don't purge directly, but remove and do purge at the end

If we want a package to be purged from the system tell dpkg in the
ordering (if it has to touch it explicitly) to remove it and cover the
purging of the config files at the end with a --purge --pending call.

That should help packages move conffiles around between packages
correctly even if the user is purging packages directly in big actions
like dist-upgrades involving many packages.

1 files changed, 86 insertions, 61 deletions

diff --git a/apt-pkg/deb/dpkgpm.cc b/apt-pkg/deb/dpkgpm.cc
index e4f9550b0..b47988d6c 100644
--- a/apt-pkg/deb/dpkgpm.cc
+++ b/apt-pkg/deb/dpkgpm.cc
@@ -51,6 +51,7 @@
 #include <map>
 #include <set>
 #include <string>
+#include <type_traits>
 #include <utility>
 #include <vector>
 #include <sstream>
@@ -1273,6 +1274,15 @@ static void cleanUpTmpDir(char * const tmpdir)				/*{{{*/
  */
 bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
 {
+   // we remove the last configures (and after that removes) from the list here
+   // as they will be covered by the pending calls, so explicit calls are busy work
+   decltype(List)::const_iterator::difference_type const explicitIdx =
+      std::distance(List.cbegin(),
+	    _config->FindB("Dpkg::ExplicitLastConfigure", false) ? List.cend() :
+	    std::find_if_not(
+	       std::find_if_not(List.crbegin(), List.crend(), [](Item const &i) { return i.Op == Item::Configure; }),
+	       List.crend(), [](Item const &i) { return i.Op == Item::Remove || i.Op == Item::Purge; }).base());
+
    auto const ItemIsEssential = [](pkgDPkgPM::Item const &I) {
       static auto const cachegen = _config->Find("pkgCacheGen::Essential");
       if (cachegen == "none" || cachegen == "native")
@@ -1282,6 +1292,13 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
       return (I.Pkg->Flags & pkgCache::Flag::Essential) != 0;
    };
 
+   auto const StripAlreadyDoneFromPending = [&](APT::VersionVector & Pending) {
+      Pending.erase(std::remove_if(Pending.begin(), Pending.end(), [&](pkgCache::VerIterator const &Ver) {
+	    auto const PN = Ver.ParentPkg().FullName();
+	    return PackageOps[PN].size() <= PackageOpsDone[PN];
+	 }), Pending.end());
+   };
+
    pkgPackageManager::SigINTStop = false;
    d->progress = progress;
 
@@ -1329,28 +1346,9 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
    // FIXME: workaround for dpkg bug, see our ./test-bug-740843-versioned-up-down-breaks test
    bool const dpkg_recursive_install_numbered = _config->FindB("dpkg::install::recursive::numbered", true);
 
-   decltype(List)::const_iterator::difference_type const notconfidx =
-      _config->FindB("Dpkg::ExplicitLastConfigure", false) ? std::numeric_limits<decltype(notconfidx)>::max() :
-      std::distance(List.cbegin(), std::find_if_not(List.crbegin(), List.crend(), [](Item const &i) { return i.Op == Item::Configure; }).base());
-
-   // support subpressing of triggers processing for special
-   // cases like d-i that runs the triggers handling manually
-   bool const TriggersPending = _config->FindB("DPkg::TriggersPending", false);
-   bool const ConfigurePending = _config->FindB("DPkg::ConfigurePending", true);
-   if (ConfigurePending)
-      List.push_back(Item(Item::ConfigurePending, PkgIterator()));
-
    // for the progress
    BuildPackagesProgressMap();
 
-   if (notconfidx != std::numeric_limits<decltype(notconfidx)>::max())
-   {
-      if (ConfigurePending)
-	 List.erase(std::next(List.begin(), notconfidx), std::prev(List.end()));
-      else
-	 List.erase(std::next(List.begin(), notconfidx), List.end());
-   }
-
    APT::StateChanges currentStates;
    if (_config->FindB("dpkg::selection::current::saveandrestore", true))
    {
@@ -1388,34 +1386,29 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
 	 return false;
       }
 
