Path: utzoo!utgpu!watserv1!watmath!att!mcdchg!ddsw1!corpane!disk!stevenw
From: stevenw@disk.UUCP (Steven Weller)
Newsgroups: comp.os.os9
Subject: Re: signal problem
Message-ID: <3943@disk.UUCP>
Date: 20 Aug 90 00:41:32 GMT
References: <5596@ethz.UUCP>
Organization: Digital Information Systems of Ky (DISK), Louisville, Ky
Lines: 49

stp@ethz.UUCP (Stephan Paschedag) writes:


>Hi There !

>I have a Question about signal handling of the OS-9/68k kernel.

>Situation : 

>        I have a filemanager which has executed a F$Sleep call (time=0).
>	During that sleep a signal arrives for the sleeping process.

>Question :
>     
>        Is it necessary to exit from the FM to ensure that the intercept-
>        handler of the process is called.
>	Or is the intercept handler called before the process returns from
>	the F$Sleep (system state !), so that the FM can ignore the 
>        unexpected return from the sleeping state :

>              Loop: moveq.l #0,d0
>                    os9 F$Sleep
>                    bcs.s Loop    (E$NoClk is ignored for this example !)

>Thanks in advance for your help !


IYour second guess is correct.  OS-9 queues signals that are received
by a process, calling the intercept routine before the process is
given CPU time (note that the intercept routine uses time out of
the process time slice).

This is true of the later versions of OS-9.  Earlier versions did not
have a queue for signals.  It is worth checking the signal code in
your program fragment.  If it is a fatal signal - hangup, quit, abort
etc. then you should return with the signal code as the error number
with the carry flag set.  If you don't do this, someone may be 
bashing away at the ^E key and getting very frustrated !

For a similar reason, check if the process has been killed.  The
condemn bit in the process state will be set if this is the case.
Exit with a 224 error.

Hope this helps,  Steve
-- 
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