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/8.3/sys/kern/subr_clock.c 217302 2011-01-12 10:12:32Z bz $");
   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 int tz_minuteswest;
   53 int tz_dsttime;
   54 
   55 /*
   56  * The adjkerntz and wall_cmos_clock sysctls are in the "machdep" sysctl
   57  * namespace because they were misplaced there originally.
   58  */
   59 static int adjkerntz;
   60 static int
   61 sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
   62 {
   63         int error;
   64         error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
   65         if (!error && req->newptr)
   66                 resettodr();
   67         return (error);
   68 }
   69 SYSCTL_PROC(_machdep, OID_AUTO, adjkerntz, CTLTYPE_INT|CTLFLAG_RW,
   70     &adjkerntz, 0, sysctl_machdep_adjkerntz, "I",
   71     "Local offset from UTC in seconds");
   72 
   73 static int ct_debug;
   74 SYSCTL_INT(_debug, OID_AUTO, clocktime, CTLFLAG_RW,
   75     &ct_debug, 0, "Enable printing of clocktime debugging");
   76 
   77 static int wall_cmos_clock;
   78 SYSCTL_INT(_machdep, OID_AUTO, wall_cmos_clock, CTLFLAG_RW,
   79     &wall_cmos_clock, 0, "Enables application of machdep.adjkerntz");
   80 
   81 /*--------------------------------------------------------------------*
   82  * Generic routines to convert between a POSIX date
   83  * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
   84  * Derived from NetBSD arch/hp300/hp300/clock.c
   85  */
   86 
   87 
   88 #define FEBRUARY        2
   89 #define days_in_year(y)         (leapyear(y) ? 366 : 365)
   90 #define days_in_month(y, m) \
   91         (month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
   92 /* Day of week. Days are counted from 1/1/1970, which was a Thursday */
   93 #define day_of_week(days)       (((days) + 4) % 7)
   94 
   95 static const int month_days[12] = {
   96         31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
   97 };
   98 
   99 
  100 /*
  101  * This inline avoids some unnecessary modulo operations
  102  * as compared with the usual macro:
  103  *   ( ((year % 4) == 0 &&
  104  *      (year % 100) != 0) ||
  105  *     ((year % 400) == 0) )
  106  * It is otherwise equivalent.
  107  */
  108 static int
  109 leapyear(int year)
  110 {
  111         int rv = 0;
  112 
  113         if ((year & 3) == 0) {
  114                 rv = 1;
  115                 if ((year % 100) == 0) {
  116                         rv = 0;
  117                         if ((year % 400) == 0)
  118                                 rv = 1;
  119                 }
  120         }
  121         return (rv);
  122 }
  123 
  124 static void
  125 print_ct(struct clocktime *ct)
  126 {
  127         printf("[%04d-%02d-%02d %02d:%02d:%02d]",
  128             ct->year, ct->mon, ct->day,
  129             ct->hour, ct->min, ct->sec);
  130 }
  131 
  132 int
  133 clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
  134 {
  135         time_t secs;
  136         int i, year, days;
  137 
  138         year = ct->year;
  139 
  140         if (ct_debug) {
  141                 printf("ct_to_ts(");
  142                 print_ct(ct);
  143                 printf(")");
  144         }
  145 
  146         /* Sanity checks. */
  147         if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
  148             ct->day > days_in_month(year, ct->mon) ||
  149             ct->hour > 23 ||  ct->min > 59 || ct->sec > 59 ||
  150             ct->year > 2037) {          /* time_t overflow */
  151                 if (ct_debug)
  152                         printf(" = EINVAL\n");
  153                 return (EINVAL);
  154         }
  155 
  156         /*
  157          * Compute days since start of time
  158          * First from years, then from months.
  159          */
  160         days = 0;
  161         for (i = POSIX_BASE_YEAR; i < year; i++)
  162                 days += days_in_year(i);
  163 
  164         /* Months */
  165         for (i = 1; i < ct->mon; i++)
  166                 days += days_in_month(year, i);
  167         days += (ct->day - 1);
  168 
  169         /* Add hours, minutes, seconds. */
  170         secs = ((days * 24 + ct->hour) * 60 + ct->min) * 60 + ct->sec;
  171 
  172         ts->tv_sec = secs;
  173         ts->tv_nsec = ct->nsec;
  174         if (ct_debug)
  175                 printf(" = %ld.%09ld\n", (long)ts->tv_sec, (long)ts->tv_nsec);
  176         return (0);
  177 }
  178 
  179 void
  180 clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
  181 {
  182         int i, year, days;
  183         time_t rsec;    /* remainder seconds */
  184         time_t secs;
  185 
  186         secs = ts->tv_sec;
  187         days = secs / SECDAY;
  188         rsec = secs % SECDAY;
  189 
  190         ct->dow = day_of_week(days);
  191 
  192         /* Subtract out whole years, counting them in i. */
  193         for (year = POSIX_BASE_YEAR; days >= days_in_year(year); year++)
  194                 days -= days_in_year(year);
  195         ct->year = year;
  196 
  197         /* Subtract out whole months, counting them in i. */
  198         for (i = 1; days >= days_in_month(year, i); i++)
  199                 days -= days_in_month(year, i);
  200         ct->mon = i;
  201 
  202         /* Days are what is left over (+1) from all that. */
  203         ct->day = days + 1;
  204 
  205         /* Hours, minutes, seconds are easy */
  206         ct->hour = rsec / 3600;
  207         rsec = rsec % 3600;
  208         ct->min  = rsec / 60;
  209         rsec = rsec % 60;
  210         ct->sec  = rsec;
  211         ct->nsec = ts->tv_nsec;
  212         if (ct_debug) {
  213                 printf("ts_to_ct(%ld.%09ld) = ",
  214                     (long)ts->tv_sec, (long)ts->tv_nsec);
  215                 print_ct(ct);
  216                 printf("\n");
  217         }
  218 }
  219 
  220 int
  221 utc_offset(void)
  222 {
  223 
  224         return (tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0));
  225 }

Cache object: 58785bc145512429c702c9eacfa028c9


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