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

/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1980 Regents of the University of California.\n\
All rights reserved.\n";
#endif not lint

#ifndef lint
static char sccsid[] = "@(#)who.c       5.1 (Berkeley) %G%";
#endif not lint

/*
* who
*/

#include <stdio.h>
#include <utmp.h>
#include <pwd.h>
#include <ctype.h>

#define NMAX sizeof(utmp.ut_name)
#define LMAX sizeof(utmp.ut_line)
#define HMAX sizeof(utmp.ut_host)

struct  utmp utmp;
struct  passwd *pw;
struct  passwd *getpwuid();
char    hostname[32];

char    *ttyname(), *rindex(), *ctime(), *strcpy();

main(argc, argv)
       int argc;
       char **argv;
{
       register char *tp, *s;
       register FILE *fi;
       extern char _sobuf[];

       setbuf(stdout, _sobuf);
       s = "/etc/utmp";
       if(argc == 2)
               s = argv[1];
       if (argc == 3) {
               tp = ttyname(0);
               if (tp)
                       tp = rindex(tp, '/') + 1;
               else {  /* no tty - use best guess from passwd file */
                       pw = getpwuid(getuid());
                       strncpy(utmp.ut_name, pw ? pw->pw_name : "?", NMAX);
                       strcpy(utmp.ut_line, "tty??");
                       time(&utmp.ut_time);
                       putline();
                       exit(0);
               }
       }
       if ((fi = fopen(s, "r")) == NULL) {
               puts("who: cannot open utmp");
               exit(1);
       }
       while (fread((char *)&utmp, sizeof(utmp), 1, fi) == 1) {
               if (argc == 3) {
                       gethostname(hostname, sizeof (hostname));
                       if (strcmp(utmp.ut_line, tp))
                               continue;
                       printf("%s!", hostname);
                       putline();
                       exit(0);
               }
               if (utmp.ut_name[0] == '\0' && argc == 1)
                       continue;
               putline();
       }
}

putline()
{
       register char *cbuf;

       printf("%-*.*s %-*.*s",
               NMAX, NMAX, utmp.ut_name,
               LMAX, LMAX, utmp.ut_line);
       cbuf = ctime(&utmp.ut_time);
       printf("%.12s", cbuf+4);
       if (utmp.ut_host[0])
               printf("\t(%.*s)", HMAX, utmp.ut_host);
       putchar('\n');
}