/* Leap second stress test
 *              by: John Stultz (john.stultz@linaro.org)
 *              (C) Copyright IBM 2012
 *              (C) Copyright 2013, 2015 Linaro Limited
 *              Licensed under the GPLv2
 *
 *  This test signals the kernel to insert a leap second
 *  every day at midnight GMT. This allows for stessing the
 *  kernel's leap-second behavior, as well as how well applications
 *  handle the leap-second discontinuity.
 *
 *  Usage: leap-a-day [-s] [-i <num>]
 *
 *  Options:
 *      -s:     Each iteration, set the date to 10 seconds before midnight GMT.
 *              This speeds up the number of leapsecond transitions tested,
 *              but because it calls settimeofday frequently, advancing the
 *              time by 24 hours every ~16 seconds, it may cause application
 *              disruption.
 *
 *      -i:     Number of iterations to run (default: infinite)
 *
 *  Other notes: Disabling NTP prior to running this is advised, as the two
 *               may conflict in their commands to the kernel.
 *
 *  To build:
 *      $ gcc leap-a-day.c -o leap-a-day -lrt
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 */



#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <sys/timex.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#ifdef KTEST
#include "../kselftest.h"
#else
static inline int ksft_exit_pass(void)
{
        exit(0);
}
static inline int ksft_exit_fail(void)
{
        exit(1);
}
#endif

#define NSEC_PER_SEC 1000000000ULL
#define CLOCK_TAI 11

/* returns 1 if a <= b, 0 otherwise */
static inline int in_order(struct timespec a, struct timespec b)
{
        if (a.tv_sec < b.tv_sec)
                return 1;
        if (a.tv_sec > b.tv_sec)
                return 0;
        if (a.tv_nsec > b.tv_nsec)
                return 0;
        return 1;
}

struct timespec timespec_add(struct timespec ts, unsigned long long ns)
{
        ts.tv_nsec += ns;
        while (ts.tv_nsec >= NSEC_PER_SEC) {
                ts.tv_nsec -= NSEC_PER_SEC;
                ts.tv_sec++;
        }
        return ts;
}

char *time_state_str(int state)
{
        switch (state) {
        case TIME_OK:   return "TIME_OK";
        case TIME_INS:  return "TIME_INS";
        case TIME_DEL:  return "TIME_DEL";
        case TIME_OOP:  return "TIME_OOP";
        case TIME_WAIT: return "TIME_WAIT";
        case TIME_BAD:  return "TIME_BAD";
        }
        return "ERROR";
}

/* clear NTP time_status & time_state */
int clear_time_state(void)
{
        struct timex tx;
        int ret;

        /*
         * We have to call adjtime twice here, as kernels
         * prior to 6b1859dba01c7 (included in 3.5 and
         * -stable), had an issue with the state machine
         * and wouldn't clear the STA_INS/DEL flag directly.
         */
        tx.modes = ADJ_STATUS;
        tx.status = STA_PLL;
        ret = adjtimex(&tx);

        /* Clear maxerror, as it can cause UNSYNC to be set */
        tx.modes = ADJ_MAXERROR;
        tx.maxerror = 0;
        ret = adjtimex(&tx);

        /* Clear the status */
        tx.modes = ADJ_STATUS;
        tx.status = 0;
        ret = adjtimex(&tx);

        return ret;
}

/* Make sure we cleanup on ctrl-c */
void handler(int unused)
{
        clear_time_state();
        exit(0);
}

/* Test for known hrtimer failure */
void test_hrtimer_failure(void)
{
        struct timespec now, target;

        clock_gettime(CLOCK_REALTIME, &now);
        target = timespec_add(now, NSEC_PER_SEC/2);
        clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, &target, NULL);
        clock_gettime(CLOCK_REALTIME, &now);

        if (!in_order(target, now))
                printf("ERROR: hrtimer early expiration failure observed.\n");
}

int main(int argc, char **argv)
{
        int settime = 0;
        int tai_time = 0;
        int insert = 1;
        int iterations = -1;
        int opt;

        /* Process arguments */
        while ((opt = getopt(argc, argv, "sti:")) != -1) {
                switch (opt) {
                case 's':
                        printf("Setting time to speed up testing\n");
                        settime = 1;
                        break;
                case 'i':
                        iterations = atoi(optarg);
                        break;
                case 't':
                        tai_time = 1;
                        break;
                default:
                        printf("Usage: %s [-s] [-i <iterations>]\n", argv[0]);
                        printf("        -s: Set time to right before leap second each iteration\n");
                        printf("        -i: Number of iterations\n");
                        printf("        -t: Print TAI time\n");
                        exit(-1);
                }
        }

