/* Demo leapsecond deadlock
 *              by: John Stultz (john.stultz@linaro.org)
 *              (C) Copyright IBM 2012
 *              (C) Copyright 2013, 2015 Linaro Limited
 *              Licensed under the GPL
 *
 * This test demonstrates leapsecond deadlock that is possible
 * on kernels from 2.6.26 to 3.3.
 *
 * WARNING: THIS WILL LIKELY HARD HANG SYSTEMS AND MAY LOSE DATA
 * RUN AT YOUR OWN RISK!
 *  To build:
 *      $ gcc leapcrash.c -o leapcrash -lrt
 */



#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <sys/timex.h>
#include <string.h>
#include <signal.h>
#include "kselftest.h"

/* 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);

        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);
}


int main(void)
{
        struct timex tx;
        struct timespec ts;
        time_t next_leap;
        int count = 0;

        setbuf(stdout, NULL);

        signal(SIGINT, handler);
        signal(SIGKILL, handler);
        printf("This runs for a few minutes. Press ctrl-c to stop\n");

        clear_time_state();


        /* 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);

        for (count = 0; count < 20; count++) {
                struct timeval tv;


                /* set the time to 2 seconds before the leap */
                tv.tv_sec = next_leap - 2;
                tv.tv_usec = 0;
                if (settimeofday(&tv, NULL)) {
                        printf("Error: You're likely not running with proper (ie: root) permissions\n");
                        ksft_exit_fail();
                }
                tx.modes = 0;
                adjtimex(&tx);

                /* hammer on adjtime w/ STA_INS */
                while (tx.time.tv_sec < next_leap + 1) {
                        /* Set the leap second insert flag */
                        tx.modes = ADJ_STATUS;
                        tx.status = STA_INS;
                        adjtimex(&tx);
                }
                clear_time_state();
                printf(".");
                fflush(stdout);
        }
        printf("[OK]\n");
        ksft_exit_pass();
}