try to avoid removal of crossgraded packages

The user has to approve the removal of a crossgraded package as it might
be needed to remove it (temporarily) in the process, but in most cases
we can happily avoid it and let dpkg unpack over it skipping the
remove. This has some effects on progress reporting and how deal with
selections through which makes this a tiny bit complicated.

2 files changed, 189 insertions, 26 deletions

diff --git a/apt-pkg/deb/dpkgpm.cc b/apt-pkg/deb/dpkgpm.cc
index 025dfbfd3..d14155d01 100644
--- a/apt-pkg/deb/dpkgpm.cc
+++ b/apt-pkg/deb/dpkgpm.cc
@@ -670,27 +670,23 @@ void pkgDPkgPM::ProcessDpkgStatusLine(char *line)
       // if there are multiple pkgs dpkg would send us a full pkgname:arch
       pkgCache::GrpIterator Grp = Cache.FindGrp(pkgname);
       if (Grp.end() == false)
-      {
-	 pkgCache::PkgIterator P = Grp.PackageList();
-	 for (; P.end() != true; P = Grp.NextPkg(P))
-	 {
+	 for (auto P = Grp.PackageList(); P.end() != true; P = Grp.NextPkg(P))
 	    if(Cache[P].Keep() == false || Cache[P].ReInstall() == true)
 	    {
-	       pkgname = P.FullName();
+	       auto fullname = P.FullName();
+	       if (Cache[P].Delete() && PackageOps[fullname].size() <= PackageOpsDone[fullname])
+		  continue;
+	       pkgname = std::move(fullname);
 	       break;
 	    }
-	 }
-      }
    }
 
-   const char* const pkg = pkgname.c_str();
-   std::string short_pkgname = StringSplit(pkgname, ":")[0];
    std::string arch = "";
    if (pkgname.find(":") != string::npos)
       arch = StringSplit(pkgname, ":")[1];
    std::string i18n_pkgname = pkgname;
    if (arch.size() != 0)
-      strprintf(i18n_pkgname, "%s (%s)", short_pkgname.c_str(), arch.c_str());
+      strprintf(i18n_pkgname, "%s (%s)", StringSplit(pkgname, ":")[0].c_str(), arch.c_str());
 
    // 'processing' from dpkg looks like
    // 'processing: action: pkg'
@@ -720,21 +716,21 @@ void pkgDPkgPM::ProcessDpkgStatusLine(char *line)
 
    if (prefix == "status")
    {
-      std::vector<struct DpkgState> &states = PackageOps[pkg];
+      std::vector<struct DpkgState> &states = PackageOps[pkgname];
       if (action == "triggers-pending")
       {
 	 if (Debug == true)
-	    std::clog << "(parsed from dpkg) pkg: " << short_pkgname
+	    std::clog << "(parsed from dpkg) pkg: " << pkgname
 	       << " action: " << action << " (prefix 2 to "
-	       << PackageOpsDone[pkg] << " of " << states.size() << ")" << endl;
+	       << PackageOpsDone[pkgname] << " of " << states.size() << ")" << endl;
 
 	 states.insert(states.begin(), {"installed", N_("Installed %s")});
 	 states.insert(states.begin(), {"half-configured", N_("Configuring %s")});
 	 PackagesTotal += 2;
       }
-      else if(PackageOpsDone[pkg] < states.size())
+      else if(PackageOpsDone[pkgname] < states.size())
       {
-	 char const * next_action = states[PackageOpsDone[pkg]].state;
+	 char const * next_action = states[PackageOpsDone[pkgname]].state;
 	 if (next_action)
 	 {
 	    /*
@@ -751,24 +747,52 @@ void pkgDPkgPM::ProcessDpkgStatusLine(char *line)
 	    }
 	    */
 	    if (Debug == true)
-	       std::clog << "(parsed from dpkg) pkg: " << short_pkgname
+	       std::clog << "(parsed from dpkg) pkg: " << pkgname
 		  << " action: " << action << " (expected: '" << next_action << "' "
-		  << PackageOpsDone[pkg] << " of " << states.size() << ")" << endl;
+		  << PackageOpsDone[pkgname] << " of " << states.size() << ")" << endl;
 
 	    // check if the package moved to the next dpkg state
 	    if(action == next_action)
 	    {
 	       // only read the translation if there is actually a next action
-	       char const * const translation = _(states[PackageOpsDone[pkg]].str);
+	       char const * const translation = _(states[PackageOpsDone[pkgname]].str);
 