        /* Make sure TAI support is present if -t was used */
        if (tai_time) {
                struct timespec ts;

                if (clock_gettime(CLOCK_TAI, &ts)) {
                        printf("System doesn't support CLOCK_TAI\n");
                        ksft_exit_fail();
                }
        }

        signal(SIGINT, handler);
        signal(SIGKILL, handler);

        if (iterations < 0)
                printf("This runs continuously. Press ctrl-c to stop\n");
        else
                printf("Running for %i iterations. Press ctrl-c to stop\n", iterations);

        printf("\n");
        while (1) {
                int ret;
                struct timespec ts;
                struct timex tx;
                time_t now, next_leap;

                /* Get the current time */
                clock_gettime(CLOCK_REALTIME, &ts);

                /* Calculate the next possible leap second 23:59:60 GMT */
                next_leap = ts.tv_sec;
                next_leap += 86400 - (next_leap % 86400);

                if (settime) {
                        struct timeval tv;

                        tv.tv_sec = next_leap - 10;
                        tv.tv_usec = 0;
                        settimeofday(&tv, NULL);
                        printf("Setting time to %s", ctime(&tv.tv_sec));
                }

                /* Reset NTP time state */
                clear_time_state();

                /* Set the leap second insert flag */
                tx.modes = ADJ_STATUS;
                if (insert)
                        tx.status = STA_INS;
                else
                        tx.status = STA_DEL;
                ret = adjtimex(&tx);
                if (ret < 0) {
                        printf("Error: Problem setting STA_INS/STA_DEL!: %s\n",
                                                        time_state_str(ret));
                        return ksft_exit_fail();
                }

                /* Validate STA_INS was set */
                tx.modes = 0;
                ret = adjtimex(&tx);
                if (tx.status != STA_INS && tx.status != STA_DEL) {
                        printf("Error: STA_INS/STA_DEL not set!: %s\n",
                                                        time_state_str(ret));
                        return ksft_exit_fail();
                }

                if (tai_time) {
                        printf("Using TAI time,"
                                " no inconsistencies should be seen!\n");
                }

                printf("Scheduling leap second for %s", ctime(&next_leap));

                /* Wake up 3 seconds before leap */
                ts.tv_sec = next_leap - 3;
                ts.tv_nsec = 0;

                while (clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, &ts, NULL))
                        printf("Something woke us up, returning to sleep\n");

                /* Validate STA_INS is still set */
                tx.modes = 0;
                ret = adjtimex(&tx);
                if (tx.status != STA_INS && tx.status != STA_DEL) {
                        printf("Something cleared STA_INS/STA_DEL, setting it again.\n");
                        tx.modes = ADJ_STATUS;
                        if (insert)
                                tx.status = STA_INS;
                        else
                                tx.status = STA_DEL;
                        ret = adjtimex(&tx);
                }

                /* Check adjtimex output every half second */
                now = tx.time.tv_sec;
                while (now < next_leap + 2) {
                        char buf[26];
                        struct timespec tai;

                        tx.modes = 0;
                        ret = adjtimex(&tx);

                        if (tai_time) {
                                clock_gettime(CLOCK_TAI, &tai);
                                printf("%ld sec, %9ld ns\t%s\n",
                                                tai.tv_sec,
                                                tai.tv_nsec,
                                                time_state_str(ret));
                        } else {
                                ctime_r(&tx.time.tv_sec, buf);
                                buf[strlen(buf)-1] = 0; /*remove trailing\n */

                                printf("%s + %6ld us (%i)\t%s\n",
                                                buf,
                                                tx.time.tv_usec,
                                                tx.tai,
                                                time_state_str(ret));
                        }
                        now = tx.time.tv_sec;
                        /* Sleep for another half second */
                        ts.tv_sec = 0;
                        ts.tv_nsec = NSEC_PER_SEC / 2;
                        clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL);
                }
                /* Switch to using other mode */
                insert = !insert;

                /* Note if kernel has known hrtimer failure */
                test_hrtimer_failure();

                printf("Leap complete\n\n");

                if ((iterations != -1) && !(--iterations))
                        break;
        }

        clear_time_state();
        return ksft_exit_pass();
}