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

2017年7月31日 15:33:46 +0000 (11:33 -0400)

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.

src/pl/plperl/plperl.c patch | blob | blame | history

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);

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