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From: stripes@eng.umd.edu (Joshua Osborne)
Newsgroups: comp.windows.x
Subject: Re: Design problem with XSetIOErrorHandler
Message-ID: <1991Jan24.010427.29654@eng.umd.edu>
Date: 24 Jan 91 01:04:27 GMT
References: <2959@laura.UUCP>
Sender: news@eng.umd.edu (C-News)
Reply-To: stripes@eng.umd.edu (Joshua Osborne)
Organization: College of Engineering, Maryversity of Uniland, College Park
Lines: 30

In article <2959@laura.UUCP>, klute@tommy.informatik.uni-dortmund.de (Rainer Klute) writes:
> May I cite from the Xlib MIT X Consortium Standard on XSetIOErrorHandler:
> 
> 	"The XSetIOErrorHandler sets the fatal I/O error handler.
> 	Xlib calls the program's supplied error handler if any sort
> 	of system call error occurs (for example, the connection to
> 	the server was lost). This is assumed to be a fatal condition,
> 	and the called routine should not return. If the I/O error
> 	handler does return, the client process exits."
> 
> I wonder why the Standard considers I/O errors "fatal" and the why the X
> client has no other chance than to quit execution.
> 
> The application I am writing wants to deal with I/O errors itself - and in
> quite another way than exiting. Especially the example quoted from the
> Standard (connection to server lost) is the problem I want to handle. My
> application opens connections to several servers, and if one of them breaks
> the program is still able to operate. So why should it exit?

I had this problem in a multi-player game (xtrek, havn't fixed xtank yet) under
X11R3.  Using longjmp() worked Ok.  I checked all the displays, when I found the
one that had closed I re-opened a connection and displayed a message ("Please
don't kill xtrek, just Self Destruct").  It was kind of a pain & using WM_DELETE
is much nicer, I'm glad the ICCCM gave a thought to it...
-- 
           stripes@eng.umd.edu          "Security for Unix is like
      Josh_Osborne@Real_World,The          Multitasking for MS-DOS"
      "The dyslexic porgramer"                  - Kevin Lockwood
"CNN is the only nuclear capable news network..."
    - lbruck@eng.umd.edu (Lewis Bruck)