 	       // we moved from one dpkg state to a new one, report that
-	       ++PackageOpsDone[pkg];
+	       ++PackageOpsDone[pkgname];
 	       ++PackagesDone;
 
 	       std::string msg;
 	       strprintf(msg, translation, i18n_pkgname.c_str());
 	       d->progress->StatusChanged(pkgname, PackagesDone, PackagesTotal, msg);
 	    }
+	    else if (action == "unpacked" && strcmp(next_action, "config-files") == 0)
+	    {
+	       // in a crossgrade what looked like a remove first is really an unpack over it
+	       ++PackageOpsDone[pkgname];
+	       ++PackagesDone;
+
+	       auto const Pkg = Cache.FindPkg(pkgname);
+	       if (likely(Pkg.end() == false))
+	       {
+		  auto const Grp = Pkg.Group();
+		  if (likely(Grp.end() == false))
+		  {
+		     for (auto P = Grp.PackageList(); P.end() != true; P = Grp.NextPkg(P))
+			if(Cache[P].Install())
+			{
+			   auto && Ops = PackageOps[P.FullName()];
+			   auto const unpackOp = std::find_if(Ops.cbegin(), Ops.cend(), [](DpkgState const &s) { return strcmp(s.state, "unpacked") == 0; });
+			   if (unpackOp != Ops.cend())
+			   {
+			      auto const skipped = std::distance(Ops.cbegin(), unpackOp);
+			      PackagesDone += skipped;
+			      PackageOpsDone[P.FullName()] += skipped;
+			      break;
+			   }
+			}
+		  }
+	       }
+	    }
 	 }
       }
    }
@@ -1277,7 +1301,7 @@ 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 =
+   decltype(List)::const_iterator::difference_type explicitIdx =
       std::distance(List.cbegin(),
 	    _config->FindB("Dpkg::ExplicitLastConfigure", false) ? List.cend() :
 	    std::find_if_not(
@@ -1379,6 +1403,101 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
    // for the progress
    BuildPackagesProgressMap();
 
