apt/debfile.py

#  Copyright (c) 2005-2010 Canonical
#
#  Author: Michael Vogt <michael.vogt@ubuntu.com>
#
#  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
"""Classes for working with locally available Debian packages."""
from __future__ import print_function

import apt
import apt_inst
import apt_pkg
import gzip
import os
import sys

from typing import Dict, Iterable, List, Optional, Set, Tuple, Union, cast

from apt_pkg import gettext as _
from io import BytesIO


class NoDebArchiveException(IOError):
    """Exception which is raised if a file is no Debian archive."""


class DebPackage(object):
    """A Debian Package (.deb file)."""

    # Constants for comparing the local package file with the version
    # in the cache
    (VERSION_NONE,
     VERSION_OUTDATED,
     VERSION_SAME,
     VERSION_NEWER) = range(4)

    debug = 0

    def __init__(self, filename=None, cache=None):
        # type: (Optional[str], Optional[apt.Cache]) -> None
        if cache is None:
            cache = apt.Cache()
        self._cache = cache
        self._debfile = cast(apt_inst.DebFile, None)
        self.pkgname = ""
        self.filename = None  # type: Optional[str]
        self._sections = {}  # type: Union[Dict[str, str], apt_pkg.TagSection[str]]  # noqa
        self._need_pkgs = []  # type: List[str]
        self._check_was_run = False
        self._failure_string = ""
        self._multiarch = None  # type: Optional[str]
        if filename:
            self.open(filename)

    def open(self, filename):
        # type: (str) -> None
        """ open given debfile """
        self._dbg(3, "open '%s'" % filename)
        self._need_pkgs = []
        self._installed_conflicts = set()  # type: Set[str]
        self._failure_string = ""
        self.filename = filename
        self._debfile = apt_inst.DebFile(self.filename)
        control = self._debfile.control.extractdata("control")
        self._sections = apt_pkg.TagSection(control)
        self.pkgname = self._sections["Package"]
        self._check_was_run = False

    def __getitem__(self, key):
        # type: (str) -> str
        return self._sections[key]

    def __contains__(self, key):
        # type: (str) -> bool
        return key in self._sections

    @property
    def filelist(self):
        # type: () -> List[str]
        """return the list of files in the deb."""
        files = []
        try:
            self._debfile.data.go(lambda item, data: files.append(item.name))
        except SystemError:
            return [_("List of files for '%s' could not be read") %
                    self.filename]
        return files

    @property
    def control_filelist(self):
        # type: () -> List[str]
        """ return the list of files in control.tar.gz """
        control = []
        try:
            self._debfile.control.go(
                lambda item, data: control.append(item.name))
        except SystemError:
            return [_("List of control files for '%s' could not be read") %
                    self.filename]
        return sorted(control)

    # helper that will return a pkgname with a multiarch suffix if needed
    def _maybe_append_multiarch_suffix(self, pkgname,
                                       in_conflict_checking=False):
        # type: (str, bool) -> str
        # trivial cases
        if ":" in pkgname:
            return pkgname
        if not self._multiarch:
            return pkgname
        elif self._cache.is_virtual_package(pkgname):
            return pkgname
        elif (pkgname in self._cache and
              self._cache[pkgname].candidate is not None and
              cast(apt.package.Version,
                   self._cache[pkgname].candidate).architecture == "all"):
            return pkgname
        # now do the real multiarch checking
        multiarch_pkgname = "%s:%s" % (pkgname, self._multiarch)
        # the upper layers will handle this
        if multiarch_pkgname not in self._cache:
            return multiarch_pkgname
        multiarch_pkg = self._cache[multiarch_pkgname]
        if multiarch_pkg.candidate is None:
            return multiarch_pkgname
        # now check the multiarch state
        cand = multiarch_pkg.candidate._cand
        #print pkgname, multiarch_pkgname, cand.multi_arch
        # the default is to add the suffix, unless its a pkg that can satify
        # foreign dependencies
        if cand.multi_arch & cand.MULTI_ARCH_FOREIGN:
            return pkgname
        # for conflicts we need a special case here, any not multiarch enabled
        # package has a implicit conflict
        if (in_conflict_checking and
                not (cand.multi_arch & cand.MULTI_ARCH_SAME)):
            return pkgname
        return multiarch_pkgname

    def _is_or_group_satisfied(self, or_group):
        # type: (List[Tuple[str, str, str]]) -> bool
        """Return True if at least one dependency of the or-group is satisfied.

