#include <iostream>
#include <fstream>
#include <cstdlib>

using namespace std;

#include <utmp.h>

void show_info(struct utmp * current_record) {
  if (current_record->ut_type==USER_PROCESS) {
    char * s=ctime(&current_record->ut_time)+4; /*start at month*/
    s[12]='\0'; /*end at minutes*/
    cout<<current_record->ut_name<<"\t"<<current_record->ut_line<<"\t"<<s<<"\t";
    if (strlen(current_record->ut_host)!=0)
      cout<<current_record->ut_host;
    cout<<"\n";
  }
}

void show_info(struct utmp * records, int n) {
  for (int i=0; i<n; i++) 
    show_info(records+i);
}

int compare(const void * e1, const void * e2) {
  utmp * record1=(utmp *)e1;
  utmp * record2=(utmp *)e2;
  int i=record1->ut_time;
  int j=record2->ut_time;
  if (i<j)
    return -1;
  if (i==j)
    return 0;
  if (i>j)
    return 1;
}

int main() {
  struct utmp * records;
  ifstream utmpfile(UTMP_FILE, ios::in | ios::binary);
  
  //determine num of records
  utmpfile.seekg(0, ios_base::end);
  int n=utmpfile.tellg()/sizeof(utmp);
  utmpfile.seekg(0, ios_base::beg);
  records=new utmp[n];

  int i=0;
  while(true) {
    utmpfile.read((char *)(records+i++), sizeof(utmp));
    if (utmpfile.eof()) {
      break;
    }
  }
  qsort(records, n, sizeof(utmp), &compare);
  show_info(records, n);
  utmpfile.close();
  delete[] records;
  cout<<sizeof(utmp);
}