-      {
-	 std::vector<bool> toBeRemoved(Cache.Head().PackageCount, false);
-	 std::vector<bool> toBePurged(Cache.Head().PackageCount, false);
-	 for (auto Pkg = Cache.PkgBegin(); Pkg.end() == false; ++Pkg)
-	    if (Cache[Pkg].Purge())
-	       toBePurged[Pkg->ID] = true;
-	    else if (Cache[Pkg].Delete())
-	       toBeRemoved[Pkg->ID] = true;
-	 for (auto && I: approvedStates.Remove())
-	    toBeRemoved[I.ParentPkg()->ID] = false;
-	 for (auto && I: approvedStates.Purge())
-	    toBePurged[I.ParentPkg()->ID] = false;
-	 if (std::find(toBeRemoved.begin(), toBeRemoved.end(), true) != toBeRemoved.end())
-	 {
-	    if (ConfigurePending)
-	       List.emplace(std::prev(List.end()), Item::RemovePending, pkgCache::PkgIterator());
-	    else
-	       List.emplace_back(Item::RemovePending, pkgCache::PkgIterator());
-	 }
-	 if (std::find(toBePurged.begin(), toBePurged.end(), true) != toBePurged.end())
-	 {
-	    if (ConfigurePending)
-	       List.emplace(std::prev(List.end()), Item::PurgePending, pkgCache::PkgIterator());
-	    else
-	       List.emplace_back(Item::PurgePending, pkgCache::PkgIterator());
-	 }
-      }
+      List.erase(std::next(List.begin(), explicitIdx), List.end());
+
+      std::vector<bool> toBeRemoved(Cache.Head().PackageCount, false);
+      for (auto && I: approvedStates.Remove())
+	 toBeRemoved[I.ParentPkg()->ID] = true;
+      for (auto && I: approvedStates.Purge())
+	 toBeRemoved[I.ParentPkg()->ID] = true;
+
+      for (auto && I: List)
+	 if (I.Op == Item::Remove || I.Op == Item::Purge)
+	    toBeRemoved[I.Pkg->ID] = false;
+
+      if (std::find(toBeRemoved.begin(), toBeRemoved.end(), true) != toBeRemoved.end())
+	 List.emplace_back(Item::RemovePending, pkgCache::PkgIterator());
+      if (approvedStates.Purge().empty() == false)
+	 List.emplace_back(Item::PurgePending, pkgCache::PkgIterator());
+
+      // support subpressing of triggers processing for special
+      // cases like d-i that runs the triggers handling manually
+      if (_config->FindB("DPkg::ConfigurePending", true))
+	 List.emplace_back(Item::ConfigurePending, pkgCache::PkgIterator());
    }
+   bool const TriggersPending = _config->FindB("DPkg::TriggersPending", false);
 
    d->stdin_is_dev_null = false;
 
@@ -1431,7 +1424,7 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
    d->progress->Start(d->master);
 
    // this loop is runs once per dpkg operation
-   vector<Item>::const_iterator I = List.begin();
+   vector<Item>::const_iterator I = List.cbegin();
    while (I != List.end())
    {
       // Do all actions with the same Op in one run
@@ -1448,9 +1441,10 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
 	       continue;
 	    break;
 	 }
+      else if (J->Op == Item::Remove || J->Op == Item::Purge)
+	 J = std::find_if(J, List.cend(), [](Item const &I) { return I.Op != Item::Remove && I.Op != Item::Purge; });
       else
-	 for (; J != List.end() && J->Op == I->Op; ++J)
-	    /* nothing */;
+	 J = std::find_if(J, List.cend(), [&J](Item const &I) { return I.Op != J->Op; });
 
       auto const size = (J - I) + 10;
 
