib.daksubprocess.Popen(cmd, stdout=subprocess.PIPE)

        key = None
        need_fingerprint = False

        for line in p.stdout:
            field = line.split(":")
            if field[0] == "pub":
                key = field[4]
                self.keys[key] = {}
                (name, addr) = self.parse_address(field[9])
                if "@" in addr:
                    self.keys[key]["email"] = addr
                    self.keys[key]["name"] = name
                need_fingerprint = True
            elif key and field[0] == "uid":
                (name, addr) = self.parse_address(field[9])
                if "email" not in self.keys[key] and "@" in addr:
                    self.keys[key]["email"] = addr
                    self.keys[key]["name"] = name
            elif need_fingerprint and field[0] == "fpr":
                self.keys[key]["fingerprints"] = [field[9]]
                self.fpr_lookup[field[9]] = key
                need_fingerprint = False

        r = p.wait()
        if r != 0:
            raise subprocess.CalledProcessError(r, cmd)

    def import_users_from_ldap(self, session):
        import ldap
        cnf = Config()

        LDAPDn = cnf["Import-LDAP-Fingerprints::LDAPDn"]
        LDAPServer = cnf["Import-LDAP-Fingerprints::LDAPServer"]
        ca_cert_file = cnf.get('Import-LDAP-Fingerprints::CACertFile')

        l = ldap.open(LDAPServer)

        if ca_cert_file:
            l.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_HARD)
            l.set_option(ldap.OPT_X_TLS_CACERTFILE, ca_cert_file)
            l.set_option(ldap.OPT_X_TLS_NEWCTX, True)
            l.start_tls_s()

        l.simple_bind_s("", "")
        Attrs = l.search_s(LDAPDn, ldap.SCOPE_ONELEVEL,
               "(&(keyfingerprint=*)(supplementaryGid=%s))" % (cnf["Import-Users-From-Passwd::ValidGID"]),
               ["uid", "keyfingerprint", "cn", "mn", "sn"])

        ldap_fin_uid_id = {}

        byuid = {}
        byname = {}

        for i in Attrs:
            entry = i[1]
            uid = entry["uid"][0]
            name = get_ldap_name(entry)
            fingerprints = entry["keyFingerPrint"]
            keyid = None
            for f in fingerprints:
                key = self.fpr_lookup.get(f, None)
                if key not in self.keys:
                    continue
                self.keys[key]["uid"] = uid

                if keyid is not None:
                    continue
                keyid = get_or_set_uid(uid, session).uid_id
                byuid[keyid] = (uid, name)
                byname[uid] = (keyid, name)

        return (byname, byuid)

    def generate_users_from_keyring(self, format, session):
        byuid = {}
        byname = {}
        any_invalid = False
        for x in self.keys.keys():
            if "email" not in self.keys[x]:
                any_invalid = True
                self.keys[x]["uid"] = format % "invalid-uid"
            else:
                uid = format % self.keys[x]["email"]
                keyid = get_or_set_uid(uid, session).uid_id
                byuid[keyid] = (uid, self.keys[x]["name"])
                byname[uid] = (keyid, self.keys[x]["name"])
                self.keys[x]["uid"] = uid

        if any_invalid:
            uid = format % "invalid-uid"
            keyid = get_or_set_uid(uid, session).uid_id
            byuid[keyid] = (uid, "ungeneratable user id")
            byname[uid] = (keyid, "ungeneratable user id")

        return (byname, byuid)

__all__.append('Keyring')


@session_wrapper
def get_keyring(keyring, session=None):
    """
    If C{keyring} does not have an entry in the C{keyrings} table yet, return None
    If C{keyring} already has an entry, simply return the existing Keyring

    @type keyring: string
    @param keyring: the keyring name

    @rtype: Keyring
    @return: the Keyring object for this keyring
    """

    q = session.query(Keyring).filter_by(keyring_name=keyring)

    try:
        return q.one()
    except NoResultFound:
        return None

__all__.append('get_keyring')


@session_wrapper
def get_active_keyring_paths(session=None):
    """
    @rtype: list
    @return: list of active keyring paths
    """
    return [x.keyring_name for x in session.query(Keyring).filter(Keyring.active == True).order_by(desc(Keyring.priority)).all()]  # noqa:E712

__all__.append('get_active_keyring_paths')

################################################################################


class DBChange(object):
    def __init__(self, *args, **kwargs):
        pass

    def __repr__(self):
        return '<DBChange %s>' % self.changesname

__all__.append('DBChange')


@session_wrapper
def get_dbchange(filename, session=None):
    """
    returns DBChange object for given C{filename}.

    @type filename: string
    @param filename: the name of the file

    @type session: Session
    @param session: Optional SQLA session object (a temporary one will be
    generated if not supplied)

    @rtype: DBChange
    @return:  DBChange object for the given filename (C{None} if not present)

    """
    q = session.query(DBChange).filter_by(changesname=filename)

    try:
        return q.one()
    except NoResultFound:
        return None

__all__.append('get_dbchange')

################################################################################


class Maintainer(ORMObject):
    def __init__(self, name=None):
        self.name = name

    def properties(self):
        return ['name', 'maintainer_id']

    def get_split_maintainer(self):
        if not hasattr(self, 'name') or self.name is None:
            return ('', '', '', '')

        return fix_maintainer(self.name.strip())

__all__.append('Maintainer')


@session_wrapper
def get_or_set_maintainer(name, session=None):
    """
    Returns Maintainer object for given maintainer name.

    If no matching maintainer name is found, a row is inserted.

    @type name: string
    @param name: The maintainer name to add

    @type session: SQLAlchemy
    @param session: Optional SQL session object (a temporary one will be
    generated if not supplied).  If not passed, a commit will be performed at
    the end of the function, otherwise the caller is responsible for commiting.
    A flush will be performed either way.

