simulate all package manager actions explicitly

If a planner lets actions to be figured out by dpkg in pending calls
these actions aren't mentioned in a simulation. While that might be
a good thing for debugging, it would be a change in behavior and
especially if a planner avoids explicit removals could be confusing for
users. As such we perform the same 'trick' as in the dpkg implementation
by performing explicitly what would be done by the pending calls.

To save us some work and avoid desyncs we perform a layer violation by
using deb/ code in the generic simulation – and further we perform ugly
dynamic_cast to avoid breaking the ABI for nothing; aptitude is the only
other user of the simulation class according to codesearch.d.n and for
that our little trick works. It just isn't working if you happen to
extend pkgSimulate or otherwise manage to call the protected Go methods
directly – which isn't very realistic/practical.

1 files changed, 63 insertions, 2 deletions

diff --git a/apt-pkg/algorithms.cc b/apt-pkg/algorithms.cc
index b173979c3..65c5ff85d 100644
--- a/apt-pkg/algorithms.cc
+++ b/apt-pkg/algorithms.cc
@@ -25,22 +25,29 @@
 #include <apt-pkg/pkgcache.h>
 #include <apt-pkg/cacheiterators.h>
 #include <apt-pkg/prettyprinters.h>
+#include <apt-pkg/dpkgpm.h>
 
 #include <string.h>
 #include <string>
 #include <cstdlib>
 #include <iostream>
+#include <utility>
 
 #include <apti18n.h>
 									/*}}}*/
 using namespace std;
 
+class APT_HIDDEN pkgSimulatePrivate
+{
+public:
+   std::vector<pkgDPkgPM::Item> List;
+};
 // Simulate::Simulate - Constructor					/*{{{*/
 // ---------------------------------------------------------------------
 /* The legacy translations here of input Pkg iterators is obsolete, 
    this is not necessary since the pkgCaches are fully shared now. */
 pkgSimulate::pkgSimulate(pkgDepCache *Cache) : pkgPackageManager(Cache),
-		            d(NULL), iPolicy(Cache),
+		            d(new pkgSimulatePrivate()), iPolicy(Cache),
 			    Sim(&Cache->GetCache(),&iPolicy),
 			    group(Sim)
 {
@@ -58,6 +65,7 @@ pkgSimulate::pkgSimulate(pkgDepCache *Cache) : pkgPackageManager(Cache),
 pkgSimulate::~pkgSimulate()
 {
    delete[] Flags;
+   delete d;
 }
 									/*}}}*/
 // Simulate::Describe - Describe a package				/*{{{*/
@@ -90,7 +98,14 @@ void pkgSimulate::Describe(PkgIterator Pkg,ostream &out,bool Current,bool Candid
 // Simulate::Install - Simulate unpacking of a package			/*{{{*/
 // ---------------------------------------------------------------------
 /* */
-bool pkgSimulate::Install(PkgIterator iPkg,string /*File*/)
+bool pkgSimulate::Install(PkgIterator iPkg,string File)
+{
+   if (iPkg.end() || File.empty())
+      return false;
+   d->List.emplace_back(pkgDPkgPM::Item::Install, iPkg, File);
+   return true;
+}
+bool pkgSimulate::RealInstall(PkgIterator iPkg,string /*File*/)
 {
    // Adapt the iterator
    PkgIterator Pkg = Sim.FindPkg(iPkg.Name(), iPkg.Arch());
@@ -138,6 +153,13 @@ bool pkgSimulate::Install(PkgIterator iPkg,string /*File*/)
    however. */
 bool pkgSimulate::Configure(PkgIterator iPkg)
 {
+   if (iPkg.end())
+      return false;
+   d->List.emplace_back(pkgDPkgPM::Item::Configure, iPkg);
+   return true;
+}
+bool pkgSimulate::RealConfigure(PkgIterator iPkg)
+{
    // Adapt the iterator
    PkgIterator Pkg = Sim.FindPkg(iPkg.Name(), iPkg.Arch());
    
@@ -188,6 +210,13 @@ bool pkgSimulate::Configure(PkgIterator iPkg)
 /* */
 bool pkgSimulate::Remove(PkgIterator iPkg,bool Purge)
 {
+   if (iPkg.end())
+      return false;
+   d->List.emplace_back(Purge ? pkgDPkgPM::Item::Purge : pkgDPkgPM::Item::Remove, iPkg);
+   return true;
+}
+bool pkgSimulate::RealRemove(PkgIterator iPkg,bool Purge)
+{
    // Adapt the iterator
    PkgIterator Pkg = Sim.FindPkg(iPkg.Name(), iPkg.Arch());
    if (Pkg.end() == true)
@@ -232,6 +261,38 @@ void pkgSimulate::ShortBreaks()
    cout << ']' << endl;
 }
 									/*}}}*/
+bool pkgSimulate::Go2(APT::Progress::PackageManager *)			/*{{{*/
+{
+   if (pkgDPkgPM::ExpandPendingCalls(d->List, Cache) == false)
+      return false;
+   for (auto && I : d->List)
+      switch (I.Op)
+      {
+	 case pkgDPkgPM::Item::Install:
+	    if (RealInstall(I.Pkg, I.File) == false)
+	       return false;
+	    break;
+	 case pkgDPkgPM::Item::Configure:
+	    if (RealConfigure(I.Pkg) == false)
+	       return false;
+	    break;
+	 case pkgDPkgPM::Item::Remove:
+	    if (RealRemove(I.Pkg, false) == false)
+	       return false;
+	    break;
+	 case pkgDPkgPM::Item::Purge:
+	    if (RealRemove(I.Pkg, true) == false)
+	       return false;
+	    break;
+	 case pkgDPkgPM::Item::ConfigurePending:
+	 case pkgDPkgPM::Item::TriggersPending:
+	 case pkgDPkgPM::Item::RemovePending:
+	 case pkgDPkgPM::Item::PurgePending:
+	    return _error->Error("Internal error, simulation encountered unexpected pending item");
+      }
+   return true;
+}
+									/*}}}*/
 // ApplyStatus - Adjust for non-ok packages				/*{{{*/
 // ---------------------------------------------------------------------
 /* We attempt to change the state of the all packages that have failed