FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_clock.c

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1988 University of Utah.
      * Copyright (c) 1982, 1990, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * the Systems Programming Group of the University of Utah Computer
     * Science Department.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      from: Utah $Hdr: clock.c 1.18 91/01/21$
     *      from: @(#)clock.c       8.2 (Berkeley) 1/12/94
     *      from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
     *      and
     *      from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/bus.h>
    #include <sys/clock.h>
    #include <sys/limits.h>
    #include <sys/sysctl.h>
    #include <sys/timetc.h>
    
    int tz_minuteswest;
    int tz_dsttime;
    
    /*
     * The adjkerntz and wall_cmos_clock sysctls are in the "machdep" sysctl
     * namespace because they were misplaced there originally.
     */
    static int adjkerntz;
    static int
    sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
    {
            int error;
            error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
            if (!error && req->newptr)
                    resettodr();
            return (error);
    }
    SYSCTL_PROC(_machdep, OID_AUTO, adjkerntz, CTLTYPE_INT | CTLFLAG_RW |
        CTLFLAG_MPSAFE, &adjkerntz, 0, sysctl_machdep_adjkerntz, "I",
        "Local offset from UTC in seconds");
    
    static int ct_debug;
    SYSCTL_INT(_debug, OID_AUTO, clocktime, CTLFLAG_RWTUN,
        &ct_debug, 0, "Enable printing of clocktime debugging");
    
    static int wall_cmos_clock;
    SYSCTL_INT(_machdep, OID_AUTO, wall_cmos_clock, CTLFLAG_RW,
        &wall_cmos_clock, 0, "Enables application of machdep.adjkerntz");
    
    /*--------------------------------------------------------------------*
     * Generic routines to convert between a POSIX date
     * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
     * Derived from NetBSD arch/hp300/hp300/clock.c
     */
    
    
    #define FEBRUARY        2
    #define days_in_year(y)         (leapyear(y) ? 366 : 365)
    #define days_in_month(y, m) \
            (month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
    /* Day of week. Days are counted from 1/1/1970, which was a Thursday */
    #define day_of_week(days)       (((days) + 4) % 7)
    
    static const int month_days[12] = {
            31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
   };
   
   /*
    * Optimization: using a precomputed count of days between POSIX_BASE_YEAR and
    * some recent year avoids lots of unnecessary loop iterations in conversion.
    * recent_base_days is the number of days before the start of recent_base_year.
    */
   static const int recent_base_year = 2017;
   static const int recent_base_days = 17167;
   
   /*
    * Table to 'calculate' pow(10, 9 - nsdigits) via lookup of nsdigits.
    * Before doing the lookup, the code asserts 0 <= nsdigits <= 9.
    */
   static u_int nsdivisors[] = {
       1000000000, 100000000, 10000000, 1000000, 100000, 10000, 1000, 100, 10, 1
   };
   
   /*
    * This inline avoids some unnecessary modulo operations
    * as compared with the usual macro:
    *   ( ((year % 4) == 0 &&
    *      (year % 100) != 0) ||
    *     ((year % 400) == 0) )
    * It is otherwise equivalent.
    */
   static int
   leapyear(int year)
   {
           int rv = 0;
   
           if ((year & 3) == 0) {
                   rv = 1;
                   if ((year % 100) == 0) {
                           rv = 0;
                           if ((year % 400) == 0)
                                   rv = 1;
                   }
           }
           return (rv);
   }
   
   int
   clock_ct_to_ts(const struct clocktime *ct, struct timespec *ts)
   {
           int i, year, days;
   
           if (ct_debug) {
                   printf("ct_to_ts([");
                   clock_print_ct(ct, 9);
                   printf("])");
           }
   
           /*
            * Many realtime clocks store the year as 2-digit BCD; pivot on 70 to
            * determine century.  Some clocks have a "century bit" and drivers do
            * year += 100, so interpret values between 70-199 as relative to 1900.
            */
           year = ct->year;
           if (year < 70)
                   year += 2000;
           else if (year < 200)
                   year += 1900;
   