    @rtype: Maintainer
    @return: the Maintainer object for the given maintainer
    """

    q = session.query(Maintainer).filter_by(name=name)
    try:
        ret = q.one()
    except NoResultFound:
        maintainer = Maintainer()
        maintainer.name = name
        session.add(maintainer)
        session.commit_or_flush()
        ret = maintainer

    return ret

__all__.append('get_or_set_maintainer')


@session_wrapper
def get_maintainer(maintainer_id, session=None):
    """
    Return the name of the maintainer behind C{maintainer_id} or None if that
    maintainer_id is invalid.

    @type maintainer_id: int
    @param maintainer_id: the id of the maintainer

    @rtype: Maintainer
    @return: the Maintainer with this C{maintainer_id}
    """

    return session.query(Maintainer).get(maintainer_id)

__all__.append('get_maintainer')

################################################################################


class NewComment(object):
    def __init__(self, *args, **kwargs):
        pass

    def __repr__(self):
        return '''<NewComment for '%s %s' (%s)>''' % (self.package, self.version, self.comment_id)

__all__.append('NewComment')


@session_wrapper
def has_new_comment(policy_queue, package, version, session=None):
    """
    Returns true if the given combination of C{package}, C{version} has a comment.

    @type package: string
    @param package: name of the package

    @type version: string
    @param version: package version

    @type session: Session
    @param session: Optional SQLA session object (a temporary one will be
    generated if not supplied)

    @rtype: boolean
    @return: true/false
    """

    q = session.query(NewComment).filter_by(policy_queue=policy_queue)
    q = q.filter_by(package=package)
    q = q.filter_by(version=version)

    return bool(q.count() > 0)

__all__.append('has_new_comment')


@session_wrapper
def get_new_comments(policy_queue, package=None, version=None, comment_id=None, session=None):
    """
    Returns (possibly empty) list of NewComment objects for the given
    parameters

    @type package: string (optional)
    @param package: name of the package

    @type version: string (optional)
    @param version: package version

    @type comment_id: int (optional)
    @param comment_id: An id of a comment

    @type session: Session
    @param session: Optional SQLA session object (a temporary one will be
    generated if not supplied)

    @rtype: list
    @return: A (possibly empty) list of NewComment objects will be returned
    """

    q = session.query(NewComment).filter_by(policy_queue=policy_queue)
    if package is not None:
        q = q.filter_by(package=package)
    if version is not None:
        q = q.filter_by(version=version)
    if comment_id is not None:
        q = q.filter_by(comment_id=comment_id)

    return q.all()

__all__.append('get_new_comments')

################################################################################


class Override(ORMObject):
    def __init__(self, package=None, suite=None, component=None, overridetype=None,
        section=None, priority=None):
        self.package = package
        self.suite = suite
        self.component = component
        self.overridetype = overridetype
        self.section = section
        self.priority = priority

    def properties(self):
        return ['package', 'suite', 'component', 'overridetype', 'section',
            'priority']

__all__.append('Override')


@session_wrapper
def get_override(package, suite=None, component=None, overridetype=None, session=None):
    """
    Returns Override object for the given parameters

    @type package: string
    @param package: The name of the package

    @type suite: string, list or None
    @param suite: The name of the suite (or suites if a list) to limit to.  If
                  None, don't limit.  Defaults to None.

    @type component: string, list or None
    @param component: The name of the component (or components if a list) to
                      limit to.  If None, don't limit.  Defaults to None.

    @type overridetype: string, list or None
    @param overridetype: The name of the overridetype (or overridetypes if a list) to
                         limit to.  If None, don't limit.  Defaults to None.

    @type session: Session
    @param session: Optional SQLA session object (a temporary one will be
    generated if not supplied)

    @rtype: list
    @return: A (possibly empty) list of Override objects will be returned
    """

    q = session.query(Override)
    q = q.filter_by(package=package)

    if suite is not None:
        if not isinstance(suite, list):
            suite = [suite]
        q = q.join(Suite).filter(Suite.suite_name.in_(suite))

    if component is not None:
        if not isinstance(component, list):
            component = [component]
        q = q.join(Component).filter(Component.component_name.in_(component))

    if overridetype is not None:
        if not isinstance(overridetype, list):
            overridetype = [overridetype]
        q = q.join(OverrideType).filter(OverrideType.overridetype.in_(overridetype))

    return q.all()

__all__.append('get_override')


################################################################################

class OverrideType(ORMObject):
    def __init__(self, overridetype=None):
        self.overridetype = overridetype

    def properties(self):
        return ['overridetype', 'overridetype_id', 'overrides_count']

__all__.append('OverrideType')


@session_wrapper
def get_override_type(override_type, session=None):
    """
    Returns OverrideType object for given C{override type}.

    @type override_type: string
    @param override_type: The name of the override type

    @type session: Session
    @param session: Optional SQLA session object (a temporary one will be
    generated if not supplied)

    @rtype: int
    @return: the database id for the given override type
    """

    q = session.query(OverrideType).filter_by(overridetype=override_type)

    try:
        return q.one()
    except NoResultFound:
        return None

__all__.append('get_override_type')

################################################################################


class PolicyQueue(object):
    def __init__(self, *args, **kwargs):
        pass

    def __repr__(self):
        return '<PolicyQueue %s>' % self.queue_name

__all__.append('PolicyQueue')


@session_wrapper
def get_policy_queue(queuename, session=None):
    """
    Returns PolicyQueue object for given C{queue name}

    @type queuename: string
    @param queuename: The name of the queue

    @type session: Session
    @param session: Optional SQLA session object (a temporary one will be
    generated if not supplied)

    @rtype: PolicyQueue
    @return: PolicyQueue object for the given queue
    """

    q = session.query(PolicyQueue).filter_by(queue_name=queuename)

    try:
        return q.one()
    except NoResultFound:
        return None

__all__.append('get_policy_queue')

################################################################################


@functools.total_ordering
class PolicyQueueUpload(object):
    def _key(self):
        return (
            self.changes.source,
            AptVersion(self.changes.version),
            self.source is None,
            self.changes.changesname
        )

    def __eq__(self, other):
        return self._key() == other._key()

    def __lt__(self, other):
        return self._key() < other._key()

