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NetBSD/dist/ntp/libntp/systime.c

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/* $NetBSD: systime.c,v 1.5 2006/06/11 19:34:10 kardel Exp $ */
/*
* systime -- routines to fiddle a UNIX clock.
*
* ATTENTION: Get approval from Dave Mills on all changes to this file!
*
*/
#include "ntp_machine.h"
#include "ntp_fp.h"
#include "ntp_syslog.h"
#include "ntp_unixtime.h"
#include "ntp_stdlib.h"
#include "ntp_random.h"
#include "ntpd.h" /* for sys_precision */
#ifdef SIM
# include "ntpsim.h"
#endif /*SIM */
#ifdef HAVE_SYS_PARAM_H
# include <sys/param.h>
#endif
#ifdef HAVE_UTMP_H
# include <utmp.h>
#endif /* HAVE_UTMP_H */
#ifdef HAVE_UTMPX_H
# include <utmpx.h>
#endif /* HAVE_UTMPX_H */
/*
* These routines (get_systime, step_systime, adj_systime) implement an
* interface between the system independent NTP clock and the Unix
* system clock in various architectures and operating systems.
*
* Time is a precious quantity in these routines and every effort is
* made to minimize errors by always rounding toward zero and amortizing
* adjustment residues. By default the adjustment quantum is 1 us for
* the usual Unix tickadj() system call, but this can be increased if
* necessary by the tick configuration command. For instance, when the
* adjtime() quantum is a clock tick for a 100-Hz clock, the quantum
* should be 10 ms.
*/
#if defined RELIANTUNIX_CLOCK || defined SCO5_CLOCK
double sys_tick = 10e-3; /* 10 ms tickadj() */
#else
double sys_tick = 1e-6; /* 1 us tickadj() */
#endif
double sys_residual = 0; /* adjustment residue (s) */
#ifndef SIM
/*
* get_systime - return system time in NTP timestamp format.
*/
void
get_systime(
l_fp *now /* system time */
)
{
double dtemp;
#if defined(HAVE_CLOCK_GETTIME) || defined(HAVE_GETCLOCK)
struct timespec ts; /* seconds and nanoseconds */
/*
* Convert Unix clock from seconds and nanoseconds to seconds.
* The bottom is only two bits down, so no need for fuzz.
* Some systems don't have that level of precision, however...
*/
# ifdef HAVE_CLOCK_GETTIME
clock_gettime(CLOCK_REALTIME, &ts);
# else
getclock(TIMEOFDAY, &ts);
# endif
now->l_i = ts.tv_sec + JAN_1970;
dtemp = ts.tv_nsec / 1e9;
#else /* HAVE_CLOCK_GETTIME || HAVE_GETCLOCK */
struct timeval tv; /* seconds and microseconds */
/*
* Convert Unix clock from seconds and microseconds to seconds.
* Add in unbiased random fuzz beneath the microsecond.
*/
GETTIMEOFDAY(&tv, NULL);
now->l_i = tv.tv_sec + JAN_1970;
dtemp = tv.tv_usec / 1e6;
#endif /* HAVE_CLOCK_GETTIME || HAVE_GETCLOCK */
/*
* ntp_random() produces 31 bits (always nonnegative).
* This bit is done only after the precision has been
* determined.
*/
if (sys_precision != 0)
dtemp += (ntp_random() / FRAC - .5) / (1 <<
-sys_precision);
/*
* Renormalize to seconds past 1900 and fraction.
*/
dtemp += sys_residual;
if (dtemp >= 1) {
dtemp -= 1;
now->l_i++;
} else if (dtemp < 0) {
dtemp += 1;
now->l_i--;
}
dtemp *= FRAC;
now->l_uf = (u_int32)dtemp;
}
/*
* adj_systime - adjust system time by the argument.
*/
#if !defined SYS_WINNT
int /* 0 okay, 1 error */
adj_systime(
double now /* adjustment (s) */
)
{
struct timeval adjtv; /* new adjustment */
struct timeval oadjtv; /* residual adjustment */
double dtemp;
long ticks;
int isneg = 0;
/*
* Most Unix adjtime() implementations adjust the system clock
* in microsecond quanta, but some adjust in 10-ms quanta. We
* carefully round the adjustment to the nearest quantum, then
* adjust in quanta and keep the residue for later.
