pym/portage/dbapi/vartree.py

# Copyright 1998-2014 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2

from __future__ import division, unicode_literals

__all__ = [
	"vardbapi", "vartree", "dblink"] + \
	["write_contents", "tar_contents"]

import portage
portage.proxy.lazyimport.lazyimport(globals(),
	'portage.checksum:_perform_md5_merge@perform_md5',
	'portage.data:portage_gid,portage_uid,secpass',
	'portage.dbapi.dep_expand:dep_expand',
	'portage.dbapi._MergeProcess:MergeProcess',
	'portage.dbapi._SyncfsProcess:SyncfsProcess',
	'portage.dep:dep_getkey,isjustname,isvalidatom,match_from_list,' + \
	 	'use_reduce,_slot_separator,_repo_separator',
	'portage.eapi:_get_eapi_attrs',
	'portage.elog:collect_ebuild_messages,collect_messages,' + \
		'elog_process,_merge_logentries',
	'portage.locks:lockdir,unlockdir,lockfile,unlockfile',
	'portage.output:bold,colorize',
	'portage.package.ebuild.doebuild:doebuild_environment,' + \
		'_merge_unicode_error', '_spawn_phase',
	'portage.package.ebuild.prepare_build_dirs:prepare_build_dirs',
	'portage.package.ebuild._ipc.QueryCommand:QueryCommand',
	'portage.util:apply_secpass_permissions,ConfigProtect,ensure_dirs,' + \
		'writemsg,writemsg_level,write_atomic,atomic_ofstream,writedict,' + \
		'grabdict,normalize_path,new_protect_filename',
	'portage.util.digraph:digraph',
	'portage.util.env_update:env_update',
	'portage.util.listdir:dircache,listdir',
	'portage.util.movefile:movefile',
	'portage.util.writeable_check:get_ro_checker',
	'portage.util._dyn_libs.PreservedLibsRegistry:PreservedLibsRegistry',
	'portage.util._dyn_libs.LinkageMapELF:LinkageMapELF@LinkageMap',
	'portage.util._async.SchedulerInterface:SchedulerInterface',
	'portage.util._eventloop.EventLoop:EventLoop',
	'portage.util._eventloop.global_event_loop:global_event_loop',
	'portage.versions:best,catpkgsplit,catsplit,cpv_getkey,vercmp,' + \
		'_get_slot_re,_pkgsplit@pkgsplit,_pkg_str,_unknown_repo',
	'subprocess',
	'tarfile',
)

from portage.const import CACHE_PATH, CONFIG_MEMORY_FILE, \
	MERGING_IDENTIFIER, PORTAGE_PACKAGE_ATOM, PRIVATE_PATH, VDB_PATH
from portage.dbapi import dbapi
from portage.exception import CommandNotFound, \
	InvalidData, InvalidLocation, InvalidPackageName, \
	FileNotFound, PermissionDenied, UnsupportedAPIException
from portage.localization import _

from portage import abssymlink, _movefile, bsd_chflags

# This is a special version of the os module, wrapped for unicode support.
from portage import os
from portage import shutil
from portage import _encodings
from portage import _os_merge
from portage import _selinux_merge
from portage import _unicode_decode
from portage import _unicode_encode

from _emerge.EbuildBuildDir import EbuildBuildDir
from _emerge.EbuildPhase import EbuildPhase
from _emerge.emergelog import emergelog
from _emerge.MiscFunctionsProcess import MiscFunctionsProcess
from _emerge.SpawnProcess import SpawnProcess

import errno
import fileinput
import fnmatch
import gc
import grp
import io
from itertools import chain
import logging
import os as _os
import platform
import pwd
import re
import stat
import sys
import tempfile
import textwrap
import time
import warnings

try:
	import cPickle as pickle
except ImportError:
	import pickle

if sys.hexversion >= 0x3000000:
	# pylint: disable=W0622
	basestring = str
	long = int
	_unicode = str
else:
	_unicode = unicode

class vardbapi(dbapi):

	_excluded_dirs = ["CVS", "lost+found"]
	_excluded_dirs = [re.escape(x) for x in _excluded_dirs]
	_excluded_dirs = re.compile(r'^(\..*|' + MERGING_IDENTIFIER + '.*|' + \
		"|".join(_excluded_dirs) + r')$')

	_aux_cache_version        = "1"
	_owners_cache_version     = "1"

	# Number of uncached packages to trigger cache update, since
	# it's wasteful to update it for every vdb change.
	_aux_cache_threshold = 5

	_aux_cache_keys_re = re.compile(r'^NEEDED\..*$')
	_aux_multi_line_re = re.compile(r'^(CONTENTS|NEEDED\..*)$')

	def __init__(self, _unused_param=DeprecationWarning,
		categories=None, settings=None, vartree=None):
		"""
		The categories parameter is unused since the dbapi class
		now has a categories property that is generated from the
		available packages.
		"""

		# Used by emerge to check whether any packages
		# have been added or removed.
		self._pkgs_changed = False

		# The _aux_cache_threshold doesn't work as designed
		# if the cache is flushed from a subprocess, so we
		# use this to avoid waste vdb cache updates.
		self._flush_cache_enabled = True

		#cache for category directory mtimes
		self.mtdircache = {}

		#cache for dependency checks
		self.matchcache = {}

		#cache for cp_list results
		self.cpcache = {}

		self.blockers = None
		if settings is None:
			settings = portage.settings
		self.settings = settings

		if _unused_param is not DeprecationWarning:
			warnings.warn("The first parameter of the "
				"portage.dbapi.vartree.vardbapi"
				" constructor is now unused. Instead "
				"settings['ROOT'] is used.",
				DeprecationWarning, stacklevel=2)

		self._eroot = settings['EROOT']
		self._dbroot = self._eroot + VDB_PATH
		self._lock = None
		self._lock_count = 0

		self._conf_mem_file = self._eroot + CONFIG_MEMORY_FILE
		self._fs_lock_obj = None
		self._fs_lock_count = 0

		if vartree is None:
			vartree = portage.db[settings['EROOT']]['vartree']
		self.vartree = vartree
		self._aux_cache_keys = set(
			["BUILD_TIME", "CHOST", "COUNTER", "DEPEND", "DESCRIPTION",
			"EAPI", "HDEPEND", "HOMEPAGE", "IUSE", "KEYWORDS",
			"LICENSE", "PDEPEND", "PROPERTIES", "PROVIDE", "RDEPEND",
			"repository", "RESTRICT" , "SLOT", "USE", "DEFINED_PHASES",
			])
		self._aux_cache_obj = None
		self._aux_cache_filename = os.path.join(self._eroot,
			CACHE_PATH, "vdb_metadata.pickle")
		self._counter_path = os.path.join(self._eroot,
			CACHE_PATH, "counter")

		self._plib_registry = PreservedLibsRegistry(settings["ROOT"],
			os.path.join(self._eroot, PRIVATE_PATH, "preserved_libs_registry"))
		self._linkmap = LinkageMap(self)
		self._owners = self._owners_db(self)

		self._cached_counter = None

	@property
	def root(self):
		warnings.warn("The root attribute of "
			"portage.dbapi.vartree.vardbapi"
			" is deprecated. Use "
			"settings['ROOT'] instead.",
			DeprecationWarning, stacklevel=3)
		return self.settings['ROOT']

	def getpath(self, mykey, filename=None):
		# This is an optimized hotspot, so don't use unicode-wrapped
		# os module and don't use os.path.join().
		rValue = self._eroot + VDB_PATH + _os.sep + mykey
		if filename is not None:
			# If filename is always relative, we can do just
			# rValue += _os.sep + filename
			rValue = _os.path.join(rValue, filename)
		return rValue

	def lock(self):
		"""
		Acquire a reentrant lock, blocking, for cooperation with concurrent
		processes. State is inherited by subprocesses, allowing subprocesses
		to reenter a lock that was acquired by a parent process. However,
		a lock can be released only by the same process that acquired it.
		"""
		if self._lock_count:
			self._lock_count += 1
		elif os.environ.get("PORTAGE_LOCKS") != "false":
			if self._lock is not None:
				raise AssertionError("already locked")
			# At least the parent needs to exist for the lock file.
			ensure_dirs(self._dbroot)
			self._lock = lockdir(self._dbroot)
			self._lock_count += 1

	def unlock(self):
		"""
		Release a lock, decrementing the recursion level. Each unlock() call
		must be matched with a prior lock() call, or else an AssertionError
		will be raised if unlock() is called while not locked.
		"""
		if self._lock_count > 1:
			self._lock_count -= 1
		elif os.environ.get("PORTAGE_LOCKS") != "false":
			if self._lock is None:
				raise AssertionError("not locked")
			self._lock_count = 0
			unlockdir(self._lock)
			self._lock = None

	def _fs_lock(self):
		"""
		Acquire a reentrant lock, blocking, for cooperation with concurrent
		processes.
		"""
		if self._fs_lock_count < 1:
			if self._fs_lock_obj is not None:
				raise AssertionError("already locked")
			try:
				self._fs_lock_obj = lockfile(self._conf_mem_file)
			except InvalidLocation:
				self.settings._init_dirs()
				self._fs_lock_obj = lockfile(self._conf_mem_file)
		self._fs_lock_count += 1

	def _fs_unlock(self):
		"""
		Release a lock, decrementing the recursion level.
		"""
		if self._fs_lock_count <= 1:
			if self._fs_lock_obj is None:
				raise AssertionError("not locked")
			unlockfile(self._fs_lock_obj)
			self._fs_lock_obj = None
		self._fs_lock_count -= 1

	def _bump_mtime(self, cpv):
		"""
		This is called before an after any modifications, so that consumers
		can use directory mtimes to validate caches. See bug #290428.
		"""
		base = self._eroot + VDB_PATH
		cat = catsplit(cpv)[0]
		catdir = base + _os.sep + cat
		t = time.time()
		t = (t, t)
		try:
			for x in (catdir, base):
				os.utime(x, t)
		except OSError:
			ensure_dirs(catdir)

	def cpv_exists(self, mykey, myrepo=None):
		"Tells us whether an actual ebuild exists on disk (no masking)"
		return os.path.exists(self.getpath(mykey))

	def cpv_counter(self, mycpv):
		"This method will grab the COUNTER. Returns a counter value."
		try:
			return long(self.aux_get(mycpv, ["COUNTER"])[0])
		except (KeyError, ValueError):
			pass
		writemsg_level(_("portage: COUNTER for %s was corrupted; " \
			"resetting to value of 0\n") % (mycpv,),
			level=logging.ERROR, noiselevel=-1)
		return 0

	def cpv_inject(self, mycpv):
		"injects a real package into our on-disk database; assumes mycpv is valid and doesn't already exist"
		ensure_dirs(self.getpath(mycpv))
		counter = self.counter_tick(mycpv=mycpv)
		# write local package counter so that emerge clean does the right thing
		write_atomic(self.getpath(mycpv, filename="COUNTER"), str(counter))

	def isInjected(self, mycpv):
		if self.cpv_exists(mycpv):
			if os.path.exists(self.getpath(mycpv, filename="INJECTED")):
				return True
			if not os.path.exists(self.getpath(mycpv, filename="CONTENTS")):
				return True
		return False

	def move_ent(self, mylist, repo_match=None):
		origcp = mylist[1]
		newcp = mylist[2]

		# sanity check
		for atom in (origcp, newcp):
			if not isjustname(atom):
				raise InvalidPackageName(str(atom))
		origmatches = self.match(origcp, use_cache=0)
		moves = 0
		if not origmatches:
			return moves
		for mycpv in origmatches:
			try:
				mycpv = self._pkg_str(mycpv, None)
			except (KeyError, InvalidData):
				continue
			mycpv_cp = cpv_getkey(mycpv)
			if mycpv_cp != origcp:
				# Ignore PROVIDE virtual match.
				continue
			if repo_match is not None \
				and not repo_match(mycpv.repo):
				continue

