From 56e9bcabe984acd4479ff7fef9a2a0ca669abc76 Mon Sep 17 00:00:00 2001
From: m-holger <m-holger@kubitscheck.org>
Date: Sun, 14 Aug 2022 01:05:32 +0100
Subject: Add methods QPDFObject::setObjGen and QPDFObject::resetObjGen

Also, modify QPDFObject::swapWith to update the ObjGens of the swapped
objects.

Modify QPDF::newIndirect and QPDF::updateCache to keep object ObjGens
up to date.
---
 include/qpdf/QPDFObject.hh | 18 ++++++++++++++++++
 libqpdf/QPDF.cc            |  3 +++
 2 files changed, 21 insertions(+)

diff --git a/include/qpdf/QPDFObject.hh b/include/qpdf/QPDFObject.hh
index 198488dd..7bb7c6e1 100644
--- a/include/qpdf/QPDFObject.hh
+++ b/include/qpdf/QPDFObject.hh
@@ -133,7 +133,25 @@ class QPDFObject
         auto v = value;
         value = o->value;
         o->value = v;
+        auto og = value->og;
+        value->og = o->value->og;
+        o->value->og = og;
     }
+
+    // The following two methods are for use by class QPDF only
+    void
+    setObjGen(QPDF* qpdf, QPDFObjGen const& og)
+    {
+        value->qpdf = qpdf;
+        value->og = og;
+    }
+    void
+    resetObjGen()
+    {
+        value->qpdf = nullptr;
+        value->og = QPDFObjGen();
+    }
+
     bool
     isUnresolved()
     {
diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index f33e2920..1e73f794 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -2109,6 +2109,7 @@ QPDF::resolveObjectsInStream(int obj_stream_number)
 QPDFObjectHandle
 QPDF::newIndirect(QPDFObjGen const& og, std::shared_ptr<QPDFObject> const& obj)
 {
+    obj->setObjGen(this, og);
     if (!obj->hasDescription()) {
         obj->setDescription(this, "object " + og.unparse(' '));
     }
@@ -2122,8 +2123,10 @@ QPDF::updateCache(
     qpdf_offset_t end_before_space,
     qpdf_offset_t end_after_space)
 {
+    object->setObjGen(this, og);
     if (isCached(og)) {
         auto& cache = m->obj_cache[og];
+        cache.object->resetObjGen();
         cache.object->assign(object);
         cache.end_before_space = end_before_space;
         cache.end_after_space = end_after_space;
-- 
cgit v1.2.3-54-g00ecf