Thread: PQsetdbLogin bug?

Sometimes PQfinish() does not return forever in the following program.

conn = PQsetdbLogin();
if(PQstatus(conn) == CONNECTION_BAD)
{ PQfinish(conn);    /* blocks here */
}

PQfinish calls closePGconn that call pqPuts. pqPuts calls select(2)
and it never returns if a connection associated with the socket is not
established.

This could happend if the connection is not established, but the
socket is still opened by PQsetdbLogin. Possible fixes are:

1) close the socket in PQsetdbLogin if it is in a situation being  returns CONNECTION_BAD
    case PGRES_POLLING_WRITING:        if (pqWait(0, 1, conn))        {            conn->status = CONNECTION_BAD;
    close(conn->sock); <-- add this            conn->sock == -1;  <-- add this            return 0;        }
break;


2) check if the status of handle returned PQsetdbLogin is  CONNECTION_BAD closePGconn. if so, do not call pqPuts (and
pqFlush)
  change this:if (conn->sock >= 0)
  to:if (conn->status != CONNECTION_BAD && conn->sock >= 0)

any thoughts?
--
Tatsuo Ishii

Tatsuo Ishii <t-ishii@sra.co.jp> writes:
> 2) check if the status of handle returned PQsetdbLogin is
>    CONNECTION_BAD closePGconn. if so, do not call pqPuts (and
>    pqFlush)

I like this approach.  The other way, you'd have to be sure that all
failure paths close the socket before returning; even if you get it
right today, somebody will break it again in future.  The sending of
the final 'X' is really quite optional anyhow, so I'd say it's fine
not to do it when there's any question about whether it's safe.
        regards, tom lane

> Tatsuo Ishii <t-ishii@sra.co.jp> writes:
> > 2) check if the status of handle returned PQsetdbLogin is
> >    CONNECTION_BAD closePGconn. if so, do not call pqPuts (and
> >    pqFlush)
> 
> I like this approach.  The other way, you'd have to be sure that all
> failure paths close the socket before returning; even if you get it
> right today, somebody will break it again in future.  The sending of
> the final 'X' is really quite optional anyhow, so I'd say it's fine
> not to do it when there's any question about whether it's safe.

done.
--
Tatsuo Ishii