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 static unsigned long long xstrtoull(const char *p, char **end) 24 { 25 if (*p == '0') { 26 *end = (char *)p + 1; 27 return 0; 28 } else if ('1' <= *p && *p <= '9') { 29 unsigned long long val; 30 31 errno = 0; 32 val = strtoull(p, end, 10); 33 assert(errno == 0); 34 return val; 35 } else 36 assert(0); 37 } 38 39 static void proc_uptime(int fd, uint64_t *uptime, uint64_t *idle) 40 { 41 uint64_t val1, val2; 42 char buf[64], *p; 43 ssize_t rv; 44 45 /* save "p < end" checks */ 46 memset(buf, 0, sizeof(buf)); 47 rv = pread(fd, buf, sizeof(buf), 0); 48 assert(0 <= rv && rv <= sizeof(buf)); 49 buf[sizeof(buf) - 1] = '\0'; 50 51 p = buf; 52 53 val1 = xstrtoull(p, &p); 54 assert(p[0] == '.'); 55 assert('0' <= p[1] && p[1] <= '9'); 56 assert('0' <= p[2] && p[2] <= '9'); 57 assert(p[3] == ' '); 58 59 val2 = (p[1] - '0') * 10 + p[2] - '0'; 60 *uptime = val1 * 100 + val2; 61 62 p += 4; 63 64 val1 = xstrtoull(p, &p); 65 assert(p[0] == '.'); 66 assert('0' <= p[1] && p[1] <= '9'); 67 assert('0' <= p[2] && p[2] <= '9'); 68 assert(p[3] == '\n'); 69 70 val2 = (p[1] - '0') * 10 + p[2] - '0'; 71 *idle = val1 * 100 + val2; 72 73 assert(p + 4 == buf + rv); 74 } 75