*/
dtemp = now + sys_residual;
if (dtemp < 0) {
isneg = 1;
dtemp = -dtemp;
}
adjtv.tv_sec = (long)dtemp;
dtemp -= adjtv.tv_sec;
ticks = (long)(dtemp / sys_tick + .5);
adjtv.tv_usec = (long)(ticks * sys_tick * 1e6);
dtemp -= adjtv.tv_usec / 1e6;
sys_residual = dtemp;
/*
* Convert to signed seconds and microseconds for the Unix
* adjtime() system call. Note we purposely lose the adjtime()
* leftover.
*/
if (isneg) {
adjtv.tv_sec = -adjtv.tv_sec;
adjtv.tv_usec = -adjtv.tv_usec;
sys_residual = -sys_residual;
}
if (adjtv.tv_sec != 0 || adjtv.tv_usec != 0) {
if (adjtime(&adjtv, &oadjtv) < 0) {
msyslog(LOG_ERR, "adj_systime: %m");
return (0);
}
}
return (1);
}
#endif
/*
* step_systime - step the system clock.
*/
int
step_systime(
double now
)
{
struct timeval timetv, adjtv, oldtimetv;
int isneg = 0;
double dtemp;
#if defined(HAVE_CLOCK_GETTIME) || defined(HAVE_GETCLOCK)
struct timespec ts;
#endif
dtemp = sys_residual + now;
if (dtemp < 0) {
isneg = 1;
dtemp = - dtemp;
adjtv.tv_sec = (int32)dtemp;
adjtv.tv_usec = (u_int32)((dtemp -
(double)adjtv.tv_sec) * 1e6 + .5);
} else {
adjtv.tv_sec = (int32)dtemp;
adjtv.tv_usec = (u_int32)((dtemp -
(double)adjtv.tv_sec) * 1e6 + .5);
}
#if defined(HAVE_CLOCK_GETTIME) || defined(HAVE_GETCLOCK)
# ifdef HAVE_CLOCK_GETTIME
(void) clock_gettime(CLOCK_REALTIME, &ts);
# else
(void) getclock(TIMEOFDAY, &ts);
# endif
timetv.tv_sec = ts.tv_sec;
timetv.tv_usec = ts.tv_nsec / 1000;
#else /* not HAVE_GETCLOCK */
(void) GETTIMEOFDAY(&timetv, (struct timezone *)0);
#endif /* not HAVE_GETCLOCK */
oldtimetv = timetv;
#ifdef DEBUG
if (debug)
printf("step_systime: step %.6f residual %.6f\n", now, sys_residual);
#endif
if (isneg) {
timetv.tv_sec -= adjtv.tv_sec;
timetv.tv_usec -= adjtv.tv_usec;
if (timetv.tv_usec < 0) {
timetv.tv_sec--;
timetv.tv_usec += 1000000;
}
} else {
timetv.tv_sec += adjtv.tv_sec;
timetv.tv_usec += adjtv.tv_usec;
if (timetv.tv_usec >= 1000000) {
timetv.tv_sec++;
timetv.tv_usec -= 1000000;
}
}
if (ntp_set_tod(&timetv, NULL) != 0) {
msyslog(LOG_ERR, "step-systime: %m");
return (0);
}
sys_residual = 0;
#ifdef NEED_HPUX_ADJTIME
/*
* CHECKME: is this correct when called by ntpdate?????
*/
_clear_adjtime();
#endif
/*
* FreeBSD, for example, has:
* struct utmp {
* char ut_line[UT_LINESIZE];
* char ut_name[UT_NAMESIZE];
* char ut_host[UT_HOSTSIZE];
* long ut_time;
* };
* and appends line="|", name="date", host="", time for the OLD
* and appends line="{", name="date", host="", time for the NEW
* to _PATH_WTMP .
*
* Some OSes have utmp, some have utmpx.
*/
/*
* Write old and new time entries in utmp and wtmp if step
* adjustment is greater than one second.
