wmcpuload/src/cpu_freebsd.c

   1 /*
   2  * cpu_freebsd.c - module to get cpu usage, for FreeBSD
   3  *
   4  * Copyright (c) 2001, 2002 Seiichi SATO <ssato@sh.rim.or.jp>
   5  *
   6  * Licensed under the GPL
   7  */
   8
   9 #ifdef HAVE_CONFIG_H
  10 #include "config.h"
  11 #endif
  12
  13 #include <stdio.h>
  14 #include <unistd.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include "cpu.h"
  18
  19 #include <kvm.h>
  20 #include <fcntl.h>
  21 #include <sys/dkstat.h>
  22
  23 static kvm_t *kd = NULL;
  24 static struct nlist nlst[] = { {"_cp_time"}, {0} };
  25
  26 void
  27 cpu_init(void)
  28 {
  29
  30     kd = kvm_open(NULL, NULL, NULL, O_RDONLY, "kvm_open");
  31
  32     if (kd == NULL) {
  33         fprintf(stderr, "can't open kernel virtual memory");
  34         exit(1);
  35     }
  36
  37     kvm_nlist(kd, nlst);
  38
  39     if (nlst[0].n_type == 0) {
  40         fprintf(stderr, "error extracting symbols");
  41         exit(1);
  42     }
  43
  44     /* drop setgid & setuid (the latter should not be there really) */
  45     seteuid(getuid());
  46     setegid(getgid());
  47
  48     if (geteuid() != getuid() || getegid() != getgid()) {
  49         fprintf(stderr, "unable to drop privileges");
  50         exit(1);
  51     }
  52 }
  53
  54 /* returns current CPU usage in percent */
  55 int
  56 cpu_get_usage(cpu_options *opts)
  57 {
  58     static int pre_used, pre_total;
  59     int used, total, result;
  60     unsigned long int cpu_time[CPUSTATES];
  61
  62     if (kvm_read(kd, nlst[0].n_value, &cpu_time, sizeof(cpu_time)) !=
  63         sizeof(cpu_time))
  64         return 0;
  65
  66     used = cpu_time[CP_USER] + cpu_time[CP_SYS];
  67     if (!opts->ignore_nice)
  68         used += cpu_time[CP_NICE];
  69     total = used + cpu_time[CP_IDLE];
  70
  71     if (pre_total == 0) {
  72         result = 0;
  73     } else if ((total - pre_total) > 0) {
  74         result = (100 * (double) (used - pre_used)) / (double) (total -
  75                  pre_total);
  76     } else {
  77         result = 0;
  78     }
  79
  80     pre_used = used;
  81     pre_total = total;
  82
  83     return result;
  84 }