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.

1 files changed, 36 insertions, 6 deletions

diff --git a/apt-pkg/deb/dpkgpm.cc b/apt-pkg/deb/dpkgpm.cc
index c82a09b09..38285d14b 100644
--- a/apt-pkg/deb/dpkgpm.cc
+++ b/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"));