           /* Sanity checks. */
           if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
               ct->day > days_in_month(year, ct->mon) ||
               ct->hour > 23 ||  ct->min > 59 || ct->sec > 59 || year < 1970 ||
               (sizeof(time_t) == 4 && year > 2037)) {     /* time_t overflow */
                   if (ct_debug)
                           printf(" = EINVAL\n");
                   return (EINVAL);
           }
   
           /*
            * Compute days since start of time
            * First from years, then from months.
            */
           if (year >= recent_base_year) {
                   i = recent_base_year;
                   days = recent_base_days;
           } else {
                   i = POSIX_BASE_YEAR;
                   days = 0;
           }
           for (; i < year; i++)
                   days += days_in_year(i);
   
           /* Months */
           for (i = 1; i < ct->mon; i++)
                   days += days_in_month(year, i);
           days += (ct->day - 1);
   
           ts->tv_sec = (((time_t)days * 24 + ct->hour) * 60 + ct->min) * 60 +
               ct->sec;
           ts->tv_nsec = ct->nsec;
   
           if (ct_debug)
                   printf(" = %jd.%09ld\n", (intmax_t)ts->tv_sec, ts->tv_nsec);
           return (0);
   }
   
   int
   clock_bcd_to_ts(const struct bcd_clocktime *bct, struct timespec *ts, bool ampm)
   {
           struct clocktime ct;
           int bcent, byear;
   
           /*
            * Year may come in as 2-digit or 4-digit BCD.  Split the value into
            * separate BCD century and year values for validation and conversion.
            */
           bcent = bct->year >> 8;
           byear = bct->year & 0xff;
   
           /*
            * Ensure that all values are valid BCD numbers, to avoid assertions in
            * the BCD-to-binary conversion routines.  clock_ct_to_ts() will further
            * validate the field ranges (such as 0 <= min <= 59) during conversion.
            */
           if (!validbcd(bcent) || !validbcd(byear) || !validbcd(bct->mon) ||
               !validbcd(bct->day) || !validbcd(bct->hour) ||
               !validbcd(bct->min) || !validbcd(bct->sec)) {
                   if (ct_debug)
                           printf("clock_bcd_to_ts: bad BCD: "
                               "[%04x-%02x-%02x %02x:%02x:%02x]\n",
                               bct->year, bct->mon, bct->day,
                               bct->hour, bct->min, bct->sec);
                   return (EINVAL);
           }
   
           ct.year = FROMBCD(byear) + FROMBCD(bcent) * 100;
           ct.mon  = FROMBCD(bct->mon);
           ct.day  = FROMBCD(bct->day);
           ct.hour = FROMBCD(bct->hour);
           ct.min  = FROMBCD(bct->min);
           ct.sec  = FROMBCD(bct->sec);
           ct.dow  = bct->dow;
           ct.nsec = bct->nsec;
   
           /* If asked to handle am/pm, convert from 12hr+pmflag to 24hr. */
           if (ampm) {
                   if (ct.hour == 12)
                           ct.hour = 0;
                   if (bct->ispm)
                           ct.hour += 12;
           }
   
           return (clock_ct_to_ts(&ct, ts));
   }
   
   void
   clock_ts_to_ct(const struct timespec *ts, struct clocktime *ct)
   {
           time_t i, year, days;
           time_t rsec;    /* remainder seconds */
           time_t secs;
   
           secs = ts->tv_sec;
           days = secs / SECDAY;
           rsec = secs % SECDAY;
   
           ct->dow = day_of_week(days);
   
           /* Subtract out whole years. */
           if (days >= recent_base_days) {
                   year = recent_base_year;
                   days -= recent_base_days;
           } else {
                   year = POSIX_BASE_YEAR;
           }
           for (; days >= days_in_year(year); year++)
                   days -= days_in_year(year);
           ct->year = year;
   
           /* Subtract out whole months, counting them in i. */
           for (i = 1; days >= days_in_month(year, i); i++)
                   days -= days_in_month(year, i);
           ct->mon = i;
   
           /* Days are what is left over (+1) from all that. */
           ct->day = days + 1;
   