@@ -1483,17 +1477,11 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
       switch (I->Op)
       {
 	 case Item::Remove:
-	 ADDARGC("--force-depends");
-	 if (std::any_of(I, J, ItemIsEssential))
-	    ADDARGC("--force-remove-essential");
-	 ADDARGC("--remove");
-	 break;
-
 	 case Item::Purge:
 	 ADDARGC("--force-depends");
 	 if (std::any_of(I, J, ItemIsEssential))
 	    ADDARGC("--force-remove-essential");
-	 ADDARGC("--purge");
+	 ADDARGC("--remove");
 	 break;
 
 	 case Item::Configure:
@@ -1569,10 +1557,37 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
 	    }
 	 }
       }
+      else if (I->Op == Item::RemovePending)
+      {
+	 ++I;
+	 StripAlreadyDoneFromPending(approvedStates.Remove());
+	 if (approvedStates.Remove().empty())
+	    continue;
+      }
+      else if (I->Op == Item::PurgePending)
+      {
+	 ++I;
+	 // explicit removes of packages without conffiles passthrough the purge states instantly, too.
+	 // Setting these non-installed packages up for purging generates 'unknown pkg' warnings from dpkg
+	 StripAlreadyDoneFromPending(approvedStates.Purge());
+	 if (approvedStates.Purge().empty())
+	    continue;
+	 std::remove_reference<decltype(approvedStates.Remove())>::type approvedRemoves;
+	 std::swap(approvedRemoves, approvedStates.Remove());
+	 // we apply it again here as an explicit remove in the ordering will have cleared the purge state
+	 if (approvedStates.Save(false) == false)
+	 {
+	    _error->Error("Couldn't record the approved purges as dpkg selection states");
+	    if (currentStates.Save(false) == false)
+	       _error->Error("Couldn't restore dpkg selection states which were present before this interaction!");
+	    return false;
+	 }
+	 std::swap(approvedRemoves, approvedStates.Remove());
+      }
       else
       {
 	 string const nativeArch = _config->Find("APT::Architecture");
-	 unsigned long const oldSize = I->Op == Item::Configure ? Size : 0;
+	 unsigned long const oldSize = I->Pkg.end() == false ? Size : 0;
 	 for (;I != J && Size < MaxArgBytes; ++I)
 	 {
 	    if((*I).Pkg.end() == true)
@@ -1591,8 +1606,15 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
 	    {
 	       pkgCache::VerIterator PkgVer;
 	       std::string name = I->Pkg.Name();
-	       if (Op == Item::Remove || Op == Item::Purge)
-		  PkgVer = FindToBeRemovedVersion(I->Pkg);
+	       if (Op == Item::Remove)
+		  PkgVer = I->Pkg.CurrentVer();
+	       else if (Op == Item::Purge)
+	       {
+		  // we purge later with --purge --pending, so if it isn't installed (aka rc-only), skip it here
+		  PkgVer = I->Pkg.CurrentVer();
+		  if (PkgVer.end() == true)
+		     continue;
+	       }
 	       else
 		  PkgVer = Cache[I->Pkg].InstVerIter(Cache);
 	       if (strcmp(I->Pkg.Arch(), "none") == 0)
@@ -1798,11 +1820,14 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
 
    if (d->dpkg_error.empty() == false)
    {
+      // no point in reseting packages we already completed removal for
+      StripAlreadyDoneFromPending(approvedStates.Remove());
+      StripAlreadyDoneFromPending(approvedStates.Purge());
       APT::StateChanges undo;
       auto && undoRem = approvedStates.Remove();
-      std::move(undoRem.begin(), undoRem.end(), std::back_inserter(undo.Remove()));
+      std::move(undoRem.begin(), undoRem.end(), std::back_inserter(undo.Install()));
       auto && undoPur = approvedStates.Purge();
-      std::move(undoPur.begin(), undoPur.end(), std::back_inserter(undo.Purge()));
+      std::move(undoPur.begin(), undoPur.end(), std::back_inserter(undo.Install()));
       approvedStates.clear();
       if (undo.Save(false) == false)
 	 _error->Error("Couldn't revert dpkg selection for approved remove/purge after an error was encountered!");