From:	ADVAX::"mcnc!VM1.NoDak.EDU!bill%WAIKATO.AC.NZ"  6-JUL-1990 09:04:01.90
To:	Multiple recipients of list ANU-NEWS <ANU-NEWS@NDSUVM1>
CC:	
Subj:	Correction to Shutdown Code

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From: mcnc!VM1.NoDak.EDU!bill%WAIKATO.AC.NZ
Subject:      Correction to Shutdown Code
To: Multiple recipients of list ANU-NEWS <ANU-NEWS@NDSUVM1>
 
Opps! The updated shutdown code has a slight error (the lock should remain
in Exclusive mode; a convert from EXMODE to EXMODE still writes the lock
value block to the resource's copy. The corrected shutdown module is :
 
---------------------------------------------------------------------------
/* SHUTDOWN.C.
   This program tries to obtain an exclusive mode lock which causes
   blocking ASTs to be delivered to the other programs that have called
   init_lock();
   The program needs to be run with SYSLCK privilege */
 
#define LOCKNAME "NEWS_LOCK"
#include descrip
#include lckdef
 
typedef volatile struct {
   int lksb_l_status;
   int lksb_l_lock_id;
   int lksb_l_value;
} LKSB_TYPE;
 
LKSB_TYPE lksb;
 
main()
{
        int status;
        $DESCRIPTOR( lock_desc, LOCKNAME );
 
        status = sys$enqw( 0, LCK$K_NLMODE, &lksb, LCK$M_SYSTEM,
            &lock_desc, 0, 0, 0, 0, 0, 0 );
        if (!(status & 1)) lib$stop(status);
        status = sys$enqw( 0, LCK$K_EXMODE, &lksb, LCK$M_CONVERT,
            0, 0, 0, 0, 0, 0, 0 );
        if (!(status & 1)) lib$stop(status);
 
        /* send across lock value 99 to indicate shutdown */
        lksb.lksb_l_value = 99;
        status = sys$enqw( 0, LCK$K_EXMODE, &lksb, LCK$M_CONVERT + LCK$M_VALBLK,
            0, 0, 0, 0, 0, 0, 0 );
        if (!(status & 1)) lib$stop(status);
        printf( "Completed\n" );
 
/*      keep EXMODE lock until utility re-started
        sys$hiber();
 */
}