wmcpuload/src/cpu_freebsd.c

   1 /*
   2  * cpu_freebsd.c - module to get cpu usage, for FreeBSD
   3  *
   4  * Copyright (c) 2001, 2002, 2004 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
  22 #include <sys/param.h>
  23
  24 #if __FreeBSD_version < 500101
  25 #   include <sys/dkstat.h>
  26 #else
  27 #   include <sys/resource.h>
  28 #endif /* __FreeBSD_version < 500101 */
  29
  30 static kvm_t *kd = NULL;
  31 static struct nlist nlst[] = { {"_cp_time"}, {0} };
  32
  33 void
  34 cpu_init(void)
  35 {
  36
  37     kd = kvm_open(NULL, NULL, NULL, O_RDONLY, "kvm_open");
  38
  39     if (kd == NULL) {
  40         fprintf(stderr, "can't open kernel virtual memory");
  41         exit(1);
  42     }
  43
  44     kvm_nlist(kd, nlst);
  45
  46     if (nlst[0].n_type == 0) {
  47         fprintf(stderr, "error extracting symbols");
  48         exit(1);
  49     }
  50
  51     /* drop setgid & setuid (the latter should not be there really) */
  52     seteuid(getuid());
  53     setegid(getgid());
  54
  55     if (geteuid() != getuid() || getegid() != getgid()) {
  56         fprintf(stderr, "unable to drop privileges");
  57         exit(1);
  58     }
  59 }
  60
  61 /* returns current CPU usage in percent */
  62 int
  63 cpu_get_usage(cpu_options *opts)
  64 {
  65     static int pre_used, pre_total;
  66     int used, total, result;
  67     unsigned long int cpu_time[CPUSTATES];
  68
  69     if (kvm_read(kd, nlst[0].n_value, &cpu_time, sizeof(cpu_time)) !=
  70         sizeof(cpu_time))
  71         return 0;
  72
  73     /* calculate usage */
  74     total = cpu_time[CP_USER] + cpu_time[CP_SYS] + cpu_time[CP_INTR] +
  75             cpu_time[CP_NICE] + cpu_time[CP_IDLE];
  76     used = cpu_time[CP_USER] + cpu_time[CP_SYS] + cpu_time[CP_INTR] +
  77            (opts->ignore_nice ? 0 : cpu_time[CP_NICE]);
  78     if ((pre_total == 0) || !(total - pre_total > 0)) {
  79         result = 0;
  80     } else {
  81         result = 100 * (double)(used - pre_used) / (double)(total - pre_total);
  82     }
  83
  84     /* save used/total for next calculation */
  85     pre_used = used;
  86     pre_total = total;
  87
  88     return result;
  89 }