Hello,
On Wed, Jul 08, 2009 at 04:33:02PM +0200, Carl Fredrik Hammar wrote:
> On Tue, Jul 07, 2009 at 09:24:27PM +0300, Sergiu Ivanov wrote:
> > /* Opens the port on which to set the mountee. */
> > error_t
> > open_port (int flags, mach_port_t * underlying,
> > mach_msg_type_name_t * underlying_type, task_t task,
> > void *cookie)
> > {
> > err = 0;
> >
> > /* Create a port to `np`. */
> > newpi = netfs_make_protid
> > (netfs_make_peropen (np, flags, NULL), user);
> > if (!newpi)
> > {
> > iohelp_free_iouser (user);
> > return errno;
> > }
> >
> > *underlying = underlying_port = ports_get_send_right (newpi);
> > *underlying_type = MACH_MSG_TYPE_COPY_SEND;
> >
> > ports_port_deref (newpi);
> >
> > return err;
> > } /*open_port */
> >
> > [...]
> >
> > Now the question: can the reason for such failure be the fact that the
> > port right stored in underlying_node is used both in unionmount and in
> > the mountee? If so, is there a way to clone the port right?
>
> This issue has been resolved in IRC, but I'll answer the question
> for the record. The port right is copied by mach_msg, if its type
> is MACH_MSG_TYPE_COPY_SEND. And this is the type you passed in
> UNDERLYING_TYPE, so it is copied. To move it you use ..._MOVE_SEND,
> you can also create a send right from a receive right with ..._MAKE_SEND.
Aha, clear, thank you. I understand the general meaning of port right
types, but now I've got a better idea of what's happening.
Regards,
scolobb
