From d9b31e4859df5325b7d3d2cc94b0e907f1cf1d3e Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 4 Jun 2012 20:12:50 -0400
Subject: [PATCH] Fix some more bugs in contrib/xml2's xslt_process().

It failed to check for error return from xsltApplyStylesheet(), as reported
by Peter Gagarinov.  (So far as I can tell, libxslt provides no convenient
way to get a useful error message in failure cases.  There might be some
inconvenient way, but considering that this code is deprecated it's hard to
get enthusiastic about putting lots of work into it.  So I just made it say
"failed to apply stylesheet", in line with the existing error checks.)

While looking at the code I also noticed that the string returned by
xsltSaveResultToString was never freed, resulting in a session-lifespan
memory leak.

Back-patch to all supported versions.
---
 contrib/xml2/xslt_proc.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/contrib/xml2/xslt_proc.c b/contrib/xml2/xslt_proc.c
index a8e481a3ce8..ba1171a041f 100644
--- a/contrib/xml2/xslt_proc.c
+++ b/contrib/xml2/xslt_proc.c
@@ -54,6 +54,7 @@ xslt_process(PG_FUNCTION_ARGS)
 
 	text	   *doct = PG_GETARG_TEXT_P(0);
 	text	   *ssheet = PG_GETARG_TEXT_P(1);
+	text	   *result;
 	text	   *paramstr;
 	const char **params;
 	PgXmlErrorContext *xmlerrcxt;
@@ -112,6 +113,11 @@ xslt_process(PG_FUNCTION_ARGS)
 					"failed to parse stylesheet");
 
 	restree = xsltApplyStylesheet(stylesheet, doctree, params);
+
+	if (restree == NULL)
+		xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
+					"failed to apply stylesheet");
+
 	resstat = xsltSaveResultToString(&resstr, &reslen, restree, stylesheet);
 	}
 	PG_CATCH();
@@ -137,10 +143,16 @@ xslt_process(PG_FUNCTION_ARGS)
 
 	pg_xml_done(xmlerrcxt, false);
 
+	/* XXX this is pretty dubious, really ought to throw error instead */
 	if (resstat < 0)
 		PG_RETURN_NULL();
 
-	PG_RETURN_TEXT_P(cstring_to_text_with_len((char *) resstr, reslen));
+	result = cstring_to_text_with_len((char *) resstr, reslen);
+
+	if (resstr)
+		xmlFree(resstr);
+
+	PG_RETURN_TEXT_P(result);
 #else							/* !USE_LIBXSLT */
 
 	ereport(ERROR,
-- 
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