__all__.append('PolicyQueueUpload')

################################################################################


class PolicyQueueByhandFile(object):
    pass

__all__.append('PolicyQueueByhandFile')

################################################################################


class Priority(ORMObject):
    def __init__(self, priority=None, level=None):
        self.priority = priority
        self.level = level

    def properties(self):
        return ['priority', 'priority_id', 'level', 'overrides_count']

    def __eq__(self, val):
        if isinstance(val, str):
            return (self.priority == val)
        # This signals to use the normal comparison operator
        return NotImplemented

    def __ne__(self, val):
        if isinstance(val, str):
            return (self.priority != val)
        # This signals to use the normal comparison operator
        return NotImplemented

__all__.append('Priority')


@session_wrapper
def get_priority(priority, session=None):
    """
    Returns Priority object for given C{priority name}.

    @type priority: string
    @param priority: The name of the priority

    @type session: Session
    @param session: Optional SQLA session object (a temporary one will be
    generated if not supplied)

    @rtype: Priority
    @return: Priority object for the given priority
    """

    q = session.query(Priority).filter_by(priority=priority)

    try:
        return q.one()
    except NoResultFound:
        return None

__all__.append('get_priority')


@session_wrapper
def get_priorities(session=None):
    """
    Returns dictionary of priority names -> id mappings

    @type session: Session
    @param session: Optional SQL session object (a temporary one will be
    generated if not supplied)

    @rtype: dictionary
    @return: dictionary of priority names -> id mappings
    """

    ret = {}
    q = session.query(Priority)
    for x in q.all():
        ret[x.priority] = x.priority_id

    return ret

__all__.append('get_priorities')

################################################################################


from .database.section import Section

__all__.append('Section')


@session_wrapper
def get_section(section, session=None):
    """
    Returns Section object for given C{section name}.

    @type section: string
    @param section: The name of the section

    @type session: Session
    @param session: Optional SQLA session object (a temporary one will be
    generated if not supplied)

    @rtype: Section
    @return: Section object for the given section name
    """

    q = session.query(Section).filter_by(section=section)

    try:
        return q.one()
    except NoResultFound:
        return None

__all__.append('get_section')


@session_wrapper
def get_sections(session=None):
    """
    Returns dictionary of section names -> id mappings

    @type session: Session
    @param session: Optional SQL session object (a temporary one will be
    generated if not supplied)

    @rtype: dictionary
    @return: dictionary of section names -> id mappings
    """

    ret = {}
    q = session.query(Section)
    for x in q.all():
        ret[x.section] = x.section_id

    return ret

__all__.append('get_sections')

################################################################################


class SignatureHistory(ORMObject):
    @classmethod
    def from_signed_file(cls, signed_file):
        """signature history entry from signed file

        @type  signed_file: L{daklib.gpg.SignedFile}
        @param signed_file: signed file

        @rtype: L{SignatureHistory}
        """
        self = cls()
        self.fingerprint = signed_file.primary_fingerprint
        self.signature_timestamp = signed_file.signature_timestamp
        self.contents_sha1 = signed_file.contents_sha1()
        return self

    def query(self, session):
        return session.query(SignatureHistory).filter_by(fingerprint=self.fingerprint, signature_timestamp=self.signature_timestamp, contents_sha1=self.contents_sha1).first()

__all__.append('SignatureHistory')

################################################################################


class SrcContents(ORMObject):
    def __init__(self, file=None, source=None):
        self.file = file
        self.source = source

    def properties(self):
        return ['file', 'source']

__all__.append('SrcContents')

################################################################################

from debian.debfile import Deb822

# Temporary Deb822 subclass to fix bugs with : handling; see #597249


class Dak822(Deb822):
    def _internal_parser(self, sequence, fields=None):
        # The key is non-whitespace, non-colon characters before any colon.
        key_part = r"^(?P<key>[^: \t\n\r\f\v]+)\s*:\s*"
        single = re.compile(key_part + r"(?P<data>\S.*?)\s*$")
        multi = re.compile(key_part + r"$")
        multidata = re.compile(r"^\s(?P<data>.+?)\s*$")

        wanted_field = lambda f: fields is None or f in fields

        if isinstance(sequence, basestring):
            sequence = sequence.splitlines()

        curkey = None
        content = ""
        for line in self.gpg_stripped_paragraph(sequence):
            m = single.match(line)
            if m:
                if curkey:
                    self[curkey] = content

                if not wanted_field(m.group('key')):
                    curkey = None
                    continue

                curkey = m.group('key')
                content = m.group('data')
                continue

            m = multi.match(line)
            if m:
                if curkey:
                    self[curkey] = content

                if not wanted_field(m.group('key')):
                    curkey = None
                    continue

                curkey = m.group('key')
                content = ""
                continue

            m = multidata.match(line)
            if m:
                content += '\n' + line # XXX not m.group('data')?
                continue

        if curkey:
            self[curkey] = content


class DBSource(ORMObject):
    def __init__(self, source=None, version=None, maintainer=None,
        changedby=None, poolfile=None, install_date=None, fingerprint=None):
        self.source = source
        self.version = version
        self.maintainer = maintainer
        self.changedby = changedby
        self.poolfile = poolfile
        self.install_date = install_date
        self.fingerprint = fingerprint

    @property
    def pkid(self):
        return self.source_id

    def properties(self):
        return ['source', 'source_id', 'maintainer', 'changedby',
            'fingerprint', 'poolfile', 'version', 'suites_count',
            'install_date', 'binaries_count', 'uploaders_count']

    def read_control_fields(self):
        '''
        Reads the control information from a dsc