*
* This might become even Uglier...
*/
if (oldtimetv.tv_sec != timetv.tv_sec)
{
#ifdef HAVE_UTMP_H
struct utmp ut;
#endif
#ifdef HAVE_UTMPX_H
struct utmpx utx;
#endif
#ifdef HAVE_UTMP_H
memset((char *)&ut, 0, sizeof(ut));
#endif
#ifdef HAVE_UTMPX_H
memset((char *)&utx, 0, sizeof(utx));
#endif
/* UTMP */
#ifdef UPDATE_UTMP
# ifdef HAVE_PUTUTLINE
ut.ut_type = OLD_TIME;
(void)strcpy(ut.ut_line, OTIME_MSG);
ut.ut_time = oldtimetv.tv_sec;
pututline(&ut);
setutent();
ut.ut_type = NEW_TIME;
(void)strcpy(ut.ut_line, NTIME_MSG);
ut.ut_time = timetv.tv_sec;
pututline(&ut);
endutent();
# else /* not HAVE_PUTUTLINE */
# endif /* not HAVE_PUTUTLINE */
#endif /* UPDATE_UTMP */
/* UTMPX */
#ifdef UPDATE_UTMPX
# ifdef HAVE_PUTUTXLINE
utx.ut_type = OLD_TIME;
(void)strcpy(utx.ut_line, OTIME_MSG);
utx.ut_tv = oldtimetv;
pututxline(&utx);
setutxent();
utx.ut_type = NEW_TIME;
(void)strcpy(utx.ut_line, NTIME_MSG);
utx.ut_tv = timetv;
pututxline(&utx);
endutxent();
# else /* not HAVE_PUTUTXLINE */
# endif /* not HAVE_PUTUTXLINE */
#endif /* UPDATE_UTMPX */
/* WTMP */
#ifdef UPDATE_WTMP
# ifdef HAVE_PUTUTLINE
utmpname(WTMP_FILE);
ut.ut_type = OLD_TIME;
(void)strcpy(ut.ut_line, OTIME_MSG);
ut.ut_time = oldtimetv.tv_sec;
pututline(&ut);
ut.ut_type = NEW_TIME;
(void)strcpy(ut.ut_line, NTIME_MSG);
ut.ut_time = timetv.tv_sec;
pututline(&ut);
endutent();
# else /* not HAVE_PUTUTLINE */
# endif /* not HAVE_PUTUTLINE */
#endif /* UPDATE_WTMP */
/* WTMPX */
#ifdef UPDATE_WTMPX
# ifdef HAVE_PUTUTXLINE
utx.ut_type = OLD_TIME;
utx.ut_tv = oldtimetv;
(void)strcpy(utx.ut_line, OTIME_MSG);
# ifdef HAVE_UPDWTMPX
updwtmpx(WTMPX_FILE, &utx);
# else /* not HAVE_UPDWTMPX */
# endif /* not HAVE_UPDWTMPX */
# else /* not HAVE_PUTUTXLINE */
# endif /* not HAVE_PUTUTXLINE */
# ifdef HAVE_PUTUTXLINE
utx.ut_type = NEW_TIME;
utx.ut_tv = timetv;
(void)strcpy(utx.ut_line, NTIME_MSG);
# ifdef HAVE_UPDWTMPX
updwtmpx(WTMPX_FILE, &utx);
# else /* not HAVE_UPDWTMPX */
# endif /* not HAVE_UPDWTMPX */
# else /* not HAVE_PUTUTXLINE */
# endif /* not HAVE_PUTUTXLINE */
#endif /* UPDATE_WTMPX */
}
return (1);
}
#else /* SIM */
/*
* Clock routines for the simulator - Harish Nair, with help
*/
/*
* get_systime - return the system time in NTP timestamp format
*/
void
get_systime(
l_fp *now /* current system time in l_fp */ )
{
/*
* To fool the code that determines the local clock precision,
* we advance the clock a minimum of 200 nanoseconds on every
* clock read. This is appropriate for a typical modern machine
* with nanosecond clocks. Note we make no attempt here to
* simulate reading error, since the error is so small. This may
* change when the need comes to implement picosecond clocks.
