LXR linux/tools/testing/selftests/proc/proc-uptime-001.c

   1/*
   2 * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
   3 *
   4 * Permission to use, copy, modify, and distribute this software for any
   5 * purpose with or without fee is hereby granted, provided that the above
   6 * copyright notice and this permission notice appear in all copies.
   7 *
   8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15 */
  16// Test that values in /proc/uptime increment monotonically.
  17#undef NDEBUG
  18#include <assert.h>
  19#include <stdint.h>
  20#include <sys/types.h>
  21#include <sys/stat.h>
  22#include <fcntl.h>
  23
  24#include "proc-uptime.h"
  25
  26int main(void)
  27{
  28        uint64_t start, u0, u1, i0, i1;
  29        int fd;
  30
  31        fd = open("/proc/uptime", O_RDONLY);
  32        assert(fd >= 0);
  33
  34        proc_uptime(fd, &u0, &i0);
  35        start = u0;
  36        do {
  37                proc_uptime(fd, &u1, &i1);
  38                assert(u1 >= u0);
  39                assert(i1 >= i0);
  40                u0 = u1;
  41                i0 = i1;
  42        } while (u1 - start < 100);
  43
  44        return 0;
  45}
  46