        This method gets an 'or_group' and analyzes if at least one dependency
        of this group is already satisfied.
        """
        self._dbg(2, "_checkOrGroup(): %s " % (or_group))

        for dep in or_group:
            depname = dep[0]
            ver = dep[1]
            oper = dep[2]

            # multiarch
            depname = self._maybe_append_multiarch_suffix(depname)

            # check for virtual pkgs
            if depname not in self._cache:
                if self._cache.is_virtual_package(depname):
                    self._dbg(
                        3, "_is_or_group_satisfied(): %s is virtual dep" %
                        depname)
                    for pkg in self._cache.get_providing_packages(depname):
                        if pkg.is_installed:
                            return True
                continue
            # check real dependency
            inst = self._cache[depname].installed
            if inst is not None and apt_pkg.check_dep(inst.version, oper, ver):
                return True

            # if no real dependency is installed, check if there is
            # a package installed that provides this dependency
            # (e.g. scrollkeeper dependecies are provided by rarian-compat)
            # but only do that if there is no version required in the
            # dependency (we do not supprot versionized dependencies)
            if not oper:
                for ppkg in self._cache.get_providing_packages(
                    depname, include_nonvirtual=True):
                    if ppkg.is_installed:
                        self._dbg(
                            3, "found installed '%s' that provides '%s'" % (
                                ppkg.name, depname))
                        return True
        return False

    def _satisfy_or_group(self, or_group):
        # type: (List[Tuple[str, str, str]]) -> bool
        """Try to satisfy the or_group."""
        for dep in or_group:
            depname, ver, oper = dep

            # multiarch
            depname = self._maybe_append_multiarch_suffix(depname)

            # if we don't have it in the cache, it may be virtual
            if depname not in self._cache:
                if not self._cache.is_virtual_package(depname):
                    continue
                providers = self._cache.get_providing_packages(depname)
                # if a package just has a single virtual provider, we
                # just pick that (just like apt)
                if len(providers) != 1:
                    continue
                depname = providers[0].name

            # now check if we can satisfy the deps with the candidate(s)
            # in the cache
            pkg = self._cache[depname]
            cand = self._cache._depcache.get_candidate_ver(pkg._pkg)
            if not cand:
                continue
            if not apt_pkg.check_dep(cand.ver_str, oper, ver):
                continue

            # check if we need to install it
            self._dbg(2, "Need to get: %s" % depname)
            self._need_pkgs.append(depname)
            return True

        # if we reach this point, we failed
        or_str = ""
        for dep in or_group:
            or_str += dep[0]
            if ver and oper:
                or_str += " (%s %s)" % (dep[2], dep[1])
            if dep != or_group[len(or_group) - 1]:
                or_str += "|"
        self._failure_string += _(
            "Dependency is not satisfiable: %s\n") % or_str
        return False

    def _check_single_pkg_conflict(self, pkgname, ver, oper):
        # type: (str, str, str) -> bool
        """Return True if a pkg conflicts with a real installed/marked pkg."""
        # FIXME: deal with conflicts against its own provides
        #        (e.g. Provides: ftp-server, Conflicts: ftp-server)
        self._dbg(
            3, "_check_single_pkg_conflict() pkg='%s' ver='%s' oper='%s'" % (
                pkgname, ver, oper))
        pkg = self._cache[pkgname]
        if pkg.is_installed:
            assert pkg.installed is not None
            pkgver = pkg.installed.version
        elif pkg.marked_install:
            assert pkg.candidate is not None
            pkgver = pkg.candidate.version
        else:
            return False
        #print "pkg: %s" % pkgname
        #print "ver: %s" % ver
        #print "pkgver: %s " % pkgver
        #print "oper: %s " % oper
        if (apt_pkg.check_dep(pkgver, oper, ver) and not
                self.replaces_real_pkg(pkgname, oper, ver)):
            self._failure_string += _("Conflicts with the installed package "
                                      "'%s'") % pkg.name
            self._dbg(3, "conflicts with installed pkg '%s'" % pkg.name)
            return True
        return False

