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

     /*-
      * 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.
     * 4. 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: releng/11.0/sys/kern/subr_clock.c 302251 2016-06-28 16:42:40Z kib $");
    
    #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_RW,
        &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
    };
    
   
   /*
    * 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);
   }
   
   static void
   print_ct(struct clocktime *ct)
   {
           printf("[%04d-%02d-%02d %02d:%02d:%02d]",
               ct->year, ct->mon, ct->day,
               ct->hour, ct->min, ct->sec);
   }
   
   int
   clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
   {
           int i, year, days;
   
           year = ct->year;
   
           if (ct_debug) {
                   printf("ct_to_ts(");
                   print_ct(ct);
                   printf(")");
           }
   
           /* 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 ||
               (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.
            */
           days = 0;
           for (i = POSIX_BASE_YEAR; 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(" = %ld.%09ld\n", (long)ts->tv_sec, (long)ts->tv_nsec);
           return (0);
   }
   
   void
   clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
   {
           int 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, counting them in i. */
           for (year = POSIX_BASE_YEAR; 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(%ld.%09ld) = ",
                       (long)ts->tv_sec, (long)ts->tv_nsec);
                   print_ct(ct);
                   printf("\n");
           }
   }
   
   int
   utc_offset(void)
   {
   
           return (tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0));
   }

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