*/
if (ntp_node.ntp_time == ntp_node.last_time)
ntp_node.ntp_time += 200e-9;
ntp_node.last_time = ntp_node.ntp_time;
DTOLFP(ntp_node.ntp_time, now);
}
/*
* adj_systime - advance or retard the system clock exactly like the
* real thng.
*/
int /* always succeeds */
adj_systime(
double now /* time adjustment (s) */
)
{
struct timeval adjtv; /* new adjustment */
double dtemp;
long ticks;
int isneg = 0;
/*
* Most Unix adjtime() implementations adjust the system clock
* in microsecond quanta, but some adjust in 10-ms quanta. We
* carefully round the adjustment to the nearest quantum, then
* adjust in quanta and keep the residue for later.
*/
dtemp = now + sys_residual;
if (dtemp < 0) {
isneg = 1;
dtemp = -dtemp;
}
adjtv.tv_sec = (long)dtemp;
dtemp -= adjtv.tv_sec;
ticks = (long)(dtemp / sys_tick + .5);
adjtv.tv_usec = (long)(ticks * sys_tick * 1e6);
dtemp -= adjtv.tv_usec / 1e6;
sys_residual = dtemp;
/*
* Convert to signed seconds and microseconds for the Unix
* adjtime() system call. Note we purposely lose the adjtime()
* leftover.
*/
if (isneg) {
adjtv.tv_sec = -adjtv.tv_sec;
adjtv.tv_usec = -adjtv.tv_usec;
sys_residual = -sys_residual;
}
ntp_node.adj = now;
return (1);
}
/*
* step_systime - step the system clock. We are religious here.
*/
int /* always succeeds */
step_systime(
double now /* step adjustment (s) */
)
{
#ifdef DEBUG
if (debug)
printf("step_systime: time %.6f adj %.6f\n",
ntp_node.ntp_time, now);
#endif
ntp_node.ntp_time += now;
return (1);
}
/*
* node_clock - update the clocks
*/
int /* always succeeds */
node_clock(
Node *n, /* global node pointer */
double t /* node time */
)
{
double dtemp;
/*
* Advance client clock (ntp_time). Advance server clock
* (clk_time) adjusted for systematic and random frequency
* errors. The random error is a random walk computed as the
* integral of samples from a Gaussian distribution.
*/
dtemp = t - n->ntp_time;
n->time = t;
n->ntp_time += dtemp;
n->ferr += gauss(0, dtemp * n->fnse);
n->clk_time += dtemp * (1 + n->ferr);
/*
* Perform the adjtime() function. If the adjustment completed
* in the previous interval, amortize the entire amount; if not,
* carry the leftover to the next interval.
*/
dtemp *= n->slew;
if (dtemp < fabs(n->adj)) {
if (n->adj < 0) {
n->adj += dtemp;
n->ntp_time -= dtemp;
} else {
n->adj -= dtemp;
n->ntp_time += dtemp;
}
} else {
n->ntp_time += n->adj;
n->adj = 0;
}
return (0);
}
/*
* gauss() - returns samples from a gaussion distribution
*/
double /* Gaussian sample */
gauss(
double m, /* sample mean */
double s /* sample standard deviation (sigma) */
)
{
double q1, q2;
/*
* Roll a sample from a Gaussian distribution with mean m and
* standard deviation s. For m = 0, s = 1, mean(y) = 0,
* std(y) = 1.
*/
if (s == 0)
return (m);
while ((q1 = drand48()) == 0);
q2 = drand48();
return (m + s * sqrt(-2. * log(q1)) * cos(2. * PI * q2));
}
/*
* poisson() - returns samples from a network delay distribution
*/
double /* delay sample (s) */
poisson(
double m, /* fixed propagation delay (s) */
double s /* exponential parameter (mu) */
)
{
double q1;
/*
* Roll a sample from a composite distribution with propagation
* delay m and exponential distribution time with parameter s.
* For m = 0, s = 1, mean(y) = std(y) = 1.
*/
if (s == 0)
return (m);
while ((q1 = drand48()) == 0);
return (m - s * log(q1 * s));
}
#endif /* SIM */
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