        @rtype: tuple
        @return: fields is the dsc information in a dictionary form
        '''
        fullpath = self.poolfile.fullpath
        fields = Dak822(open(self.poolfile.fullpath, 'r'))
        return fields

    metadata = association_proxy('key', 'value')

    def scan_contents(self):
        '''
        Returns a set of names for non directories. The path names are
        normalized after converting them from either utf-8 or iso8859-1
        encoding.
        '''
        fullpath = self.poolfile.fullpath
        from daklib.contents import UnpackedSource
        unpacked = UnpackedSource(fullpath)
        fileset = set()
        for name in unpacked.get_all_filenames():
            # enforce proper utf-8 encoding
            try:
                name.decode('utf-8')
            except UnicodeDecodeError:
                name = name.decode('iso8859-1').encode('utf-8')
            fileset.add(name)
        return fileset

    @property
    def proxy(self):
        session = object_session(self)
        query = session.query(SourceMetadata).filter_by(source=self)
        return MetadataProxy(session, query)

__all__.append('DBSource')


@session_wrapper
def get_suites_source_in(source, session=None):
    """
    Returns list of Suite objects which given C{source} name is in

    @type source: str
    @param source: DBSource package name to search for

    @rtype: list
    @return: list of Suite objects for the given source
    """

    return session.query(Suite).filter(Suite.sources.any(source=source)).all()

__all__.append('get_suites_source_in')

# FIXME: This function fails badly if it finds more than 1 source package and
# its implementation is trivial enough to be inlined.


@session_wrapper
def get_source_in_suite(source, suite_name, session=None):
    """
    Returns a DBSource object for a combination of C{source} and C{suite_name}.

      - B{source} - source package name, eg. I{mailfilter}, I{bbdb}, I{glibc}
      - B{suite_name} - a suite name, eg. I{unstable}

    @type source: string
    @param source: source package name

    @type suite_name: string
    @param suite: the suite name

    @rtype: string
    @return: the version for I{source} in I{suite}

    """
    suite = get_suite(suite_name, session)
    if suite is None:
        return None
    try:
        return suite.get_sources(source).one()
    except NoResultFound:
        return None

__all__.append('get_source_in_suite')


@session_wrapper
def import_metadata_into_db(obj, session=None):
    """
    This routine works on either DBBinary or DBSource objects and imports
    their metadata into the database
    """
    fields = obj.read_control_fields()
    for k in fields.keys():
        try:
            # Try raw ASCII
            val = str(fields[k])
        except UnicodeEncodeError:
            # Fall back to UTF-8
            try:
                val = fields[k].encode('utf-8')
            except UnicodeEncodeError:
                # Finally try iso8859-1
                val = fields[k].encode('iso8859-1')
                # Otherwise we allow the exception to percolate up and we cause
                # a reject as someone is playing silly buggers

        obj.metadata[get_or_set_metadatakey(k, session)] = val

    session.commit_or_flush()

__all__.append('import_metadata_into_db')

################################################################################


class SrcFormat(object):
    def __init__(self, *args, **kwargs):
        pass

    def __repr__(self):
        return '<SrcFormat %s>' % (self.format_name)

__all__.append('SrcFormat')

################################################################################

SUITE_FIELDS = [('SuiteName', 'suite_name'),
                 ('SuiteID', 'suite_id'),
                 ('Version', 'version'),
                 ('Origin', 'origin'),
                 ('Label', 'label'),
                 ('Description', 'description'),
                 ('Untouchable', 'untouchable'),
                 ('Announce', 'announce'),
                 ('Codename', 'codename'),
                 ('OverrideCodename', 'overridecodename'),
                 ('ValidTime', 'validtime'),
                 ('Priority', 'priority'),
                 ('NotAutomatic', 'notautomatic'),
                 ('CopyChanges', 'copychanges'),
                 ('OverrideSuite', 'overridesuite')]

# Why the heck don't we have any UNIQUE constraints in table suite?
# TODO: Add UNIQUE constraints for appropriate columns.


class Suite(ORMObject):
    def __init__(self, suite_name=None, version=None):
        self.suite_name = suite_name
        self.version = version

    def properties(self):
        return ['suite_name', 'version', 'sources_count', 'binaries_count',
            'overrides_count']

    def __eq__(self, val):
        if isinstance(val, str):
            return (self.suite_name == val)
        # This signals to use the normal comparison operator
        return NotImplemented

    def __ne__(self, val):
        if isinstance(val, str):
            return (self.suite_name != val)
        # This signals to use the normal comparison operator
        return NotImplemented

    def details(self):
        ret = []
        for disp, field in SUITE_FIELDS:
            val = getattr(self, field, None)
            if val is not None:
                ret.append("%s: %s" % (disp, val))

        return "\n".join(ret)

    def get_architectures(self, skipsrc=False, skipall=False):
        """
        Returns list of Architecture objects

        @type skipsrc: boolean
        @param skipsrc: Whether to skip returning the 'source' architecture entry
        (Default False)

        @type skipall: boolean
        @param skipall: Whether to skip returning the 'all' architecture entry
        (Default False)

        @rtype: list
        @return: list of Architecture objects for the given name (may be empty)
        """

        q = object_session(self).query(Architecture).with_parent(self)
        if skipsrc:
            q = q.filter(Architecture.arch_string != 'source')
        if skipall:
            q = q.filter(Architecture.arch_string != 'all')
        return q.order_by(Architecture.arch_string).all()

    def get_sources(self, source):
        """
        Returns a query object representing DBSource that is part of C{suite}.

          - B{source} - source package name, eg. I{mailfilter}, I{bbdb}, I{glibc}

        @type source: string
        @param source: source package name

        @rtype: sqlalchemy.orm.query.Query
        @return: a query of DBSource

        """

        session = object_session(self)
        return session.query(DBSource).filter_by(source=source). \
            with_parent(self)

    def get_overridesuite(self):
        if self.overridesuite is None:
            return self
        else:
            return object_session(self).query(Suite).filter_by(suite_name=self.overridesuite).one()

    def update_last_changed(self):
        self.last_changed = sqlalchemy.func.now()

    @property
    def path(self):
        return os.path.join(self.archive.path, 'dists', self.suite_name)

    @property
    def release_suite_output(self):
        if self.release_suite is not None:
            return self.release_suite
        return self.suite_name

__all__.append('Suite')


@session_wrapper
def get_suite(suite, session=None):
    """
    Returns Suite object for given C{suite name}.

