save and restore selection states before/after calling dpkg

dpkg decides certain things on its own based on selections and
especially if we want to call --pending on purge/remove actions, we need
to ensure a clean slate or otherwise we surprise the user by removing
packages we weren't allowed to remove by the user in this run (the
selection might be an overarching plan for the not-yet "future").

Ideally dpkg would have some kind of temporal selection interface for
this case, but it hasn't, so we make it temporal with the risk of
loosing state if we don't manage to restore them.

apt-pkg/deb/dpkgpm.cc

@@ -19,6 +19,7 @@
 #include <apt-pkg/install-progress.h>
 #include <apt-pkg/packagemanager.h>
 #include <apt-pkg/strutl.h>
+#include <apt-pkg/statechanges.h>
 #include <apt-pkg/cacheiterators.h>
 #include <apt-pkg/macros.h>
 #include <apt-pkg/pkgcache.h>
@@ -208,6 +209,14 @@ pkgCache::VerIterator FindNowVersion(const pkgCache::PkgIterator &Pkg)
    return Ver;
 }
 									/*}}}*/
+static pkgCache::VerIterator FindToBeRemovedVersion(pkgCache::PkgIterator const &Pkg)/*{{{*/
+{
+   auto const PV = Pkg.CurrentVer();
+   if (PV.end() == false)
+      return PV;
+   return FindNowVersion(Pkg);
+}
+									/*}}}*/
 
 // DPkgPM::pkgDPkgPM - Constructor					/*{{{*/
 // ---------------------------------------------------------------------
@@ -1342,6 +1351,28 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
 	 List.erase(std::next(List.begin(), notconfidx), List.end());
    }
 
+   APT::StateChanges currentStates;
+   if (_config->FindB("dpkg::selection::current::saveandrestore", true))
+   {
+      for (auto Pkg = Cache.PkgBegin(); Pkg.end() == false; ++Pkg)
+	 if (Pkg->CurrentVer == 0)
+	    continue;
+	 else if (Pkg->SelectedState == pkgCache::State::Purge)
+	    currentStates.Purge(FindToBeRemovedVersion(Pkg));
+	 else if (Pkg->SelectedState == pkgCache::State::DeInstall)
+	    currentStates.Remove(FindToBeRemovedVersion(Pkg));
+      if (currentStates.empty() == false)
+      {
+	 APT::StateChanges cleanStates;
+	 for (auto && P: currentStates.Remove())
+	    cleanStates.Install(P);
+	 for (auto && P: currentStates.Purge())
+	    cleanStates.Install(P);
+	 if (cleanStates.Save(false) == false)
+	    return _error->Error("Couldn't clean the currently selected dpkg states");
+      }
+   }
+
    d->stdin_is_dev_null = false;
 
    // create log
@@ -1505,12 +1536,8 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
 	    {
 	       pkgCache::VerIterator PkgVer;
 	       std::string name = I->Pkg.Name();
-	       if (Op == Item::Remove || Op == Item::Purge) 
-               {
-		  PkgVer = I->Pkg.CurrentVer();
-                  if(PkgVer.end() == true)
-                     PkgVer = FindNowVersion(I->Pkg);
-               }
+	       if (Op == Item::Remove || Op == Item::Purge)
+		  PkgVer = FindToBeRemovedVersion(I->Pkg);
 	       else
 		  PkgVer = Cache[I->Pkg].InstVerIter(Cache);
 	       if (strcmp(I->Pkg.Arch(), "none") == 0)
@@ -1714,6 +1741,9 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
    StopPtyMagic();
    CloseLog();
 
+   if (currentStates.Save(false) == false)
+      _error->Error("Couldn't restore dpkg selection states which were present before this interaction!");
+
    if (pkgPackageManager::SigINTStop)
        _error->Warning(_("Operation was interrupted before it could finish"));
 

apt-pkg/statechanges.cc

@@ -25,7 +25,8 @@ public:
 #define APT_GETTERSETTER(Name, Container) \
 void StateChanges::Name(pkgCache::VerIterator const &Ver) \
 { \
-   Container.push_back(Ver); \
+   if (Ver.end() == false) \
+      Container.push_back(Ver); \
 }\
 APT::VersionVector& StateChanges::Name() \
 { \

test/integration/test-apt-get-autoremove

@@ -18,6 +18,8 @@ testmarkedauto 'po-debconf'
 testsuccess aptget remove debhelper -y
 testdpkgnotinstalled 'debhelper'
 testdpkginstalled 'po-debconf' 'unrelated'
+echo 'unrelated purge' | dpkg --set-selections
+testdpkgstatus 'pi' '1' 'unrelated'
 
 AUTOREMOVE='apt autoremove'
 if [ -n "$SUDO_USER" ]; then
@@ -49,14 +51,17 @@ testdpkginstalled 'po-debconf'
 echo 'APT::NeverAutoRemove { "^po-debconf$"; };' > rootdir/etc/apt/apt.conf.d/00autoremove
 testsuccess aptget autoremove -y
 testdpkginstalled 'po-debconf'
+testdpkgstatus 'pi' '1' 'unrelated'
 
 echo 'APT::NeverAutoRemove { "^po-.*$"; };' > rootdir/etc/apt/apt.conf.d/00autoremove
 testsuccess aptget autoremove -y
 testdpkginstalled "po-debconf"
+testdpkgstatus 'pi' '1' 'unrelated'
 
 rm rootdir/etc/apt/apt.conf.d/00autoremove
 testsuccess aptget autoremove -y
 testdpkgnotinstalled 'po-debconf'
+testdpkgstatus 'pi' '1' 'unrelated'
 testmarkedauto
 
 sed rootdir/var/log/apt/history.log -e '/^Commandline: / d' \
@@ -71,7 +76,8 @@ Remove: debhelper:i386 (8.0.0)
 Remove: po-debconf:i386 (1.0.16)'
 
 testsuccess aptget install debhelper -y
-testdpkginstalled 'unrelated' 'debhelper' 'po-debconf'
+testdpkgstatus 'pi' '1' 'unrelated'
+testdpkginstalled 'debhelper' 'po-debconf'
 testsuccess aptmark auto debhelper
 
 testmarkedauto 'debhelper' 'po-debconf'
@@ -105,9 +111,11 @@ Reading state information...
 
 testsuccess aptget autoremove debhelper -y --allow-change-held-packages
 testdpkgnotinstalled 'po-debconf' 'debhelper'
+testdpkgstatus 'pi' '1' 'unrelated'
 testmarkedauto
 testsuccess aptget install debhelper --solver apt -y -o Debug::pkgDepCache::Marker=1
 testmarkedauto 'po-debconf'
+testdpkgstatus 'pi' '1' 'unrelated'
 
 insertinstalledpackage 'bar' 'all' '1' 'Depends: foo-provider'
 insertinstalledpackage 'foo-multi1-1' 'all' '1' 'Provides: foo-provider