    def _check_conflicts_or_group(self, or_group):
        # type: (List[Tuple[str, str, str]]) -> bool
        """Check the or-group for conflicts with installed pkgs."""
        self._dbg(2, "_check_conflicts_or_group(): %s " % (or_group))
        for dep in or_group:
            depname = dep[0]
            ver = dep[1]
            oper = dep[2]

            # FIXME: is this good enough? i.e. will apt always populate
            #        the cache with conflicting pkgnames for our arch?
            depname = self._maybe_append_multiarch_suffix(
                depname, in_conflict_checking=True)

            # check conflicts with virtual pkgs
            if depname not in self._cache:
                # FIXME: we have to check for virtual replaces here as
                #        well (to pass tests/gdebi-test8.deb)
                if self._cache.is_virtual_package(depname):
                    for pkg in self._cache.get_providing_packages(depname):
                        self._dbg(3, "conflicts virtual check: %s" % pkg.name)
                        # P/C/R on virtal pkg, e.g. ftpd
                        if self.pkgname == pkg.name:
                            self._dbg(3, "conflict on self, ignoring")
                            continue
                        if self._check_single_pkg_conflict(
                                pkg.name, ver, oper):
                            self._installed_conflicts.add(pkg.name)
                continue
            if self._check_single_pkg_conflict(depname, ver, oper):
                self._installed_conflicts.add(depname)
        return bool(self._installed_conflicts)

    @property
    def conflicts(self):
        # type: () -> List[List[Tuple[str, str, str]]]
        """List of packages conflicting with this package."""
        key = "Conflicts"
        try:
            return apt_pkg.parse_depends(self._sections[key], False)
        except KeyError:
            return []

    @property
    def depends(self):
        # type: () -> List[List[Tuple[str, str, str]]]
        """List of packages on which this package depends on."""
        depends = []
        # find depends
        for key in "Depends", "Pre-Depends":
            try:
                depends.extend(
                    apt_pkg.parse_depends(self._sections[key], False))
            except KeyError:
                pass
        return depends

    @property
    def provides(self):
        # type: () -> List[List[Tuple[str, str, str]]]
        """List of virtual packages which are provided by this package."""
        key = "Provides"
        try:
            return apt_pkg.parse_depends(self._sections[key], False)
        except KeyError:
            return []

    @property
    def replaces(self):
        # type: () -> List[List[Tuple[str, str, str]]]
        """List of packages which are replaced by this package."""
        key = "Replaces"
        try:
            return apt_pkg.parse_depends(self._sections[key], False)
        except KeyError:
            return []

    def replaces_real_pkg(self, pkgname, oper, ver):
        # type: (str, str, str) -> bool
        """Return True if a given non-virtual package is replaced.

        Return True if the deb packages replaces a real (not virtual)
        packages named (pkgname, oper, ver).
        """
        self._dbg(3, "replaces_real_pkg() %s %s %s" % (pkgname, oper, ver))
        pkg = self._cache[pkgname]
        pkgver = None  # type: Optional[str]
        if pkg.is_installed:
            assert pkg.installed is not None
            pkgver = pkg.installed.version
        elif pkg.marked_install:
            assert pkg.candidate is not None
            pkgver = pkg.candidate.version
        else:
            pkgver = None
        for or_group in self.replaces:
            for (name, ver, oper) in or_group:
                if (name == pkgname and (pkgver is None or
                        apt_pkg.check_dep(pkgver, oper, ver))):
                    self._dbg(3, "we have a replaces in our package for the "
                                 "conflict against '%s'" % (pkgname))
                    return True
        return False

    def check_conflicts(self):
        # type: () -> bool
        """Check if there are conflicts with existing or selected packages.

