Merge pull request #1112 from m-holger/gcog

Tweaks to QPDF::read_xref, removeObject and getCompressibleObjGens

1 files changed, 20 insertions, 0 deletions

diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index 3718eb7e..41ecd54a 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -706,6 +706,14 @@ QPDF::read_xref(qpdf_offset_t xref_offset)
     // We no longer need the deleted_objects table, so go ahead and clear it out to make sure we
     // never depend on its being set.
     m->deleted_objects.clear();
+
+    // Make sure we keep only the highest generation for any object.
+    QPDFObjGen last_og{-1, 0};
+    for (auto const& [og, _xref]: m->xref_table) {
+        if (og.getObj() == last_og.getObj())
+            removeObject(last_og);
+        last_og = og;
+    }
 }
 
 bool
@@ -1979,6 +1987,18 @@ QPDF::replaceObject(QPDFObjGen const& og, QPDFObjectHandle oh)
 }
 
 void
+QPDF::removeObject(QPDFObjGen og)
+{
+    m->xref_table.erase(og);
+    if (auto cached = m->obj_cache.find(og); cached != m->obj_cache.end()) {
+        // Take care of any object handles that may be floating around.
+        cached->second.object->assign(QPDF_Null::create());
+        cached->second.object->setObjGen(nullptr, QPDFObjGen());
+        m->obj_cache.erase(cached);
+    }
+}
+
+void
 QPDF::replaceReserved(QPDFObjectHandle reserved, QPDFObjectHandle replacement)
 {
     QTC::TC("qpdf", "QPDF replaceReserved");