From 225cd9dac27d685833156dfc249838cda11cd2ef Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Wed, 21 Aug 2019 12:50:36 -0400
Subject: Protect against coding error of re-entrant parsing

---
 include/qpdf/QPDF.hh | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

(limited to 'include')

diff --git a/include/qpdf/QPDF.hh b/include/qpdf/QPDF.hh
index f052cb33..5fae5a57 100644
--- a/include/qpdf/QPDF.hh
+++ b/include/qpdf/QPDF.hh
@@ -657,6 +657,31 @@ class QPDF
     };
     friend class Warner;
 
+    // ParseGuard class allows QPDFObjectHandle to detect re-entrant
+    // resolution
+    class ParseGuard
+    {
+	friend class QPDFObjectHandle;
+      private:
+        ParseGuard(QPDF* qpdf) :
+            qpdf(qpdf)
+        {
+            if (qpdf)
+            {
+                qpdf->inParse(true);
+            }
+        }
+        ~ParseGuard()
+        {
+            if (qpdf)
+            {
+                qpdf->inParse(false);
+            }
+        }
+        QPDF* qpdf;
+    };
+    friend class ParseGuard;
+
     // Pipe class is restricted to QPDF_Stream
     class Pipe
     {
@@ -816,6 +841,7 @@ class QPDF
     friend class ResolveRecorder;
 
     void parse(char const* password);
+    void inParse(bool);
     void warn(QPDFExc const& e);
     void setTrailer(QPDFObjectHandle obj);
     void read_xref(qpdf_offset_t offset);
@@ -1352,6 +1378,7 @@ class QPDF
         bool reconstructed_xref;
         bool fixed_dangling_refs;
         bool immediate_copy_from;
+        bool in_parse;
 
         // Linearization data
         qpdf_offset_t first_xref_item_offset; // actual value from file
-- 
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