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/11.2/sys/kern/subr_clock.c 331722 2018-03-29 02:50:57Z eadler $");
   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/limits.h>
   50 #include <sys/sysctl.h>
   51 #include <sys/timetc.h>
   52 
   53 int tz_minuteswest;
   54 int tz_dsttime;
   55 
   56 /*
   57  * The adjkerntz and wall_cmos_clock sysctls are in the "machdep" sysctl
   58  * namespace because they were misplaced there originally.
   59  */
   60 static int adjkerntz;
   61 static int
   62 sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
   63 {
   64         int error;
   65         error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
   66         if (!error && req->newptr)
   67                 resettodr();
   68         return (error);
   69 }
   70 SYSCTL_PROC(_machdep, OID_AUTO, adjkerntz, CTLTYPE_INT | CTLFLAG_RW |
   71     CTLFLAG_MPSAFE, &adjkerntz, 0, sysctl_machdep_adjkerntz, "I",
   72     "Local offset from UTC in seconds");
   73 
   74 static int ct_debug;
   75 SYSCTL_INT(_debug, OID_AUTO, clocktime, CTLFLAG_RWTUN,
   76     &ct_debug, 0, "Enable printing of clocktime debugging");
   77 
   78 static int wall_cmos_clock;
   79 SYSCTL_INT(_machdep, OID_AUTO, wall_cmos_clock, CTLFLAG_RW,
   80     &wall_cmos_clock, 0, "Enables application of machdep.adjkerntz");
   81 
   82 /*--------------------------------------------------------------------*
   83  * Generic routines to convert between a POSIX date
   84  * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
   85  * Derived from NetBSD arch/hp300/hp300/clock.c
   86  */
   87 
   88 
   89 #define FEBRUARY        2
   90 #define days_in_year(y)         (leapyear(y) ? 366 : 365)
   91 #define days_in_month(y, m) \
   92         (month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
   93 /* Day of week. Days are counted from 1/1/1970, which was a Thursday */
   94 #define day_of_week(days)       (((days) + 4) % 7)
   95 
   96 static const int month_days[12] = {
   97         31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
   98 };
   99 
  100 /*
  101  * Optimization: using a precomputed count of days between POSIX_BASE_YEAR and
  102  * some recent year avoids lots of unnecessary loop iterations in conversion.
  103  * recent_base_days is the number of days before the start of recent_base_year.
  104  */
  105 static const int recent_base_year = 2017;
  106 static const int recent_base_days = 17167;
  107 
  108 /*
  109  * Table to 'calculate' pow(10, 9 - nsdigits) via lookup of nsdigits.
  110  * Before doing the lookup, the code asserts 0 <= nsdigits <= 9.
  111  */
  112 static u_int nsdivisors[] = {
  113     1000000000, 100000000, 10000000, 1000000, 100000, 10000, 1000, 100, 10, 1
  114 };
  115 
  116 /*
  117  * This inline avoids some unnecessary modulo operations
  118  * as compared with the usual macro:
  119  *   ( ((year % 4) == 0 &&
  120  *      (year % 100) != 0) ||
  121  *     ((year % 400) == 0) )
  122  * It is otherwise equivalent.
  123  */
  124 static int
  125 leapyear(int year)
  126 {
  127         int rv = 0;
  128 
  129         if ((year & 3) == 0) {
  130                 rv = 1;
  131                 if ((year % 100) == 0) {
  132                         rv = 0;
  133                         if ((year % 400) == 0)
  134                                 rv = 1;
  135                 }
  136         }
  137         return (rv);
  138 }
  139 
  140 int
  141 clock_ct_to_ts(const struct clocktime *ct, struct timespec *ts)
  142 {
  143         int i, year, days;
  144 
  145         if (ct_debug) {
  146                 printf("ct_to_ts([");
  147                 clock_print_ct(ct, 9);
  148                 printf("])");
  149         }
  150 
  151         /*
  152          * Many realtime clocks store the year as 2-digit BCD; pivot on 70 to
  153          * determine century.  Some clocks have a "century bit" and drivers do
  154          * year += 100, so interpret values between 70-199 as relative to 1900.
