#include <stdio.h>
#include <utmp.h>
#include <string.h>
#include <stdlib.h>
#include <pwd.h>
#include <sys/types.h>
#include <unistd.h>
#include <dlfcn.h>
#include <fcntl.h>
#include <grp.h>

int main()
{
void *bibl;
void (*LibUser)(char *);
int error = 0;
struct utmp a;

bibl=dlopen("./libProg.so", RTLD_LAZY);
if (!bibl) error = 1;
else
{
    LibUser = dlsym(bibl, "LibUser");
    if(!LibUser) error = 1;
}
int utmp = open (_PATH_UTMP, O_RDONLY);
while(read(utmp, &a, sizeof(struct utmp))>0)
{
    if(a.ut_type=7)
    {
        if (!error) LibUser(a.ut_user);
        else printf("%s\n", a.ut_user);
    }
}
close (utmp);
if (bibl) dlclose (bibl);
return 0;
}