From 3efa07ad277efe5c1d11a2ef2b907c095f68bbef Mon Sep 17 00:00:00 2001
From: Ben Boeckel <ben.boeckel@kitware.com>
Date: Mon, 15 Apr 2024 22:22:22 -0400
Subject: [PATCH] vtkXMLDataParser: track `AppendedData` state explicitly

Newer `libexpat` doesn't like being given the appended data after the
artificially ended document anymore. Avoid pushing it through to its
parser.

(cherry picked from commit db8f9efca220c9d16a30958e179abae3379d0011)

Fixes: #19258
---
 IO/XMLParser/vtkXMLDataParser.cxx | 6 +++++-
 IO/XMLParser/vtkXMLDataParser.h   | 3 +++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/IO/XMLParser/vtkXMLDataParser.cxx b/IO/XMLParser/vtkXMLDataParser.cxx
index 1f6006d37c2..7d38092fdd7 100644
--- a/IO/XMLParser/vtkXMLDataParser.cxx
+++ b/IO/XMLParser/vtkXMLDataParser.cxx
@@ -36,6 +36,7 @@ vtkXMLDataParser::vtkXMLDataParser()
   this->RootElement = nullptr;
   this->AppendedDataPosition = 0;
   this->AppendedDataMatched = 0;
+  this->AppendedDataFound = false;
   this->DataStream = nullptr;
   this->InlineDataStream = vtkBase64InputStream::New();
   this->AppendedDataStream = vtkBase64InputStream::New();
@@ -88,6 +89,7 @@ void vtkXMLDataParser::PrintSelf(ostream& os, vtkIndent indent)
 {
   this->Superclass::PrintSelf(os, indent);
   os << indent << "AppendedDataPosition: " << this->AppendedDataPosition << "\n";
+  os << indent << "AppendedDataFound: " << this->AppendedDataFound << "\n";
   if (this->RootElement)
   {
     this->RootElement->PrintXML(os, indent);
@@ -214,7 +216,7 @@ int vtkXMLDataParser::ParsingComplete()
   // If we have reached the appended data section, we stop parsing.
   // This prevents the XML parser from having to walk over the entire
   // appended data section.
-  if (this->AppendedDataPosition)
+  if (this->AppendedDataPosition || this->AppendedDataFound)
   {
     return 1;
   }
@@ -433,6 +435,8 @@ int vtkXMLDataParser::ParseBuffer(const char* buffer, unsigned int count)
     {
       return 0;
     }
+
+    this->AppendedDataFound = true;
   }
 
   return 1;
diff --git a/IO/XMLParser/vtkXMLDataParser.h b/IO/XMLParser/vtkXMLDataParser.h
index 1504a4d400b..142bf28327d 100644
--- a/IO/XMLParser/vtkXMLDataParser.h
+++ b/IO/XMLParser/vtkXMLDataParser.h
@@ -204,6 +204,9 @@ protected:
   // How much of the string "<AppendedData" has been matched in input.
   int AppendedDataMatched;
 
+  // Whether AppendedData has been dealt with or not.
+  bool AppendedDataFound;
+
   // The byte order of the binary input.
   int ByteOrder;
 
-- 
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