xntpd 3.3b from UDel

[unix-history] / contrib / xntpd / adjtime / adjtime.c

/*************************************************************************/
/* (c) Copyright Tai Jin, 1988.  All Rights Reserved.                    */
/*     Hewlett-Packard Laboratories.                                     */
/*                                                                       */
/* Permission is hereby granted for unlimited modification, use, and     */
/* distribution.  This software is made available with no warranty of    */
/* any kind, express or implied.  This copyright notice must remain      */
/* intact in all versions of this software.                              */
/*                                                                       */
/* The author would appreciate it if any bug fixes and enhancements were */
/* to be sent back to him for incorporation into future versions of this */
/* software.  Please send changes to tai@iag.hp.com or ken@sdd.hp.com.   */
/*************************************************************************/

#ifndef lint
static char RCSid[] = "adjtime.c,v 3.1 1993/07/06 01:04:42 jbj Exp";
#endif

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <time.h>
#include <signal.h>
#include "adjtime.h"

#define abs(x)  ((x) < 0 ? -(x) : (x))
static LONG adjthresh = 400L;
static LONG saveup;


_clear_adjtime()
{
   saveup = 0L;
}


adjtime(delta, olddelta)
   register struct timeval *delta;
   register struct timeval *olddelta;
{
   struct timeval newdelta;

   /* If they are giving us seconds, ignore up to current threshold saved */
   if (delta->tv_sec) {
       saveup = 0L;
       return(_adjtime(delta, olddelta));
   }

   /* add in, needs check for overflow ? */
   saveup += delta->tv_usec;

   /* Broke the threshold, call adjtime() */
   if (abs(saveup) > adjthresh) {
       newdelta.tv_sec = 0L;
       newdelta.tv_usec = saveup;
       saveup = 0L;
       return(_adjtime(&newdelta, olddelta));
   }

   if (olddelta)
     olddelta->tv_sec = olddelta->tv_usec = 0L;
   return(0);
}


_adjtime(delta, olddelta)
   register struct timeval *delta;
   register struct timeval *olddelta;
{
   register int mqid;
   MsgBuf msg;
   register MsgBuf *msgp = &msg;

   /*
    * get the key to the adjtime message queue
    * (note that we must get it every time because the queue might have been
    *  removed and recreated)
    */
   if ((mqid = msgget(KEY, 0)) == -1)
       return (-1);

   msgp->msgb.mtype = CLIENT;
   msgp->msgb.tv = *delta;

   if (olddelta)
       msgp->msgb.code = DELTA2;
   else
       msgp->msgb.code = DELTA1;

   if (msgsnd(mqid, &msgp->msgp, MSGSIZE, 0) == -1)
       return (-1);

   if (olddelta) {
       if (msgrcv(mqid, &msgp->msgp, MSGSIZE, SERVER, 0) == -1)
           return (-1);

       *olddelta = msgp->msgb.tv;
   }

   return (0);
}