#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <utmpx.h>
#include <paths.h>
#include <string.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
#include <dlfcn.h>

extern int opterr, optopt;

void (*iddisplay)(char*);
void (*gdisplay)(char*);

int main(int argc, char **argv) {

    int c;
    struct utmpx *ptr;

    if (argc == 1) {

        ptr = getutxent();
        while (ptr != NULL) {
                printf("User : %s\n", ptr->ut_user);
                ptr = getutxent();
        }

        return -1;
    }

    void* handler = dlopen("./lib", RTLD_LAZY);

    if (handler == NULL)
    {
        dlerror();
        exit(EXIT_FAILURE);
    }


    iddisplay = dlsym(handler, "iddisplay");
    gdisplay = dlsym(handler, "gdisplay");

    opterr = 0;

    while ((c = getopt(argc, argv, "abc:")) != -1)
        switch (c) {
        case 'a':

            while ((ptr = getutxent()) != NULL) {
                iddisplay(ptr->ut_user);

            }
            break;
        case 'b':
            while ((ptr = getutxent()) != NULL) {
                gdisplay(ptr->ut_user);
            }
            break;
        case '?':
            if (optopt == 'c')
                fprintf(stderr, "Option -%c requires an argument.\n", optopt);
            else if (isprint(optopt))
                fprintf(stderr, "Unknown option `-%c'.\n", optopt);
            else
                fprintf(stderr, "Unknown option character `\\x%x'.\n", optopt);
            return 1;
        default:

            abort();
        }

    dlclose(handler);
    return 0;
}