/*
 * 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.
 */
//config:config RTCWAKE
//config:       bool "rtcwake (6.8 kb)"
//config:       default y
//config:       help
//config:       Enter a system sleep state until specified wakeup time.

//applet:IF_RTCWAKE(APPLET(rtcwake, BB_DIR_USR_SBIN, BB_SUID_DROP))

//kbuild:lib-$(CONFIG_RTCWAKE) += rtcwake.o

//usage:#define rtcwake_trivial_usage
//usage:       "[-a | -l | -u] [-d DEV] [-m MODE] [-s SEC | -t TIME]"
//usage:#define rtcwake_full_usage "\n\n"
//usage:       "Enter a system sleep state until specified wakeup time\n"
//usage:     "\n        -a      Read clock mode from "ADJTIME_PATH" (default)"
//usage:     "\n        -l      Clock is set to local time"
//usage:     "\n        -u      Clock is set to UTC time"
//usage:     "\n        -d DEV  Specify the RTC device"
//usage:     "\n        -m MODE Set sleep state (default: standby)"
//usage:     "\n        -s SEC  Set timeout in SEC seconds from now"
//usage:     "\n        -t TIME Set timeout to TIME seconds from epoch"

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

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

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 is_prefixed_with(buf, "enabled\n") != NULL;
}

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)
{
        unsigned opt;
        const char *rtcname = NULL;
        const char *suspend = "standby";
        const char *opt_seconds;
        const char *opt_time;

        time_t rtc_time;
        time_t sys_time;
        time_t alarm_time = alarm_time;
        unsigned seconds = seconds; /* for compiler */
        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"
                ;
#endif
        opt = getopt32long(argv,
                        /* Must have -s or -t, exclusive */
                        "^alud:m:s:t:" "\0" "s:t:s--t:t--s", rtcwake_longopts,
                        &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_SECONDS) {
                /* alarm time, seconds-to-sleep (relative) */
                seconds = xatou(opt_seconds);
        } else {
                /* RTCWAKE_OPT_TIME */
                /* alarm time, time_t (absolute, seconds since 1/1 1970 UTC) */
                if (sizeof(alarm_time) <= sizeof(long))
                        alarm_time = xatol(opt_time);
                else
                        alarm_time = xatoll(opt_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") != 0)
                if (!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 (opt & RTCWAKE_OPT_TIME) {
                /* Correct for RTC<->system clock difference */
                alarm_time += rtc_time - sys_time;
                if (alarm_time < rtc_time)
                        /*
                         * Compat message text.
                         * I'd say "RTC time is already ahead of ..." instead.
                         */
                        bb_error_msg_and_die("time doesn't go backward to %s", ctime(&alarm_time));
        } else
                alarm_time = rtc_time + seconds + 1;

        setup_alarm(fd, &alarm_time, rtc_time);
        sync();
#if 0 /*debug*/
        printf("sys_time: %s", ctime(&sys_time));
        printf("rtc_time: %s", ctime(&rtc_time));
#endif
        printf("wakeup from \"%s\" at %s", suspend, ctime(&alarm_time));
        fflush_all();
        usleep(10 * 1000);

        if (strcmp(suspend, "on") != 0)
                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_simple_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;
}