    @type suite: string
    @param suite: The name of the suite

    @type session: Session
    @param session: Optional SQLA session object (a temporary one will be
    generated if not supplied)

    @rtype: Suite
    @return: Suite object for the requested suite name (None if not present)
    """

    # Start by looking for the dak internal name
    q = session.query(Suite).filter_by(suite_name=suite)
    try:
        return q.one()
    except NoResultFound:
        pass

    # Now try codename
    q = session.query(Suite).filter_by(codename=suite)
    try:
        return q.one()
    except NoResultFound:
        pass

    # Finally give release_suite a try
    q = session.query(Suite).filter_by(release_suite=suite)
    try:
        return q.one()
    except NoResultFound:
        return None

__all__.append('get_suite')

################################################################################


@session_wrapper
def get_suite_architectures(suite, skipsrc=False, skipall=False, session=None):
    """
    Returns list of Architecture objects for given C{suite} name. The list is
    empty if suite does not exist.

    @type suite: str
    @param suite: Suite name to search for

    @type skipsrc: boolean
    @param skipsrc: Whether to skip returning the 'source' architecture entry
    (Default False)

    @type skipall: boolean
    @param skipall: Whether to skip returning the 'all' architecture entry
    (Default False)

    @type session: Session
    @param session: Optional SQL session object (a temporary one will be
    generated if not supplied)

    @rtype: list
    @return: list of Architecture objects for the given name (may be empty)
    """

    try:
        return get_suite(suite, session).get_architectures(skipsrc, skipall)
    except AttributeError:
        return []

__all__.append('get_suite_architectures')

################################################################################


class Uid(ORMObject):
    def __init__(self, uid=None, name=None):
        self.uid = uid
        self.name = name

    def __eq__(self, val):
        if isinstance(val, str):
            return (self.uid == val)
        # This signals to use the normal comparison operator
        return NotImplemented

    def __ne__(self, val):
        if isinstance(val, str):
            return (self.uid != val)
        # This signals to use the normal comparison operator
        return NotImplemented

    def properties(self):
        return ['uid', 'name', 'fingerprint']

__all__.append('Uid')


@session_wrapper
def get_or_set_uid(uidname, session=None):
    """
    Returns uid object for given uidname.

    If no matching uidname is found, a row is inserted.

    @type uidname: string
    @param uidname: The uid to add

    @type session: SQLAlchemy
    @param session: Optional SQL session object (a temporary one will be
    generated if not supplied).  If not passed, a commit will be performed at
    the end of the function, otherwise the caller is responsible for commiting.

    @rtype: Uid
    @return: the uid object for the given uidname
    """

    q = session.query(Uid).filter_by(uid=uidname)

    try:
        ret = q.one()
    except NoResultFound:
        uid = Uid()
        uid.uid = uidname
        session.add(uid)
        session.commit_or_flush()
        ret = uid

    return ret

__all__.append('get_or_set_uid')


@session_wrapper
def get_uid_from_fingerprint(fpr, session=None):
    q = session.query(Uid)
    q = q.join(Fingerprint).filter_by(fingerprint=fpr)

    try:
        return q.one()
    except NoResultFound:
        return None

__all__.append('get_uid_from_fingerprint')

################################################################################


class MetadataKey(ORMObject):
    def __init__(self, key=None):
        self.key = key

    def properties(self):
        return ['key']

__all__.append('MetadataKey')


@session_wrapper
def get_or_set_metadatakey(keyname, session=None):
    """
    Returns MetadataKey object for given uidname.

    If no matching keyname is found, a row is inserted.

    @type uidname: string
    @param uidname: The keyname to add

    @type session: SQLAlchemy
    @param session: Optional SQL session object (a temporary one will be
    generated if not supplied).  If not passed, a commit will be performed at
    the end of the function, otherwise the caller is responsible for commiting.

    @rtype: MetadataKey
    @return: the metadatakey object for the given keyname
    """

    q = session.query(MetadataKey).filter_by(key=keyname)

    try:
        ret = q.one()
    except NoResultFound:
        ret = MetadataKey(keyname)
        session.add(ret)
        session.commit_or_flush()

    return ret

__all__.append('get_or_set_metadatakey')

################################################################################


class BinaryMetadata(ORMObject):
    def __init__(self, key=None, value=None, binary=None):
        self.key = key
        self.value = value
        if binary is not None:
            self.binary = binary

    def properties(self):
        return ['binary', 'key', 'value']

__all__.append('BinaryMetadata')

################################################################################


class SourceMetadata(ORMObject):
    def __init__(self, key=None, value=None, source=None):
        self.key = key
        self.value = value
        if source is not None:
            self.source = source

    def properties(self):
        return ['source', 'key', 'value']

__all__.append('SourceMetadata')

################################################################################


class MetadataProxy(object):
    def __init__(self, session, query):
        self.session = session
        self.query = query

    def _get(self, key):
        metadata_key = self.session.query(MetadataKey).filter_by(key=key).first()
        if metadata_key is None:
            return None
        metadata = self.query.filter_by(key=metadata_key).first()
        return metadata

    def __contains__(self, key):
        if self._get(key) is not None:
            return True
        return False

    def __getitem__(self, key):
        metadata = self._get(key)
        if metadata is None:
            raise KeyError
        return metadata.value

    def get(self, key, default=None):
        try:
            return self[key]
        except KeyError:
            return default

################################################################################


class VersionCheck(ORMObject):
    def __init__(self, *args, **kwargs):
        pass

    def properties(self):
        #return ['suite_id', 'check', 'reference_id']
        return ['check']

