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
  26 int 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 }