The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 1988 University of Utah.
    3  * Copyright (c) 1982, 1990, 1993
    4  *      The Regents of the University of California.  All rights reserved.
    5  *
    6  * This code is derived from software contributed to Berkeley by
    7  * the Systems Programming Group of the University of Utah Computer
    8  * Science Department.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      from: Utah $Hdr: clock.c 1.18 91/01/21$
   35  *      from: @(#)clock.c       8.2 (Berkeley) 1/12/94
   36  *      from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
   37  *      and
   38  *      from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
   39  */
   40 
   41 #include <sys/cdefs.h>
   42 __FBSDID("$FreeBSD: releng/8.1/sys/kern/subr_clock.c 199583 2009-11-20 15:27:52Z jhb $");
   43 
   44 #include <sys/param.h>
   45 #include <sys/systm.h>
   46 #include <sys/kernel.h>
   47 #include <sys/bus.h>
   48 #include <sys/clock.h>
   49 #include <sys/sysctl.h>
   50 #include <sys/timetc.h>
   51 
   52 #define ct_debug bootverbose
   53 static int adjkerntz;           /* local offset from GMT in seconds */
   54 static int wall_cmos_clock;     /* wall CMOS clock assumed if != 0 */
   55 
   56 int tz_minuteswest;
   57 int tz_dsttime;
   58 
   59 /*
   60  * This have traditionally been in machdep, but should probably be moved to
   61  * kern.
   62  */
   63 SYSCTL_INT(_machdep, OID_AUTO, wall_cmos_clock,
   64         CTLFLAG_RW, &wall_cmos_clock, 0, "");
   65 
   66 static int
   67 sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
   68 {
   69         int error;
   70         error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
   71         if (!error && req->newptr)
   72                 resettodr();
   73         return (error);
   74 }
   75 
   76 SYSCTL_PROC(_machdep, OID_AUTO, adjkerntz, CTLTYPE_INT|CTLFLAG_RW,
   77         &adjkerntz, 0, sysctl_machdep_adjkerntz, "I", "");
   78 
   79 /*--------------------------------------------------------------------*
   80  * Generic routines to convert between a POSIX date
   81  * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
   82  * Derived from NetBSD arch/hp300/hp300/clock.c
   83  */
   84 
   85 
   86 #define FEBRUARY        2
   87 #define days_in_year(y)         (leapyear(y) ? 366 : 365)
   88 #define days_in_month(y, m) \
   89         (month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
   90 /* Day of week. Days are counted from 1/1/1970, which was a Thursday */
   91 #define day_of_week(days)       (((days) + 4) % 7)
   92 
   93 static const int month_days[12] = {
   94         31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
   95 };
   96 
   97 
   98 /*
   99  * This inline avoids some unnecessary modulo operations
  100  * as compared with the usual macro:
  101  *   ( ((year % 4) == 0 &&
  102  *      (year % 100) != 0) ||
  103  *     ((year % 400) == 0) )
  104  * It is otherwise equivalent.
  105  */
  106 static int
  107 leapyear(int year)
  108 {
  109         int rv = 0;
  110 
  111         if ((year & 3) == 0) {
  112                 rv = 1;
  113                 if ((year % 100) == 0) {
  114                         rv = 0;
  115                         if ((year % 400) == 0)
  116                                 rv = 1;
  117                 }
  118         }
  119         return (rv);
  120 }
  121 
  122 static void
  123 print_ct(struct clocktime *ct)
  124 {
  125         printf("[%04d-%02d-%02d %02d:%02d:%02d]",
  126             ct->year, ct->mon, ct->day,
  127             ct->hour, ct->min, ct->sec);
  128 }
  129 
  130 int
  131 clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
  132 {
  133         time_t secs;
  134         int i, year, days;
  135 
  136         year = ct->year;
  137 
  138         if (ct_debug) {
  139                 printf("ct_to_ts(");
  140                 print_ct(ct);
  141                 printf(")");
  142         }
  143 
  144         /* Sanity checks. */
  145         if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
  146             ct->day > days_in_month(year, ct->mon) ||
  147             ct->hour > 23 ||  ct->min > 59 || ct->sec > 59 ||
  148             ct->year > 2037) {          /* time_t overflow */
  149                 if (ct_debug)
  150                         printf(" = EINVAL\n");
  151                 return (EINVAL);
  152         }
  153 
  154         /*
  155          * Compute days since start of time
  156          * First from years, then from months.
  157          */
  158         days = 0;
  159         for (i = POSIX_BASE_YEAR; i < year; i++)
  160                 days += days_in_year(i);
  161 
  162         /* Months */
  163         for (i = 1; i < ct->mon; i++)
  164                 days += days_in_month(year, i);
  165         days += (ct->day - 1);
  166 
  167         /* XXX Dow sanity check. Dow is not used, so should we check it? */
  168         if (ct->dow != -1 && ct->dow != day_of_week(days))
  169                 return (EINVAL);
  170 
  171         /* Add hours, minutes, seconds. */
  172         secs = ((days * 24 + ct->hour) * 60 + ct->min) * 60 + ct->sec;
  173 
  174         ts->tv_sec = secs;
  175         ts->tv_nsec = ct->nsec;
  176         if (ct_debug)
  177                 printf(" = %ld.%09ld\n", (long)ts->tv_sec, (long)ts->tv_nsec);
  178         return (0);
  179 }
  180 
  181 void
  182 clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
  183 {
  184         int i, year, days;
  185         time_t rsec;    /* remainder seconds */
  186         time_t secs;
  187 
  188         secs = ts->tv_sec;
  189         days = secs / SECDAY;
  190         rsec = secs % SECDAY;
  191 
  192         ct->dow = day_of_week(days);
  193 
  194         /* Subtract out whole years, counting them in i. */
  195         for (year = POSIX_BASE_YEAR; days >= days_in_year(year); year++)
  196                 days -= days_in_year(year);
  197         ct->year = year;
  198 
  199         /* Subtract out whole months, counting them in i. */
  200         for (i = 1; days >= days_in_month(year, i); i++)
  201                 days -= days_in_month(year, i);
  202         ct->mon = i;
  203 
  204         /* Days are what is left over (+1) from all that. */
  205         ct->day = days + 1;
  206 
  207         /* Hours, minutes, seconds are easy */
  208         ct->hour = rsec / 3600;
  209         rsec = rsec % 3600;
  210         ct->min  = rsec / 60;
  211         rsec = rsec % 60;
  212         ct->sec  = rsec;
  213         ct->nsec = ts->tv_nsec;
  214         if (ct_debug) {
  215                 printf("ts_to_ct(%ld.%09ld) = ",
  216                     (long)ts->tv_sec, (long)ts->tv_nsec);
  217                 print_ct(ct);
  218                 printf("\n");
  219         }
  220 }
  221 
  222 int
  223 utc_offset(void)
  224 {
  225 
  226         return (tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0));
  227 }

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