Re: gnutls error handling

[Jan D.]

 Eli Zaretskii skrev 2010-10-17 17:22:
> > From: Lars Magne Ingebrigtsen<address@hidden>
> > Date: Sun, 17 Oct 2010 15:55:24 +0200
> > Mail-Copies-To: never
> >
> > poll([{fd=4, events=POLLIN}, {fd=3, events=POLLIN}], 2, 0) = 0 (Timeout)
> > select(15, [3 4 8 10 13], [], NULL, {0, 15591}) = 2 (in [8 10], left {0, 15589})
> > read(3, 0xec9b94, 4096)                 = -1 EAGAIN (Resource temporarily 
> > unavailable)
> > poll([{fd=4, events=POLLIN}, {fd=3, events=POLLIN}], 2, 0) = 0 (Timeout)
> > select(15, [3 4 8 10 13], [], NULL, {0, 15532}) = 2 (in [8 10], left {0, 15530})
> > read(3, 0xec9b94, 4096)                 = -1 EAGAIN (Resource temporarily 
> > unavailable)
> >
> > There's always a gnutls socket involved in the select call -- in this
> > instance it was fd 10.  lsof showed the socket to be in the CLOSE_WAIT
> > state.  So my suspicion is that the we're somehow now communicating back
> > to Emacs that a gnutls socket has closed.
> Not really a useful answer, but the `select' man page has this piece
> of wisdom:
>
>         Under Linux, select() may report a socket file descriptor as
>         "ready for reading", while nevertheless a subsequent read
>         blocks.  This could for example happen when data has arrived
>         but upon examination has wrong checksum and is discarded.
>         There may be other circumstances in which a file descriptor is
>         spuriously reported as ready.  Thus it may be safer to use
>         O_NONBLOCK on sockets that should not block.
>
> Of course, we already use O_NONBLOCK (AFAIK).

The question is why is Emacs reading fd 3?  It is not reported as ready 
by select, fd 8 and 10 are ready, but those aren't read.

    Jan D.