        Check if the package conflicts with a existing or to be installed
        package. Return True if the pkg is OK.
        """
        res = True
        for or_group in self.conflicts:
            if self._check_conflicts_or_group(or_group):
                #print "Conflicts with a exisiting pkg!"
                #self._failure_string = "Conflicts with a exisiting pkg!"
                res = False
        return res

    def check_breaks_existing_packages(self):
        # type: () -> bool
        """
        check if installing the package would break exsisting
        package on the system, e.g. system has:
        smc depends on smc-data (= 1.4)
        and user tries to installs smc-data 1.6
        """
        # show progress information as this step may take some time
        size = float(len(self._cache))
        steps = max(int(size / 50), 1)
        debver = self._sections["Version"]
        debarch = self._sections["Architecture"]
        # store what we provide so that we can later check against that
        provides = [x[0][0] for x in self.provides]
        for (i, pkg) in enumerate(self._cache):
            if i % steps == 0:
                self._cache.op_progress.update(float(i) / size * 100.0)
            if not pkg.is_installed:
                continue
            assert pkg.installed is not None
            # check if the exising dependencies are still satisfied
            # with the package
            ver = pkg._pkg.current_ver
            for dep_or in pkg.installed.dependencies:
                for dep in dep_or.or_dependencies:
                    if dep.name == self.pkgname:
                        if not apt_pkg.check_dep(
                                debver, dep.relation, dep.version):
                            self._dbg(2, "would break (depends) %s" % pkg.name)
                            # TRANSLATORS: the first '%s' is the package that
                            # breaks, the second the dependency that makes it
                            # break, the third the relation (e.g. >=) and the
                            # latest the version for the releation
                            self._failure_string += _(
                                "Breaks existing package '%(pkgname)s' "
                                "dependency %(depname)s "
                                "(%(deprelation)s %(depversion)s)") % {
                                    'pkgname': pkg.name,
                                    'depname': dep.name,
                                    'deprelation': dep.relation,
                                    'depversion': dep.version}
                            self._cache.op_progress.done()
                            return False
            # now check if there are conflicts against this package on
            # the existing system
            if "Conflicts" in ver.depends_list:
                for conflicts_ver_list in ver.depends_list["Conflicts"]:
                    for c_or in conflicts_ver_list:
                        if (c_or.target_pkg.name == self.pkgname and
                                c_or.target_pkg.architecture == debarch):
                            if apt_pkg.check_dep(
                                    debver, c_or.comp_type, c_or.target_ver):
                                self._dbg(
                                    2, "would break (conflicts) %s" % pkg.name)
                                # TRANSLATORS: the first '%s' is the package
                                # that conflicts, the second the packagename
                                # that it conflicts with (so the name of the
                                # deb the user tries to install), the third is
                                # the relation (e.g. >=) and the last is the
                                # version for the relation
                                self._failure_string += _(
                                    "Breaks existing package '%(pkgname)s' "
                                    "conflict: %(targetpkg)s "
                                    "(%(comptype)s %(targetver)s)") % {
                                        'pkgname': pkg.name,
                                        'targetpkg': c_or.target_pkg.name,
                                        'comptype': c_or.comp_type,
                                        'targetver': c_or.target_ver}
                                self._cache.op_progress.done()
                                return False
                        if (c_or.target_pkg.name in provides and
                                self.pkgname != pkg.name):
                            self._dbg(
                                2, "would break (conflicts) %s" % provides)
                            self._failure_string += _(
                                "Breaks existing package '%(pkgname)s' "
                                "that conflict: '%(targetpkg)s'. But the "
                                "'%(debfile)s' provides it via: "
                                "'%(provides)s'") % {
                                    'provides': ",".join(provides),
                                    'debfile': self.filename,
                                    'targetpkg': c_or.target_pkg.name,
                                    'pkgname': pkg.name}
                            self._cache.op_progress.done()
                            return False
        self._cache.op_progress.done()
        return True

    def compare_to_version_in_cache(self, use_installed=True):
        # type: (bool) -> int
        """Compare the package to the version available in the cache.

