sysctllookup.c

#include <sys/types.h>
#include <sys/sysctl.h>
#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char* argv[]) {
  if (argc != 2) {
    printf("usage: %s sysctlname\n", argv[0]);
    return 1;
  }

  const char* sysctlname = argv[1];

  size_t arrsiz = 1;

  for (const char *c = sysctlname; *c != '\0'; ++c) {
    if (*c == '.') ++arrsiz;
  }

  int *mibs = malloc(arrsiz * sizeof(int));

  int ret;
  ret = sysctlnametomib(sysctlname, mibs, &arrsiz);

  if (ret == -1) {
    ret = errno;
    printf("sysctlnametomib failed: 0x%x (%s)", ret, strerror(ret));
    return ret;
  }

  printf("arrsiz: %zu\n", arrsiz);

  for (size_t i = 0; i != arrsiz; ++i) {
    printf("mib[\t%zu] = %d\n", i, mibs[i]);
  }

  free(mibs);

  return 0;
}