           /* Hours, minutes, seconds are easy */
           ct->hour = rsec / 3600;
           rsec = rsec % 3600;
           ct->min  = rsec / 60;
           rsec = rsec % 60;
           ct->sec  = rsec;
           ct->nsec = ts->tv_nsec;
           if (ct_debug) {
                   printf("ts_to_ct(%jd.%09ld) = [",
                       (intmax_t)ts->tv_sec, ts->tv_nsec);
                   clock_print_ct(ct, 9);
                   printf("]\n");
           }
   
           KASSERT(ct->year >= 0 && ct->year < 10000,
               ("year %d isn't a 4 digit year", ct->year));
           KASSERT(ct->mon >= 1 && ct->mon <= 12,
               ("month %d not in 1-12", ct->mon));
           KASSERT(ct->day >= 1 && ct->day <= 31,
               ("day %d not in 1-31", ct->day));
           KASSERT(ct->hour >= 0 && ct->hour <= 23,
               ("hour %d not in 0-23", ct->hour));
           KASSERT(ct->min >= 0 && ct->min <= 59,
               ("minute %d not in 0-59", ct->min));
           /* Not sure if this interface needs to handle leapseconds or not. */
           KASSERT(ct->sec >= 0 && ct->sec <= 60,
               ("seconds %d not in 0-60", ct->sec));
   }
   
   void
   clock_ts_to_bcd(const struct timespec *ts, struct bcd_clocktime *bct, bool ampm)
   {
           struct clocktime ct;
   
           clock_ts_to_ct(ts, &ct);
   
           /* If asked to handle am/pm, convert from 24hr to 12hr+pmflag. */
           bct->ispm = false;
           if (ampm) {
                   if (ct.hour >= 12) {
                           ct.hour -= 12;
                           bct->ispm = true;
                   }
                   if (ct.hour == 0)
                           ct.hour = 12;
           }
   
           bct->year = TOBCD(ct.year % 100) | (TOBCD(ct.year / 100) << 8);
           bct->mon  = TOBCD(ct.mon);
           bct->day  = TOBCD(ct.day);
           bct->hour = TOBCD(ct.hour);
           bct->min  = TOBCD(ct.min);
           bct->sec  = TOBCD(ct.sec);
           bct->dow  = ct.dow;
           bct->nsec = ct.nsec;
   }
   
   void
   clock_print_bcd(const struct bcd_clocktime *bct, int nsdigits)
   {
   
           KASSERT(nsdigits >= 0 && nsdigits <= 9, ("bad nsdigits %d", nsdigits));
   
           if (nsdigits > 0) {
                   printf("%4.4x-%2.2x-%2.2x %2.2x:%2.2x:%2.2x.%*.*ld",
                       bct->year, bct->mon, bct->day,
                       bct->hour, bct->min, bct->sec,
                       nsdigits, nsdigits, bct->nsec / nsdivisors[nsdigits]);
           } else {
                   printf("%4.4x-%2.2x-%2.2x %2.2x:%2.2x:%2.2x",
                       bct->year, bct->mon, bct->day,
                       bct->hour, bct->min, bct->sec);
           }
   }
   
   void
   clock_print_ct(const struct clocktime *ct, int nsdigits)
   {
   
           KASSERT(nsdigits >= 0 && nsdigits <= 9, ("bad nsdigits %d", nsdigits));
   
           if (nsdigits > 0) {
                   printf("%04d-%02d-%02d %02d:%02d:%02d.%*.*ld",
                       ct->year, ct->mon, ct->day,
                       ct->hour, ct->min, ct->sec,
                       nsdigits, nsdigits, ct->nsec / nsdivisors[nsdigits]);
           } else {
                   printf("%04d-%02d-%02d %02d:%02d:%02d",
                       ct->year, ct->mon, ct->day,
                       ct->hour, ct->min, ct->sec);
           }
   }
   
   void
   clock_print_ts(const struct timespec *ts, int nsdigits)
   {
           struct clocktime ct;
   
           clock_ts_to_ct(ts, &ct);
           clock_print_ct(&ct, nsdigits);
   }
   
   int
   utc_offset(void)
   {
   
           return (tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0));
   }

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