Re: Error in recent pg_dump change (coverity)

Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Martijn van Oosterhout wrote:
>> I'd actually suggest zeroing out res->tuples in PQclear so this sort of
>> problem becomes much more obvious.

> Is it worthwhile to zero out the res->block array as well?

Your patch isn't doing that, merely zeroing a local variable
that will be assigned to in a moment anyway. That loop already
ensures that res->curBlock is null when it exits. So lose this:

+ block = NULL;

This part seems OK:

/* Free the top-level tuple pointer array */
if (res->tuples)
+ {
free(res->tuples);
+ res->tuples = NULL;
+ }

Another possibility is to just MemSet the whole PGresult struct
to zeroes before free'ing it. Compared to the cost of obtaining
a query result from the backend, this probably doesn't cost enough
to be worth worrying about, and it would catch a few more problems
of the same ilk.

regards, tom lane