			# Use isvalidatom() to check if this move is valid for the
			# EAPI (characters allowed in package names may vary).
			if not isvalidatom(newcp, eapi=mycpv.eapi):
				continue

			mynewcpv = mycpv.replace(mycpv_cp, _unicode(newcp), 1)
			mynewcat = catsplit(newcp)[0]
			origpath = self.getpath(mycpv)
			if not os.path.exists(origpath):
				continue
			moves += 1
			if not os.path.exists(self.getpath(mynewcat)):
				#create the directory
				ensure_dirs(self.getpath(mynewcat))
			newpath = self.getpath(mynewcpv)
			if os.path.exists(newpath):
				#dest already exists; keep this puppy where it is.
				continue
			_movefile(origpath, newpath, mysettings=self.settings)
			self._clear_pkg_cache(self._dblink(mycpv))
			self._clear_pkg_cache(self._dblink(mynewcpv))

			# We need to rename the ebuild now.
			old_pf = catsplit(mycpv)[1]
			new_pf = catsplit(mynewcpv)[1]
			if new_pf != old_pf:
				try:
					os.rename(os.path.join(newpath, old_pf + ".ebuild"),
						os.path.join(newpath, new_pf + ".ebuild"))
				except EnvironmentError as e:
					if e.errno != errno.ENOENT:
						raise
					del e
			write_atomic(os.path.join(newpath, "PF"), new_pf+"\n")
			write_atomic(os.path.join(newpath, "CATEGORY"), mynewcat+"\n")

		return moves

	def cp_list(self, mycp, use_cache=1):
		mysplit=catsplit(mycp)
		if mysplit[0] == '*':
			mysplit[0] = mysplit[0][1:]
		try:
			if sys.hexversion >= 0x3030000:
				mystat = os.stat(self.getpath(mysplit[0])).st_mtime_ns
			else:
				mystat = os.stat(self.getpath(mysplit[0])).st_mtime
		except OSError:
			mystat = 0
		if use_cache and mycp in self.cpcache:
			cpc = self.cpcache[mycp]
			if cpc[0] == mystat:
				return cpc[1][:]
		cat_dir = self.getpath(mysplit[0])
		try:
			dir_list = os.listdir(cat_dir)
		except EnvironmentError as e:
			if e.errno == PermissionDenied.errno:
				raise PermissionDenied(cat_dir)
			del e
			dir_list = []

		returnme = []
		for x in dir_list:
			if self._excluded_dirs.match(x) is not None:
				continue
			ps = pkgsplit(x)
			if not ps:
				self.invalidentry(os.path.join(self.getpath(mysplit[0]), x))
				continue
			if len(mysplit) > 1:
				if ps[0] == mysplit[1]:
					returnme.append(_pkg_str(mysplit[0]+"/"+x))
		self._cpv_sort_ascending(returnme)
		if use_cache:
			self.cpcache[mycp] = [mystat, returnme[:]]
		elif mycp in self.cpcache:
			del self.cpcache[mycp]
		return returnme

	def cpv_all(self, use_cache=1):
		"""
		Set use_cache=0 to bypass the portage.cachedir() cache in cases
		when the accuracy of mtime staleness checks should not be trusted
		(generally this is only necessary in critical sections that
		involve merge or unmerge of packages).
		"""
		returnme = []
		basepath = os.path.join(self._eroot, VDB_PATH) + os.path.sep

		if use_cache:
			from portage import listdir
		else:
			def listdir(p, **kwargs):
				try:
					return [x for x in os.listdir(p) \
						if os.path.isdir(os.path.join(p, x))]
				except EnvironmentError as e:
					if e.errno == PermissionDenied.errno:
						raise PermissionDenied(p)
					del e
					return []

		for x in listdir(basepath, EmptyOnError=1, ignorecvs=1, dirsonly=1):
			if self._excluded_dirs.match(x) is not None:
				continue
			if not self._category_re.match(x):
				continue
			for y in listdir(basepath + x, EmptyOnError=1, dirsonly=1):
				if self._excluded_dirs.match(y) is not None:
					continue
				subpath = x + "/" + y
				# -MERGING- should never be a cpv, nor should files.
				try:
					if catpkgsplit(subpath) is None:
						self.invalidentry(self.getpath(subpath))
						continue
				except InvalidData:
					self.invalidentry(self.getpath(subpath))
					continue
				returnme.append(subpath)

		return returnme

	def cp_all(self, use_cache=1):
		mylist = self.cpv_all(use_cache=use_cache)
		d={}
		for y in mylist:
			if y[0] == '*':
				y = y[1:]
			try:
				mysplit = catpkgsplit(y)
			except InvalidData:
				self.invalidentry(self.getpath(y))
				continue
			if not mysplit:
				self.invalidentry(self.getpath(y))
				continue
			d[mysplit[0]+"/"+mysplit[1]] = None
		return list(d)

	def checkblockers(self, origdep):
		pass

	def _clear_cache(self):
		self.mtdircache.clear()
		self.matchcache.clear()
		self.cpcache.clear()
		self._aux_cache_obj = None

	def _add(self, pkg_dblink):
		self._pkgs_changed = True
		self._clear_pkg_cache(pkg_dblink)

	def _remove(self, pkg_dblink):
		self._pkgs_changed = True
		self._clear_pkg_cache(pkg_dblink)

	def _clear_pkg_cache(self, pkg_dblink):
		# Due to 1 second mtime granularity in <python-2.5, mtime checks
		# are not always sufficient to invalidate vardbapi caches. Therefore,
		# the caches need to be actively invalidated here.
		self.mtdircache.pop(pkg_dblink.cat, None)
		self.matchcache.pop(pkg_dblink.cat, None)
		self.cpcache.pop(pkg_dblink.mysplit[0], None)
		dircache.pop(pkg_dblink.dbcatdir, None)

	def match(self, origdep, use_cache=1):
		"caching match function"
		mydep = dep_expand(
			origdep, mydb=self, use_cache=use_cache, settings=self.settings)
		cache_key = (mydep, mydep.unevaluated_atom)
		mykey = dep_getkey(mydep)
		mycat = catsplit(mykey)[0]
		if not use_cache:
			if mycat in self.matchcache:
				del self.mtdircache[mycat]
				del self.matchcache[mycat]
			return list(self._iter_match(mydep,
				self.cp_list(mydep.cp, use_cache=use_cache)))
		try:
			if sys.hexversion >= 0x3030000:
				curmtime = os.stat(os.path.join(self._eroot, VDB_PATH, mycat)).st_mtime_ns
			else:
				curmtime = os.stat(os.path.join(self._eroot, VDB_PATH, mycat)).st_mtime
		except (IOError, OSError):
			curmtime=0

		if mycat not in self.matchcache or \
			self.mtdircache[mycat] != curmtime:
			# clear cache entry
			self.mtdircache[mycat] = curmtime
			self.matchcache[mycat] = {}
		if mydep not in self.matchcache[mycat]:
			mymatch = list(self._iter_match(mydep,
				self.cp_list(mydep.cp, use_cache=use_cache)))
			self.matchcache[mycat][cache_key] = mymatch
		return self.matchcache[mycat][cache_key][:]

	def findname(self, mycpv, myrepo=None):
		return self.getpath(str(mycpv), filename=catsplit(mycpv)[1]+".ebuild")

	def flush_cache(self):
		"""If the current user has permission and the internal aux_get cache has
		been updated, save it to disk and mark it unmodified.  This is called
		by emerge after it has loaded the full vdb for use in dependency
		calculations.  Currently, the cache is only written if the user has
		superuser privileges (since that's required to obtain a lock), but all
		users have read access and benefit from faster metadata lookups (as
		long as at least part of the cache is still valid)."""
		if self._flush_cache_enabled and \
			self._aux_cache is not None and \
			len(self._aux_cache["modified"]) >= self._aux_cache_threshold and \
			secpass >= 2:
			self._owners.populate() # index any unindexed contents
			valid_nodes = set(self.cpv_all())
			for cpv in list(self._aux_cache["packages"]):
				if cpv not in valid_nodes:
					del self._aux_cache["packages"][cpv]
			del self._aux_cache["modified"]
			try:
				f = atomic_ofstream(self._aux_cache_filename, 'wb')
				pickle.dump(self._aux_cache, f, protocol=2)
				f.close()
				apply_secpass_permissions(
					self._aux_cache_filename, gid=portage_gid, mode=0o644)
			except (IOError, OSError) as e:
				pass
			self._aux_cache["modified"] = set()

	@property
	def _aux_cache(self):
		if self._aux_cache_obj is None:
			self._aux_cache_init()
		return self._aux_cache_obj

	def _aux_cache_init(self):
		aux_cache = None
		open_kwargs = {}
		if sys.hexversion >= 0x3000000 and sys.hexversion < 0x3020000:
			# Buffered io triggers extreme performance issues in
			# Unpickler.load() (problem observed with python-3.0.1).
			# Unfortunately, performance is still poor relative to
			# python-2.x, but buffering makes it much worse (problem
			# appears to be solved in Python >=3.2 at least).
			open_kwargs["buffering"] = 0
		try:
			with open(_unicode_encode(self._aux_cache_filename,
				encoding=_encodings['fs'], errors='strict'),
				mode='rb', **open_kwargs) as f:
				mypickle = pickle.Unpickler(f)
				try:
					mypickle.find_global = None
				except AttributeError:
					# TODO: If py3k, override Unpickler.find_class().
					pass
				aux_cache = mypickle.load()
		except (SystemExit, KeyboardInterrupt):
			raise
		except Exception as e:
			if isinstance(e, EnvironmentError) and \
				getattr(e, 'errno', None) in (errno.ENOENT, errno.EACCES):
				pass
			else:
				writemsg(_("!!! Error loading '%s': %s\n") % \
					(self._aux_cache_filename, e), noiselevel=-1)
			del e

		if not aux_cache or \
			not isinstance(aux_cache, dict) or \
			aux_cache.get("version") != self._aux_cache_version or \
			not aux_cache.get("packages"):
			aux_cache = {"version": self._aux_cache_version}
			aux_cache["packages"] = {}

		owners = aux_cache.get("owners")
		if owners is not None:
			if not isinstance(owners, dict):
				owners = None
			elif "version" not in owners:
				owners = None
			elif owners["version"] != self._owners_cache_version:
				owners = None
			elif "base_names" not in owners:
				owners = None
			elif not isinstance(owners["base_names"], dict):
				owners = None

		if owners is None:
			owners = {
				"base_names" : {},
				"version"    : self._owners_cache_version
			}
			aux_cache["owners"] = owners

		aux_cache["modified"] = set()
		self._aux_cache_obj = aux_cache

	def aux_get(self, mycpv, wants, myrepo = None):
		"""This automatically caches selected keys that are frequently needed
		by emerge for dependency calculations.  The cached metadata is
		considered valid if the mtime of the package directory has not changed
		since the data was cached.  The cache is stored in a pickled dict
		object with the following format:

