fixing coverity issue CID 13415 (ATLASSIM-1712) (ISF_HepMC_Tools-00-02-16)

	* GenEventStackFiller: fixing coverity issue CID 13415 (ATLASSIM-1712)
	* tag as ISF_HepMC_Tools-00-02-16

2014-11-07  Zach Marshall <ZLMarshall@lbl.gov>
	* GenEventVertexPositioner: Setting up vertex positioning for signal
	vertex (to be passed through xAOD)
	* tag as ISF_HepMC_Tools-00-02-15

Simulation/ISF/ISF_HepMC/ISF_HepMC_Tools/src/GenEventStackFiller.cxx

@@ -156,13 +156,19 @@ StatusCode ISF::GenEventStackFiller::fillStack(ISF::ISFParticleContainer& partic
   m_uniqueBc = 0;
   m_largestBc = 0;
 
+  StatusCode sc;
   if (!m_pMergeSvc.empty()) {
     // 1. pileup merge service has been configured.
     // retrieve and process merged mceventcollection set
-    return processMergedColls(particleColl);
+    sc = processMergedColls(particleColl);
   } else {
     // 2. try to retrieve and process regular mceventcollection, as usual
-    return processSingleColl(particleColl);
+    sc = processSingleColl(particleColl);
+  }
+
+  if (sc.isFailure()) {
+    ATH_MSG_ERROR("Unable to fill initial particle collection");
+    return StatusCode::FAILURE;
   }
 
   // register the largest barcode appearing in GEN_EVENT

Simulation/ISF/ISF_HepMC/ISF_HepMC_Tools/src/GenEventVertexPositioner.cxx

@@ -72,6 +72,9 @@ StatusCode ISF::GenEventVertexPositioner::manipulate(HepMC::GenEvent& ge)
 
     ATH_MSG_VERBOSE("Retrieved Vertex shift of: " << *curShift);
 
+    // Get the signal process vertex, just in case...
+    HepMC::FourVector old_signal_spot = ge.signal_process_vertex()?ge.signal_process_vertex()->position():HepMC::FourVector(0,0,0,0);
+
     // loop over the vertices in the event, they are in respect with another
     //   (code from Simulation/Fatras/FatrasAlgs/McEventPreProcessing.cxx)
     HepMC::GenEvent::vertex_iterator vtxIt    = ge.vertices_begin();
@@ -93,6 +96,31 @@ StatusCode ISF::GenEventVertexPositioner::manipulate(HepMC::GenEvent& ge)
       curVtx->set_position( newPos);
     }
 
+    // Do the same for the signal process vertex
+    if ( ge.signal_process_vertex() ){
+      // Signal process vertex is a pointer.  There is some risk that the pointer points 
+      //  to a vertex somewhere else in the event, rather than a unique / new vertex, in
+      //  which case we will have already modified its position in the loop above.  That
+      //  is the reason for hanging on to an old position and seeing if we've moved...
+      // I would love it if HepMC had a minus operator defined for FourVectors... or
+      //  even a get for the three vector component :(
+      HepMC::FourVector why_no_minus( ge.signal_process_vertex()->position().x() - old_signal_spot.x() ,
+                                      ge.signal_process_vertex()->position().y() - old_signal_spot.y() ,
+                                      ge.signal_process_vertex()->position().z() - old_signal_spot.z() ,
+                                      ge.signal_process_vertex()->position().t() - old_signal_spot.t() );
+      if ( why_no_minus.rho() < 0.000001 && why_no_minus.m2() < 0.000001 ){
+        const HepMC::FourVector &curPos = ge.signal_process_vertex()->position();
+        CLHEP::HepLorentzVector newPos( curPos.x(), curPos.y(), curPos.z(), curPos.t() );
+        newPos += (*curShift);
+        ge.signal_process_vertex()->set_position( newPos);
+      }
+    } else { // Have to make a new one
+      // Don't worry about ID and weights - those should never be used from this thing
+      HepMC::GenVertex * sig_proc_vert = new HepMC::GenVertex( (*curShift) );
+      // ge will now take ownership of the signal process vertex
+      ge.set_signal_process_vertex( sig_proc_vert );
+    } // Manipulated the signal process vertex
+
     // memory cleanup
     delete curShift;
   }