Re: [ECOS] network problems

[Andrew Lunn <andrew dot lunn at ascom dot ch>]

On Fri, Apr 11, 2003 at 11:29:24PM +0100, Jonathan Larmour wrote:
> Andrew Lunn wrote:
> >>My problem is, I use select to wait for multiple inputs including 
> >>the socket.
> >>Normally I recognize the a connection was closed by peer if read() 
> >>returns 0 or I get an error while write().
> >>But sometimes I have the case, the I stop reading and writing to the 
> >>socket
> >>for some reasons. So I just don't set the corresponding bit in the 
> >>fdset.
> >>but in such state I can't recognize if the connection is closed.
> >
> >
> >Try setting the bit in exceptfds. I think select will then report when
> >the socket is closed.
> 
> I'd be interested to know for other reasons if this is true! AFAIK 
> exceptfds is only used for OOB data.
> 
> BTW, did you really mean ferror() rather than 
> getsockopt(...,SO_ERROR,...)? 

----------------------------------------------------------------------
FERROR(3)           Linux Programmer's Manual                FERROR(3)
 
 
 
NAME
       clearerr, feof, ferror, fileno - check and reset stream status

[Snip]
       The function ferror tests  the  error  indicator  for  the
       stream  pointed  to by stream, returning non-zero if it is
       set.  The error indicator can only be reset by the  clear­
       err function.

---------------------------------------------------------------------- 

A socket is a stream, so this should work.

> Although in either case I'm not entirely sure they'd ever get set
> unless some operation is done on the socket first.

Why should an operation been needed? When the socket is closed because
of a timeout or the peer, i would expect the local end to be closed
and -EPIPE or something similar set in the error indicator. I've not
tried this, so i could be totally wrong.

    Andrew

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