		{version:"1", "packages":{cpv1:(mtime,{k1,v1, k2,v2, ...}), cpv2...}}

		If an error occurs while loading the cache pickle or the version is
		unrecognized, the cache will simple be recreated from scratch (it is
		completely disposable).
		"""
		cache_these_wants = self._aux_cache_keys.intersection(wants)
		for x in wants:
			if self._aux_cache_keys_re.match(x) is not None:
				cache_these_wants.add(x)

		if not cache_these_wants:
			mydata = self._aux_get(mycpv, wants)
			return [mydata[x] for x in wants]

		cache_these = set(self._aux_cache_keys)
		cache_these.update(cache_these_wants)

		mydir = self.getpath(mycpv)
		mydir_stat = None
		try:
			mydir_stat = os.stat(mydir)
		except OSError as e:
			if e.errno != errno.ENOENT:
				raise
			raise KeyError(mycpv)
		# Use float mtime when available.
		mydir_mtime = mydir_stat.st_mtime
		pkg_data = self._aux_cache["packages"].get(mycpv)
		pull_me = cache_these.union(wants)
		mydata = {"_mtime_" : mydir_mtime}
		cache_valid = False
		cache_incomplete = False
		cache_mtime = None
		metadata = None
		if pkg_data is not None:
			if not isinstance(pkg_data, tuple) or len(pkg_data) != 2:
				pkg_data = None
			else:
				cache_mtime, metadata = pkg_data
				if not isinstance(cache_mtime, (float, long, int)) or \
					not isinstance(metadata, dict):
					pkg_data = None

		if pkg_data:
			cache_mtime, metadata = pkg_data
			if isinstance(cache_mtime, float):
				cache_valid = cache_mtime == mydir_stat.st_mtime
			else:
				# Cache may contain integer mtime.
				cache_valid = cache_mtime == mydir_stat[stat.ST_MTIME]

		if cache_valid:
			# Migrate old metadata to unicode.
			for k, v in metadata.items():
				metadata[k] = _unicode_decode(v,
					encoding=_encodings['repo.content'], errors='replace')

			mydata.update(metadata)
			pull_me.difference_update(mydata)

		if pull_me:
			# pull any needed data and cache it
			aux_keys = list(pull_me)
			mydata.update(self._aux_get(mycpv, aux_keys, st=mydir_stat))
			if not cache_valid or cache_these.difference(metadata):
				cache_data = {}
				if cache_valid and metadata:
					cache_data.update(metadata)
				for aux_key in cache_these:
					cache_data[aux_key] = mydata[aux_key]
				self._aux_cache["packages"][_unicode(mycpv)] = \
					(mydir_mtime, cache_data)
				self._aux_cache["modified"].add(mycpv)

		eapi_attrs = _get_eapi_attrs(mydata['EAPI'])
		if _get_slot_re(eapi_attrs).match(mydata['SLOT']) is None:
			# Empty or invalid slot triggers InvalidAtom exceptions when
			# generating slot atoms for packages, so translate it to '0' here.
			mydata['SLOT'] = '0'

		return [mydata[x] for x in wants]

	def _aux_get(self, mycpv, wants, st=None):
		mydir = self.getpath(mycpv)
		if st is None:
			try:
				st = os.stat(mydir)
			except OSError as e:
				if e.errno == errno.ENOENT:
					raise KeyError(mycpv)
				elif e.errno == PermissionDenied.errno:
					raise PermissionDenied(mydir)
				else:
					raise
		if not stat.S_ISDIR(st.st_mode):
			raise KeyError(mycpv)
		results = {}
		env_keys = []
		for x in wants:
			if x == "_mtime_":
				results[x] = st[stat.ST_MTIME]
				continue
			try:
				with io.open(
					_unicode_encode(os.path.join(mydir, x),
					encoding=_encodings['fs'], errors='strict'),
					mode='r', encoding=_encodings['repo.content'],
					errors='replace') as f:
					myd = f.read()
			except IOError:
				if x not in self._aux_cache_keys and \
					self._aux_cache_keys_re.match(x) is None:
					env_keys.append(x)
					continue
				myd = ''

			# Preserve \n for metadata that is known to
			# contain multiple lines.
			if self._aux_multi_line_re.match(x) is None:
				myd = " ".join(myd.split())

			results[x] = myd

		if env_keys:
			env_results = self._aux_env_search(mycpv, env_keys)
			for k in env_keys:
				v = env_results.get(k)
				if v is None:
					v = ''
				if self._aux_multi_line_re.match(k) is None:
					v = " ".join(v.split())
				results[k] = v

		if results.get("EAPI") == "":
			results["EAPI"] = '0'

		return results

	def _aux_env_search(self, cpv, variables):
		"""
		Search environment.bz2 for the specified variables. Returns
		a dict mapping variables to values, and any variables not
		found in the environment will not be included in the dict.
		This is useful for querying variables like ${SRC_URI} and
		${A}, which are not saved in separate files but are available
		in environment.bz2 (see bug #395463).
		"""
		env_file = self.getpath(cpv, filename="environment.bz2")
		if not os.path.isfile(env_file):
			return {}
		bunzip2_cmd = portage.util.shlex_split(
			self.settings.get("PORTAGE_BUNZIP2_COMMAND", ""))
		if not bunzip2_cmd:
			bunzip2_cmd = portage.util.shlex_split(
				self.settings["PORTAGE_BZIP2_COMMAND"])
			bunzip2_cmd.append("-d")
		args = bunzip2_cmd + ["-c", env_file]
		try:
			proc = subprocess.Popen(args, stdout=subprocess.PIPE)
		except EnvironmentError as e:
			if e.errno != errno.ENOENT:
				raise
			raise portage.exception.CommandNotFound(args[0])

		# Parts of the following code are borrowed from
		# filter-bash-environment.py (keep them in sync).
		var_assign_re = re.compile(r'(^|^declare\s+-\S+\s+|^declare\s+|^export\s+)([^=\s]+)=("|\')?(.*)$')
		close_quote_re = re.compile(r'(\\"|"|\')\s*$')
		def have_end_quote(quote, line):
			close_quote_match = close_quote_re.search(line)
			return close_quote_match is not None and \
				close_quote_match.group(1) == quote

		variables = frozenset(variables)
		results = {}
		for line in proc.stdout:
			line = _unicode_decode(line,
				encoding=_encodings['content'], errors='replace')
			var_assign_match = var_assign_re.match(line)
			if var_assign_match is not None:
				key = var_assign_match.group(2)
				quote = var_assign_match.group(3)
				if quote is not None:
					if have_end_quote(quote,
						line[var_assign_match.end(2)+2:]):
						value = var_assign_match.group(4)
					else:
						value = [var_assign_match.group(4)]
						for line in proc.stdout:
							line = _unicode_decode(line,
								encoding=_encodings['content'],
								errors='replace')
							value.append(line)
							if have_end_quote(quote, line):
								break
						value = ''.join(value)
					# remove trailing quote and whitespace
					value = value.rstrip()[:-1]
				else:
					value = var_assign_match.group(4).rstrip()

				if key in variables:
					results[key] = value

		proc.wait()
		proc.stdout.close()
		return results

	def aux_update(self, cpv, values):
		mylink = self._dblink(cpv)
		if not mylink.exists():
			raise KeyError(cpv)
		self._bump_mtime(cpv)
		self._clear_pkg_cache(mylink)
		for k, v in values.items():
			if v:
				mylink.setfile(k, v)
			else:
				try:
					os.unlink(os.path.join(self.getpath(cpv), k))
				except EnvironmentError:
					pass
		self._bump_mtime(cpv)

	def counter_tick(self, myroot=None, mycpv=None):
		"""
		@param myroot: ignored, self._eroot is used instead
		"""
		return self.counter_tick_core(incrementing=1, mycpv=mycpv)

	def get_counter_tick_core(self, myroot=None, mycpv=None):
		"""
		Use this method to retrieve the counter instead
		of having to trust the value of a global counter
		file that can lead to invalid COUNTER
		generation. When cache is valid, the package COUNTER
		files are not read and we rely on the timestamp of
		the package directory to validate cache. The stat
		calls should only take a short time, so performance
		is sufficient without having to rely on a potentially
		corrupt global counter file.

		The global counter file located at
		$CACHE_PATH/counter serves to record the
		counter of the last installed package and
		it also corresponds to the total number of
		installation actions that have occurred in
		the history of this package database.

		@param myroot: ignored, self._eroot is used instead
		"""
		del myroot
		counter = -1
		try:
			with io.open(
				_unicode_encode(self._counter_path,
				encoding=_encodings['fs'], errors='strict'),
				mode='r', encoding=_encodings['repo.content'],
				errors='replace') as f:
				try:
					counter = long(f.readline().strip())
				except (OverflowError, ValueError) as e:
					writemsg(_("!!! COUNTER file is corrupt: '%s'\n") %
						self._counter_path, noiselevel=-1)
					writemsg("!!! %s\n" % (e,), noiselevel=-1)
		except EnvironmentError as e:
			# Silently allow ENOENT since files under
			# /var/cache/ are allowed to disappear.
			if e.errno != errno.ENOENT:
				writemsg(_("!!! Unable to read COUNTER file: '%s'\n") % \
					self._counter_path, noiselevel=-1)
				writemsg("!!! %s\n" % str(e), noiselevel=-1)
			del e

		if self._cached_counter == counter:
			max_counter = counter
		else:
			# We must ensure that we return a counter
			# value that is at least as large as the
			# highest one from the installed packages,
			# since having a corrupt value that is too low
			# can trigger incorrect AUTOCLEAN behavior due
			# to newly installed packages having lower
			# COUNTERs than the previous version in the
			# same slot.
			max_counter = counter
			for cpv in self.cpv_all():
				try:
					pkg_counter = int(self.aux_get(cpv, ["COUNTER"])[0])
				except (KeyError, OverflowError, ValueError):
					continue
				if pkg_counter > max_counter:
					max_counter = pkg_counter

		return max_counter + 1

	def counter_tick_core(self, myroot=None, incrementing=1, mycpv=None):
		"""
		This method will grab the next COUNTER value and record it back
		to the global file. Note that every package install must have
		a unique counter, since a slotmove update can move two packages
		into the same SLOT and in that case it's important that both
		packages have different COUNTER metadata.

		@param myroot: ignored, self._eroot is used instead
		@param mycpv: ignored
		@rtype: int
		@return: new counter value
		"""
		myroot = None
		mycpv = None
		self.lock()
		try:
			counter = self.get_counter_tick_core() - 1
			if incrementing:
				#increment counter
				counter += 1
				# update new global counter file
				try:
					write_atomic(self._counter_path, str(counter))
				except InvalidLocation:
					self.settings._init_dirs()
					write_atomic(self._counter_path, str(counter))
			self._cached_counter = counter

			# Since we hold a lock, this is a good opportunity
			# to flush the cache. Note that this will only
			# flush the cache periodically in the main process
			# when _aux_cache_threshold is exceeded.
			self.flush_cache()
		finally:
			self.unlock()

		return counter

	def _dblink(self, cpv):
		category, pf = catsplit(cpv)
		return dblink(category, pf, settings=self.settings,
			vartree=self.vartree, treetype="vartree")

	def removeFromContents(self, pkg, paths, relative_paths=True):
		"""
		@param pkg: cpv for an installed package
		@type pkg: string
		@param paths: paths of files to remove from contents
		@type paths: iterable
		"""
		if not hasattr(pkg, "getcontents"):
			pkg = self._dblink(pkg)
		root = self.settings['ROOT']
		root_len = len(root) - 1
		new_contents = pkg.getcontents().copy()
		removed = 0

		for filename in paths:
			filename = _unicode_decode(filename,
				encoding=_encodings['content'], errors='strict')
			filename = normalize_path(filename)
			if relative_paths:
				relative_filename = filename
			else:
				relative_filename = filename[root_len:]
			contents_key = pkg._match_contents(relative_filename)
			if contents_key:
				# It's possible for two different paths to refer to the same
				# contents_key, due to directory symlinks. Therefore, pass a
				# default value to pop, in order to avoid a KeyError which
				# could otherwise be triggered (see bug #454400).
				new_contents.pop(contents_key, None)
				removed += 1

		if removed:
			self.writeContentsToContentsFile(pkg, new_contents)

	def writeContentsToContentsFile(self, pkg, new_contents):
		"""
		@param pkg: package to write contents file for
		@type pkg: dblink
		@param new_contents: contents to write to CONTENTS file
		@type new_contents: contents dictionary of the form
					{u'/path/to/file' : (contents_attribute 1, ...), ...}
		"""
		root = self.settings['ROOT']
		self._bump_mtime(pkg.mycpv)
		f = atomic_ofstream(os.path.join(pkg.dbdir, "CONTENTS"))
		write_contents(new_contents, root, f)
		f.close()
		self._bump_mtime(pkg.mycpv)
		pkg._clear_contents_cache()

	class _owners_cache(object):
		"""
		This class maintains an hash table that serves to index package
		contents by mapping the basename of file to a list of possible
		packages that own it. This is used to optimize owner lookups
		by narrowing the search down to a smaller number of packages.
		"""
		try:
			from hashlib import md5 as _new_hash
		except ImportError:
			from md5 import new as _new_hash