        Checks if the package is already installed or availabe in the cache
        and if so in what version, returns one of (VERSION_NONE,
        VERSION_OUTDATED, VERSION_SAME, VERSION_NEWER).
        """
        self._dbg(3, "compare_to_version_in_cache")
        pkgname = self._sections["Package"]
        architecture = self._sections["Architecture"]

        # Arch qualify the package name
        pkgname = ":".join([pkgname, architecture])

        debver = self._sections["Version"]
        self._dbg(1, "debver: %s" % debver)
        if pkgname in self._cache:
            pkg = self._cache[pkgname]
            if use_installed and pkg.installed is not None:
                cachever = pkg.installed.version
            elif not use_installed and pkg.candidate is not None:
                cachever = pkg.candidate.version
            else:
                return self.VERSION_NONE
            if cachever is not None:
                cmp = apt_pkg.version_compare(cachever, debver)
                self._dbg(1, "CompareVersion(debver,instver): %s" % cmp)
                if cmp == 0:
                    return self.VERSION_SAME
                elif cmp < 0:
                    return self.VERSION_NEWER
                elif cmp > 0:
                    return self.VERSION_OUTDATED
        return self.VERSION_NONE

    def check(self, allow_downgrade=False):
        # type: (bool) -> bool
        """Check if the package is installable."""
        self._dbg(3, "check")

        self._check_was_run = True

        # check arch
        if "Architecture" not in self._sections:
            self._dbg(1, "ERROR: no architecture field")
            self._failure_string = _("No Architecture field in the package")
            return False
        arch = self._sections["Architecture"]
        if arch != "all" and arch != apt_pkg.config.find("APT::Architecture"):
            if arch in apt_pkg.get_architectures():
                self._multiarch = arch
                self.pkgname = "%s:%s" % (self.pkgname, self._multiarch)
                self._dbg(1, "Found multiarch arch: '%s'" % arch)
            else:
                self._dbg(1, "ERROR: Wrong architecture dude!")
                self._failure_string = _("Wrong architecture '%s' "
                                         "-- Run dpkg --add-architecture to "
                                         "add it and update afterwards") % arch
                return False

        # check version
        if (not allow_downgrade and
            self.compare_to_version_in_cache() == self.VERSION_OUTDATED):
            if self._cache[self.pkgname].installed:
                # the deb is older than the installed
                self._failure_string = _(
                    "A later version is already installed")
                return False

        # FIXME: this sort of error handling sux
        self._failure_string = ""

        # check conflicts
        if not self.check_conflicts():
            return False

        # check if installing it would break anything on the
        # current system
        if not self.check_breaks_existing_packages():
            return False

        # try to satisfy the dependencies
        if not self._satisfy_depends(self.depends):
            return False

        # check for conflicts again (this time with the packages that are
        # makeed for install)
        if not self.check_conflicts():
            return False

        if self._cache._depcache.broken_count > 0:
            self._failure_string = _("Failed to satisfy all dependencies "
                                     "(broken cache)")
            # clean the cache again
            self._cache.clear()
            return False
        return True

    def satisfy_depends_str(self, dependsstr):
        # type: (str) -> bool
        """Satisfy the dependencies in the given string."""
        return self._satisfy_depends(apt_pkg.parse_depends(dependsstr, False))

    def _satisfy_depends(self, depends):
        # type: (List[List[Tuple[str, str, str]]]) -> bool
        """Satisfy the dependencies."""
        # turn off MarkAndSweep via a action group (if available)
        try:
            _actiongroup = apt_pkg.ActionGroup(self._cache._depcache)
            _actiongroup  # pyflakes
        except AttributeError:
            pass
        # check depends
        for or_group in depends:
            if not self._is_or_group_satisfied(or_group):
                if not self._satisfy_or_group(or_group):
                    return False
        # now try it out in the cache
        for pkg in self._need_pkgs:
            try:
                self._cache[pkg].mark_install(from_user=False)
            except SystemError:
                self._failure_string = _("Cannot install '%s'") % pkg
                self._cache.clear()
                return False
        return True

    @property
    def missing_deps(self):
        # type: () -> List[str]
        """Return missing dependencies."""
        self._dbg(1, "Installing: %s" % self._need_pkgs)
        if not self._check_was_run:
            raise AttributeError(
                "property only available after check() was run")
        return self._need_pkgs

    @property
    def required_changes(self):
        # type: () -> Tuple[List[str], List[str], List[str]]
        """Get the changes required to satisfy the dependencies.