  155          */
  156         year = ct->year;
  157         if (year < 70)
  158                 year += 2000;
  159         else if (year < 200)
  160                 year += 1900;
  161 
  162         /* Sanity checks. */
  163         if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
  164             ct->day > days_in_month(year, ct->mon) ||
  165             ct->hour > 23 ||  ct->min > 59 || ct->sec > 59 || year < 1970 ||
  166             (sizeof(time_t) == 4 && year > 2037)) {     /* time_t overflow */
  167                 if (ct_debug)
  168                         printf(" = EINVAL\n");
  169                 return (EINVAL);
  170         }
  171 
  172         /*
  173          * Compute days since start of time
  174          * First from years, then from months.
  175          */
  176         if (year >= recent_base_year) {
  177                 i = recent_base_year;
  178                 days = recent_base_days;
  179         } else {
  180                 i = POSIX_BASE_YEAR;
  181                 days = 0;
  182         }
  183         for (; i < year; i++)
  184                 days += days_in_year(i);
  185 
  186         /* Months */
  187         for (i = 1; i < ct->mon; i++)
  188                 days += days_in_month(year, i);
  189         days += (ct->day - 1);
  190 
  191         ts->tv_sec = (((time_t)days * 24 + ct->hour) * 60 + ct->min) * 60 +
  192             ct->sec;
  193         ts->tv_nsec = ct->nsec;
  194 
  195         if (ct_debug)
  196                 printf(" = %jd.%09ld\n", (intmax_t)ts->tv_sec, ts->tv_nsec);
  197         return (0);
  198 }
  199 
  200 int
  201 clock_bcd_to_ts(const struct bcd_clocktime *bct, struct timespec *ts, bool ampm)
  202 {
  203         struct clocktime ct;
  204         int bcent, byear;
  205 
  206         /*
  207          * Year may come in as 2-digit or 4-digit BCD.  Split the value into
  208          * separate BCD century and year values for validation and conversion.
  209          */
  210         bcent = bct->year >> 8;
  211         byear = bct->year & 0xff;
  212 
  213         /*
  214          * Ensure that all values are valid BCD numbers, to avoid assertions in
  215          * the BCD-to-binary conversion routines.  clock_ct_to_ts() will further
  216          * validate the field ranges (such as 0 <= min <= 59) during conversion.
  217          */
  218         if (!validbcd(bcent) || !validbcd(byear) || !validbcd(bct->mon) ||
  219             !validbcd(bct->day) || !validbcd(bct->hour) ||
  220             !validbcd(bct->min) || !validbcd(bct->sec)) {
  221                 if (ct_debug)
  222                         printf("clock_bcd_to_ts: bad BCD: "
  223                             "[%04x-%02x-%02x %02x:%02x:%02x]\n",
  224                             bct->year, bct->mon, bct->day,
  225                             bct->hour, bct->min, bct->sec);
  226                 return (EINVAL);
  227         }
  228 
  229         ct.year = FROMBCD(byear) + FROMBCD(bcent) * 100;
  230         ct.mon  = FROMBCD(bct->mon);
  231         ct.day  = FROMBCD(bct->day);
  232         ct.hour = FROMBCD(bct->hour);
  233         ct.min  = FROMBCD(bct->min);
  234         ct.sec  = FROMBCD(bct->sec);
  235         ct.dow  = bct->dow;
  236         ct.nsec = bct->nsec;
  237 
  238         /* If asked to handle am/pm, convert from 12hr+pmflag to 24hr. */
  239         if (ampm) {
  240                 if (ct.hour == 12)
  241                         ct.hour = 0;
  242                 if (bct->ispm)
  243                         ct.hour += 12;
  244         }
  245 
  246         return (clock_ct_to_ts(&ct, ts));
  247 }
  248 
  249 void
  250 clock_ts_to_ct(const struct timespec *ts, struct clocktime *ct)
  251 {
  252         int i, year, days;
  253         time_t rsec;    /* remainder seconds */
  254         time_t secs;
  255 
  256         secs = ts->tv_sec;
  257         days = secs / SECDAY;
  258         rsec = secs % SECDAY;
  259 
  260         ct->dow = day_of_week(days);
  261 
