Add range_check method to QIntC

2 files changed, 14 insertions, 2 deletions

diff --git a/include/qpdf/BufferInputSource.hh b/include/qpdf/BufferInputSource.hh
index 65206d50..561018f6 100644
--- a/include/qpdf/BufferInputSource.hh
+++ b/include/qpdf/BufferInputSource.hh
@@ -54,8 +54,6 @@ class BufferInputSource: public InputSource
     virtual void unreadCh(char ch);
 
   private:
-    static void range_check(qpdf_offset_t cur, qpdf_offset_t delta);
-
     class Members
     {
         friend class BufferInputSource;
diff --git a/include/qpdf/QIntC.hh b/include/qpdf/QIntC.hh
index 6f1f4b63..5f7f21bb 100644
--- a/include/qpdf/QIntC.hh
+++ b/include/qpdf/QIntC.hh
@@ -222,6 +222,20 @@ namespace QIntC // QIntC = qpdf Integer Conversion
     {
         return IntConverter<T, unsigned long long>::convert(i);
     }
+
+    template <typename T>
+    void range_check(T const& cur, T const& delta)
+    {
+        if ((delta > 0) &&
+            ((std::numeric_limits<T>::max() - cur) < delta))
+        {
+            std::ostringstream msg;
+            msg.imbue(std::locale::classic());
+            msg << "adding " << delta << " to " << cur
+                << " would cause an integer overflow";
+            throw std::range_error(msg.str());
+        }
+    }
 };
 
 #endif // QINTC_HH