// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <math.h>
#include <sched.h>
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>

#include "log.h"
#include "timens.h"

/*
 * Test shouldn't be run for a day, so add 10 days to child
 * time and check parent's time to be in the same day.
 */
#define MAX_TEST_TIME_SEC               (60*5)
#define DAY_IN_SEC                      (60*60*24)
#define TEN_DAYS_IN_SEC                 (10*DAY_IN_SEC)

static int child_ns, parent_ns;

static int switch_ns(int fd)
{
        if (setns(fd, CLONE_NEWTIME))
                return pr_perror("setns()");

        return 0;
}

static int init_namespaces(void)
{
        char path[] = "/proc/self/ns/time_for_children";
        struct stat st1, st2;

        parent_ns = open(path, O_RDONLY);
        if (parent_ns <= 0)
                return pr_perror("Unable to open %s", path);

        if (fstat(parent_ns, &st1))
                return pr_perror("Unable to stat the parent timens");

        if (unshare_timens())
                return -1;

        child_ns = open(path, O_RDONLY);
        if (child_ns <= 0)
                return pr_perror("Unable to open %s", path);

        if (fstat(child_ns, &st2))
                return pr_perror("Unable to stat the timens");

        if (st1.st_ino == st2.st_ino)
                return pr_err("The same child_ns after CLONE_NEWTIME");

        if (_settime(CLOCK_BOOTTIME, TEN_DAYS_IN_SEC))
                return -1;

        return 0;
}

static int read_proc_uptime(struct timespec *uptime)
{
        unsigned long up_sec, up_nsec;
        FILE *proc;

        proc = fopen("/proc/uptime", "r");
        if (proc == NULL) {
                pr_perror("Unable to open /proc/uptime");
                return -1;
        }

        if (fscanf(proc, "%lu.%02lu", &up_sec, &up_nsec) != 2) {
                if (errno) {
                        pr_perror("fscanf");
                        return -errno;
                }
                pr_err("failed to parse /proc/uptime");
                return -1;
        }
        fclose(proc);

        uptime->tv_sec = up_sec;
        uptime->tv_nsec = up_nsec;
        return 0;
}

static int read_proc_stat_btime(unsigned long long *boottime_sec)
{
        FILE *proc;
        char line_buf[2048];

        proc = fopen("/proc/stat", "r");
        if (proc == NULL) {
                pr_perror("Unable to open /proc/stat");
                return -1;
        }

        while (fgets(line_buf, 2048, proc)) {
                if (sscanf(line_buf, "btime %llu", boottime_sec) != 1)
                        continue;
                fclose(proc);
                return 0;
        }
        if (errno) {
                pr_perror("fscanf");
                fclose(proc);
                return -errno;
        }
        pr_err("failed to parse /proc/stat");
        fclose(proc);
        return -1;
}

static int check_uptime(void)
{
        struct timespec uptime_new, uptime_old;
        time_t uptime_expected;
        double prec = MAX_TEST_TIME_SEC;

        if (switch_ns(parent_ns))
                return pr_err("switch_ns(%d)", parent_ns);

        if (read_proc_uptime(&uptime_old))
                return 1;

        if (switch_ns(child_ns))
                return pr_err("switch_ns(%d)", child_ns);

        if (read_proc_uptime(&uptime_new))
                return 1;

        uptime_expected = uptime_old.tv_sec + TEN_DAYS_IN_SEC;
        if (fabs(difftime(uptime_new.tv_sec, uptime_expected)) > prec) {
                pr_fail("uptime in /proc/uptime: old %ld, new %ld [%ld]",
                        uptime_old.tv_sec, uptime_new.tv_sec,
                        uptime_old.tv_sec + TEN_DAYS_IN_SEC);
                return 1;
        }

        ksft_test_result_pass("Passed for /proc/uptime\n");
        return 0;
}

static int check_stat_btime(void)
{
        unsigned long long btime_new, btime_old;
        unsigned long long btime_expected;

        if (switch_ns(parent_ns))
                return pr_err("switch_ns(%d)", parent_ns);

        if (read_proc_stat_btime(&btime_old))
                return 1;

        if (switch_ns(child_ns))
                return pr_err("switch_ns(%d)", child_ns);

        if (read_proc_stat_btime(&btime_new))
                return 1;

        btime_expected = btime_old - TEN_DAYS_IN_SEC;
        if (btime_new != btime_expected) {
                pr_fail("btime in /proc/stat: old %llu, new %llu [%llu]",
                        btime_old, btime_new, btime_expected);
                return 1;
        }

        ksft_test_result_pass("Passed for /proc/stat btime\n");
        return 0;
}

int main(int argc, char *argv[])
{
        int ret = 0;

        ksft_print_header();

        nscheck();

        ksft_set_plan(2);

        if (init_namespaces())
                return 1;

        ret |= check_uptime();
        ret |= check_stat_btime();

        if (ret)
                ksft_exit_fail();
        ksft_exit_pass();
        return ret;
}