source: MondoRescue/branches/2.2.9/mindi-busybox/util-linux/rtcwake.c@ 3320

/*
 * rtcwake -- enter a system sleep state until specified wakeup time.
 *
 * This version was taken from util-linux and scrubbed down for busybox.
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 *
 * This uses cross-platform Linux interfaces to enter a system sleep state,
 * and leave it no later than a specified time.  It uses any RTC framework
 * driver that supports standard driver model wakeup flags.
 *
 * This is normally used like the old "apmsleep" utility, to wake from a
 * suspend state like ACPI S1 (standby) or S3 (suspend-to-RAM).  Most
 * platforms can implement those without analogues of BIOS, APM, or ACPI.
 *
 * On some systems, this can also be used like "nvram-wakeup", waking
 * from states like ACPI S4 (suspend to disk).  Not all systems have
 * persistent media that are appropriate for such suspend modes.
 *
 * The best way to set the system's RTC is so that it holds the current
 * time in UTC.  Use the "-l" flag to tell this program that the system
 * RTC uses a local timezone instead (maybe you dual-boot MS-Windows).
 * That flag should not be needed on systems with adjtime support.
 */

#include "libbb.h"
#include "rtc_.h"

#define SYS_RTC_PATH   "/sys/class/rtc/%s/device/power/wakeup"
#define SYS_POWER_PATH "/sys/power/state"
#define DEFAULT_MODE   "standby"

static NOINLINE bool may_wakeup(const char *rtcname)
{
    ssize_t ret;
    char buf[128];

    /* strip "/dev/" from the rtcname here */
    rtcname = skip_dev_pfx(rtcname);

    snprintf(buf, sizeof(buf), SYS_RTC_PATH, rtcname);
    ret = open_read_close(buf, buf, sizeof(buf));
    if (ret < 0)
        return false;

    /* wakeup events could be disabled or not supported */
    return strncmp(buf, "enabled\n", 8) == 0;
}

static NOINLINE void setup_alarm(int fd, time_t *wakeup, time_t rtc_time)
{
    struct tm *ptm;
    struct linux_rtc_wkalrm wake;

    /* The wakeup time is in POSIX time (more or less UTC).
     * Ideally RTCs use that same time; but PCs can't do that
     * if they need to boot MS-Windows.  Messy...
     *
     * When running in utc mode this process's timezone is UTC,
     * so we'll pass a UTC date to the RTC.
     *
     * Else mode is local so the time given to the RTC
     * will instead use the local time zone.
     */
    ptm = localtime(wakeup);

    wake.time.tm_sec = ptm->tm_sec;
    wake.time.tm_min = ptm->tm_min;
    wake.time.tm_hour = ptm->tm_hour;
    wake.time.tm_mday = ptm->tm_mday;
    wake.time.tm_mon = ptm->tm_mon;
    wake.time.tm_year = ptm->tm_year;
    /* wday, yday, and isdst fields are unused by Linux */
    wake.time.tm_wday = -1;
    wake.time.tm_yday = -1;
    wake.time.tm_isdst = -1;

    /* many rtc alarms only support up to 24 hours from 'now',
     * so use the "more than 24 hours" request only if we must
     */
    if ((rtc_time + (24 * 60 * 60)) > *wakeup) {
        xioctl(fd, RTC_ALM_SET, &wake.time);
        xioctl(fd, RTC_AIE_ON, 0);
    } else {
        /* avoid an extra AIE_ON call */
        wake.enabled = 1;
        xioctl(fd, RTC_WKALM_SET, &wake);
    }
}

#define RTCWAKE_OPT_AUTO         0x01
#define RTCWAKE_OPT_LOCAL        0x02
#define RTCWAKE_OPT_UTC          0x04
#define RTCWAKE_OPT_DEVICE       0x08
#define RTCWAKE_OPT_SUSPEND_MODE 0x10
#define RTCWAKE_OPT_SECONDS      0x20
#define RTCWAKE_OPT_TIME         0x40

int rtcwake_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int rtcwake_main(int argc UNUSED_PARAM, char **argv)
{
    time_t rtc_time;

    unsigned opt;
    const char *rtcname = NULL;
    const char *suspend;
    const char *opt_seconds;
    const char *opt_time;

    time_t sys_time;
    time_t alarm_time = 0;
    unsigned seconds = 0;
    int utc = -1;
    int fd;

#if ENABLE_LONG_OPTS
    static const char rtcwake_longopts[] ALIGN1 =
        "auto\0"    No_argument "a"
        "local\0"   No_argument "l"
        "utc\0"     No_argument "u"
        "device\0"  Required_argument "d"
        "mode\0"    Required_argument "m"
        "seconds\0" Required_argument "s"
        "time\0"    Required_argument "t"
        ;
    applet_long_options = rtcwake_longopts;
#endif
    opt = getopt32(argv, "alud:m:s:t:", &rtcname, &suspend, &opt_seconds, &opt_time);

    /* this is the default
    if (opt & RTCWAKE_OPT_AUTO)
        utc = -1;
    */
    if (opt & (RTCWAKE_OPT_UTC | RTCWAKE_OPT_LOCAL))
        utc = opt & RTCWAKE_OPT_UTC;
    if (!(opt & RTCWAKE_OPT_SUSPEND_MODE))
        suspend = DEFAULT_MODE;
    if (opt & RTCWAKE_OPT_SECONDS)
        /* alarm time, seconds-to-sleep (relative) */
        seconds = xatoi(opt_seconds);
    if (opt & RTCWAKE_OPT_TIME)
        /* alarm time, time_t (absolute, seconds since 1/1 1970 UTC) */
        alarm_time = xatol(opt_time);

    if (!alarm_time && !seconds)
        bb_error_msg_and_die("must provide wake time");

    if (utc == -1)
        utc = rtc_adjtime_is_utc();

    /* the rtcname is relative to /dev */
    xchdir("/dev");

    /* this RTC must exist and (if we'll sleep) be wakeup-enabled */
    fd = rtc_xopen(&rtcname, O_RDONLY);

    if (strcmp(suspend, "on") && !may_wakeup(rtcname))
        bb_error_msg_and_die("%s not enabled for wakeup events", rtcname);

    /* relative or absolute alarm time, normalized to time_t */
    sys_time = time(NULL);
    {
        struct tm tm_time;
        rtc_read_tm(&tm_time, fd);
        rtc_time = rtc_tm2time(&tm_time, utc);
    }


    if (alarm_time) {
        if (alarm_time < sys_time)
            bb_error_msg_and_die("time doesn't go backward to %s", ctime(&alarm_time));
        alarm_time += sys_time - rtc_time;
    } else
        alarm_time = rtc_time + seconds + 1;
    setup_alarm(fd, &alarm_time, rtc_time);

    sync();
    printf("wakeup from \"%s\" at %s", suspend, ctime(&alarm_time));
    fflush_all();
    usleep(10 * 1000);

    if (strcmp(suspend, "on"))
        xopen_xwrite_close(SYS_POWER_PATH, suspend);
    else {
        /* "fake" suspend ... we'll do the delay ourselves */
        unsigned long data;

        do {
            ssize_t ret = safe_read(fd, &data, sizeof(data));
            if (ret < 0) {
                bb_perror_msg("rtc read");
                break;
            }
        } while (!(data & RTC_AF));
    }

    xioctl(fd, RTC_AIE_OFF, 0);

    if (ENABLE_FEATURE_CLEAN_UP)
        close(fd);

    return EXIT_SUCCESS;
}