new version from Michael Fischbein.

[unix-history] / usr / src / usr.bin / who / who.c

/*
* Copyright (c) 1989 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Michael Fischbein.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley.  The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1989 The Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)who.c       5.10 (Berkeley) %G%";
#endif /* not lint */

#include <sys/types.h>
#include <sys/file.h>
#include <sys/time.h>
#include <pwd.h>
#include <utmp.h>
#include <stdio.h>

main(argc, argv)
       int argc;
       char **argv;
{
       register char *p;
       struct utmp usr;
       struct passwd *pw;
       FILE *ufp, *file();
       char *t, *rindex(), *strcpy(), *strncpy(), *ttyname();
       time_t time();

       switch (argc) {
       case 1:                                 /* who */
               ufp = file(_PATH_UTMP);
               /* only entries with both name and line fields */
               while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1)
                       if (*usr.ut_name && *usr.ut_line)
                               output(&usr);
               break;
       case 2:                                 /* who utmp_file */
               ufp = file(argv[1]);
               /* all entries */
               while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1)
                       output(&usr);
               break;
       case 3:                                 /* who am i */
               ufp = file(_PATH_UTMP);

               /* search through the utmp and find an entry for this tty */
               if (p = ttyname(0)) {
                       /* strip any directory component */
                       if (t = rindex(p, '/'))
                               p = t + 1;
                       while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1)
                               if (usr.ut_name && !strcmp(usr.ut_line, p)) {
                                       output(&usr);
                                       exit(0);
                               }
                       /* well, at least we know what the tty is */
                       (void)strncpy(usr.ut_line, p, UT_LINESIZE);
               } else
                       (void)strcpy(usr.ut_line, "tty??");
               pw = getpwuid(getuid());
               (void)strncpy(usr.ut_name, pw ? pw->pw_name : "?", UT_NAMESIZE);
               (void)time(&usr.ut_time);
               *usr.ut_host = '\0';
               output(&usr);
               break;
       default:
               (void)fprintf(stderr, "usage: who [ file ]\n       who am i\n");
               exit(1);
       }
       exit(0);
}

output(up)
       struct utmp *up;
{
       char *ctime();

       (void)printf("%-*.*s %-*.*s", UT_NAMESIZE, UT_NAMESIZE, up->ut_name,
           UT_LINESIZE, UT_LINESIZE, up->ut_line);
       (void)printf("%.12s", ctime(&up->ut_time) + 4);
       if (*up->ut_host)
               printf("\t(%.*s)", UT_HOSTSIZE, up->ut_host);
       (void)putchar('\n');
}

FILE *
file(name)
       char *name;
{
       extern int errno;
       FILE *ufp;
       char *strerror();

       if (!(ufp = fopen(name, "r"))) {
               (void)fprintf(stderr, "who: %s: %s.\n", name, strerror(errno));
               exit(1);
       }
       return(ufp);
}