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/* $Id: port-linux.c 1793 2007-01-28 20:55:08Z tg $ */
/* part of the adjtime-linux patch */
/*
* Copyright (c) 2004 Darren Tucker <dtucker at zip com au>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#ifdef USE_ADJTIMEX
#include <sys/timex.h>
#include <errno.h>
#ifdef adjtime
# undef adjtime
#endif
#include "ntpd.h"
/* scale factor used by adjtimex freq param. 1 ppm = 65536 */
#define ADJTIMEX_FREQ_SCALE 65536
/* maximum change to skew per adjustment, in PPM */
#define MAX_SKEW_DELTA 5.0
int
_compat_adjtime(const struct timeval *delta, struct timeval *olddelta)
{
static struct timeval tlast = {0,0};
static double tskew = 0;
static int synced = -1;
struct timeval tnow, tdelta;
double skew = 0, newskew, deltaskew, adjust, interval = 0;
struct timex tmx;
int result, saved_errno;
gettimeofday(&tnow, NULL);
adjust = (double)delta->tv_sec;
adjust += (double)delta->tv_usec / 1000000;
/* Even if the caller doesn't care about the olddelta, we do */
if (olddelta == NULL)
olddelta = &tdelta;
result = adjtime(delta, olddelta);
saved_errno = errno;
if (olddelta->tv_sec == 0 && olddelta->tv_usec == 0 &&
synced != INT_MAX)
synced++;
else
synced = 0;
/*
* do skew calculations if we have synced
*/
if (synced == 0 ) {
tmx.modes = 0;
if (adjtimex(&tmx) == -1)
log_warn("adjtimex get failed");
else
tskew = (double)tmx.freq / ADJTIMEX_FREQ_SCALE;
} else if (synced >= 1) {
interval = (double)(tnow.tv_sec - tlast.tv_sec);
interval += (double)(tnow.tv_usec - tlast.tv_usec) / 1000000;
skew = (adjust * 1000000) / interval;
newskew = ((tskew * synced) + skew) / synced;
deltaskew = newskew - tskew;
if (deltaskew > MAX_SKEW_DELTA) {
log_info("skew change %0.3lf exceeds limit", deltaskew);
tskew += MAX_SKEW_DELTA;
} else if (deltaskew < -MAX_SKEW_DELTA) {
log_info("skew change %0.3lf exceeds limit", deltaskew);
tskew -= MAX_SKEW_DELTA;
} else {
tskew = newskew;
}
/* Adjust the kernel skew. */
tmx.freq = (long)(tskew * ADJTIMEX_FREQ_SCALE);
tmx.modes = ADJ_FREQUENCY;
if (adjtimex(&tmx) == -1)
log_warn("adjtimex set freq failed");
}
log_debug("interval %0.3lf skew %0.3lf total skew %0.3lf", interval,
skew, tskew);
tlast = tnow;
errno = saved_errno;
return result;
}
#endif
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