__all__.append('VersionCheck')


@session_wrapper
def get_version_checks(suite_name, check=None, session=None):
    suite = get_suite(suite_name, session)
    if not suite:
        # Make sure that what we return is iterable so that list comprehensions
        # involving this don't cause a traceback
        return []
    q = session.query(VersionCheck).filter_by(suite=suite)
    if check:
        q = q.filter_by(check=check)
    return q.all()

__all__.append('get_version_checks')

################################################################################


class DBConn(object):
    """
    database module init.
    """
    __shared_state = {}

    db_meta = None

    tbl_architecture = Architecture.__table__

    tables = (
        'acl',
        'acl_architecture_map',
        'acl_fingerprint_map',
        'acl_per_source',
        'archive',
        'bin_associations',
        'bin_contents',
        'binaries',
        'binaries_metadata',
        'build_queue',
        'changelogs_text',
        'changes',
        'component',
        'component_suite',
        'config',
        'dsc_files',
        'external_files',
        'external_overrides',
        'external_signature_requests',
        'extra_src_references',
        'files',
        'files_archive_map',
        'fingerprint',
        'hashfile',
        'keyrings',
        'maintainer',
        'metadata_keys',
        'new_comments',
        # TODO: the maintainer column in table override should be removed.
        'override',
        'override_type',
        'policy_queue',
        'policy_queue_upload',
        'policy_queue_upload_binaries_map',
        'policy_queue_byhand_file',
        'priority',
        'signature_history',
        'source',
        'source_metadata',
        'src_associations',
        'src_contents',
        'src_format',
        'src_uploaders',
        'suite',
        'suite_acl_map',
        'suite_architectures',
        'suite_build_queue_copy',
        'suite_permission',
        'suite_src_formats',
        'uid',
        'version_check',
    )

    views = (
        'bin_associations_binaries',
        'changelogs',
        'newest_source',
        'newest_src_association',
        'package_list',
        'source_suite',
        'src_associations_src',
    )

    def __init__(self, *args, **kwargs):
        self.__dict__ = self.__shared_state

        if not getattr(self, 'initialised', False):
            self.initialised = True
            self.debug = 'debug' in kwargs
            self.__createconn()

    def __setuptables(self):
        for table_name in self.tables:
            table = Table(table_name, self.db_meta,
                autoload=True, useexisting=True)
            setattr(self, 'tbl_%s' % table_name, table)

        for view_name in self.views:
            view = Table(view_name, self.db_meta, autoload=True)
            setattr(self, 'view_%s' % view_name, view)

    def __setupmappers(self):
        mapper(ACL, self.tbl_acl,
               properties=dict(
                   architectures=relation(Architecture, secondary=self.tbl_acl_architecture_map, collection_class=set),
                   fingerprints=relation(Fingerprint, secondary=self.tbl_acl_fingerprint_map, collection_class=set),
                   match_keyring=relation(Keyring, primaryjoin=(self.tbl_acl.c.match_keyring_id == self.tbl_keyrings.c.id)),
                   per_source=relation(ACLPerSource, collection_class=set),
                   ))

        mapper(ACLPerSource, self.tbl_acl_per_source,
               properties=dict(
                   acl=relation(ACL),
                   fingerprint=relation(Fingerprint, primaryjoin=(self.tbl_acl_per_source.c.fingerprint_id == self.tbl_fingerprint.c.id)),
                   created_by=relation(Fingerprint, primaryjoin=(self.tbl_acl_per_source.c.created_by_id == self.tbl_fingerprint.c.id)),
                   ))

        mapper(Archive, self.tbl_archive,
               properties=dict(archive_id=self.tbl_archive.c.id,
                                 archive_name=self.tbl_archive.c.name))

        mapper(ArchiveFile, self.tbl_files_archive_map,
               properties=dict(archive=relation(Archive, backref='files'),
                                 component=relation(Component),
                                 file=relation(PoolFile, backref='archives')))

        mapper(BuildQueue, self.tbl_build_queue,
               properties=dict(queue_id=self.tbl_build_queue.c.id,
                                 suite=relation(Suite, primaryjoin=(self.tbl_build_queue.c.suite_id == self.tbl_suite.c.id))))

        mapper(DBBinary, self.tbl_binaries,
               properties=dict(binary_id=self.tbl_binaries.c.id,
                                 package=self.tbl_binaries.c.package,
                                 version=self.tbl_binaries.c.version,
                                 maintainer_id=self.tbl_binaries.c.maintainer,
                                 maintainer=relation(Maintainer),
                                 source_id=self.tbl_binaries.c.source,
                                 source=relation(DBSource, backref='binaries'),
                                 arch_id=self.tbl_binaries.c.architecture,
                                 architecture=relation(Architecture),
                                 poolfile_id=self.tbl_binaries.c.file,
                                 poolfile=relation(PoolFile),
                                 binarytype=self.tbl_binaries.c.type,
                                 fingerprint_id=self.tbl_binaries.c.sig_fpr,
                                 fingerprint=relation(Fingerprint),
                                 install_date=self.tbl_binaries.c.install_date,
                                 suites=relation(Suite, secondary=self.tbl_bin_associations,
                                     backref=backref('binaries', lazy='dynamic')),
                                 extra_sources=relation(DBSource, secondary=self.tbl_extra_src_references,
                                     backref=backref('extra_binary_references', lazy='dynamic')),
                                 key=relation(BinaryMetadata, cascade='all',
                                     collection_class=attribute_mapped_collection('key'))),
        )

        mapper(Component, self.tbl_component,
               properties=dict(component_id=self.tbl_component.c.id,
                                 component_name=self.tbl_component.c.name),
        )

        mapper(DBConfig, self.tbl_config,
               properties=dict(config_id=self.tbl_config.c.id))

        mapper(DSCFile, self.tbl_dsc_files,
               properties=dict(dscfile_id=self.tbl_dsc_files.c.id,
                                 source_id=self.tbl_dsc_files.c.source,
                                 source=relation(DBSource),
                                 poolfile_id=self.tbl_dsc_files.c.file,
                                 poolfile=relation(PoolFile)))

