#include <stdio.h>
#include <sys/sysctl.h>

int main()
{
  struct kinfo_proc info_proc;

  int mib[4] = { CTL_KERN, KERN_PROC, KERN_PROC_PID, getpid() };

  size_t size = sizeof(info_proc);
  sysctl(mib, 4, &info_proc, &size, NULL, 0);

  const int flag = info_proc.kp_proc.p_flag;
  printf("traced = %d\n", (flag & P_TRACED) == P_TRACED);

  return 0;
}