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.

diff --git a/contrib/xml2/xslt_proc.c b/contrib/xml2/xslt_proc.c
index f8f7d7263f989d0348735b66d5594cc3506f8103..1bfeedfa885bd7d3353548e8db1eb0d9203e5196 100644 (file)
--- 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;
        xsltStylesheetPtr stylesheet = NULL;
@@ -117,6 +118,16 @@ xslt_process(PG_FUNCTION_ARGS)
        }
 
        restree = xsltApplyStylesheet(stylesheet, doctree, params);
+
+       if (restree == NULL)
+       {
+               xsltFreeStylesheet(stylesheet);
+               xmlFreeDoc(doctree);
+               xsltCleanupGlobals();
+               xml_ereport(ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
+                                       "failed to apply stylesheet");
+       }
+
        resstat = xsltSaveResultToString(&resstr, &reslen, restree, stylesheet);
 
        xsltFreeStylesheet(stylesheet);
@@ -125,10 +136,16 @@ xslt_process(PG_FUNCTION_ARGS)
 
        xsltCleanupGlobals();
 
+       /* 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,