Remove xmlCleanupParser calls from contrib/xml2.

These are unnecessary and probably dangerous.  I don't see any immediate
risk situations in the core XML support or contrib/xml2 itself, but there
could be issues with external uses of libxml2, and in any case it's an
accident waiting to happen.

contrib/xml2/xpath.c

 /*
- * $PostgreSQL: pgsql/contrib/xml2/xpath.c,v 1.27 2010/02/28 21:31:57 tgl Exp $
+ * $PostgreSQL: pgsql/contrib/xml2/xpath.c,v 1.28 2010/03/01 05:16:35 tgl Exp $
  *
  * Parser interface for DOM-based parser (libxml) rather than
  * stream-based SAX-type parser
@@ -145,12 +145,8 @@ xml_is_well_formed(PG_FUNCTION_ARGS)
 
 	doctree = xmlParseMemory((char *) VARDATA(t), docsize);
 	if (doctree == NULL)
-	{
-		xmlCleanupParser();
 		PG_RETURN_BOOL(false);	/* i.e. not well-formed */
-	}
 	xmlFreeDoc(doctree);
-	xmlCleanupParser();
 	PG_RETURN_BOOL(true);
 }
 
@@ -297,7 +293,6 @@ xpath_nodeset(PG_FUNCTION_ARGS)
 	xpres = pgxml_result_to_text(pgxml_xpath(PG_GETARG_TEXT_P(0), xpath),
 								 toptag, septag, NULL);
 
-	/* xmlCleanupParser(); done by result_to_text routine */
 	pfree(xpath);
 
 	if (xpres == NULL)
@@ -332,7 +327,6 @@ xpath_list(PG_FUNCTION_ARGS)
 	xpres = pgxml_result_to_text(pgxml_xpath(PG_GETARG_TEXT_P(0), xpath),
 								 NULL, NULL, plainsep);
 
-	/* xmlCleanupParser(); done by result_to_text routine */
 	pfree(xpath);
 
 	if (xpres == NULL)
@@ -371,7 +365,6 @@ xpath_string(PG_FUNCTION_ARGS)
 	xpres = pgxml_result_to_text(pgxml_xpath(PG_GETARG_TEXT_P(0), xpath),
 								 NULL, NULL, NULL);
 
-	xmlCleanupParser();
 	pfree(xpath);
 
 	if (xpres == NULL)
@@ -403,13 +396,10 @@ xpath_number(PG_FUNCTION_ARGS)
 	pfree(xpath);
 
 	if (res == NULL)
-	{
-		xmlCleanupParser();
 		PG_RETURN_NULL();
-	}
 
 	fRes = xmlXPathCastToNumber(res);
-	xmlCleanupParser();
+
 	if (xmlXPathIsNaN(fRes))
 		PG_RETURN_NULL();
 
@@ -440,13 +430,10 @@ xpath_bool(PG_FUNCTION_ARGS)
 	pfree(xpath);
 
 	if (res == NULL)
-	{
-		xmlCleanupParser();
 		PG_RETURN_BOOL(false);
-	}
 
 	bRes = xmlXPathCastToBoolean(res);
-	xmlCleanupParser();
+
 	PG_RETURN_BOOL(bRes);
 }
 
@@ -469,9 +456,7 @@ pgxml_xpath(text *document, xmlChar *xpath)
 
 	doctree = xmlParseMemory((char *) VARDATA(document), docsize);
 	if (doctree == NULL)
-	{							/* not well-formed */
-		return NULL;
-	}
+		return NULL;			/* not well-formed */
 
 	ctxt = xmlXPathNewContext(doctree);
 	ctxt->node = xmlDocGetRootElement(doctree);
@@ -480,7 +465,6 @@ pgxml_xpath(text *document, xmlChar *xpath)
 	comppath = xmlXPathCompile(xpath);
 	if (comppath == NULL)
 	{
-		xmlCleanupParser();
 		xmlFreeDoc(doctree);
 		elog_error("XPath Syntax Error", true);
 	}
@@ -492,7 +476,6 @@ pgxml_xpath(text *document, xmlChar *xpath)
 	if (res == NULL)
 	{
 		xmlXPathFreeContext(ctxt);
-		/* xmlCleanupParser(); */
 		xmlFreeDoc(doctree);
 
 		return NULL;
@@ -511,10 +494,8 @@ pgxml_result_to_text(xmlXPathObjectPtr res,
 	text	   *xpres;
 
 	if (res == NULL)
-	{
-		xmlCleanupParser();
 		return NULL;
-	}
+
 	switch (res->type)
 	{
 		case XPATH_NODESET:
@@ -536,9 +517,6 @@ pgxml_result_to_text(xmlXPathObjectPtr res,
 	xpres = cstring_to_text((char *) xpresstr);
 
 	/* Free various storage */
-	xmlCleanupParser();
-	/* xmlFreeDoc(doctree);  -- will die at end of tuple anyway */
-
 	xmlFree(xpresstr);
 
 	elog_error("XPath error", false);
@@ -779,7 +757,6 @@ xpath_table(PG_FUNCTION_ARGS)
 					comppath = xmlXPathCompile(xpaths[j]);
 					if (comppath == NULL)
 					{
-						xmlCleanupParser();
 						xmlFreeDoc(doctree);
 						elog_error("XPath Syntax Error", true);
 					}
@@ -844,8 +821,6 @@ xpath_table(PG_FUNCTION_ARGS)
 			pfree(xmldoc);
 	}
 
-	xmlCleanupParser();
-
 	tuplestore_donestoring(tupstore);
 
 	SPI_finish();

contrib/xml2/xslt_proc.c

 /*
- * $PostgreSQL: pgsql/contrib/xml2/xslt_proc.c,v 1.17 2010/02/28 19:51:37 tgl Exp $
+ * $PostgreSQL: pgsql/contrib/xml2/xslt_proc.c,v 1.18 2010/03/01 05:16:35 tgl Exp $
  *
  * XSLT processing functions (requiring libxslt)
  *
@@ -79,7 +79,6 @@ xslt_process(PG_FUNCTION_ARGS)
 
 	if (doctree == NULL)
 	{
-		xmlCleanupParser();
 		elog_error("error parsing XML document", false);
 
 		PG_RETURN_NULL();
@@ -93,7 +92,6 @@ xslt_process(PG_FUNCTION_ARGS)
 		if (ssdoc == NULL)
 		{
 			xmlFreeDoc(doctree);
-			xmlCleanupParser();
 			elog_error("error parsing stylesheet as XML document", false);
 			PG_RETURN_NULL();
 		}
@@ -108,7 +106,6 @@ xslt_process(PG_FUNCTION_ARGS)
 	{
 		xmlFreeDoc(doctree);
 		xsltCleanupGlobals();
-		xmlCleanupParser();
 		elog_error("failed to parse stylesheet", false);
 		PG_RETURN_NULL();
 	}
@@ -121,7 +118,6 @@ xslt_process(PG_FUNCTION_ARGS)
 	xmlFreeDoc(doctree);
 
 	xsltCleanupGlobals();
-	xmlCleanupParser();
 
 	if (resstat < 0)
 		PG_RETURN_NULL();