Fix core dump in contrib/xml2's xpath_table() when the input query returns

a NULL value.  Per bug #4058.

diff --git a/contrib/xml2/xpath.c b/contrib/xml2/xpath.c
index b4b06a039d78656481ad90bf7411815a14ebe84b..14f49d53f3fcd615a1fd718675012e2774f822db 100644 (file)
--- a/contrib/xml2/xpath.c
+++ b/contrib/xml2/xpath.c
@@ -806,12 +806,10 @@ xpath_table(PG_FUNCTION_ARGS)
                xmlXPathCompExprPtr comppath;
 
                /* Extract the row data as C Strings */
-
                spi_tuple = tuptable->vals[i];
                pkey = SPI_getvalue(spi_tuple, spi_tupdesc, 1);
                xmldoc = SPI_getvalue(spi_tuple, spi_tupdesc, 2);
 
-
                /*
                 * Clear the values array, so that not-well-formed documents return
                 * NULL in all columns.
@@ -825,11 +823,14 @@ xpath_table(PG_FUNCTION_ARGS)
                values[0] = pkey;
 
                /* Parse the document */
-               doctree = xmlParseMemory(xmldoc, strlen(xmldoc));
+               if (xmldoc)
+                       doctree = xmlParseMemory(xmldoc, strlen(xmldoc));
+               else                                    /* treat NULL as not well-formed */
+                       doctree = NULL;
 
                if (doctree == NULL)
-               {                                               /* not well-formed, so output all-NULL tuple */
-
+               {
+                       /* not well-formed, so output all-NULL tuple */
                        ret_tuple = BuildTupleFromCStrings(attinmeta, values);
                        oldcontext = MemoryContextSwitchTo(per_query_ctx);
                        tuplestore_puttuple(tupstore, ret_tuple);
@@ -921,8 +922,10 @@ xpath_table(PG_FUNCTION_ARGS)
 
                xmlFreeDoc(doctree);
 
-               pfree(pkey);
-               pfree(xmldoc);
+               if (pkey)
+                       pfree(pkey);
+               if (xmldoc)
+                       pfree(xmldoc);
        }
 
        xmlCleanupParser();