xml2: Replace deprecated routines with recommended ones

Some functions are used in the tree and are currently marked as
deprecated by upstream.  This commit refreshes the code to use the
recommended functions, leading to the following changes:
- xmlSubstituteEntitiesDefault() is gone, and needs to be replaced with
XML_PARSE_NOENT for the paths doing the parsing.
- xmlParseMemory() -> xmlReadMemory().

These functions, as well as more functions setting global states, have
been officially marked as deprecated by upstream in August 2022.  Their
replacements exist since the 2001-ish area, as far as I have checked,
so that should be safe.

This has been originally applied as 65c5864d7fac without a backpatch,
and this has come up as well when working on 400928b83.  Per request
from Tom Lane, for new buildfarm member indri that is able to see
deprecation warnings with xmlSubstituteEntitiesDefault() in 16 and older
stable branches.

Author: Dmitry Koval
Discussion: https://postgr.es/m/[email protected]
Discussion: https://postgr.es/m/[email protected]
Bakpatch-through: 12

2 files changed, 12 insertions, 9 deletions

diff --git a/contrib/xml2/xpath.c b/contrib/xml2/xpath.c
index 94641930f7b..b999b1f7066 100644
--- a/contrib/xml2/xpath.c
+++ b/contrib/xml2/xpath.c
@@ -74,8 +74,6 @@ pgxml_parser_init(PgXmlStrictness strictness)
 	/* Initialize libxml */
 	xmlInitParser();
 
-	xmlSubstituteEntitiesDefault(1);
-
 	return xmlerrcxt;
 }
 
@@ -379,8 +377,9 @@ pgxml_xpath(text *document, xmlChar *xpath, xpath_workspace *workspace)
 
 	PG_TRY();
 	{
-		workspace->doctree = xmlParseMemory((char *) VARDATA_ANY(document),
-											docsize);
+		workspace->doctree = xmlReadMemory((char *) VARDATA_ANY(document),
+										   docsize, NULL, NULL,
+										   XML_PARSE_NOENT);
 		if (workspace->doctree != NULL)
 		{
 			workspace->ctxt = xmlXPathNewContext(workspace->doctree);
@@ -623,7 +622,9 @@ xpath_table(PG_FUNCTION_ARGS)
 
 			/* Parse the document */
 			if (xmldoc)
-				doctree = xmlParseMemory(xmldoc, strlen(xmldoc));
+				doctree = xmlReadMemory(xmldoc, strlen(xmldoc),
+										NULL, NULL,
+										XML_PARSE_NOENT);
 			else				/* treat NULL as not well-formed */
 				doctree = NULL;
 
diff --git a/contrib/xml2/xslt_proc.c b/contrib/xml2/xslt_proc.c
index 2189bca86ff..f30a3a42c03 100644
--- a/contrib/xml2/xslt_proc.c
+++ b/contrib/xml2/xslt_proc.c
@@ -85,16 +85,18 @@ xslt_process(PG_FUNCTION_ARGS)
 		bool		xslt_sec_prefs_error;
 
 		/* Parse document */
-		doctree = xmlParseMemory((char *) VARDATA_ANY(doct),
-								 VARSIZE_ANY_EXHDR(doct));
+		doctree = xmlReadMemory((char *) VARDATA_ANY(doct),
+								VARSIZE_ANY_EXHDR(doct), NULL, NULL,
+								XML_PARSE_NOENT);
 
 		if (doctree == NULL)
 			xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
 						"error parsing XML document");
 
 		/* Same for stylesheet */
-		ssdoc = xmlParseMemory((char *) VARDATA_ANY(ssheet),
-							   VARSIZE_ANY_EXHDR(ssheet));
+		ssdoc = xmlReadMemory((char *) VARDATA_ANY(ssheet),
+							  VARSIZE_ANY_EXHDR(ssheet), NULL, NULL,
+							  XML_PARSE_NOENT);
 
 		if (ssdoc == NULL)
 			xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,