		_hash_bits = 16
		_hex_chars = _hash_bits // 4

		def __init__(self, vardb):
			self._vardb = vardb

		def add(self, cpv):
			eroot_len = len(self._vardb._eroot)
			contents = self._vardb._dblink(cpv).getcontents()
			pkg_hash = self._hash_pkg(cpv)
			if not contents:
				# Empty path is a code used to represent empty contents.
				self._add_path("", pkg_hash)

			for x in contents:
				self._add_path(x[eroot_len:], pkg_hash)

			self._vardb._aux_cache["modified"].add(cpv)

		def _add_path(self, path, pkg_hash):
			"""
			Empty path is a code that represents empty contents.
			"""
			if path:
				name = os.path.basename(path.rstrip(os.path.sep))
				if not name:
					return
			else:
				name = path
			name_hash = self._hash_str(name)
			base_names = self._vardb._aux_cache["owners"]["base_names"]
			pkgs = base_names.get(name_hash)
			if pkgs is None:
				pkgs = {}
				base_names[name_hash] = pkgs
			pkgs[pkg_hash] = None

		def _hash_str(self, s):
			h = self._new_hash()
			# Always use a constant utf_8 encoding here, since
			# the "default" encoding can change.
			h.update(_unicode_encode(s,
				encoding=_encodings['repo.content'],
				errors='backslashreplace'))
			h = h.hexdigest()
			h = h[-self._hex_chars:]
			h = int(h, 16)
			return h

		def _hash_pkg(self, cpv):
			counter, mtime = self._vardb.aux_get(
				cpv, ["COUNTER", "_mtime_"])
			try:
				counter = int(counter)
			except ValueError:
				counter = 0
			return (_unicode(cpv), counter, mtime)

	class _owners_db(object):

		def __init__(self, vardb):
			self._vardb = vardb

		def populate(self):
			self._populate()

		def _populate(self):
			owners_cache = vardbapi._owners_cache(self._vardb)
			cached_hashes = set()
			base_names = self._vardb._aux_cache["owners"]["base_names"]

			# Take inventory of all cached package hashes.
			for name, hash_values in list(base_names.items()):
				if not isinstance(hash_values, dict):
					del base_names[name]
					continue
				cached_hashes.update(hash_values)

			# Create sets of valid package hashes and uncached packages.
			uncached_pkgs = set()
			hash_pkg = owners_cache._hash_pkg
			valid_pkg_hashes = set()
			for cpv in self._vardb.cpv_all():
				hash_value = hash_pkg(cpv)
				valid_pkg_hashes.add(hash_value)
				if hash_value not in cached_hashes:
					uncached_pkgs.add(cpv)

			# Cache any missing packages.
			for cpv in uncached_pkgs:
				owners_cache.add(cpv)

			# Delete any stale cache.
			stale_hashes = cached_hashes.difference(valid_pkg_hashes)
			if stale_hashes:
				for base_name_hash, bucket in list(base_names.items()):
					for hash_value in stale_hashes.intersection(bucket):
						del bucket[hash_value]
					if not bucket:
						del base_names[base_name_hash]

			return owners_cache

		def get_owners(self, path_iter):
			"""
			@return the owners as a dblink -> set(files) mapping.
			"""
			owners = {}
			for owner, f in self.iter_owners(path_iter):
				owned_files = owners.get(owner)
				if owned_files is None:
					owned_files = set()
					owners[owner] = owned_files
				owned_files.add(f)
			return owners

		def getFileOwnerMap(self, path_iter):
			owners = self.get_owners(path_iter)
			file_owners = {}
			for pkg_dblink, files in owners.items():
				for f in files:
					owner_set = file_owners.get(f)
					if owner_set is None:
						owner_set = set()
						file_owners[f] = owner_set
					owner_set.add(pkg_dblink)
			return file_owners

		def iter_owners(self, path_iter):
			"""
			Iterate over tuples of (dblink, path). In order to avoid
			consuming too many resources for too much time, resources
			are only allocated for the duration of a given iter_owners()
			call. Therefore, to maximize reuse of resources when searching
			for multiple files, it's best to search for them all in a single
			call.
			"""

			if not isinstance(path_iter, list):
				path_iter = list(path_iter)
			owners_cache = self._populate()
			vardb = self._vardb
			root = vardb._eroot
			hash_pkg = owners_cache._hash_pkg
			hash_str = owners_cache._hash_str
			base_names = self._vardb._aux_cache["owners"]["base_names"]

			dblink_cache = {}

			def dblink(cpv):
				x = dblink_cache.get(cpv)
				if x is None:
					if len(dblink_cache) > 20:
						# Ensure that we don't run out of memory.
						raise StopIteration()
					x = self._vardb._dblink(cpv)
					dblink_cache[cpv] = x
				return x

			while path_iter:

				path = path_iter.pop()
				is_basename = os.sep != path[:1]
				if is_basename:
					name = path
				else:
					name = os.path.basename(path.rstrip(os.path.sep))

				if not name:
					continue

				name_hash = hash_str(name)
				pkgs = base_names.get(name_hash)
				owners = []
				if pkgs is not None:
					try:
						for hash_value in pkgs:
							if not isinstance(hash_value, tuple) or \
								len(hash_value) != 3:
								continue
							cpv, counter, mtime = hash_value
							if not isinstance(cpv, basestring):
								continue
							try:
								current_hash = hash_pkg(cpv)
							except KeyError:
								continue

							if current_hash != hash_value:
								continue

							if is_basename:
								for p in dblink(cpv).getcontents():
									if os.path.basename(p) == name:
										owners.append((cpv, p[len(root):]))
							else:
								if dblink(cpv).isowner(path):
									owners.append((cpv, path))

					except StopIteration:
						path_iter.append(path)
						del owners[:]
						dblink_cache.clear()
						gc.collect()
						for x in self._iter_owners_low_mem(path_iter):
							yield x
						return
					else:
						for cpv, p in owners:
							yield (dblink(cpv), p)

		def _iter_owners_low_mem(self, path_list):
			"""
			This implemention will make a short-lived dblink instance (and
			parse CONTENTS) for every single installed package. This is
			slower and but uses less memory than the method which uses the
			basename cache.
			"""

			if not path_list:
				return

			path_info_list = []
			for path in path_list:
				is_basename = os.sep != path[:1]
				if is_basename:
					name = path
				else:
					name = os.path.basename(path.rstrip(os.path.sep))
				path_info_list.append((path, name, is_basename))

			# Do work via the global event loop, so that it can be used
			# for indication of progress during the search (bug #461412).
			event_loop = (portage._internal_caller and
				global_event_loop() or EventLoop(main=False))
			root = self._vardb._eroot

			def search_pkg(cpv):
				dblnk = self._vardb._dblink(cpv)
				for path, name, is_basename in path_info_list:
					if is_basename:
						for p in dblnk.getcontents():
							if os.path.basename(p) == name:
								search_pkg.results.append((dblnk, p[len(root):]))
					else:
						if dblnk.isowner(path):
							search_pkg.results.append((dblnk, path))
				search_pkg.complete = True
				return False

			search_pkg.results = []

			for cpv in self._vardb.cpv_all():
				del search_pkg.results[:]
				search_pkg.complete = False
				event_loop.idle_add(search_pkg, cpv)
				while not search_pkg.complete:
					event_loop.iteration()
				for result in search_pkg.results:
					yield result

class vartree(object):
	"this tree will scan a var/db/pkg database located at root (passed to init)"
	def __init__(self, root=None, virtual=DeprecationWarning, categories=None,
		settings=None):

		if settings is None:
			settings = portage.settings

		if root is not None and root != settings['ROOT']:
			warnings.warn("The 'root' parameter of the "
				"portage.dbapi.vartree.vartree"
				" constructor is now unused. Use "
				"settings['ROOT'] instead.",
				DeprecationWarning, stacklevel=2)

		if virtual is not DeprecationWarning:
			warnings.warn("The 'virtual' parameter of the "
				"portage.dbapi.vartree.vartree"
				" constructor is unused",
				DeprecationWarning, stacklevel=2)

		self.settings = settings
		self.dbapi = vardbapi(settings=settings, vartree=self)
		self.populated = 1

	@property
	def root(self):
		warnings.warn("The root attribute of "
			"portage.dbapi.vartree.vartree"
			" is deprecated. Use "
			"settings['ROOT'] instead.",
			DeprecationWarning, stacklevel=3)
		return self.settings['ROOT']

	def getpath(self, mykey, filename=None):
		return self.dbapi.getpath(mykey, filename=filename)

	def zap(self, mycpv):
		return

	def inject(self, mycpv):
		return

	def get_provide(self, mycpv):
		myprovides = []
		mylines = None
		try:
			mylines, myuse = self.dbapi.aux_get(mycpv, ["PROVIDE", "USE"])
			if mylines:
				myuse = myuse.split()
				mylines = use_reduce(mylines, uselist=myuse, flat=True)
				for myprovide in mylines:
					mys = catpkgsplit(myprovide)
					if not mys:
						mys = myprovide.split("/")
					myprovides += [mys[0] + "/" + mys[1]]
			return myprovides
		except SystemExit as e:
			raise
		except Exception as e:
			mydir = self.dbapi.getpath(mycpv)
			writemsg(_("\nParse Error reading PROVIDE and USE in '%s'\n") % mydir,
				noiselevel=-1)
			if mylines:
				writemsg(_("Possibly Invalid: '%s'\n") % str(mylines),
					noiselevel=-1)
			writemsg(_("Exception: %s\n\n") % str(e), noiselevel=-1)
			return []

	def get_all_provides(self):
		myprovides = {}
		for node in self.getallcpv():
			for mykey in self.get_provide(node):
				if mykey in myprovides:
					myprovides[mykey] += [node]
				else:
					myprovides[mykey] = [node]
		return myprovides

	def dep_bestmatch(self, mydep, use_cache=1):
		"compatibility method -- all matches, not just visible ones"
		#mymatch=best(match(dep_expand(mydep,self.dbapi),self.dbapi))
		mymatch = best(self.dbapi.match(
			dep_expand(mydep, mydb=self.dbapi, settings=self.settings),
			use_cache=use_cache))
		if mymatch is None:
			return ""
		else:
			return mymatch

	def dep_match(self, mydep, use_cache=1):
		"compatibility method -- we want to see all matches, not just visible ones"
		#mymatch = match(mydep,self.dbapi)
		mymatch = self.dbapi.match(mydep, use_cache=use_cache)
		if mymatch is None:
			return []
		else:
			return mymatch

	def exists_specific(self, cpv):
		return self.dbapi.cpv_exists(cpv)

	def getallcpv(self):
		"""temporary function, probably to be renamed --- Gets a list of all
		category/package-versions installed on the system."""
		return self.dbapi.cpv_all()

	def getallnodes(self):
		"""new behavior: these are all *unmasked* nodes.  There may or may not be available
		masked package for nodes in this nodes list."""
		return self.dbapi.cp_all()

	def getebuildpath(self, fullpackage):
		cat, package = catsplit(fullpackage)
		return self.getpath(fullpackage, filename=package+".ebuild")

	def getslot(self, mycatpkg):
		"Get a slot for a catpkg; assume it exists."
		try:
			return self.dbapi._pkg_str(mycatpkg, None).slot
		except KeyError:
			return ""

	def populate(self):
		self.populated=1

class dblink(object):
	"""
	This class provides an interface to the installed package database
	At present this is implemented as a text backend in /var/db/pkg.
	"""

	import re
	_normalize_needed = re.compile(r'//|^[^/]|./$|(^|/)\.\.?(/|$)')

	_contents_re = re.compile(r'^(' + \
		r'(?P<dir>(dev|dir|fif) (.+))|' + \
		r'(?P<obj>(obj) (.+) (\S+) (\d+))|' + \
		r'(?P<sym>(sym) (.+) -> (.+) ((\d+)|(?P<oldsym>(' + \
		r'\(\d+, \d+L, \d+L, \d+, \d+, \d+, \d+L, \d+, (\d+), \d+\)))))' + \
		r')$'
	)

	# These files are generated by emerge, so we need to remove
	# them when they are the only thing left in a directory.
	_infodir_cleanup = frozenset(["dir", "dir.old"])

	_ignored_unlink_errnos = (
		errno.EBUSY, errno.ENOENT,
		errno.ENOTDIR, errno.EISDIR)

	_ignored_rmdir_errnos = (
		errno.EEXIST, errno.ENOTEMPTY,
		errno.EBUSY, errno.ENOENT,
		errno.ENOTDIR, errno.EISDIR,
		errno.EPERM)

	def __init__(self, cat, pkg, myroot=None, settings=None, treetype=None,
		vartree=None, blockers=None, scheduler=None, pipe=None):
		"""
		Creates a DBlink object for a given CPV.
		The given CPV may not be present in the database already.

