cmd/rtc/rtc.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/sysi86.h>
#include <errno.h>
#include <time.h>
#include <string.h>
#include <sys/stat.h>

static char *progname;
static char *zonefile = "/etc/rtc_config";
static FILE *zonefptr;
static char zone_info[256];
static char zone_lag[256];
static char tz[256] = "TZ=";
int debug = 0;
int lag;
int errors_ok = 0; /* allow "rtc no-args" to be quiet when not configured */
static time_t clock_val;
static char zone_comment[] =
    "#\n"
    "#  This file (%s) contains information used to manage the\n"
    "#  x86 real time clock hardware.  The hardware is kept in\n"
    "#  the machine's local time for compatibility with other x86\n"
    "#  operating systems.  This file is read by the kernel at\n"
    "#  boot time.  It is set and updated by the /usr/sbin/rtc\n"
    "#  command.  The 'zone_info' field designates the local\n"
    "#  time zone.  The 'zone_lag' field indicates the number\n"
    "#  of seconds between local time and Greenwich Mean Time.\n"
    "#\n";

/*
 *  Open the configuration file and extract the
 *  zone_info and the zone_lag.  Return 0 if successful.
 */
int
open_zonefile()
{
    char b[256], *s;
    int lag_hrs;

    if ((zonefptr = fopen(zonefile, "r")) == NULL) {
        if (errors_ok == 0)
            (void) fprintf(stderr,
                "%s: cannot open %s: errno = %d\n",
                progname, zonefile, errno);
        return (1);
    }

    for (;;) {
        if ((s = fgets(b, sizeof (b), zonefptr)) == NULL)
            break;
        if ((s = strchr(s, 'z')) == NULL)
            continue;
        if (strncmp(s, "zone_info", 9) == 0) {
            s += 9;
            while (*s != 0 && *s != '=')
                s++;
            if (*s == '=') {
                s++;
                while (*s != 0 && (*s == ' ' || *s == '\t'))
                    s++;
                (void) strncpy(zone_info, s,
                    sizeof (zone_info));
                s = zone_info;
                while (*s != 0 && *s != '\n')
                    s++;
                if (*s == '\n')
                    *s = 0;
            }
        } else if (strncmp(s, "zone_lag", 8) == 0) {
            s += 8;
            while (*s != 0 && *s != '=')
                s++;
            if (*s == '=') {
                s++;
                while (*s != 0 && (*s == ' ' || *s == '\t'))
                    s++;
                (void) strncpy(zone_lag, s, sizeof (zone_lag));
                s = zone_lag;
                while (*s != 0 && *s != '\n')
                    s++;
                if (*s == '\n')
                    *s = 0;
            }
        }
    }
    lag = atoi(zone_lag);
    lag_hrs = lag / 3600;
    if (zone_info[0] == 0) {
        (void) fprintf(stderr, "%s: zone_info field is invalid\n",
            progname);
        zone_info[0] = 0;
        zone_lag[0] = 0;
        return (1);
    }
    if (zone_lag[0] == 0) {
        (void) fprintf(stderr, "%s: zone_lag field is invalid\n",
            progname);
        zone_lag[0] = 0;
        return (1);
    }
    if ((lag_hrs < -24) || (lag_hrs > 24)) {
        (void) fprintf(stderr, "%s: a GMT lag of %d is out of range\n",
            progname, lag_hrs);
        zone_info[0] = 0;
        zone_lag[0] = 0;
        return (1);
    }
    if (debug)
        (void) fprintf(stderr, "zone_info = %s,   zone_lag = %s\n",
            zone_info, zone_lag);
    if (debug)
        (void) fprintf(stderr, "lag (decimal) is %d\n", lag);

    (void) fclose(zonefptr);
    zonefptr = NULL;
    return (0);
}

void
display_zone_string(void)
{
    if (open_zonefile() == 0)
        (void) printf("%s\n", zone_info);
    else
        (void) printf("GMT\n");
}

long
set_zone(char *zone_string)
{
    struct tm *tm;
    long current_lag;

    (void) umask(0022);
    if ((zonefptr = fopen(zonefile, "w")) == NULL) {
        (void) fprintf(stderr, "%s: cannot open %s: errno = %d\n",
            progname, zonefile, errno);
        return (0);
    }

    tz[3] = 0;
    (void) strncat(tz, zone_string, 253);
    if (debug)
        (void) fprintf(stderr, "Time Zone string is '%s'\n", tz);

    (void) putenv(tz);
    if (debug)
        (void) system("env | grep TZ");

    (void) time(&clock_val);

    tm = localtime(&clock_val);
    current_lag = tm->tm_isdst ? altzone : timezone;
    if (debug)
        (void) printf("%s DST.    Lag is %ld.\n", tm->tm_isdst ? "Is" :
            "Is NOT",  tm->tm_isdst ? altzone : timezone);

    (void) fprintf(zonefptr, zone_comment, zonefile);
    (void) fprintf(zonefptr, "zone_info=%s\n", zone_string);
    (void) fprintf(zonefptr, "zone_lag=%ld\n",
        tm->tm_isdst ? altzone : timezone);
    (void) fclose(zonefptr);
    zonefptr = NULL;
    return (current_lag);
}

void
correct_rtc_and_lag()
{
    struct tm *tm;
    long kernels_lag;
    long current_lag;

    if (open_zonefile())
        return;

    tz[3] = 0;
    (void) strncat(tz, zone_info, 253);
    if (debug)
        (void) fprintf(stderr, "Time Zone string is '%s'\n", tz);

    (void) putenv(tz);
    if (debug)
        (void) system("env | grep TZ");

    (void) time(&clock_val);
    tm = localtime(&clock_val);
    current_lag = tm->tm_isdst ? altzone : timezone;

    if (current_lag != lag) {   /* if file is wrong */
        if (debug)
            (void) fprintf(stderr, "correcting file");
        (void) set_zone(zone_info); /* then rewrite file */
    }

    (void) sysi86(GGMTL, &kernels_lag);
    if (current_lag != kernels_lag) {
        if (debug)
            (void) fprintf(stderr, "correcting kernel's lag");
        (void) sysi86(SGMTL, current_lag);  /* correct the lag */
        (void) sysi86(WTODC);           /* set the rtc to */
                            /* new local time */
    }
}

void
initialize_zone(char *zone_string)
{
    long current_lag;

    /* write the config file */
    current_lag = set_zone(zone_string);

    /* correct the lag */
    (void) sysi86(SGMTL, current_lag);

    /*
     * set the unix time from the rtc,
     * assuming the rtc was the correct
     * local time.
     */
    (void) sysi86(RTCSYNC);
}

void
usage()
{
    static char Usage[] = "Usage:\n\
rtc [-c] [-z time_zone] [-?]\n";

    (void) fprintf(stderr, Usage);
}

void
verbose_usage()
{
    static char Usage1[] = "\
    Options:\n\
        -c\t\tCheck and correct for daylight savings time rollover.\n\
        -z [zone]\tRecord the zone info in the config file.\n";

    (void) fprintf(stderr, Usage1);
}

int
main(int argc, char *argv[])
{
    int c;

    progname = argv[0];

    if (argc == 1) {
        errors_ok = 1;
        display_zone_string();
    }

    while ((c = getopt(argc, argv, "cz:d")) != EOF) {
        switch (c) {
        case 'c':
            correct_rtc_and_lag();
            continue;
        case 'z':
            initialize_zone(optarg);
            continue;
        case 'd':
            debug = 1;
            continue;
        case '?':
            verbose_usage();
            return (0);
        default:
            usage();
            return (1);
        }
    }
    return (0);
}