[Spice-devel] [PATCH server v2 05/13] red-channel: send marshaller message fd

[Frediano Ziglio]

> 
> Hi
> 
> On Fri, Jan 15, 2016 at 11:44 AM, Frediano Ziglio <fziglio at redhat.com> wrote:
> >>
> >> From: Marc-André Lureau <mlureau at redhat.com>
> >>
> >> Send the fd associated to the last message sent.
> >>
> >> Even if the fd is invalid, the sendfd msg is appended to the protocol,
> >> for 2 reasons:
> >> - trying to send an invalid fd does not have to close the connection (it
> >>   would with an invalid fd)
> >> - even if the fd is invalid, the protocol expects an extra byte for the
> >>   ancillary data
> >>
> >> Signed-off-by: Marc-André Lureau <marcandre.lureau at gmail.com>
> >> ---
> >>  server/red-channel.c | 16 ++++++++++++++++
> >>  1 file changed, 16 insertions(+)
> >>
> >> diff --git a/server/red-channel.c b/server/red-channel.c
> >> index 306c87d..b33c91d 100644
> >> --- a/server/red-channel.c
> >> +++ b/server/red-channel.c
> >> @@ -608,8 +608,24 @@ static inline void
> >> red_channel_client_release_sent_item(RedChannelClient *rcc)
> >>  static void red_channel_peer_on_out_msg_done(void *opaque)
> >>  {
> >>      RedChannelClient *rcc = (RedChannelClient *)opaque;
> >> +    int fd = spice_marshaller_get_fd(rcc->send_data.marshaller);
> >>
> >>      rcc->send_data.size = 0;
> >> +
> >> +    if (fd != -1) {
> >> +        if (fcntl(fd, F_GETFD) == -1) {
> >
> > Is not clear what's the reason for this test.
> > Why should fail?
> 
> It should not fail, but if the caller has set an invalid fd (or it
> became invalid), I think it is better to deal with it and not
> disconnect the client. (trying to send an invalid fd over sendmsg
> closes the connection)
> 

The file descriptor is saved with a dup. If the handle became invalid
it means some internal corruption happened. In this case I would even
abort the program.

> >
> >> +            close(fd);
> >> +            fd = -1;
> >> +        }
> >> +
> >> +        if (reds_stream_send_msgfd(rcc->stream, fd) < 0) {
> >> +            perror("sendfd");
> >> +            red_channel_client_disconnect(rcc);
> >> +            return;
> >
> > I think here you should close the file descriptor too to avoid leak.
> >
> 
> agreed
> 
> >> +        }
> >> +        close(fd);
> >> +    }
> >> +
> >>      red_channel_client_release_sent_item(rcc);
> >>      if (rcc->send_data.blocked) {
> >>          rcc->send_data.blocked = FALSE;

Frediano