		@param cat: Category
		@type cat: String
		@param pkg: Package (PV)
		@type pkg: String
		@param myroot: ignored, settings['ROOT'] is used instead
		@type myroot: String (Path)
		@param settings: Typically portage.settings
		@type settings: portage.config
		@param treetype: one of ['porttree','bintree','vartree']
		@type treetype: String
		@param vartree: an instance of vartree corresponding to myroot.
		@type vartree: vartree
		"""

		if settings is None:
			raise TypeError("settings argument is required")

		mysettings = settings
		self._eroot = mysettings['EROOT']
		self.cat = cat
		self.pkg = pkg
		self.mycpv = self.cat + "/" + self.pkg
		if self.mycpv == settings.mycpv and \
			isinstance(settings.mycpv, _pkg_str):
			self.mycpv = settings.mycpv
		else:
			self.mycpv = _pkg_str(self.mycpv)
		self.mysplit = list(self.mycpv.cpv_split[1:])
		self.mysplit[0] = self.mycpv.cp
		self.treetype = treetype
		if vartree is None:
			vartree = portage.db[self._eroot]["vartree"]
		self.vartree = vartree
		self._blockers = blockers
		self._scheduler = scheduler
		self.dbroot = normalize_path(os.path.join(self._eroot, VDB_PATH))
		self.dbcatdir = self.dbroot+"/"+cat
		self.dbpkgdir = self.dbcatdir+"/"+pkg
		self.dbtmpdir = self.dbcatdir+"/"+MERGING_IDENTIFIER+pkg
		self.dbdir = self.dbpkgdir
		self.settings = mysettings
		self._verbose = self.settings.get("PORTAGE_VERBOSE") == "1"

		self.myroot = self.settings['ROOT']
		self._installed_instance = None
		self.contentscache = None
		self._contents_inodes = None
		self._contents_basenames = None
		self._linkmap_broken = False
		self._device_path_map = {}
		self._hardlink_merge_map = {}
		self._hash_key = (self._eroot, self.mycpv)
		self._protect_obj = None
		self._pipe = pipe

		# When necessary, this attribute is modified for
		# compliance with RESTRICT=preserve-libs.
		self._preserve_libs = "preserve-libs" in mysettings.features

	def __hash__(self):
		return hash(self._hash_key)

	def __eq__(self, other):
		return isinstance(other, dblink) and \
			self._hash_key == other._hash_key

	def _get_protect_obj(self):

		if self._protect_obj is None:
			self._protect_obj = ConfigProtect(self._eroot,
			portage.util.shlex_split(
				self.settings.get("CONFIG_PROTECT", "")),
			portage.util.shlex_split(
				self.settings.get("CONFIG_PROTECT_MASK", "")))

		return self._protect_obj

	def isprotected(self, obj):
		return self._get_protect_obj().isprotected(obj)

	def updateprotect(self):
		self._get_protect_obj().updateprotect()

	def lockdb(self):
		self.vartree.dbapi.lock()

	def unlockdb(self):
		self.vartree.dbapi.unlock()

	def getpath(self):
		"return path to location of db information (for >>> informational display)"
		return self.dbdir

	def exists(self):
		"does the db entry exist?  boolean."
		return os.path.exists(self.dbdir)

	def delete(self):
		"""
		Remove this entry from the database
		"""
		try:
			os.lstat(self.dbdir)
		except OSError as e:
			if e.errno not in (errno.ENOENT, errno.ENOTDIR, errno.ESTALE):
				raise
			return

		# Check validity of self.dbdir before attempting to remove it.
		if not self.dbdir.startswith(self.dbroot):
			writemsg(_("portage.dblink.delete(): invalid dbdir: %s\n") % \
				self.dbdir, noiselevel=-1)
			return

		shutil.rmtree(self.dbdir)
		# If empty, remove parent category directory.
		try:
			os.rmdir(os.path.dirname(self.dbdir))
		except OSError:
			pass
		self.vartree.dbapi._remove(self)

		# Use self.dbroot since we need an existing path for syncfs.
		try:
			self._merged_path(self.dbroot, os.lstat(self.dbroot))
		except OSError:
			pass

		self._post_merge_sync()

	def clearcontents(self):
		"""
		For a given db entry (self), erase the CONTENTS values.
		"""
		self.lockdb()
		try:
			if os.path.exists(self.dbdir+"/CONTENTS"):
				os.unlink(self.dbdir+"/CONTENTS")
		finally:
			self.unlockdb()

	def _clear_contents_cache(self):
		self.contentscache = None
		self._contents_inodes = None
		self._contents_basenames = None

	def getcontents(self):
		"""
		Get the installed files of a given package (aka what that package installed)
		"""
		contents_file = os.path.join(self.dbdir, "CONTENTS")
		if self.contentscache is not None:
			return self.contentscache
		pkgfiles = {}
		try:
			with io.open(_unicode_encode(contents_file,
				encoding=_encodings['fs'], errors='strict'),
				mode='r', encoding=_encodings['repo.content'],
				errors='replace') as f:
				mylines = f.readlines()
		except EnvironmentError as e:
			if e.errno != errno.ENOENT:
				raise
			del e
			self.contentscache = pkgfiles
			return pkgfiles

		null_byte = "\0"
		normalize_needed = self._normalize_needed
		contents_re = self._contents_re
		obj_index = contents_re.groupindex['obj']
		dir_index = contents_re.groupindex['dir']
		sym_index = contents_re.groupindex['sym']
		# The old symlink format may exist on systems that have packages
		# which were installed many years ago (see bug #351814).
		oldsym_index = contents_re.groupindex['oldsym']
		# CONTENTS files already contain EPREFIX
		myroot = self.settings['ROOT']
		if myroot == os.path.sep:
			myroot = None
		# used to generate parent dir entries
		dir_entry = ("dir",)
		eroot_split_len = len(self.settings["EROOT"].split(os.sep)) - 1
		pos = 0
		errors = []
		for pos, line in enumerate(mylines):
			if null_byte in line:
				# Null bytes are a common indication of corruption.
				errors.append((pos + 1, _("Null byte found in CONTENTS entry")))
				continue
			line = line.rstrip("\n")
			m = contents_re.match(line)
			if m is None:
				errors.append((pos + 1, _("Unrecognized CONTENTS entry")))
				continue

			if m.group(obj_index) is not None:
				base = obj_index
				#format: type, mtime, md5sum
				data = (m.group(base+1), m.group(base+4), m.group(base+3))
			elif m.group(dir_index) is not None:
				base = dir_index
				#format: type
				data = (m.group(base+1),)
			elif m.group(sym_index) is not None:
				base = sym_index
				if m.group(oldsym_index) is None:
					mtime = m.group(base+5)
				else:
					mtime = m.group(base+8)
				#format: type, mtime, dest
				data = (m.group(base+1), mtime, m.group(base+3))
			else:
				# This won't happen as long the regular expression
				# is written to only match valid entries.
				raise AssertionError(_("required group not found " + \
					"in CONTENTS entry: '%s'") % line)

			path = m.group(base+2)
			if normalize_needed.search(path) is not None:
				path = normalize_path(path)
				if not path.startswith(os.path.sep):
					path = os.path.sep + path

			if myroot is not None:
				path = os.path.join(myroot, path.lstrip(os.path.sep))

			# Implicitly add parent directories, since we can't necessarily
			# assume that they are explicitly listed in CONTENTS, and it's
			# useful for callers if they can rely on parent directory entries
			# being generated here (crucial for things like dblink.isowner()).
			path_split = path.split(os.sep)
			path_split.pop()
			while len(path_split) > eroot_split_len:
				parent = os.sep.join(path_split)
				if parent in pkgfiles:
					break
				pkgfiles[parent] = dir_entry
				path_split.pop()

			pkgfiles[path] = data

		if errors:
			writemsg(_("!!! Parse error in '%s'\n") % contents_file, noiselevel=-1)
			for pos, e in errors:
				writemsg(_("!!!   line %d: %s\n") % (pos, e), noiselevel=-1)
		self.contentscache = pkgfiles
		return pkgfiles

	def _prune_plib_registry(self, unmerge=False,
		needed=None, preserve_paths=None):
		# remove preserved libraries that don't have any consumers left
		if not (self._linkmap_broken or
			self.vartree.dbapi._linkmap is None or
			self.vartree.dbapi._plib_registry is None):
			self.vartree.dbapi._fs_lock()
			plib_registry = self.vartree.dbapi._plib_registry
			plib_registry.lock()
			try:
				plib_registry.load()

				unmerge_with_replacement = \
					unmerge and preserve_paths is not None
				if unmerge_with_replacement:
					# If self.mycpv is about to be unmerged and we
					# have a replacement package, we want to exclude
					# the irrelevant NEEDED data that belongs to
					# files which are being unmerged now.
					exclude_pkgs = (self.mycpv,)
				else:
					exclude_pkgs = None

				self._linkmap_rebuild(exclude_pkgs=exclude_pkgs,
					include_file=needed, preserve_paths=preserve_paths)

				if unmerge:
					unmerge_preserve = None
					if not unmerge_with_replacement:
						unmerge_preserve = \
							self._find_libs_to_preserve(unmerge=True)
					counter = self.vartree.dbapi.cpv_counter(self.mycpv)
					try:
						slot = self.mycpv.slot
					except AttributeError:
						slot = _pkg_str(self.mycpv, slot=self.settings["SLOT"]).slot
					plib_registry.unregister(self.mycpv, slot, counter)
					if unmerge_preserve:
						for path in sorted(unmerge_preserve):
							contents_key = self._match_contents(path)
							if not contents_key:
								continue
							obj_type = self.getcontents()[contents_key][0]
							self._display_merge(_(">>> needed   %s %s\n") % \
								(obj_type, contents_key), noiselevel=-1)
						plib_registry.register(self.mycpv,
							slot, counter, unmerge_preserve)
						# Remove the preserved files from our contents
						# so that they won't be unmerged.
						self.vartree.dbapi.removeFromContents(self,
							unmerge_preserve)

				unmerge_no_replacement = \
					unmerge and not unmerge_with_replacement
				cpv_lib_map = self._find_unused_preserved_libs(
					unmerge_no_replacement)
				if cpv_lib_map:
					self._remove_preserved_libs(cpv_lib_map)
					self.vartree.dbapi.lock()
					try:
						for cpv, removed in cpv_lib_map.items():
							if not self.vartree.dbapi.cpv_exists(cpv):
								continue
							self.vartree.dbapi.removeFromContents(cpv, removed)
					finally:
						self.vartree.dbapi.unlock()

				plib_registry.store()
			finally:
				plib_registry.unlock()
				self.vartree.dbapi._fs_unlock()

	def unmerge(self, pkgfiles=None, trimworld=None, cleanup=True,
		ldpath_mtimes=None, others_in_slot=None, needed=None,
		preserve_paths=None):
		"""
		Calls prerm
		Unmerges a given package (CPV)
		calls postrm
		calls cleanrm
		calls env_update

		@param pkgfiles: files to unmerge (generally self.getcontents() )
		@type pkgfiles: Dictionary
		@param trimworld: Unused
		@type trimworld: Boolean
		@param cleanup: cleanup to pass to doebuild (see doebuild)
		@type cleanup: Boolean
		@param ldpath_mtimes: mtimes to pass to env_update (see env_update)
		@type ldpath_mtimes: Dictionary
		@param others_in_slot: all dblink instances in this slot, excluding self
		@type others_in_slot: list
		@param needed: Filename containing libraries needed after unmerge.
		@type needed: String
		@param preserve_paths: Libraries preserved by a package instance that
			is currently being merged. They need to be explicitly passed to the
			LinkageMap, since they are not registered in the
			PreservedLibsRegistry yet.
		@type preserve_paths: set
		@rtype: Integer
		@return:
		1. os.EX_OK if everything went well.
		2. return code of the failed phase (for prerm, postrm, cleanrm)
		"""

		if trimworld is not None:
			warnings.warn("The trimworld parameter of the " + \
				"portage.dbapi.vartree.dblink.unmerge()" + \
				" method is now unused.",
				DeprecationWarning, stacklevel=2)

		background = False
		log_path = self.settings.get("PORTAGE_LOG_FILE")
		if self._scheduler is None:
			# We create a scheduler instance and use it to
			# log unmerge output separately from merge output.
			self._scheduler = SchedulerInterface(portage._internal_caller and
				global_event_loop() or EventLoop(main=False))
		if self.settings.get("PORTAGE_BACKGROUND") == "subprocess":
			if self.settings.get("PORTAGE_BACKGROUND_UNMERGE") == "1":
				self.settings["PORTAGE_BACKGROUND"] = "1"
				self.settings.backup_changes("PORTAGE_BACKGROUND")
				background = True
			elif self.settings.get("PORTAGE_BACKGROUND_UNMERGE") == "0":
				self.settings["PORTAGE_BACKGROUND"] = "0"
				self.settings.backup_changes("PORTAGE_BACKGROUND")
		elif self.settings.get("PORTAGE_BACKGROUND") == "1":
			background = True

		self.vartree.dbapi._bump_mtime(self.mycpv)
		showMessage = self._display_merge
		if self.vartree.dbapi._categories is not None:
			self.vartree.dbapi._categories = None