        mapper(ExternalOverride, self.tbl_external_overrides,
                properties=dict(
                    suite_id=self.tbl_external_overrides.c.suite,
                    suite=relation(Suite),
                    component_id=self.tbl_external_overrides.c.component,
                    component=relation(Component)))

        mapper(PoolFile, self.tbl_files,
               properties=dict(file_id=self.tbl_files.c.id,
                                 filesize=self.tbl_files.c.size),
        )

        mapper(Fingerprint, self.tbl_fingerprint,
               properties=dict(fingerprint_id=self.tbl_fingerprint.c.id,
                                 uid_id=self.tbl_fingerprint.c.uid,
                                 uid=relation(Uid),
                                 keyring_id=self.tbl_fingerprint.c.keyring,
                                 keyring=relation(Keyring),
                                 acl=relation(ACL)),
        )

        mapper(Keyring, self.tbl_keyrings,
               properties=dict(keyring_name=self.tbl_keyrings.c.name,
                                 keyring_id=self.tbl_keyrings.c.id,
                                 acl=relation(ACL, primaryjoin=(self.tbl_keyrings.c.acl_id == self.tbl_acl.c.id)))),

        mapper(DBChange, self.tbl_changes,
               properties=dict(change_id=self.tbl_changes.c.id,
                                 seen=self.tbl_changes.c.seen,
                                 source=self.tbl_changes.c.source,
                                 binaries=self.tbl_changes.c.binaries,
                                 architecture=self.tbl_changes.c.architecture,
                                 distribution=self.tbl_changes.c.distribution,
                                 urgency=self.tbl_changes.c.urgency,
                                 maintainer=self.tbl_changes.c.maintainer,
                                 changedby=self.tbl_changes.c.changedby,
                                 date=self.tbl_changes.c.date,
                                 version=self.tbl_changes.c.version))

        mapper(Maintainer, self.tbl_maintainer,
               properties=dict(maintainer_id=self.tbl_maintainer.c.id,
                   maintains_sources=relation(DBSource, backref='maintainer',
                       primaryjoin=(self.tbl_maintainer.c.id == self.tbl_source.c.maintainer)),
                   changed_sources=relation(DBSource, backref='changedby',
                       primaryjoin=(self.tbl_maintainer.c.id == self.tbl_source.c.changedby))),
        )

        mapper(NewComment, self.tbl_new_comments,
               properties=dict(comment_id=self.tbl_new_comments.c.id,
                                 policy_queue=relation(PolicyQueue)))

        mapper(Override, self.tbl_override,
               properties=dict(suite_id=self.tbl_override.c.suite,
                                 suite=relation(Suite,
                                    backref=backref('overrides', lazy='dynamic')),
                                 package=self.tbl_override.c.package,
                                 component_id=self.tbl_override.c.component,
                                 component=relation(Component,
                                    backref=backref('overrides', lazy='dynamic')),
                                 priority_id=self.tbl_override.c.priority,
                                 priority=relation(Priority,
                                    backref=backref('overrides', lazy='dynamic')),
                                 section_id=self.tbl_override.c.section,
                                 section=relation(Section,
                                    backref=backref('overrides', lazy='dynamic')),
                                 overridetype_id=self.tbl_override.c.type,
                                 overridetype=relation(OverrideType,
                                    backref=backref('overrides', lazy='dynamic'))))

        mapper(OverrideType, self.tbl_override_type,
               properties=dict(overridetype=self.tbl_override_type.c.type,
                                 overridetype_id=self.tbl_override_type.c.id))

        mapper(PolicyQueue, self.tbl_policy_queue,
               properties=dict(policy_queue_id=self.tbl_policy_queue.c.id,
                                 suite=relation(Suite, primaryjoin=(self.tbl_policy_queue.c.suite_id == self.tbl_suite.c.id))))

        mapper(PolicyQueueUpload, self.tbl_policy_queue_upload,
               properties=dict(
                   changes=relation(DBChange),
                   policy_queue=relation(PolicyQueue, backref='uploads'),
                   target_suite=relation(Suite),
                   source=relation(DBSource),
                   binaries=relation(DBBinary, secondary=self.tbl_policy_queue_upload_binaries_map),
                   ))

        mapper(PolicyQueueByhandFile, self.tbl_policy_queue_byhand_file,
               properties=dict(
                   upload=relation(PolicyQueueUpload, backref='byhand'),
                   )
               )

        mapper(Priority, self.tbl_priority,
               properties=dict(priority_id=self.tbl_priority.c.id))

        mapper(SignatureHistory, self.tbl_signature_history)

        mapper(DBSource, self.tbl_source,
               properties=dict(source_id=self.tbl_source.c.id,
                                 version=self.tbl_source.c.version,
                                 maintainer_id=self.tbl_source.c.maintainer,
                                 poolfile_id=self.tbl_source.c.file,
                                 poolfile=relation(PoolFile),
                                 fingerprint_id=self.tbl_source.c.sig_fpr,
                                 fingerprint=relation(Fingerprint),
                                 changedby_id=self.tbl_source.c.changedby,
                                 srcfiles=relation(DSCFile,
                                                     primaryjoin=(self.tbl_source.c.id == self.tbl_dsc_files.c.source)),
                                 suites=relation(Suite, secondary=self.tbl_src_associations,
                                     backref=backref('sources', lazy='dynamic')),
                                 uploaders=relation(Maintainer,
                                     secondary=self.tbl_src_uploaders),
                                 key=relation(SourceMetadata, cascade='all',
                                     collection_class=attribute_mapped_collection('key'))),
        )

        mapper(SrcFormat, self.tbl_src_format,
               properties=dict(src_format_id=self.tbl_src_format.c.id,
                                 format_name=self.tbl_src_format.c.format_name))