  262         /* Subtract out whole years. */
  263         if (days >= recent_base_days) {
  264                 year = recent_base_year;
  265                 days -= recent_base_days;
  266         } else {
  267                 year = POSIX_BASE_YEAR;
  268         }
  269         for (; days >= days_in_year(year); year++)
  270                 days -= days_in_year(year);
  271         ct->year = year;
  272 
  273         /* Subtract out whole months, counting them in i. */
  274         for (i = 1; days >= days_in_month(year, i); i++)
  275                 days -= days_in_month(year, i);
  276         ct->mon = i;
  277 
  278         /* Days are what is left over (+1) from all that. */
  279         ct->day = days + 1;
  280 
  281         /* Hours, minutes, seconds are easy */
  282         ct->hour = rsec / 3600;
  283         rsec = rsec % 3600;
  284         ct->min  = rsec / 60;
  285         rsec = rsec % 60;
  286         ct->sec  = rsec;
  287         ct->nsec = ts->tv_nsec;
  288         if (ct_debug) {
  289                 printf("ts_to_ct(%jd.%09ld) = [",
  290                     (intmax_t)ts->tv_sec, ts->tv_nsec);
  291                 clock_print_ct(ct, 9);
  292                 printf("]\n");
  293         }
  294 }
  295 
  296 void
  297 clock_ts_to_bcd(const struct timespec *ts, struct bcd_clocktime *bct, bool ampm)
  298 {
  299         struct clocktime ct;
  300 
  301         clock_ts_to_ct(ts, &ct);
  302 
  303         /* If asked to handle am/pm, convert from 24hr to 12hr+pmflag. */
  304         bct->ispm = false;
  305         if (ampm) {
  306                 if (ct.hour >= 12) {
  307                         ct.hour -= 12;
  308                         bct->ispm = true;
  309                 }
  310                 if (ct.hour == 0)
  311                         ct.hour = 12;
  312         }
  313 
  314         bct->year = TOBCD(ct.year % 100) | (TOBCD(ct.year / 100) << 8);
  315         bct->mon  = TOBCD(ct.mon);
  316         bct->day  = TOBCD(ct.day);
  317         bct->hour = TOBCD(ct.hour);
  318         bct->min  = TOBCD(ct.min);
  319         bct->sec  = TOBCD(ct.sec);
  320         bct->dow  = ct.dow;
  321         bct->nsec = ct.nsec;
  322 }
  323 
  324 void
  325 clock_print_bcd(const struct bcd_clocktime *bct, int nsdigits)
  326 {
  327 
  328         KASSERT(nsdigits >= 0 && nsdigits <= 9, ("bad nsdigits %d", nsdigits));
  329 
  330         if (nsdigits > 0) {
  331                 printf("%4.4x-%2.2x-%2.2x %2.2x:%2.2x:%2.2x.%*.*ld",
  332                     bct->year, bct->mon, bct->day,
  333                     bct->hour, bct->min, bct->sec,
  334                     nsdigits, nsdigits, bct->nsec / nsdivisors[nsdigits]);
  335         } else {
  336                 printf("%4.4x-%2.2x-%2.2x %2.2x:%2.2x:%2.2x",
  337                     bct->year, bct->mon, bct->day,
  338                     bct->hour, bct->min, bct->sec);
  339         }
  340 }
  341 
  342 void
  343 clock_print_ct(const struct clocktime *ct, int nsdigits)
  344 {
  345 
  346         KASSERT(nsdigits >= 0 && nsdigits <= 9, ("bad nsdigits %d", nsdigits));
  347 
  348         if (nsdigits > 0) {
  349                 printf("%04d-%02d-%02d %02d:%02d:%02d.%*.*ld",
  350                     ct->year, ct->mon, ct->day,
  351                     ct->hour, ct->min, ct->sec,
  352                     nsdigits, nsdigits, ct->nsec / nsdivisors[nsdigits]);
  353         } else {
  354                 printf("%04d-%02d-%02d %02d:%02d:%02d",
  355                     ct->year, ct->mon, ct->day,
  356                     ct->hour, ct->min, ct->sec);
  357         }
  358 }
  359 
  360 void
  361 clock_print_ts(const struct timespec *ts, int nsdigits)
  362 {
  363         struct clocktime ct;
  364 
  365         clock_ts_to_ct(ts, &ct);
  366         clock_print_ct(&ct, nsdigits);
  367 }
  368 
  369 int
  370 utc_offset(void)
  371 {
  372 
  373         return (tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0));
  374 }

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