		# When others_in_slot is not None, the backup has already been
		# handled by the caller.
		caller_handles_backup = others_in_slot is not None

		# When others_in_slot is supplied, the security check has already been
		# done for this slot, so it shouldn't be repeated until the next
		# replacement or unmerge operation.
		if others_in_slot is None:
			slot = self.vartree.dbapi._pkg_str(self.mycpv, None).slot
			slot_matches = self.vartree.dbapi.match(
				"%s:%s" % (portage.cpv_getkey(self.mycpv), slot))
			others_in_slot = []
			for cur_cpv in slot_matches:
				if cur_cpv == self.mycpv:
					continue
				others_in_slot.append(dblink(self.cat, catsplit(cur_cpv)[1],
					settings=self.settings, vartree=self.vartree,
					treetype="vartree", pipe=self._pipe))

			retval = self._security_check([self] + others_in_slot)
			if retval:
				return retval

		contents = self.getcontents()
		# Now, don't assume that the name of the ebuild is the same as the
		# name of the dir; the package may have been moved.
		myebuildpath = os.path.join(self.dbdir, self.pkg + ".ebuild")
		failures = 0
		ebuild_phase = "prerm"
		mystuff = os.listdir(self.dbdir)
		for x in mystuff:
			if x.endswith(".ebuild"):
				if x[:-7] != self.pkg:
					# Clean up after vardbapi.move_ent() breakage in
					# portage versions before 2.1.2
					os.rename(os.path.join(self.dbdir, x), myebuildpath)
					write_atomic(os.path.join(self.dbdir, "PF"), self.pkg+"\n")
				break

		if self.mycpv != self.settings.mycpv or \
			"EAPI" not in self.settings.configdict["pkg"]:
			# We avoid a redundant setcpv call here when
			# the caller has already taken care of it.
			self.settings.setcpv(self.mycpv, mydb=self.vartree.dbapi)

		eapi_unsupported = False
		try:
			doebuild_environment(myebuildpath, "prerm",
				settings=self.settings, db=self.vartree.dbapi)
		except UnsupportedAPIException as e:
			eapi_unsupported = e

		if self._preserve_libs and "preserve-libs" in \
			self.settings["PORTAGE_RESTRICT"].split():
			self._preserve_libs = False

		builddir_lock = None
		scheduler = self._scheduler
		retval = os.EX_OK
		try:
			# Only create builddir_lock if the caller
			# has not already acquired the lock.
			if "PORTAGE_BUILDDIR_LOCKED" not in self.settings:
				builddir_lock = EbuildBuildDir(
					scheduler=scheduler,
					settings=self.settings)
				builddir_lock.lock()
				prepare_build_dirs(settings=self.settings, cleanup=True)
				log_path = self.settings.get("PORTAGE_LOG_FILE")

			# Do this before the following _prune_plib_registry call, since
			# that removes preserved libraries from our CONTENTS, and we
			# may want to backup those libraries first.
			if not caller_handles_backup:
				retval = self._pre_unmerge_backup(background)
				if retval != os.EX_OK:
					showMessage(_("!!! FAILED prerm: quickpkg: %s\n") % retval,
						level=logging.ERROR, noiselevel=-1)
					return retval

			self._prune_plib_registry(unmerge=True, needed=needed,
				preserve_paths=preserve_paths)

			# Log the error after PORTAGE_LOG_FILE is initialized
			# by prepare_build_dirs above.
			if eapi_unsupported:
				# Sometimes this happens due to corruption of the EAPI file.
				failures += 1
				showMessage(_("!!! FAILED prerm: %s\n") % \
					os.path.join(self.dbdir, "EAPI"),
					level=logging.ERROR, noiselevel=-1)
				showMessage("%s\n" % (eapi_unsupported,),
					level=logging.ERROR, noiselevel=-1)
			elif os.path.isfile(myebuildpath):
				phase = EbuildPhase(background=background,
					phase=ebuild_phase, scheduler=scheduler,
					settings=self.settings)
				phase.start()
				retval = phase.wait()

				# XXX: Decide how to handle failures here.
				if retval != os.EX_OK:
					failures += 1
					showMessage(_("!!! FAILED prerm: %s\n") % retval,
						level=logging.ERROR, noiselevel=-1)

			self.vartree.dbapi._fs_lock()
			try:
				self._unmerge_pkgfiles(pkgfiles, others_in_slot)
			finally:
				self.vartree.dbapi._fs_unlock()
			self._clear_contents_cache()

			if not eapi_unsupported and os.path.isfile(myebuildpath):
				ebuild_phase = "postrm"
				phase = EbuildPhase(background=background,
					phase=ebuild_phase, scheduler=scheduler,
					settings=self.settings)
				phase.start()
				retval = phase.wait()

				# XXX: Decide how to handle failures here.
				if retval != os.EX_OK:
					failures += 1
					showMessage(_("!!! FAILED postrm: %s\n") % retval,
						level=logging.ERROR, noiselevel=-1)

		finally:
			self.vartree.dbapi._bump_mtime(self.mycpv)
			try:
					if not eapi_unsupported and os.path.isfile(myebuildpath):
						if retval != os.EX_OK:
							msg_lines = []
							msg = _("The '%(ebuild_phase)s' "
							"phase of the '%(cpv)s' package "
							"has failed with exit value %(retval)s.") % \
							{"ebuild_phase":ebuild_phase, "cpv":self.mycpv,
							"retval":retval}
							from textwrap import wrap
							msg_lines.extend(wrap(msg, 72))
							msg_lines.append("")

							ebuild_name = os.path.basename(myebuildpath)
							ebuild_dir = os.path.dirname(myebuildpath)
							msg = _("The problem occurred while executing "
							"the ebuild file named '%(ebuild_name)s' "
							"located in the '%(ebuild_dir)s' directory. "
							"If necessary, manually remove "
							"the environment.bz2 file and/or the "
							"ebuild file located in that directory.") % \
							{"ebuild_name":ebuild_name, "ebuild_dir":ebuild_dir}
							msg_lines.extend(wrap(msg, 72))
							msg_lines.append("")

							msg = _("Removal "
							"of the environment.bz2 file is "
							"preferred since it may allow the "
							"removal phases to execute successfully. "
							"The ebuild will be "
							"sourced and the eclasses "
							"from the current portage tree will be used "
							"when necessary. Removal of "
							"the ebuild file will cause the "
							"pkg_prerm() and pkg_postrm() removal "
							"phases to be skipped entirely.")
							msg_lines.extend(wrap(msg, 72))

							self._eerror(ebuild_phase, msg_lines)

					self._elog_process(phasefilter=("prerm", "postrm"))

					if retval == os.EX_OK:
						try:
							doebuild_environment(myebuildpath, "cleanrm",
								settings=self.settings, db=self.vartree.dbapi)
						except UnsupportedAPIException:
							pass
						phase = EbuildPhase(background=background,
							phase="cleanrm", scheduler=scheduler,
							settings=self.settings)
						phase.start()
						retval = phase.wait()
			finally:
					if builddir_lock is not None:
						builddir_lock.unlock()

		if log_path is not None:

			if not failures and 'unmerge-logs' not in self.settings.features:
				try:
					os.unlink(log_path)
				except OSError:
					pass

			try:
				st = os.stat(log_path)
			except OSError:
				pass
			else:
				if st.st_size == 0:
					try:
						os.unlink(log_path)
					except OSError:
						pass

		if log_path is not None and os.path.exists(log_path):
			# Restore this since it gets lost somewhere above and it
			# needs to be set for _display_merge() to be able to log.
			# Note that the log isn't necessarily supposed to exist
			# since if PORT_LOGDIR is unset then it's a temp file
			# so it gets cleaned above.
			self.settings["PORTAGE_LOG_FILE"] = log_path
		else:
			self.settings.pop("PORTAGE_LOG_FILE", None)

		env_update(target_root=self.settings['ROOT'],
			prev_mtimes=ldpath_mtimes,
			contents=contents, env=self.settings,
			writemsg_level=self._display_merge, vardbapi=self.vartree.dbapi)

		unmerge_with_replacement = preserve_paths is not None
		if not unmerge_with_replacement:
			# When there's a replacement package which calls us via treewalk,
			# treewalk will automatically call _prune_plib_registry for us.
			# Otherwise, we need to call _prune_plib_registry ourselves.
			# Don't pass in the "unmerge=True" flag here, since that flag
			# is intended to be used _prior_ to unmerge, not after.
			self._prune_plib_registry()

		return os.EX_OK

	def _display_merge(self, msg, level=0, noiselevel=0):
		if not self._verbose and noiselevel >= 0 and level < logging.WARN:
			return
		if self._scheduler is None:
			writemsg_level(msg, level=level, noiselevel=noiselevel)
		else:
			log_path = None
			if self.settings.get("PORTAGE_BACKGROUND") != "subprocess":
				log_path = self.settings.get("PORTAGE_LOG_FILE")
			background = self.settings.get("PORTAGE_BACKGROUND") == "1"

			if background and log_path is None:
				if level >= logging.WARN:
					writemsg_level(msg, level=level, noiselevel=noiselevel)
			else:
				self._scheduler.output(msg,
					log_path=log_path, background=background,
					level=level, noiselevel=noiselevel)

	def _show_unmerge(self, zing, desc, file_type, file_name):
		self._display_merge("%s %s %s %s\n" % \
			(zing, desc.ljust(8), file_type, file_name))

	def _unmerge_pkgfiles(self, pkgfiles, others_in_slot):
		"""

		Unmerges the contents of a package from the liveFS
		Removes the VDB entry for self

		@param pkgfiles: typically self.getcontents()
		@type pkgfiles: Dictionary { filename: [ 'type', '?', 'md5sum' ] }
		@param others_in_slot: all dblink instances in this slot, excluding self
		@type others_in_slot: list
		@rtype: None
		"""

		os = _os_merge
		perf_md5 = perform_md5
		showMessage = self._display_merge
		show_unmerge = self._show_unmerge
		ignored_unlink_errnos = self._ignored_unlink_errnos
		ignored_rmdir_errnos = self._ignored_rmdir_errnos

		if not pkgfiles:
			showMessage(_("No package files given... Grabbing a set.\n"))
			pkgfiles = self.getcontents()

		if others_in_slot is None:
			others_in_slot = []
			slot = self.vartree.dbapi._pkg_str(self.mycpv, None).slot
			slot_matches = self.vartree.dbapi.match(
				"%s:%s" % (portage.cpv_getkey(self.mycpv), slot))
			for cur_cpv in slot_matches:
				if cur_cpv == self.mycpv:
					continue
				others_in_slot.append(dblink(self.cat, catsplit(cur_cpv)[1],
					settings=self.settings,
					vartree=self.vartree, treetype="vartree", pipe=self._pipe))

		cfgfiledict = grabdict(self.vartree.dbapi._conf_mem_file)
		stale_confmem = []
		protected_symlinks = {}

		unmerge_orphans = "unmerge-orphans" in self.settings.features
		calc_prelink = "prelink-checksums" in self.settings.features

		if pkgfiles:
			self.updateprotect()
			mykeys = list(pkgfiles)
			mykeys.sort()
			mykeys.reverse()

