Re: Error in recent pg_dump change (coverity) - Mailing list pgsql-hackers

Alvaro Herrera <alvherre@commandprompt.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