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

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

        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 */
                        (void)strcpy(utmp.ut_line, "tty??");
                        guess();
                        exit(0);
                }
        }
        if (!(fi = fopen(s, "r"))) {
                fprintf(stderr, "who: cannot read %s.\n", s);
                exit(1);
        }
        while (fread((char *)&utmp, sizeof(utmp), 1, fi) == 1) {
                if (argc == 3) {
                        if (strcmp(utmp.ut_line, tp))
                                continue;
                        putline();
                        exit(0);
                }
                if (utmp.ut_name[0] == '\0' && argc == 1)
                        continue;
                putline();
        }
        if (argc == 3) {
                strncpy(utmp.ut_line, tp, sizeof(utmp.ut_line));
                guess();
        }
        exit(0);
}

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');
}

guess()
{

        pw = getpwuid(getuid());
        strncpy(utmp.ut_name, pw ? pw->pw_name : "?", NMAX);
        time(&utmp.ut_time);
        putline();
}