/*      $OpenBSD: who.c,v 1.33 2021/11/11 08:48:48 mestre Exp $ */
/*      $NetBSD: who.c,v 1.4 1994/12/07 04:28:49 jtc Exp $      */

/*
 * Copyright (c) 1989, 1993
 *      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, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <paths.h>
#include <pwd.h>
#include <utmp.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <err.h>

void  output(struct utmp *);
void  output_labels(void);
void  who_am_i(FILE *);
void  usage(void);
FILE *file(char *);

int only_current_term;          /* show info about the current terminal only */
int show_term;                  /* show term state */
int show_idle;                  /* show idle time */
int show_labels;                /* show column labels */
int show_quick;                 /* quick, names only */

#define NAME_WIDTH      8
#define HOST_WIDTH      45

int hostwidth = HOST_WIDTH;
char *mytty;

int
main(int argc, char *argv[])
{
        struct utmp usr;
        FILE *ufp;
        char *t;
        int c;

        if (pledge("stdio unveil rpath getpw", NULL) == -1)
                err(1, "pledge");

        if ((mytty = ttyname(0))) {
                /* strip any directory component */
                if ((t = strrchr(mytty, '/')))
                        mytty = t + 1;
        }

        only_current_term = show_term = show_idle = show_labels = 0;
        show_quick = 0;
        while ((c = getopt(argc, argv, "HmqTu")) != -1) {
                switch (c) {
                case 'H':
                        show_labels = 1;
                        break;
                case 'm':
                        only_current_term = 1;
                        break;
                case 'q':
                        show_quick = 1;
                        break;
                case 'T':
                        show_term = 1;
                        break;
                case 'u':
                        show_idle = 1;
                        break;
                default:
                        usage();
                        /* NOTREACHED */
                }
        }
        argc -= optind;
        argv += optind;

        if (show_quick) {
                only_current_term = show_term = show_idle = show_labels = 0;
        }

        if (show_term)
                hostwidth -= 2;
        if (show_idle)
                hostwidth -= 6;

        if (show_labels)
                output_labels();

        if (unveil(_PATH_UTMP, "r") == -1)
                err(1, "unveil %s", _PATH_UTMP);
        if (show_term || show_idle) {
                if (unveil(_PATH_DEV, "r") == -1)
                        err(1, "unveil %s", _PATH_DEV);
        }
        if (argc == 1) {
                if (unveil(*argv, "r") == -1)
                        err(1, "unveil %s", *argv);
        }
        if (pledge("stdio rpath getpw", NULL) == -1)
                err(1, "pledge");

        switch (argc) {
        case 0:                                 /* who */
                ufp = file(_PATH_UTMP);

                if (only_current_term) {
                        who_am_i(ufp);
                } else if (show_quick) {
                        int count = 0;

                        while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1) {
                                if (*usr.ut_name && *usr.ut_line) {
                                        (void)printf("%-*.*s ", NAME_WIDTH,
                                                UT_NAMESIZE, usr.ut_name);
                                        if ((++count % 8) == 0)
                                                (void) printf("\n");
                                }
                        }
                        if (count % 8)
                                (void) printf("\n");
                        (void) printf ("# users=%d\n", count);
                } else {
                        /* 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 1:                                 /* who utmp_file */
                ufp = file(*argv);

                if (only_current_term) {
                        who_am_i(ufp);
                } else if (show_quick) {
                        int count = 0;

                        while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1) {
                                if (*usr.ut_name && *usr.ut_line) {
                                        (void)printf("%-*.*s ", NAME_WIDTH,
                                                UT_NAMESIZE, usr.ut_name);
                                        if ((++count % 8) == 0)
                                                (void) printf("\n");
                                }
                        }
                        if (count % 8)
                                (void) printf("\n");
                        (void) printf ("# users=%d\n", count);
                } else {
                        /* all entries */
                        while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1)
                                output(&usr);
                }
                break;
        case 2:                                 /* who am i */
                ufp = file(_PATH_UTMP);
                who_am_i(ufp);
                break;
        default:
                usage();
                /* NOTREACHED */
        }
        exit(0);
}

void
who_am_i(FILE *ufp)
{
        struct utmp usr;
        struct passwd *pw;

        /* search through the utmp and find an entry for this tty */
        if (mytty) {
                while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1)
                        if (*usr.ut_name && !strcmp(usr.ut_line, mytty)) {
                                output(&usr);
                                return;
                        }
                /* well, at least we know what the tty is */
                (void)strncpy(usr.ut_line, mytty, UT_LINESIZE);
        } else
                (void)strncpy(usr.ut_line, "tty??", UT_LINESIZE);

        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);
}

void
output(struct utmp *up)
{
        struct stat sb;
        char line[sizeof(_PATH_DEV) + sizeof (up->ut_line)];
        char state = '?';
        static time_t now = 0;
        time_t idle = 0;

        if (show_term || show_idle) {
                if (now == 0)
                        time(&now);

                memset(line, 0, sizeof line);
                strlcpy(line, _PATH_DEV, sizeof line);
                strlcat(line, up->ut_line, sizeof line);

                if (stat(line, &sb) == 0) {
                        state = (sb.st_mode & 020) ? '+' : '-';
                        idle = now - sb.st_atime;
                } else {
                        state = '?';
                        idle = 0;
                }
        }

        (void)printf("%-*.*s ", NAME_WIDTH, UT_NAMESIZE, up->ut_name);

        if (show_term) {
                (void)printf("%c ", state);
        }

        (void)printf("%-*.*s ", UT_LINESIZE, UT_LINESIZE, up->ut_line);
        (void)printf("%.12s ", ctime(&up->ut_time) + 4);

        if (show_idle) {
                if (idle < 60)
                        (void)printf("  .   ");
                else if (idle < (24 * 60 * 60))
                        (void)printf("%02d:%02d ",
                                     ((int)idle / (60 * 60)),
                                     ((int)idle % (60 * 60)) / 60);
                else
                        (void)printf(" old  ");
        }

        if (*up->ut_host)
                printf("  (%.*s)", hostwidth, up->ut_host);
        (void)putchar('\n');
}

void
output_labels(void)
{
        (void)printf("%-*.*s ", NAME_WIDTH, UT_NAMESIZE, "USER");

        if (show_term)
                (void)printf("S ");

        (void)printf("%-*.*s ", UT_LINESIZE, UT_LINESIZE, "LINE");
        (void)printf("WHEN         ");

        if (show_idle)
                (void)printf("IDLE  ");

        (void)printf("  %.*s", hostwidth, "FROM");

        (void)putchar('\n');
}

FILE *
file(char *name)
{
        FILE *ufp;

        if (!(ufp = fopen(name, "r"))) {
                err(1, "%s", name);
                /* NOTREACHED */
        }
        if (!show_term && !show_idle) {
                if (pledge("stdio getpw", NULL) == -1)
                        err(1, "pledge");
        }
        return(ufp);
}

void
usage(void)
{
        (void)fprintf(stderr, "usage: who [-HmqTu] [file]\n       who am i\n");
        exit(1);
}