Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!samsung!uunet!infonode!doyle
From: doyle@infonode.ingr.com (Doyle Davidson)
Newsgroups: comp.windows.x
Subject: Signals in X
Message-ID: <1991Apr5.162131.7816@infonode.ingr.com>
Date: 5 Apr 91 16:21:31 GMT
Organization: Intergraph Corp. Huntsville, AL
Lines: 46

Under X11R4 how does one design a signal handler in an 
X application that needs to make X calls itself?  Since Xlib
is not reentrant(?), how can one make Xlib calls in response
to a signal?

Example: Child process dies so I need to create a window with a message.

A solution that I came up with is as follows (with details removed):

main_loop()
{
  while (True)
  {
    release_signals(...);		allow signals to pass
    err = select(...);			Wait for server data or a signal
    block_signals(...);			block signals from X
    while (XCheckMaskEvent(my_events))	look for any events
	process_event(...);		process it
  }
}

The signal can only fire while I am in select (assuming indivisible 
instructions) and at that point I am not inside any X calls.

Or can I get away with only blocking signals around my 
"process_event()" routine?

Is there a better/more appropriate way?
I checked my out of date FAQ list and couldn't find anything.
I know this has been discussed before but I can't
find any old postings about it.

Thanks in advance,

Doyle
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Doyle C. Davidson              |
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