From 5895157fafbde30fa745f5c1c6e0d06d1d771e9f Mon Sep 17 00:00:00 2001
From: mmusich <marco.musich@cern.ch>
Date: Fri, 15 Jul 2022 16:22:29 +0200
Subject: [PATCH] avoid overflowing firstStrip_ in case of approximated
 clusters

---
 .../SiStripCluster/interface/SiStripCluster.h |  2 +-
 .../SiStripCluster/src/SiStripCluster.cc      | 12 +++++--
 .../plugins/SiStripApprox2Clusters.cc         | 32 ++++++++++++++-----
 3 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/DataFormats/SiStripCluster/interface/SiStripCluster.h b/DataFormats/SiStripCluster/interface/SiStripCluster.h
index 23f523f2c3b8f..383e3960f629e 100644
--- a/DataFormats/SiStripCluster/interface/SiStripCluster.h
+++ b/DataFormats/SiStripCluster/interface/SiStripCluster.h
@@ -38,7 +38,7 @@ class SiStripCluster {
       firstStrip_ |= mergedValueMask;  // if this is a candidate merged cluster
   }
 
-  SiStripCluster(const SiStripApproximateCluster cluster);
+  SiStripCluster(const SiStripApproximateCluster cluster, const uint16_t maxStrips);
 
   // extend the cluster
   template <typename Iter>
diff --git a/DataFormats/SiStripCluster/src/SiStripCluster.cc b/DataFormats/SiStripCluster/src/SiStripCluster.cc
index b03ebb025a937..6e3431d9ce9df 100644
--- a/DataFormats/SiStripCluster/src/SiStripCluster.cc
+++ b/DataFormats/SiStripCluster/src/SiStripCluster.cc
@@ -1,4 +1,4 @@
-
+#include "FWCore/Utilities/interface/Likely.h"
 #include "DataFormats/SiStripCluster/interface/SiStripCluster.h"
 
 SiStripCluster::SiStripCluster(const SiStripDigiRange& range) : firstStrip_(range.first->strip()), error_x(-99999.9) {
@@ -22,13 +22,19 @@ SiStripCluster::SiStripCluster(const SiStripDigiRange& range) : firstStrip_(rang
   amplitudes_ = v;
 }
 
-SiStripCluster::SiStripCluster(const SiStripApproximateCluster cluster) : error_x(-99999.9) {
+SiStripCluster::SiStripCluster(const SiStripApproximateCluster cluster, const uint16_t maxStrips) : error_x(-99999.9) {
   barycenter_ = cluster.barycenter();
   charge_ = cluster.width() * cluster.avgCharge();
   amplitudes_.resize(cluster.width(), cluster.avgCharge());
 
+  float halfwidth_ = 0.5f * float(cluster.width());
+
   //initialize firstStrip_
-  firstStrip_ = cluster.barycenter() - cluster.width() / 2;
+  firstStrip_ = std::max(barycenter_ - halfwidth_, 0.f);
+
+  if UNLIKELY (firstStrip_ + cluster.width() > maxStrips) {
+    firstStrip_ = maxStrips - cluster.width();
+  }
 }
 
 int SiStripCluster::charge() const {
diff --git a/RecoLocalTracker/SiStripClusterizer/plugins/SiStripApprox2Clusters.cc b/RecoLocalTracker/SiStripClusterizer/plugins/SiStripApprox2Clusters.cc
index a1bd8d382cb2c..ad2bbd85d6aaa 100644
--- a/RecoLocalTracker/SiStripClusterizer/plugins/SiStripApprox2Clusters.cc
+++ b/RecoLocalTracker/SiStripClusterizer/plugins/SiStripApprox2Clusters.cc
@@ -1,15 +1,18 @@
-#include "FWCore/Framework/interface/MakerMacros.h"
+#include "DataFormats/Common/interface/DetSetVector.h"
+#include "DataFormats/Common/interface/DetSetVectorNew.h"
+#include "DataFormats/SiStripCluster/interface/SiStripApproximateCluster.h"
+#include "DataFormats/SiStripCluster/interface/SiStripCluster.h"
+#include "FWCore/Framework/interface/Event.h"
 #include "FWCore/Framework/interface/Frameworkfwd.h"
+#include "FWCore/Framework/interface/MakerMacros.h"
 #include "FWCore/Framework/interface/global/EDProducer.h"
-#include "FWCore/Framework/interface/Event.h"
-#include "FWCore/ParameterSet/interface/ParameterSet.h"
 #include "FWCore/ParameterSet/interface/ConfigurationDescriptions.h"
+#include "FWCore/ParameterSet/interface/ParameterSet.h"
 #include "FWCore/ParameterSet/interface/ParameterSetDescription.h"
 #include "FWCore/Utilities/interface/InputTag.h"
-#include "DataFormats/SiStripCluster/interface/SiStripApproximateCluster.h"
-#include "DataFormats/SiStripCluster/interface/SiStripCluster.h"
-#include "DataFormats/Common/interface/DetSetVectorNew.h"
-#include "DataFormats/Common/interface/DetSetVector.h"
+#include "Geometry/Records/interface/TrackerDigiGeometryRecord.h"
+#include "Geometry/TrackerGeometryBuilder/interface/StripGeomDetUnit.h"
+#include "Geometry/TrackerGeometryBuilder/interface/TrackerGeometry.h"
 
 #include <vector>
 #include <memory>
@@ -23,11 +26,13 @@ class SiStripApprox2Clusters : public edm::global::EDProducer<> {
 
 private:
   edm::EDGetTokenT<edmNew::DetSetVector<SiStripApproximateCluster>> clusterToken_;
+  edm::ESGetToken<TrackerGeometry, TrackerDigiGeometryRecord> tkGeomToken_;
 };
 
 SiStripApprox2Clusters::SiStripApprox2Clusters(const edm::ParameterSet& conf) {
   clusterToken_ = consumes<edmNew::DetSetVector<SiStripApproximateCluster>>(
       conf.getParameter<edm::InputTag>("inputApproxClusters"));
+  tkGeomToken_ = esConsumes();
   produces<edmNew::DetSetVector<SiStripCluster>>();
 }
 
@@ -35,11 +40,22 @@ void SiStripApprox2Clusters::produce(edm::StreamID id, edm::Event& event, const
   auto result = std::make_unique<edmNew::DetSetVector<SiStripCluster>>();
   const auto& clusterCollection = event.get(clusterToken_);
 
+  const auto& tkGeom = &iSetup.getData(tkGeomToken_);
+  const auto tkDets = tkGeom->dets();
+
   for (const auto& detClusters : clusterCollection) {
     edmNew::DetSetVector<SiStripCluster>::FastFiller ff{*result, detClusters.id()};
+    unsigned int detId = detClusters.id();
+
+    uint16_t nStrips{0};
+    auto det = std::find_if(tkDets.begin(), tkDets.end(), [detId](auto& elem) -> bool {
+      return (elem->geographicalId().rawId() == detId);
+    });
+    const StripTopology& p = dynamic_cast<const StripGeomDetUnit*>(*det)->specificTopology();
+    nStrips = p.nstrips() - 1;
 
     for (const auto& cluster : detClusters) {
-      ff.push_back(SiStripCluster(cluster));
+      ff.push_back(SiStripCluster(cluster, nStrips));
     }
   }