Tighten coding for non-composite case in plperl's return_next.

Coverity complained about this code's practice of using scalar variables
as single-element arrays.  While that's really just nitpicking, it probably
is more readable to declare them as arrays, so let's do that.  A more
important point is that the code was just blithely assuming that the
result tupledesc has exactly one column; if it doesn't, we'd likely get
a crash of some sort in tuplestore_putvalues.  Since the tupledesc is
manufactured outside of plperl, that seems like an uncomfortably long
chain of assumptions.  We can nail it down at little cost with a sanity
check earlier in the function.

diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c
index b10b4434aa74033d7858dc76ad6da4d6c77035d5..afebec910d6cb71ed1629457e63384901548faac 100644 (file)
--- a/src/pl/plperl/plperl.c
+++ b/src/pl/plperl/plperl.c
@@ -3247,12 +3247,18 @@ plperl_return_next_internal(SV *sv)
 
        /*
         * This is the first call to return_next in the current PL/Perl
-        * function call, so memoize some lookups
+        * function call, so identify the output tuple descriptor and create a
+        * tuplestore to hold the result rows.
         */
        if (prodesc->fn_retistuple)
            (void) get_call_result_type(fcinfo, NULL, &tupdesc);
        else
+       {
            tupdesc = rsi->expectedDesc;
+           /* Protect assumption below that we return exactly one column */
+           if (tupdesc == NULL || tupdesc->natts != 1)
+               elog(ERROR, "expected single-column result descriptor for non-composite SETOF result");
+       }
 
        /*
         * Make sure the tuple_store and ret_tdesc are sufficiently
@@ -3300,20 +3306,20 @@ plperl_return_next_internal(SV *sv)
    }
    else
    {
-       Datum       ret;
-       bool        isNull;
+       Datum       ret[1];
+       bool        isNull[1];
 
-       ret = plperl_sv_to_datum(sv,
-                                prodesc->result_oid,
-                                -1,
-                                fcinfo,
-                                &prodesc->result_in_func,
-                                prodesc->result_typioparam,
-                                &isNull);
+       ret[0] = plperl_sv_to_datum(sv,
+                                   prodesc->result_oid,
+                                   -1,
+                                   fcinfo,
+                                   &prodesc->result_in_func,
+                                   prodesc->result_typioparam,
+                                   &isNull[0]);
 
        tuplestore_putvalues(current_call_data->tuple_store,
                             current_call_data->ret_tdesc,
-                            &ret, &isNull);
+                            ret, isNull);
    }
 
    MemoryContextSwitchTo(old_cxt);