        mapper(Suite, self.tbl_suite,
               properties=dict(suite_id=self.tbl_suite.c.id,
                                 policy_queue=relation(PolicyQueue, primaryjoin=(self.tbl_suite.c.policy_queue_id == self.tbl_policy_queue.c.id)),
                                 new_queue=relation(PolicyQueue, primaryjoin=(self.tbl_suite.c.new_queue_id == self.tbl_policy_queue.c.id)),
                                 debug_suite=relation(Suite, remote_side=[self.tbl_suite.c.id]),
                                 copy_queues=relation(BuildQueue,
                                     secondary=self.tbl_suite_build_queue_copy),
                                 srcformats=relation(SrcFormat, secondary=self.tbl_suite_src_formats,
                                     backref=backref('suites', lazy='dynamic')),
                                 archive=relation(Archive, backref='suites'),
                                 acls=relation(ACL, secondary=self.tbl_suite_acl_map, collection_class=set),
                                 components=relation(Component, secondary=self.tbl_component_suite,
                                                   order_by=self.tbl_component.c.ordering,
                                                   backref=backref('suites')),
                                 architectures=relation(Architecture, secondary=self.tbl_suite_architectures,
                                     backref=backref('suites'))),
        )

        mapper(Uid, self.tbl_uid,
               properties=dict(uid_id=self.tbl_uid.c.id,
                                 fingerprint=relation(Fingerprint)),
        )

        mapper(BinContents, self.tbl_bin_contents,
            properties=dict(
                binary=relation(DBBinary,
                    backref=backref('contents', lazy='dynamic', cascade='all')),
                file=self.tbl_bin_contents.c.file))

        mapper(SrcContents, self.tbl_src_contents,
            properties=dict(
                source=relation(DBSource,
                    backref=backref('contents', lazy='dynamic', cascade='all')),
                file=self.tbl_src_contents.c.file))

        mapper(MetadataKey, self.tbl_metadata_keys,
            properties=dict(
                key_id=self.tbl_metadata_keys.c.key_id,
                key=self.tbl_metadata_keys.c.key))

        mapper(BinaryMetadata, self.tbl_binaries_metadata,
            properties=dict(
                binary_id=self.tbl_binaries_metadata.c.bin_id,
                binary=relation(DBBinary),
                key_id=self.tbl_binaries_metadata.c.key_id,
                key=relation(MetadataKey),
                value=self.tbl_binaries_metadata.c.value))

        mapper(SourceMetadata, self.tbl_source_metadata,
            properties=dict(
                source_id=self.tbl_source_metadata.c.src_id,
                source=relation(DBSource),
                key_id=self.tbl_source_metadata.c.key_id,
                key=relation(MetadataKey),
                value=self.tbl_source_metadata.c.value))

        mapper(VersionCheck, self.tbl_version_check,
            properties=dict(
                suite_id=self.tbl_version_check.c.suite,
                suite=relation(Suite, primaryjoin=self.tbl_version_check.c.suite == self.tbl_suite.c.id),
                reference_id=self.tbl_version_check.c.reference,
                reference=relation(Suite, primaryjoin=self.tbl_version_check.c.reference == self.tbl_suite.c.id, lazy='joined')))

    ## Connection functions
    def __createconn(self):
        from .config import Config
        cnf = Config()
        if "DB::Service" in cnf:
            connstr = "postgresql://service=%s" % cnf["DB::Service"]
        elif "DB::Host" in cnf:
            # TCP/IP
            connstr = "postgresql://%s" % cnf["DB::Host"]
            if "DB::Port" in cnf and cnf["DB::Port"] != "-1":
                connstr += ":%s" % cnf["DB::Port"]
            connstr += "/%s" % cnf["DB::Name"]
        else:
            # Unix Socket
            connstr = "postgresql:///%s" % cnf["DB::Name"]
            if "DB::Port" in cnf and cnf["DB::Port"] != "-1":
                connstr += "?port=%s" % cnf["DB::Port"]

        engine_args = {'echo': self.debug}
        if 'DB::PoolSize' in cnf:
            engine_args['pool_size'] = int(cnf['DB::PoolSize'])
        if 'DB::MaxOverflow' in cnf:
            engine_args['max_overflow'] = int(cnf['DB::MaxOverflow'])
        if cnf.get('DB::Unicode') == 'false':
            engine_args['use_native_unicode'] = False

        # Monkey patch a new dialect in in order to support service= syntax
        import sqlalchemy.dialects.postgresql
        from sqlalchemy.dialects.postgresql.psycopg2 import PGDialect_psycopg2
        class PGDialect_psycopg2_dak(PGDialect_psycopg2):
            def create_connect_args(self, url):
                if str(url).startswith('postgresql://service='):
                    # Eww
                    servicename = str(url)[21:]
                    return (['service=%s' % servicename], {})
                else:
                    return PGDialect_psycopg2.create_connect_args(self, url)

        sqlalchemy.dialects.postgresql.base.dialect = PGDialect_psycopg2_dak

        try:
            self.db_pg = create_engine(connstr, **engine_args)
            self.db_smaker = sessionmaker(bind=self.db_pg,
                                          autoflush=True,
                                          autocommit=False)

            if self.db_meta is None:
                self.__class__.db_meta = Base.metadata
                self.__class__.db_meta.bind = self.db_pg
                self.__setuptables()
                self.__setupmappers()

        except OperationalError as e:
            from . import utils
            utils.fubar("Cannot connect to database (%s)" % str(e))

        self.pid = os.getpid()

    def session(self, work_mem=0):
        '''
        Returns a new session object. If a work_mem parameter is provided a new
        transaction is started and the work_mem parameter is set for this
        transaction. The work_mem parameter is measured in MB. A default value
        will be used if the parameter is not set.
        '''
        # reinitialize DBConn in new processes
        if self.pid != os.getpid():
            self.__createconn()
        session = self.db_smaker()
        if work_mem > 0:
            session.execute("SET LOCAL work_mem TO '%d MB'" % work_mem)
        return session

__all__.append('DBConn')