			#process symlinks second-to-last, directories last.
			mydirs = set()

			uninstall_ignore = portage.util.shlex_split(
				self.settings.get("UNINSTALL_IGNORE", ""))

			def unlink(file_name, lstatobj):
				if bsd_chflags:
					if lstatobj.st_flags != 0:
						bsd_chflags.lchflags(file_name, 0)
					parent_name = os.path.dirname(file_name)
					# Use normal stat/chflags for the parent since we want to
					# follow any symlinks to the real parent directory.
					pflags = os.stat(parent_name).st_flags
					if pflags != 0:
						bsd_chflags.chflags(parent_name, 0)
				try:
					if not stat.S_ISLNK(lstatobj.st_mode):
						# Remove permissions to ensure that any hardlinks to
						# suid/sgid files are rendered harmless.
						os.chmod(file_name, 0)
					os.unlink(file_name)
				except OSError as ose:
					# If the chmod or unlink fails, you are in trouble.
					# With Prefix this can be because the file is owned
					# by someone else (a screwup by root?), on a normal
					# system maybe filesystem corruption.  In any case,
					# if we backtrace and die here, we leave the system
					# in a totally undefined state, hence we just bleed
					# like hell and continue to hopefully finish all our
					# administrative and pkg_postinst stuff.
					self._eerror("postrm",
						["Could not chmod or unlink '%s': %s" % \
						(file_name, ose)])
				else:

					# Even though the file no longer exists, we log it
					# here so that _unmerge_dirs can see that we've
					# removed a file from this device, and will record
					# the parent directory for a syncfs call.
					self._merged_path(file_name, lstatobj, exists=False)

				finally:
					if bsd_chflags and pflags != 0:
						# Restore the parent flags we saved before unlinking
						bsd_chflags.chflags(parent_name, pflags)

			unmerge_desc = {}
			unmerge_desc["cfgpro"] = _("cfgpro")
			unmerge_desc["replaced"] = _("replaced")
			unmerge_desc["!dir"] = _("!dir")
			unmerge_desc["!empty"] = _("!empty")
			unmerge_desc["!fif"] = _("!fif")
			unmerge_desc["!found"] = _("!found")
			unmerge_desc["!md5"] = _("!md5")
			unmerge_desc["!mtime"] = _("!mtime")
			unmerge_desc["!obj"] = _("!obj")
			unmerge_desc["!sym"] = _("!sym")
			unmerge_desc["!prefix"] = _("!prefix")

			real_root = self.settings['ROOT']
			real_root_len = len(real_root) - 1
			eroot = self.settings["EROOT"]

			infodirs = frozenset(infodir for infodir in chain(
				self.settings.get("INFOPATH", "").split(":"),
				self.settings.get("INFODIR", "").split(":")) if infodir)
			infodirs_inodes = set()
			for infodir in infodirs:
				infodir = os.path.join(real_root, infodir.lstrip(os.sep))
				try:
					statobj = os.stat(infodir)
				except OSError:
					pass
				else:
					infodirs_inodes.add((statobj.st_dev, statobj.st_ino))

			for i, objkey in enumerate(mykeys):

				obj = normalize_path(objkey)
				if os is _os_merge:
					try:
						_unicode_encode(obj,
							encoding=_encodings['merge'], errors='strict')
					except UnicodeEncodeError:
						# The package appears to have been merged with a
						# different value of sys.getfilesystemencoding(),
						# so fall back to utf_8 if appropriate.
						try:
							_unicode_encode(obj,
								encoding=_encodings['fs'], errors='strict')
						except UnicodeEncodeError:
							pass
						else:
							os = portage.os
							perf_md5 = portage.checksum.perform_md5

				file_data = pkgfiles[objkey]
				file_type = file_data[0]

				# don't try to unmerge the prefix offset itself
				if len(obj) <= len(eroot) or not obj.startswith(eroot):
					show_unmerge("---", unmerge_desc["!prefix"], file_type, obj)
					continue

				statobj = None
				try:
					statobj = os.stat(obj)
				except OSError:
					pass
				lstatobj = None
				try:
					lstatobj = os.lstat(obj)
				except (OSError, AttributeError):
					pass
				islink = lstatobj is not None and stat.S_ISLNK(lstatobj.st_mode)
				if lstatobj is None:
						show_unmerge("---", unmerge_desc["!found"], file_type, obj)
						continue

				f_match = obj[len(eroot)-1:]
				ignore = False
				for pattern in uninstall_ignore:
					if fnmatch.fnmatch(f_match, pattern):
						ignore = True
						break

				if not ignore:
					if islink and f_match in \
						("/lib", "/usr/lib", "/usr/local/lib"):
						# Ignore libdir symlinks for bug #423127.
						ignore = True

				if ignore:
					show_unmerge("---", unmerge_desc["cfgpro"], file_type, obj)
					continue

				# don't use EROOT, CONTENTS entries already contain EPREFIX
				if obj.startswith(real_root):
					relative_path = obj[real_root_len:]
					is_owned = False
					for dblnk in others_in_slot:
						if dblnk.isowner(relative_path):
							is_owned = True
							break

					if is_owned and islink and \
						file_type in ("sym", "dir") and \
						statobj and stat.S_ISDIR(statobj.st_mode):
						# A new instance of this package claims the file, so
						# don't unmerge it. If the file is symlink to a
						# directory and the unmerging package installed it as
						# a symlink, but the new owner has it listed as a
						# directory, then we'll produce a warning since the
						# symlink is a sort of orphan in this case (see
						# bug #326685).
						symlink_orphan = False
						for dblnk in others_in_slot:
							parent_contents_key = \
								dblnk._match_contents(relative_path)
							if not parent_contents_key:
								continue
							if not parent_contents_key.startswith(
								real_root):
								continue
							if dblnk.getcontents()[
								parent_contents_key][0] == "dir":
								symlink_orphan = True
								break

						if symlink_orphan:
							protected_symlinks.setdefault(
								(statobj.st_dev, statobj.st_ino),
								[]).append(relative_path)

					if is_owned:
						show_unmerge("---", unmerge_desc["replaced"], file_type, obj)
						continue
					elif relative_path in cfgfiledict:
						stale_confmem.append(relative_path)

				# Don't unlink symlinks to directories here since that can
				# remove /lib and /usr/lib symlinks.
				if unmerge_orphans and \
					lstatobj and not stat.S_ISDIR(lstatobj.st_mode) and \
					not (islink and statobj and stat.S_ISDIR(statobj.st_mode)) and \
					not self.isprotected(obj):
					try:
						unlink(obj, lstatobj)
					except EnvironmentError as e:
						if e.errno not in ignored_unlink_errnos:
							raise
						del e
					show_unmerge("<<<", "", file_type, obj)
					continue

				lmtime = str(lstatobj[stat.ST_MTIME])
				if (pkgfiles[objkey][0] not in ("dir", "fif", "dev")) and (lmtime != pkgfiles[objkey][1]):
					show_unmerge("---", unmerge_desc["!mtime"], file_type, obj)
					continue

				if file_type == "dir" and not islink:
					if lstatobj is None or not stat.S_ISDIR(lstatobj.st_mode):
						show_unmerge("---", unmerge_desc["!dir"], file_type, obj)
						continue
					mydirs.add((obj, (lstatobj.st_dev, lstatobj.st_ino)))
				elif file_type == "sym" or (file_type == "dir" and islink):
					if not islink:
						show_unmerge("---", unmerge_desc["!sym"], file_type, obj)
						continue

					# If this symlink points to a directory then we don't want
					# to unmerge it if there are any other packages that
					# installed files into the directory via this symlink
					# (see bug #326685).
					# TODO: Resolving a symlink to a directory will require
					# simulation if $ROOT != / and the link is not relative.
					if islink and statobj and stat.S_ISDIR(statobj.st_mode) \
						and obj.startswith(real_root):

						relative_path = obj[real_root_len:]
						try:
							target_dir_contents = os.listdir(obj)
						except OSError:
							pass
						else:
							if target_dir_contents:
								# If all the children are regular files owned
								# by this package, then the symlink should be
								# safe to unmerge.
								all_owned = True
								for child in target_dir_contents:
									child = os.path.join(relative_path, child)
									if not self.isowner(child):
										all_owned = False
										break
									try:
										child_lstat = os.lstat(os.path.join(
											real_root, child.lstrip(os.sep)))
									except OSError:
										continue

									if not stat.S_ISREG(child_lstat.st_mode):
										# Nested symlinks or directories make
										# the issue very complex, so just
										# preserve the symlink in order to be
										# on the safe side.
										all_owned = False
										break

								if not all_owned:
									protected_symlinks.setdefault(
										(statobj.st_dev, statobj.st_ino),
										[]).append(relative_path)
									show_unmerge("---", unmerge_desc["!empty"],
										file_type, obj)
									continue

					# Go ahead and unlink symlinks to directories here when
					# they're actually recorded as symlinks in the contents.
					# Normally, symlinks such as /lib -> lib64 are not recorded
					# as symlinks in the contents of a package.  If a package
					# installs something into ${D}/lib/, it is recorded in the
					# contents as a directory even if it happens to correspond
					# to a symlink when it's merged to the live filesystem.
					try:
						unlink(obj, lstatobj)
						show_unmerge("<<<", "", file_type, obj)
					except (OSError, IOError) as e:
						if e.errno not in ignored_unlink_errnos:
							raise
						del e
						show_unmerge("!!!", "", file_type, obj)
				elif pkgfiles[objkey][0] == "obj":
					if statobj is None or not stat.S_ISREG(statobj.st_mode):
						show_unmerge("---", unmerge_desc["!obj"], file_type, obj)
						continue
					mymd5 = None
					try:
						mymd5 = perf_md5(obj, calc_prelink=calc_prelink)
					except FileNotFound as e:
						# the file has disappeared between now and our stat call
						show_unmerge("---", unmerge_desc["!obj"], file_type, obj)
						continue

					# string.lower is needed because db entries used to be in upper-case.  The
					# string.lower allows for backwards compatibility.
					if mymd5 != pkgfiles[objkey][2].lower():
						show_unmerge("---", unmerge_desc["!md5"], file_type, obj)
						continue
					try:
						unlink(obj, lstatobj)
					except (OSError, IOError) as e:
						if e.errno not in ignored_unlink_errnos:
							raise
						del e
					show_unmerge("<<<", "", file_type, obj)
				elif pkgfiles[objkey][0] == "fif":
					if not stat.S_ISFIFO(lstatobj[stat.ST_MODE]):
						show_unmerge("---", unmerge_desc["!fif"], file_type, obj)
						continue
					show_unmerge("---", "", file_type, obj)
				elif pkgfiles[objkey][0] == "dev":
					show_unmerge("---", "", file_type, obj)

			self._unmerge_dirs(mydirs, infodirs_inodes,
				protected_symlinks, unmerge_desc, unlink, os)
			mydirs.clear()

		if protected_symlinks:
			self._unmerge_protected_symlinks(others_in_slot, infodirs_inodes,
				protected_symlinks, unmerge_desc, unlink, os)

		if protected_symlinks:
			msg = "One or more symlinks to directories have been " + \
				"preserved in order to ensure that files installed " + \
				"via these symlinks remain accessible. " + \
				"This indicates that the mentioned symlink(s) may " + \
				"be obsolete remnants of an old install, and it " + \
				"may be appropriate to replace a given symlink " + \
				"with the directory that it points to."
			lines = textwrap.wrap(msg, 72)
			lines.append("")
			flat_list = set()
			flat_list.update(*protected_symlinks.values())
			flat_list = sorted(flat_list)
			for f in flat_list:
				lines.append("\t%s" % (os.path.join(real_root,
					f.lstrip(os.sep))))
			lines.append("")
			self._elog("elog", "postrm", lines)

		# Remove stale entries from config memory.
		if stale_confmem:
			for filename in stale_confmem:
				del cfgfiledict[filename]
			writedict(cfgfiledict, self.vartree.dbapi._conf_mem_file)

