From 9064542b5f23bde3e7d6826b5b5e8b0a6f356434 Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Sun, 15 May 2022 13:10:10 -0400
Subject: [PATCH] Add private methods for reserving specific objects

---
 include/qpdf/QPDF.hh             |  1 +
 include/qpdf/QPDFObjectHandle.hh |  7 +++++++
 libqpdf/QPDF.cc                  | 11 +++++++++++
 libqpdf/QPDFObjectHandle.cc      |  9 +++++++--
 4 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/include/qpdf/QPDF.hh b/include/qpdf/QPDF.hh
index 2e24b26..b547fcb 100644
--- a/include/qpdf/QPDF.hh
+++ b/include/qpdf/QPDF.hh
@@ -1079,6 +1079,7 @@ class QPDF
     std::shared_ptr<QPDFObject> resolve(int objid, int generation);
     void resolveObjectsInStream(int obj_stream_number);
     void stopOnError(std::string const& message);
+    QPDFObjectHandle reserveObjectIfNotExists(int objid, int gen);
 
     // Calls finish() on the pipeline when done but does not delete it
     bool pipeStreamData(
diff --git a/include/qpdf/QPDFObjectHandle.hh b/include/qpdf/QPDFObjectHandle.hh
index 70c7cf5..ec4a969 100644
--- a/include/qpdf/QPDFObjectHandle.hh
+++ b/include/qpdf/QPDFObjectHandle.hh
@@ -1444,6 +1444,12 @@ class QPDFObjectHandle
             return QPDFObjectHandle::newStream(
                 qpdf, objid, generation, stream_dict, offset, length);
         }
+        // Reserve an object with a specific ID
+        static QPDFObjectHandle
+        makeReserved()
+        {
+            return QPDFObjectHandle::makeReserved();
+        }
     };
     friend class Factory;
 
@@ -1561,6 +1567,7 @@ class QPDFObjectHandle
         QPDFObjectHandle stream_dict,
         qpdf_offset_t offset,
         size_t length);
+    static QPDFObjectHandle makeReserved();
 
     void typeWarning(char const* expected_type, std::string const& warning);
     void objectWarning(std::string const& warning);
diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index 2658dd2..1807a83 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -2156,6 +2156,17 @@ QPDF::makeIndirectObject(QPDFObjectHandle oh)
 }
 
 QPDFObjectHandle
+QPDF::reserveObjectIfNotExists(int objid, int gen)
+{
+    QPDFObjGen og(objid, gen);
+    if ((!this->m->obj_cache.count(og)) && (!this->m->xref_table.count(og))) {
+        resolve(objid, gen);
+        replaceObject(objid, gen, QPDFObjectHandle::Factory::makeReserved());
+    }
+    return getObjectByID(objid, gen);
+}
+
+QPDFObjectHandle
 QPDF::getObjectByObjGen(QPDFObjGen const& og)
 {
     return getObjectByID(og.getObj(), og.getGen());
diff --git a/libqpdf/QPDFObjectHandle.cc b/libqpdf/QPDFObjectHandle.cc
index 4a61f59..4a0a69a 100644
--- a/libqpdf/QPDFObjectHandle.cc
+++ b/libqpdf/QPDFObjectHandle.cc
@@ -2775,14 +2775,19 @@ QPDFObjectHandle::newReserved(QPDF* qpdf)
 {
     // Reserve a spot for this object by assigning it an object
     // number, but then return an unresolved handle to the object.
-    QPDFObjectHandle reserved =
-        qpdf->makeIndirectObject(QPDFObjectHandle(new QPDF_Reserved()));
+    QPDFObjectHandle reserved = qpdf->makeIndirectObject(makeReserved());
     QPDFObjectHandle result =
         newIndirect(qpdf, reserved.objid, reserved.generation);
     result.reserved = true;
     return result;
 }
 
+QPDFObjectHandle
+QPDFObjectHandle::makeReserved()
+{
+    return QPDFObjectHandle(new QPDF_Reserved());
+}
+
 void
 QPDFObjectHandle::setObjectDescription(
     QPDF* owning_qpdf, std::string const& object_description)
--
libgit2 0.21.4