From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 10 Jun 2009 03:44:35 +0000 (+0000)
Subject: Ensure xmlFree(NULL) is a no-op instead of a core dump.  Per report from
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=89f30c6ceb695571b04e9b70b8bccf725183bab4;p=users%2Fsimon%2Fpostgres.git

Ensure xmlFree(NULL) is a no-op instead of a core dump.  Per report from
Sergey Burladyan, there are at least some dank corners of libxml2 that
assume this behavior, even though their published documentation suggests
they shouldn't.

This is only really a live problem in 8.3, but the code is still there
for possible debugging use in HEAD, so patch both branches.
---

diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index f6292b9137..9b34a7abbc 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -1293,7 +1293,9 @@ xml_repalloc(void *ptr, size_t size)
 static void
 xml_pfree(void *ptr)
 {
-	pfree(ptr);
+	/* At least some parts of libxml assume xmlFree(NULL) is allowed */
+	if (ptr)
+		pfree(ptr);
 }