        Returns: a tuple with (install, remove, unauthenticated)
        """
        install = []
        remove = []
        unauthenticated = []
        if not self._check_was_run:
            raise AttributeError(
                "property only available after check() was run")
        for pkg in self._cache:
            if pkg.marked_install or pkg.marked_upgrade:
                assert pkg.candidate is not None
                install.append(pkg.name)
                # check authentication, one authenticated origin is enough
                # libapt will skip non-authenticated origins then
                authenticated = False
                for origin in pkg.candidate.origins:
                    authenticated |= origin.trusted
                if not authenticated:
                    unauthenticated.append(pkg.name)
            if pkg.marked_delete:
                remove.append(pkg.name)
        return (install, remove, unauthenticated)

    @staticmethod
    def to_hex(in_data):
        # type: (str) -> str
        hex = ""
        for (i, c) in enumerate(in_data):
            if i % 80 == 0:
                hex += "\n"
            hex += "%2.2x " % ord(c)
        return hex

    @staticmethod
    def to_strish(in_data):
        # type: (Union[str, Iterable[int]]) -> str
        s = ""
        # py2 compat, in_data is type string
        if isinstance(in_data, str):
            for c in in_data:
                if ord(c) < 10 or ord(c) > 127:
                    s += " "
                else:
                    s += c
        # py3 compat, in_data is type bytes
        else:
            for b in in_data:
                if b < 10 or b > 127:
                    s += " "
                else:
                    s += chr(b)
        return s

    def _get_content(self, part, name, auto_decompress=True, auto_hex=True):
        # type: (apt_inst.TarFile, str, bool, bool) -> str
        if name.startswith("./"):
            name = name[2:]
        data = part.extractdata(name)
        # check for zip content
        if name.endswith(".gz") and auto_decompress:
            io = BytesIO(data)
            gz = gzip.GzipFile(fileobj=io)
            data = _("Automatically decompressed:\n\n").encode("utf-8")
            data += gz.read()
        # auto-convert to hex
        try:
            return data.decode("utf-8")
        except Exception:
            new_data = _("Automatically converted to printable ascii:\n")
            new_data += self.to_strish(data)
            return new_data

    def control_content(self, name):
        # type: (str) -> str
        """ return the content of a specific control.tar.gz file """
        try:
            return self._get_content(self._debfile.control, name)
        except LookupError:
            return ""

    def data_content(self, name):
        # type: (str) -> str
        """ return the content of a specific control.tar.gz file """
        try:
            return self._get_content(self._debfile.data, name)
        except LookupError:
            return ""

    def _dbg(self, level, msg):
        # type: (int, str) -> None
        """Write debugging output to sys.stderr."""
        if level <= self.debug:
            print(msg, file=sys.stderr)

    def install(self, install_progress=None):
        # type: (Optional[apt.progress.base.InstallProgress]) -> int
        """Install the package."""
        if self.filename is None:
            raise apt_pkg.Error("No filename specified")
        if install_progress is None:
            return os.spawnlp(os.P_WAIT, "dpkg", "dpkg", "-i", self.filename)
        else:
            try:
                install_progress.start_update()
            except AttributeError:
                install_progress.startUpdate()  # type: ignore
            res = install_progress.run(self.filename)
            try:
                install_progress.finish_update()
            except AttributeError:
                install_progress.finishUpdate()  # type: ignore
            return res


class DscSrcPackage(DebPackage):
    """A locally available source package."""

