From 956534e02ef280795a187c16f6ac04e107f23c5d Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Tue, 4 Aug 2020 19:27:13 +0200
Subject: [PATCH] Check for custom free function in global destructor

Calling a custom deallocation function in the global destructor could
cause all kinds of unexpected problems. See for example

    https://github.com/sparklemotion/nokogiri/issues/2059

Only clean up if memory is managed with malloc/free.
---
 parser.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/parser.c b/parser.c
index e1d139d5..c66dbae4 100644
--- a/parser.c
+++ b/parser.c
@@ -14696,7 +14696,12 @@ xmlCleanupParser(void) {
 static void
 ATTRIBUTE_DESTRUCTOR
 xmlDestructor(void) {
-    xmlCleanupParser();
+    /*
+     * Calling custom deallocation functions in a destructor can cause
+     * problems, for example with Nokogiri.
+     */
+    if (xmlFree == free)
+        xmlCleanupParser();
 }
 #endif