From 68ac2179bd6fb6bda6e701ae676fc69cd85a4670 Mon Sep 17 00:00:00 2001
From: m-holger <m.holger@qpdf.org>
Date: Sat, 31 Aug 2024 12:55:53 +0100
Subject: [PATCH] In ObjTable change maximum allowable object id to
 std::vector<T>::max_size()

Given that the PDF spec requires the xref table to contain entries for all
object ids <= the maximum id present in a PDF document, max_size is a
qpdf implementation limitation for legitimate object ids.
---
 libqpdf/qpdf/ObjTable.hh | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/libqpdf/qpdf/ObjTable.hh b/libqpdf/qpdf/ObjTable.hh
index 84b51b78..9da96b30 100644
--- a/libqpdf/qpdf/ObjTable.hh
+++ b/libqpdf/qpdf/ObjTable.hh
@@ -113,6 +113,7 @@ class ObjTable: public std::vector<T>
         }
     }
 
+
     inline void
     forEach(std::function<void(int, const T&)> fn)
     {
@@ -131,24 +132,26 @@ class ObjTable: public std::vector<T>
     inline T&
     element(size_t idx)
     {
+        static const size_t max_size = std::vector<T>::max_size();
         if (idx < std::vector<T>::size()) {
             return std::vector<T>::operator[](idx);
-        } else if (idx < static_cast<size_t>(std::numeric_limits<int>::max())) {
+        } else if (idx < max_size) {
             return sparse_elements[idx];
         }
-        throw std::runtime_error("Invalid object id accessing ObjTable.");
+        throw std::runtime_error("Impossibly large object id encountered accessing ObjTable");
         return element(0); // doesn't return
     }
 
     inline T const&
     element(size_t idx) const
     {
+        static const size_t max_size = std::vector<T>::max_size();
         if (idx < std::vector<T>::size()) {
             return std::vector<T>::operator[](idx);
-        } else if (idx < static_cast<size_t>(std::numeric_limits<int>::max())) {
+        } else if (idx < max_size) {
             return sparse_elements.at(idx);
         }
-        throw std::runtime_error("Invalid object id accessing ObjTable.");
+        throw std::runtime_error("Impossibly large object id encountered accessing ObjTable");
         return element(0); // doesn't return
     }
 };