/contrib/ntp/libntp/systime.c
https://bitbucket.org/freebsd/freebsd-head/ · C · 542 lines · 347 code · 50 blank · 145 comment · 51 complexity · b3f2dd5d51f2a68f9f3468fe465afa3d MD5 · raw file
- /*
- * 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 */