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
  23 #include "proc.h"
  24
  25 static void proc_uptime(int fd, uint64_t *uptime, uint64_t *idle)
  26 {
  27         uint64_t val1, val2;
  28         char buf[64], *p;
  29         ssize_t rv;
  30
  31         /* save "p < end" checks */
  32         memset(buf, 0, sizeof(buf));
  33         rv = pread(fd, buf, sizeof(buf), 0);
  34         assert(0 <= rv && rv <= sizeof(buf));
  35         buf[sizeof(buf) - 1] = '\0';
  36
  37         p = buf;
  38
  39         val1 = xstrtoull(p, &p);
  40         assert(p[0] == '.');
  41         assert('0' <= p[1] && p[1] <= '9');
  42         assert('0' <= p[2] && p[2] <= '9');
  43         assert(p[3] == ' ');
  44
  45         val2 = (p[1] - '0') * 10 + p[2] - '0';
  46         *uptime = val1 * 100 + val2;
  47
  48         p += 4;
  49
  50         val1 = xstrtoull(p, &p);
  51         assert(p[0] == '.');
  52         assert('0' <= p[1] && p[1] <= '9');
  53         assert('0' <= p[2] && p[2] <= '9');
  54         assert(p[3] == '\n');
  55
  56         val2 = (p[1] - '0') * 10 + p[2] - '0';
  57         *idle = val1 * 100 + val2;
  58
  59         assert(p + 4 == buf + rv);
  60 }