    def __init__(self, filename=None, cache=None):
        # type: (Optional[str], Optional[apt.Cache]) -> None
        DebPackage.__init__(self, None, cache)
        self.filename = filename  # type: Optional[str]
        self._depends = []  # type: List[List[Tuple[str, str, str]]]
        self._conflicts = []  # type: List[List[Tuple[str, str, str]]]
        self._installed_conflicts = set()  # type: Set[str]
        self.pkgname = ""
        self.binaries = []  # type: List[str]
        self._sections = {}  # type: Dict[str, str]
        if self.filename is not None:
            self.open(self.filename)

    @property
    def depends(self):
        # type: () -> List[List[Tuple[str, str, str]]]
        """Return the dependencies of the package"""
        return self._depends

    @property
    def conflicts(self):
        # type: () -> List[List[Tuple[str, str, str]]]
        """Return the dependencies of the package"""
        return self._conflicts

    @property
    def filelist(self):
        # type: () -> List[str]
        """Return the list of files associated with this dsc file"""
        # Files stanza looks like (hash, size, filename, ...)
        return self._sections['Files'].split()[2::3]

    def open(self, file):
        # type: (str) -> None
        """Open the package."""
        depends_tags = ["Build-Depends", "Build-Depends-Indep"]
        conflicts_tags = ["Build-Conflicts", "Build-Conflicts-Indep"]
        fd = apt_pkg.open_maybe_clear_signed_file(file)
        fobj = os.fdopen(fd)
        tagfile = apt_pkg.TagFile(fobj)
        try:
            for sec in tagfile:
                for tag in depends_tags:
                    if tag not in sec:
                        continue
                    self._depends.extend(apt_pkg.parse_src_depends(sec[tag]))
                for tag in conflicts_tags:
                    if tag not in sec:
                        continue
                    self._conflicts.extend(apt_pkg.parse_src_depends(sec[tag]))
                if 'Source' in sec:
                    self.pkgname = sec['Source']
                if 'Binary' in sec:
                    self.binaries = [b.strip() for b in
                                     sec['Binary'].split(',')]
                for tag in sec.keys():
                    if tag in sec:
                        self._sections[tag] = sec[tag]
        finally:
            del tagfile
            fobj.close()

        s = _("Install Build-Dependencies for "
              "source package '%s' that builds %s\n") % (self.pkgname,
              " ".join(self.binaries))
        self._sections["Description"] = s
        self._check_was_run = False

    def check(self, allow_downgrade=False):
        # type: (bool) -> bool
        """Check if the package is installable.

        The second parameter is ignored and only exists for compatibility
        with parent type."""
        if not self.check_conflicts():
            for pkgname in self._installed_conflicts:
                if self._cache[pkgname]._pkg.essential:
                    raise Exception(_("An essential package would be removed"))
                self._cache[pkgname].mark_delete()
        # properties are ok now
        self._check_was_run = True
        # FIXME: a additional run of the check_conflicts()
        #        after _satisfy_depends() should probably be done
        return self._satisfy_depends(self.depends)


def _test():
    # type: () -> None
    """Test function"""
    from apt.cache import Cache
    from apt.progress.base import InstallProgress

    cache = Cache()

    vp = "www-browser"
    print("%s virtual: %s" % (vp, cache.is_virtual_package(vp)))
    providers = cache.get_providing_packages(vp)
    print("Providers for %s :" % vp)
    for pkg in providers:
        print(" %s" % pkg.name)

    d = DebPackage(sys.argv[1], cache)
    print("Deb: %s" % d.pkgname)
    if not d.check():
        print("can't be satified")
        print(d._failure_string)
    print("missing deps: %s" % d.missing_deps)
    print(d.required_changes)

    print(d.filelist)

    print("Installing ...")
    ret = d.install(InstallProgress())
    print(ret)

    #s = DscSrcPackage(cache, "../tests/3ddesktop_0.2.9-6.dsc")
    #s.check_dep()
    #print "Missing deps: ",s.missingDeps
    #print "Print required changes: ", s.requiredChanges

    s = DscSrcPackage(cache=cache)
    ds = "libc6 (>= 2.3.2), libaio (>= 0.3.96) | libaio1 (>= 0.3.96)"
    print(s._satisfy_depends(apt_pkg.parse_depends(ds, False)))


if __name__ == "__main__":
    _test()