tools/testing/selftests/proc/proc-uptime.h

   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 #undef NDEBUG
  17 #include <assert.h>
  18 #include <errno.h>
  19 #include <string.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22 #include <time.h>
  23
  24 #include "proc.h"
  25
  26 static uint64_t clock_boottime(void)
  27 {
  28         struct timespec ts;
  29         int err;
  30
  31         err = clock_gettime(CLOCK_BOOTTIME, &ts);
  32         assert(err >= 0);
  33
  34         return (ts.tv_sec * 100) + (ts.tv_nsec / 10000000);
  35 }
  36
  37 static uint64_t proc_uptime(int fd)
  38 {
  39         uint64_t val1, val2;
  40         char buf[64], *p;
  41         ssize_t rv;
  42
  43         /* save "p < end" checks */
  44         memset(buf, 0, sizeof(buf));
  45         rv = pread(fd, buf, sizeof(buf), 0);
  46         assert(0 <= rv && rv <= sizeof(buf));
  47         buf[sizeof(buf) - 1] = '\0';
  48
  49         p = buf;
  50
  51         val1 = xstrtoull(p, &p);
  52         assert(p[0] == '.');
  53         assert('0' <= p[1] && p[1] <= '9');
  54         assert('0' <= p[2] && p[2] <= '9');
  55         assert(p[3] == ' ');
  56
  57         val2 = (p[1] - '0') * 10 + p[2] - '0';
  58
  59         return val1 * 100 + val2;
  60 }