/* This program is designed to help system administrators overcome the
limitation of the last command by printing out the ip address (or host
name) fully on the right extreme */

#include <stdio.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <utmpx.h>


/* Function to display the required information */

disp(struct utmpx *u)
      {
	printf("%-8s  %-8s %-35s %s",
                u->ut_user,u->ut_line,u->ut_host, ctime(&u->ut_xtime));
	fflush(stdout);	
      }


/* Main control function */

main (int argc, char **argv)
      {
 	struct utmpx *u = (struct utmpx *) malloc (sizeof(struct utmpx));
	int i=0, n = 0, m = 0;
	char * fname = "/var/adm/wtmpx";

/* This makes sure that the default location for the program to take its
input from will be /var/adm/wtmpx, unless the user gives in his own path
*/

	int fp;
	char *name=0;
	int days=0;
	char hosts[100][100]; 
	int j=0,k=0;
	int s = sizeof(struct utmpx);
	
	for (i=1;i<argc;i++) 		// Search for flags.
	   {

	    if (!strcmp(argv[i],"-u"))
	      name  = argv[i+1];

	    else
	      if (!strcmp(argv[i],"-t"))
		days = atoi(argv[i+1]);

	    else
	      if (!strcmp(argv[i],"-f"))
		fname = argv[i+1]; 

	   }  // end for.

	fp = open(fname,O_RDONLY);

	lseek(fp,-s,SEEK_END); 

/* We need to go to the end of the wtmpx file, where the required info. is
   logged, and read from it backwards to retrieve data from the latest
   logins to the previous ones */

	while(read(fp,(struct utmpx*)u,s))
	  {
  	   if (name) 		// Check to see if theres a name flag.
	     {
 	      if ( !strcmp(name, u->ut_user) ) 

/* This part evaluates the information for a particular user */ 

		if ( u->ut_type == 7)
		  {		   		   
		   for (i=1; i<argc; i++) 

		     if (!strcmp(argv[i],"-l") )
		       m = 1;	

/* This flag is checked to see if the user wants all the logins of this
   particular user or just the host names once. */ 

		  if (m == 1) 
		   {
		    for (j=0; j<100; j++)
	 	     if (!strcmp(u->ut_host, hosts[j]))
	 	       n = 1;
		    
/* This part keeps track of the host names that have been accessed so that
   there are no repetitions. */ 

		   if (n != 1)
		    {
	  	     strcpy(hosts[k], u->ut_host);
	  	     k++;
	 	     disp(u);
	 	     i++;
		    } 	// end if.

		   else 
		     n = 0;
		  }	// end if.

		else
		 {
		  disp(u);
		  i++;
		 }	// end else.
		}	// end if.

	   lseek(fp,-2*s,SEEK_CUR);

/* The lseek is formatted in such a way that it reads back two records,
since, after reading a record, we need to go back to the record previous
to the one that was just read ... thats two records */ 

  	   continue;
	  } 	// end if.

	else
	  {
	   if ( u->ut_type == 7)
	    {
	     disp(u);
	     i++;
	    }	// end if.
	  }	// end else.

        if (lseek(fp,-2*s,SEEK_CUR) < 0 )
              {
                close(fp);
                exit(0);
              } 

     }	// end while.

} 	// End of main.