proc-uptime.h (1700B)
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}