From e1ca10ccc4009aeb79d2098da073fa94a9bb14e4 Mon Sep 17 00:00:00 2001
From: m-holger <m-holger@kubitscheck.org>
Date: Mon, 15 Jan 2024 12:01:29 +0000
Subject: [PATCH] In QPDFJob::handleUnderOverlay flatten nested fo maps

---
 include/qpdf/QPDFJob.hh |  2 +-
 libqpdf/QPDFJob.cc      | 22 +++++++++++-----------
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/qpdf/QPDFJob.hh b/include/qpdf/QPDFJob.hh
index a89d1503..c78fbc0a 100644
--- a/include/qpdf/QPDFJob.hh
+++ b/include/qpdf/QPDFJob.hh
@@ -523,7 +523,7 @@ class QPDFJob
         UnderOverlay& uo,
         std::map<std::pair<int, size_t>, std::vector<int>> const& pagenos,
         std::pair<int, size_t> pageno_uo_idx,
-        std::map<int, std::map<size_t, QPDFObjectHandle>>& fo,
+        std::map<std::pair<int, size_t>, QPDFObjectHandle>& fo,
         std::vector<QPDFPageObjectHelper>&& pages,
         QPDFPageObjectHelper& dest_page);
     void validateUnderOverlay(QPDF& pdf, UnderOverlay* uo);
diff --git a/libqpdf/QPDFJob.cc b/libqpdf/QPDFJob.cc
index 64de4b68..f68adb91 100644
--- a/libqpdf/QPDFJob.cc
+++ b/libqpdf/QPDFJob.cc
@@ -1888,7 +1888,7 @@ QPDFJob::doUnderOverlayForPage(
     UnderOverlay& uo,
     std::map<std::pair<int, size_t>, std::vector<int>> const& pagenos,
     std::pair<int, size_t> pageno_uo_idx,
-    std::map<int, std::map<size_t, QPDFObjectHandle>>& fo,
+    std::map<std::pair<int, size_t>, QPDFObjectHandle>& fo,
     std::vector<QPDFPageObjectHelper>&& pages,
     QPDFPageObjectHelper& dest_page)
 {
@@ -1910,9 +1910,12 @@ QPDFJob::doUnderOverlayForPage(
             v << "    " << uo.filename << " " << uo.which << " " << from_page.no << "\n";
         });
         auto from_page_ph = pages.at(from_page.idx);
-        if (fo[from_page.no].count(pageno_uo_idx.second) == 0) {
-            fo[from_page.no][pageno_uo_idx.second] =
-                pdf.copyForeignObject(from_page_ph.getFormXObjectForPage());
+        std::pair<int, size_t> fo_index = {from_page.no, pageno_uo_idx.second};
+        auto fo_it = fo.find(fo_index);
+        if (fo_it == fo.end()) {
+            fo_it =
+                fo.insert({fo_index, pdf.copyForeignObject(from_page_ph.getFormXObjectForPage())})
+                    .first;
         }
 
         // If the same page is overlaid or underlaid multiple times, we'll generate multiple names
@@ -1920,16 +1923,13 @@ QPDFJob::doUnderOverlayForPage(
         std::string name = resources.getUniqueResourceName("/Fx", min_suffix);
         QPDFMatrix cm;
         std::string new_content = dest_page.placeFormXObject(
-            fo[from_page.no][pageno_uo_idx.second],
-            name,
-            dest_page.getTrimBox().getArrayAsRectangle(),
-            cm);
+            fo_it->second, name, dest_page.getTrimBox().getArrayAsRectangle(), cm);
         dest_page.copyAnnotations(from_page_ph, cm, dest_afdh, make_afdh(from_page_ph));
         if (!new_content.empty()) {
             resources.mergeResources("<< /XObject << >> >>"_qpdf);
             auto xobject = resources.getKey("/XObject");
             if (xobject.isDictionary()) {
-                xobject.replaceKey(name, fo[from_page.no][pageno_uo_idx.second]);
+                xobject.replaceKey(name, fo_it->second);
             }
             ++min_suffix;
             content += new_content;
@@ -1992,8 +1992,8 @@ QPDFJob::handleUnderOverlay(QPDF& pdf)
     };
 
     std::map<unsigned long long int, std::unique_ptr<QPDFAcroFormDocumentHelper>> afdh;
-    std::map<int, std::map<size_t, QPDFObjectHandle>> underlay_fo;
-    std::map<int, std::map<size_t, QPDFObjectHandle>> overlay_fo;
+    std::map<std::pair<int, size_t>, QPDFObjectHandle> underlay_fo;
+    std::map<std::pair<int, size_t>, QPDFObjectHandle> overlay_fo;
     QPDFPageDocumentHelper main_pdh(pdf);
     auto main_pages = main_pdh.getAllPages();
     size_t main_npages = main_pages.size();