[MacPorts] #18491: XtAppPending and XtAppProcessEvent infloop

[MacPorts]

#18491: XtAppPending and XtAppProcessEvent infloop
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 Reporter:  stephen@…           |       Owner:  macports-tickets@…                   
     Type:  defect              |      Status:  new                                  
 Priority:  Normal              |   Milestone:  Port Bugs                            
Component:  ports               |     Version:  1.8.0                                
 Keywords:                      |        Port:  xorg-libXt                           
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 XtAppPending can block; this is a complex of X.org bugginess reported as
 http://bugs.freedesktop.org/show_bug.cgi?id=20048.

 On recent Mac OS X (10.5.6 and 10.4.11+security update 2008-008), one of
 the problems results in an infloop in _XtWaitForSomething, the basic event
 gathering function for both XtAppPending and XtAppProcessEvent.  I have no
 clue why, but under certain circumstances poll(2) will return with a fd in
 POLLNVAL state (ie, not open).  _XtWaitForSomething ignores this, and
 loops looking for input, but I guess the POLLNVAL fd is at the head of the
 queue and never gets processed.  (That's idle speculation, to be honest I
 really have no clue why this happens.)

 The attached patch patch-NextEvent.c-XPOLL_EXCEPT teaches
 _XtWaitForSomething to notice this event, which fixes the infloop for me.
 I recommend application to MacPorts strongly (see the bug referenced above
 for rationale).

 A second patch seems to me to be correct in principle, but it is neither
 necessary nor sufficient to fix the infloop.  Since I've got it, Ill post
 it here for your consideration.

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Ticket URL: <http://trac.macports.org/ticket/18491>
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