From e6b28661d03b67fd87facfaadb7b87cb8dd80fc7 Mon Sep 17 00:00:00 2001
From: Marino Missiroli <m.missiroli@cern.ch>
Date: Sat, 6 May 2023 15:57:39 +0200
Subject: [PATCH] do not allow crashes in isEmpty(int bx) method of BXVector

---
 DataFormats/L1Trigger/interface/BXVector.h   |  6 +++---
 DataFormats/L1Trigger/interface/BXVector.icc | 21 ++++++++++++++------
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/DataFormats/L1Trigger/interface/BXVector.h b/DataFormats/L1Trigger/interface/BXVector.h
index 6ce09f80ba5b8..7cfa8239da265 100644
--- a/DataFormats/L1Trigger/interface/BXVector.h
+++ b/DataFormats/L1Trigger/interface/BXVector.h
@@ -1,5 +1,5 @@
-#ifndef BXVector_h
-#define BXVector_h
+#ifndef DataFormats_L1Trigger_BXVector_h
+#define DataFormats_L1Trigger_BXVector_h
 
 // this class is an extension of std::vector
 // designed to store objects corresponding to several time-samples (BX)
@@ -134,4 +134,4 @@ class BXVector {
 
 #include "BXVector.icc"
 
-#endif
+#endif  // DataFormats_L1Trigger_BXVector_h
diff --git a/DataFormats/L1Trigger/interface/BXVector.icc b/DataFormats/L1Trigger/interface/BXVector.icc
index 1c4efa0803d07..efee573b2f627 100644
--- a/DataFormats/L1Trigger/interface/BXVector.icc
+++ b/DataFormats/L1Trigger/interface/BXVector.icc
@@ -1,7 +1,4 @@
-#include <vector>
-#include <iostream>
 #include <cassert>
-using namespace std;
 
 template <class T>
 BXVector<T>::BXVector(unsigned size,  // number of objects per BX
@@ -211,15 +208,27 @@ unsigned BXVector<T>::indexFromBX(int bx) const {
 // check to see if bx is empty
 template <class T>
 bool BXVector<T>::isEmpty(int bx) const {
-  if (itrs_[indexFromBX(bx)] == data_.size()) {
+  if (bx < bxFirst_) {
     return true;
   }
 
-  if (indexFromBX(bx + 1) >= itrs_.size()) {
+  auto const index_bx = indexFromBX(bx);
+
+  if (index_bx >= itrs_.size()) {
+    return true;
+  }
+
+  if (itrs_[index_bx] == data_.size()) {
+    return true;
+  }
+
+  auto const index_bxPlus1 = indexFromBX(bx + 1);
+
+  if (index_bxPlus1 >= itrs_.size()) {
     return false;
   }
 
-  if (itrs_[indexFromBX(bx)] == itrs_[indexFromBX(bx + 1)]) {
+  if (itrs_[index_bx] == itrs_[index_bxPlus1]) {
     return true;
   }