From b34d2cdc42433e07603ef1308b9430c5e2fd336c Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 26 Aug 2021 17:05:30 +0200
Subject: [PATCH] Ensure that
 beginMarkedContentProps/endMarkedContent-operators, for /XObjects, are
 balanced in corrupt documents (PR 13854 follow-up)

Something that I *just* realized is that while PR 13854 fixed an issue as reported, it could still cause bugs in other similarily broken documents since we'll not insert a matching endMarkedContent-operator in the operatorList.
---
 src/core/evaluator.js | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/core/evaluator.js b/src/core/evaluator.js
index 1e2481e57..90615b228 100644
--- a/src/core/evaluator.js
+++ b/src/core/evaluator.js
@@ -461,13 +461,15 @@ class PartialEvaluator {
     } else {
       bbox = null;
     }
-    let optionalContent = null,
-      groupOptions;
+
+    let optionalContent, groupOptions;
     if (dict.has("OC")) {
       optionalContent = await this.parseMarkedContentProps(
         dict.get("OC"),
         resources
       );
+    }
+    if (optionalContent !== undefined) {
       operatorList.addOp(OPS.beginMarkedContentProps, ["OC", optionalContent]);
     }
     const group = dict.get("Group");
@@ -528,7 +530,7 @@ class PartialEvaluator {
         operatorList.addOp(OPS.endGroup, [groupOptions]);
       }
 
-      if (optionalContent) {
+      if (optionalContent !== undefined) {
         operatorList.addOp(OPS.endMarkedContent, []);
       }
     });
@@ -575,12 +577,14 @@ class PartialEvaluator {
       return;
     }
 
-    let optionalContent = null;
+    let optionalContent;
     if (dict.has("OC")) {
       optionalContent = await this.parseMarkedContentProps(
         dict.get("OC"),
         resources
       );
+    }
+    if (optionalContent !== undefined) {
       operatorList.addOp(OPS.beginMarkedContentProps, ["OC", optionalContent]);
     }
 
@@ -620,7 +624,7 @@ class PartialEvaluator {
         });
       }
 
-      if (optionalContent) {
+      if (optionalContent !== undefined) {
         operatorList.addOp(OPS.endMarkedContent, []);
       }
       return;
@@ -645,7 +649,7 @@ class PartialEvaluator {
       imgData = imageObj.createImageData(/* forceRGBA = */ true);
       operatorList.addOp(OPS.paintInlineImageXObject, [imgData]);
 
-      if (optionalContent) {
+      if (optionalContent !== undefined) {
         operatorList.addOp(OPS.endMarkedContent, []);
       }
       return;
@@ -717,7 +721,7 @@ class PartialEvaluator {
       }
     }
 
-    if (optionalContent) {
+    if (optionalContent !== undefined) {
       operatorList.addOp(OPS.endMarkedContent, []);
     }
   }