LXR linux/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
  25static 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}
  61