+   APT::StateChanges approvedStates;
+   if (_config->FindB("dpkg::selection::remove::approved", true))
+   {
+      for (auto && I : List)
+	 if (I.Op == Item::Purge)
+	    approvedStates.Purge(FindToBeRemovedVersion(I.Pkg));
+	 else if (I.Op == Item::Remove)
+	    approvedStates.Remove(FindToBeRemovedVersion(I.Pkg));
+   }
+
+   // Skip removes if we install another architecture of this package soon (crossgrade)
+   // We can't just skip them all the time as it could be an ordering requirement [of another package]
+   if ((approvedStates.Remove().empty() == false || approvedStates.Purge().empty() == false) &&
+	 _config->FindB("dpkg::remove::crossgrade::implicit", true) == true)
+   {
+      std::unordered_set<decltype(pkgCache::Package::ID)> crossgraded;
+      std::vector<std::pair<Item*, std::string>> toCrossgrade;
+      auto const PlanedEnd = std::next(List.begin(), explicitIdx);
+      for (auto I = List.begin(); I != PlanedEnd; ++I)
+      {
+	 if (I->Op != Item::Remove && I->Op != Item::Purge)
+	    continue;
+
+	 auto const Grp = I->Pkg.Group();
+	 size_t installedInstances = 0;
+	 for (auto Pkg = Grp.PackageList(); Pkg.end() == false; Pkg = Grp.NextPkg(Pkg))
+	    if (Pkg->CurrentVer != 0 || Cache[Pkg].Install())
+	       ++installedInstances;
+	 if (installedInstances == 2)
+	 {
+	    auto const FirstInstall = std::find_if_not(I, List.end(),
+		  [](Item const &i) { return i.Op == Item::Remove || i.Op == Item::Purge; });
+	    auto const LastInstall = std::find_if_not(FirstInstall, List.end(),
+		  [](Item const &i) { return i.Op == Item::Install; });
+	    auto const crosser = std::find_if(FirstInstall, LastInstall,
+		  [&I](Item const &i) { return i.Pkg->Group == I->Pkg->Group; });
+	    if (crosser != LastInstall)
+	    {
+	       crossgraded.insert(I->Pkg->ID);
+	       toCrossgrade.emplace_back(&(*I), crosser->Pkg.FullName());
+	    }
+	 }
+      }
+      for (auto I = PlanedEnd; I != List.end(); ++I)
+      {
+	 if (I->Op != Item::Remove && I->Op != Item::Purge)
+	    continue;
+
+	 auto const Grp = I->Pkg.Group();
+	 for (auto Pkg = Grp.PackageList(); Pkg.end() == false; Pkg = Grp.NextPkg(Pkg))
+	 {
+	    if (Pkg == I->Pkg || Cache[Pkg].Install() == false)
+	       continue;
+	    toCrossgrade.emplace_back(&(*I), Pkg.FullName());
+	    break;
+	 }
+      }
+      for (auto C : toCrossgrade)
+      {
+	 // we never do purges on packages which are crossgraded, even if "requested"
+	 if (C.first->Op == Item::Purge)
+	 {
+	    C.first->Op = Item::Remove; // crossgrades should never be purged
+	    auto && Purges = approvedStates.Purge();
+	    auto const Ver = std::find_if(
+#if __GNUC__ >= 5 || (__GNUC_MINOR__ >= 9 && __GNUC__ >= 4)
+	       Purges.cbegin(), Purges.cend(),
+#else
+	       Purges.begin(), Purges.end(),
+#endif
+	       [&C](pkgCache::VerIterator const &V) { return V.ParentPkg() == C.first->Pkg; });
+	    approvedStates.Remove(*Ver);
+	    Purges.erase(Ver);
+	    auto && RemOp = PackageOps[C.first->Pkg.FullName()];
+	    if (RemOp.size() == 5)
+	    {
+	       RemOp.erase(std::next(RemOp.begin(), 3), RemOp.end());
+	       PackagesTotal -= 2;
+	    }
+	    else
+	    _error->Warning("Unexpected amount of planned ops for package %s: %lu", C.first->Pkg.FullName().c_str(), RemOp.size());
+	 }
+      }
+      if (crossgraded.empty() == false)
+      {
+	 auto const oldsize = List.size();
+	 List.erase(std::remove_if(List.begin(), PlanedEnd,
+	       [&crossgraded](Item const &i){
+		  return (i.Op == Item::Remove || i.Op == Item::Purge) &&
+		     crossgraded.find(i.Pkg->ID) != crossgraded.end();
+	       }), PlanedEnd);
+	 explicitIdx -= (oldsize - List.size());
+      }
+   }
+
    APT::StateChanges currentStates;
    if (_config->FindB("dpkg::selection::current::saveandrestore", true))
    {
@@ -1400,14 +1519,9 @@ bool pkgDPkgPM::Go(APT::Progress::PackageManager *progress)
 	    return _error->Error("Couldn't clean the currently selected dpkg states");
       }
    }
-   APT::StateChanges approvedStates;
+
    if (_config->FindB("dpkg::selection::remove::approved", true))
    {
-      for (auto && I: List)
-	 if (I.Op == Item::Remove && Cache[I.Pkg].Delete())
-	    approvedStates.Remove(FindToBeRemovedVersion(I.Pkg));
-	 else if (I.Op == Item::Purge && Cache[I.Pkg].Purge())
-	    approvedStates.Purge(FindToBeRemovedVersion(I.Pkg));
       if (approvedStates.Save(false) == false)
       {
 	 _error->Error("Couldn't record the approved state changes as dpkg selection states");
diff --git a/test/integration/test-crossgrades b/test/integration/test-crossgrades
new file mode 100755
index 000000000..d412546c1
--- /dev/null
+++ b/test/integration/test-crossgrades
@@ -0,0 +1,49 @@
+#!/bin/sh
+set -e
+
+TESTDIR="$(readlink -f "$(dirname "$0")")"
+. "$TESTDIR/framework"
+
+setupenvironment
+configarchitecture 'i386' 'amd64' 'armel'
+configdpkgnoopchroot
+
+buildsimplenativepackage 'unrelated' 'amd64' '1' 'stable'
+buildsimplenativepackage 'crosser' 'i386,armel' '1' 'stable' 'Multi-Arch: same'
+buildsimplenativepackage 'crosser' 'amd64' '2' 'unstable'
+setupaptarchive
+
+singleinstance() {
+	testsuccess apt install crosser:i386=1 unrelated:amd64 -y --planner $1
+	testdpkginstalled 'crosser:i386' 'unrelated'
+
+	testsuccess apt install crosser:amd64 -y -o Debug::pkgDpkgPm=1 -o Dpkg::Use-Pty=0 --purge --planner $1
+	cp -a rootdir/tmp/testsuccess.output crosser.output
+	testfailure grep -- '--remove.*crosser.*' crosser.output
+	testfailure grep -- '--purge' crosser.output
+	testsuccess apt install crosser:amd64 unrelated:amd64- -y -o Dpkg::Use-Pty=0 --purge -o Debug::pkgDPkgProgressReporting=1 --planner $1
+	testdpkgnotinstalled 'crosser:i386' 'unrelated'
+	testdpkginstalled 'crosser:amd64'
+
+	testsuccess apt purge crosser:amd64 -y --planner $1
+	testdpkgnotinstalled 'crosser:amd64'
+}
+singleinstance 'internal'
+singleinstance 'apt'
+
+multiinstance() {
+	testsuccess apt install crosser:i386=1 crosser:armel=1 unrelated:amd64 -y --planner $1
+	testdpkginstalled 'crosser:i386' 'crosser:armel' 'unrelated'
+
+	testsuccess apt install crosser:amd64 -y -o Debug::pkgDpkgPm=1 -o Dpkg::Use-Pty=0 --purge --planner $1
+	cp -a rootdir/tmp/testsuccess.output crosser.output
+	testsuccess grep -- '--remove.*crosser.*' crosser.output
+	testsuccess grep -- '--purge' crosser.output
+	testsuccess apt install crosser:amd64 unrelated:amd64- -y -o Dpkg::Use-Pty=0 --purge -o Debug::pkgDPkgProgressReporting=1 --planner $1
+	testdpkgnotinstalled 'crosser:i386' 'crosser:armel' 'unrelated'
+	testdpkginstalled 'crosser:amd64'
+
+	testsuccess apt purge crosser:amd64 -y --planner $1
+	testdpkgnotinstalled 'crosser:amd64'
+}
+multiinstance 'internal'