		#remove self from vartree database so that our own virtual gets zapped if we're the last node
		self.vartree.zap(self.mycpv)

	def _unmerge_protected_symlinks(self, others_in_slot, infodirs_inodes,
		protected_symlinks, unmerge_desc, unlink, os):

		real_root = self.settings['ROOT']
		show_unmerge = self._show_unmerge
		ignored_unlink_errnos = self._ignored_unlink_errnos

		flat_list = set()
		flat_list.update(*protected_symlinks.values())
		flat_list = sorted(flat_list)

		for f in flat_list:
			for dblnk in others_in_slot:
				if dblnk.isowner(f):
					# If another package in the same slot installed
					# a file via a protected symlink, return early
					# and don't bother searching for any other owners.
					return

		msg = []
		msg.append("")
		msg.append(_("Directory symlink(s) may need protection:"))
		msg.append("")

		for f in flat_list:
			msg.append("\t%s" % \
				os.path.join(real_root, f.lstrip(os.path.sep)))

		msg.append("")
		msg.append(_("Searching all installed"
			" packages for files installed via above symlink(s)..."))
		msg.append("")
		self._elog("elog", "postrm", msg)

		self.lockdb()
		try:
			owners = self.vartree.dbapi._owners.get_owners(flat_list)
			self.vartree.dbapi.flush_cache()
		finally:
			self.unlockdb()

		for owner in list(owners):
			if owner.mycpv == self.mycpv:
				owners.pop(owner, None)

		if not owners:
			msg = []
			msg.append(_("The above directory symlink(s) are all "
				"safe to remove. Removing them now..."))
			msg.append("")
			self._elog("elog", "postrm", msg)
			dirs = set()
			for unmerge_syms in protected_symlinks.values():
				for relative_path in unmerge_syms:
					obj = os.path.join(real_root,
						relative_path.lstrip(os.sep))
					parent = os.path.dirname(obj)
					while len(parent) > len(self._eroot):
						try:
							lstatobj = os.lstat(parent)
						except OSError:
							break
						else:
							dirs.add((parent,
								(lstatobj.st_dev, lstatobj.st_ino)))
							parent = os.path.dirname(parent)
					try:
						unlink(obj, os.lstat(obj))
						show_unmerge("<<<", "", "sym", obj)
					except (OSError, IOError) as e:
						if e.errno not in ignored_unlink_errnos:
							raise
						del e
						show_unmerge("!!!", "", "sym", obj)

			protected_symlinks.clear()
			self._unmerge_dirs(dirs, infodirs_inodes,
				protected_symlinks, unmerge_desc, unlink, os)
			dirs.clear()

	def _unmerge_dirs(self, dirs, infodirs_inodes,
		protected_symlinks, unmerge_desc, unlink, os):

		show_unmerge = self._show_unmerge
		infodir_cleanup = self._infodir_cleanup
		ignored_unlink_errnos = self._ignored_unlink_errnos
		ignored_rmdir_errnos = self._ignored_rmdir_errnos
		real_root = self.settings['ROOT']

		dirs = sorted(dirs)
		dirs.reverse()

		for obj, inode_key in dirs:
			# Treat any directory named "info" as a candidate here,
			# since it might have been in INFOPATH previously even
			# though it may not be there now.
			if inode_key in infodirs_inodes or \
				os.path.basename(obj) == "info":
				try:
					remaining = os.listdir(obj)
				except OSError:
					pass
				else:
					cleanup_info_dir = ()
					if remaining and \
						len(remaining) <= len(infodir_cleanup):
						if not set(remaining).difference(infodir_cleanup):
							cleanup_info_dir = remaining

					for child in cleanup_info_dir:
						child = os.path.join(obj, child)
						try:
							lstatobj = os.lstat(child)
							if stat.S_ISREG(lstatobj.st_mode):
								unlink(child, lstatobj)
								show_unmerge("<<<", "", "obj", child)
						except EnvironmentError as e:
							if e.errno not in ignored_unlink_errnos:
								raise
							del e
							show_unmerge("!!!", "", "obj", child)

			try:
				parent_name = os.path.dirname(obj)
				parent_stat = os.stat(parent_name)

				if bsd_chflags:
					lstatobj = os.lstat(obj)
					if lstatobj.st_flags != 0:
						bsd_chflags.lchflags(obj, 0)

					# Use normal stat/chflags for the parent since we want to
					# follow any symlinks to the real parent directory.
					pflags = parent_stat.st_flags
					if pflags != 0:
						bsd_chflags.chflags(parent_name, 0)
				try:
					os.rmdir(obj)
				finally:
					if bsd_chflags and pflags != 0:
						# Restore the parent flags we saved before unlinking
						bsd_chflags.chflags(parent_name, pflags)

				# Record the parent directory for use in syncfs calls.
				# Note that we use a realpath and a regular stat here, since
				# we want to follow any symlinks back to the real device where
				# the real parent directory resides.
				self._merged_path(os.path.realpath(parent_name), parent_stat)

				show_unmerge("<<<", "", "dir", obj)
			except EnvironmentError as e:
				if e.errno not in ignored_rmdir_errnos:
					raise
				if e.errno != errno.ENOENT:
					show_unmerge("---", unmerge_desc["!empty"], "dir", obj)

				# Since we didn't remove this directory, record the directory
				# itself for use in syncfs calls, if we have removed another
				# file from the same device.
				# Note that we use a realpath and a regular stat here, since
				# we want to follow any symlinks back to the real device where
				# the real directory resides.
				try:
					dir_stat = os.stat(obj)
				except OSError:
					pass
				else:
					if dir_stat.st_dev in self._device_path_map:
						self._merged_path(os.path.realpath(obj), dir_stat)

			else:
				# When a directory is successfully removed, there's
				# no need to protect symlinks that point to it.
				unmerge_syms = protected_symlinks.pop(inode_key, None)
				if unmerge_syms is not None:
					for relative_path in unmerge_syms:
						obj = os.path.join(real_root,
							relative_path.lstrip(os.sep))
						try:
							unlink(obj, os.lstat(obj))
							show_unmerge("<<<", "", "sym", obj)
						except (OSError, IOError) as e:
							if e.errno not in ignored_unlink_errnos:
								raise
							del e
							show_unmerge("!!!", "", "sym", obj)

	def isowner(self, filename, destroot=None):
		"""
		Check if a file belongs to this package. This may
		result in a stat call for the parent directory of
		every installed file, since the inode numbers are
		used to work around the problem of ambiguous paths
		caused by symlinked directories. The results of
		stat calls are cached to optimize multiple calls
		to this method.

		@param filename:
		@type filename:
		@param destroot:
		@type destroot:
		@rtype: Boolean
		@return:
		1. True if this package owns the file.
		2. False if this package does not own the file.
		"""

		if destroot is not None and destroot != self._eroot:
			warnings.warn("The second parameter of the " + \
				"portage.dbapi.vartree.dblink.isowner()" + \
				" is now unused. Instead " + \
				"self.settings['EROOT'] will be used.",
				DeprecationWarning, stacklevel=2)

		return bool(self._match_contents(filename))

	def _match_contents(self, filename, destroot=None):
		"""
		The matching contents entry is returned, which is useful
		since the path may differ from the one given by the caller,
		due to symlinks.

		@rtype: String
		@return: the contents entry corresponding to the given path, or False
			if the file is not owned by this package.
		"""

		filename = _unicode_decode(filename,
			encoding=_encodings['content'], errors='strict')

		if destroot is not None and destroot != self._eroot:
			warnings.warn("The second parameter of the " + \
				"portage.dbapi.vartree.dblink._match_contents()" + \
				" is now unused. Instead " + \
				"self.settings['ROOT'] will be used.",
				DeprecationWarning, stacklevel=2)

		# don't use EROOT here, image already contains EPREFIX
		destroot = self.settings['ROOT']

		# The given filename argument might have a different encoding than the
		# the filenames contained in the contents, so use separate wrapped os
		# modules for each. The basename is more likely to contain non-ascii
		# characters than the directory path, so use os_filename_arg for all
		# operations involving the basename of the filename arg.
		os_filename_arg = _os_merge
		os = _os_merge

		try:
			_unicode_encode(filename,
				encoding=_encodings['merge'], errors='strict')
		except UnicodeEncodeError:
			# The package appears to have been merged with a
			# different value of sys.getfilesystemencoding(),
			# so fall back to utf_8 if appropriate.
			try:
				_unicode_encode(filename,
					encoding=_encodings['fs'], errors='strict')
			except UnicodeEncodeError:
				pass
			else:
				os_filename_arg = portage.os

		destfile = normalize_path(
			os_filename_arg.path.join(destroot,
			filename.lstrip(os_filename_arg.path.sep)))

		pkgfiles = self.getcontents()
		if pkgfiles and destfile in pkgfiles:
			return destfile
		if pkgfiles:
			basename = os_filename_arg.path.basename(destfile)
			if self._contents_basenames is None:

				try:
					for x in pkgfiles:
						_unicode_encode(x,
							encoding=_encodings['merge'],
							errors='strict')
				except UnicodeEncodeError:
					# The package appears to have been merged with a
					# different value of sys.getfilesystemencoding(),
					# so fall back to utf_8 if appropriate.
					try:
						for x in pkgfiles:
							_unicode_encode(x,
								encoding=_encodings['fs'],
								errors='strict')
					except UnicodeEncodeError:
						pass
					else:
						os = portage.os

				self._contents_basenames = set(
					os.path.basename(x) for x in pkgfiles)
			if basename not in self._contents_basenames:
				# This is a shortcut that, in most cases, allows us to
				# eliminate this package as an owner without the need
				# to examine inode numbers of parent directories.
				return False

			# Use stat rather than lstat since we want to follow
			# any symlinks to the real parent directory.
			parent_path = os_filename_arg.path.dirname(destfile)
			try:
				parent_stat = os_filename_arg.stat(parent_path)
			except EnvironmentError as e:
				if e.errno != errno.ENOENT:
					raise
				del e
				return False
			if self._contents_inodes is None:

				if os is _os_merge:
					try:
						for x in pkgfiles:
							_unicode_encode(x,
								encoding=_encodings['merge'],
								errors='strict')
					except UnicodeEncodeError:
						# The package appears to have been merged with a
						# different value of sys.getfilesystemencoding(),
						# so fall back to utf_8 if appropriate.
						try:
							for x in pkgfiles:
								_unicode_encode(x,
									encoding=_encodings['fs'],
									errors='strict')
						except UnicodeEncodeError:
							pass
						else:
							os = portage.os

				self._contents_inodes = {}
				parent_paths = set()
				for x in pkgfiles:
					p_path = os.path.dirname(x)
					if p_path in parent_paths:
						continue
					parent_paths.add(p_path)
					try:
						s = os.stat(p_path)
					except OSError:
						pass
					else:
						inode_key = (s.st_dev, s.st_ino)
						# Use lists of paths in case multiple
						# paths reference the same inode.
						p_path_list = self._contents_inodes.get(inode_key)
						if p_path_list is None:
							p_path_list = []
							self._contents_inodes[inode_key] = p_path_list
						if p_path not in p_path_list:
							p_path_list.append(p_path)

			p_path_list = self._contents_inodes.get(
				(parent_stat.st_dev, parent_stat.st_ino))
			if p_path_list:
				for p_path in p_path_list:
					x = os_filename_arg.path.join(p_path, basename)
					if x in pkgfiles:
						return x

		return False

	def _linkmap_rebuild(self, **kwargs):
		"""
		Rebuild the self._linkmap if it's not broken due to missing
		scanelf binary. Also, return early if preserve-libs is disabled
		and the preserve-libs registry is empty.
		"""
		if self._linkmap_broken or \
			self.vartree.dbapi._linkmap is None or \
			self.vartree.dbapi._plib_registry is None or \
			("preserve-libs" not in self.settings.features and \
			not self.vartree.dbapi._plib_registry.hasEntries()):
			return
		try:
			self.vartree.dbapi._linkmap.rebuild(**kwargs)
		except CommandNotFound as e:
			self._linkmap_broken = True
			self._display_merge(_("!!! Disabling preserve-libs " \
				"due to error: Command Not Found: %s\n") % (e,),
				level=logging.ERROR, noiselevel=-1)

	def _find_libs_to_preserve(self, unmerge=False):
		"""
		Get set of relative paths for libraries to be preserved. When
		unmerge is False, file paths to preserve are selected from
		self._installed_instance. Otherwise, paths are selected from
		self.
		"""
		if self._linkmap_broken or \
			self.vartree.dbapi._linkmap is None or \
			self.vartree.dbapi._plib_registry is None or \
			(not unmerge and self._installed_instance is None) or \
			not self._preserve_libs:
			return set()

		os = _os_merge
		linkmap = self.vartree.dbapi._linkmap
		if unmerge:
			installed_instance = self
		else:
			installed_instance = self._installed_instance
		old_contents = installed_instance.getcontents()
		root = self.settings['ROOT']
		root_len = len(root) - 1
		lib_graph = digraph()
		path_node_map = {}

		def path_to_node(path):
			node = path_node_map.get(path)
			if node is None:
				node = LinkageMap._LibGraphNode(linkmap._obj_key(path))
				alt_path_node = lib_graph.get(node)
				if alt_path_node is not None:
					node = alt_path_node
				node.alt_paths.a