usr/src/games/dm/dm.c

/*
 * Copyright (c) 1987 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) 1987 Regents of the University of California.\n\
 All rights reserved.\n";
#endif not lint

#ifndef lint
static char sccsid[] = "@(#)dm.c        5.2 (Berkeley) %G%";
#endif not lint

#include <sys/param.h>
#include <sys/file.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <pwd.h>
#include <utmp.h>
#include <nlist.h>
#include <stdio.h>
#include <ctype.h>

#define GAMEHIDE        "/usr/games/hide"
#define NOGAMING        "/etc/nogames"
#define CONTROL         "/usr/games/game.control"
#ifdef LOG
#define LOGFILE         "/usr/adm/gamelog"
#endif

static FILE     *cfp;
static time_t   now;                    /* current time value */
static int      priority = 0;           /* priority game runs at */
static char     *game,                  /* requested game */
                *gametty;               /* from tty? */

main(argc, argv)
        int     argc;
        char    **argv;
{
        char    *C, *rindex();
        double  load();

        nogamefile();

        if (!strcmp(*argv, "dm"))
                exit(0);

        if (!(cfp = fopen(CONTROL, "r"))) {
                fprintf(stderr, "dm: unable to read %s.\n", CONTROL);
                exit(1);
        }

        read_days();
        read_ttys();

        game = (C = rindex(*argv, '/')) ? ++C : *argv;
        read_games();

#ifdef LOG
        logfile();
#endif
        play(argv);
/*NOTREACHED*/
}

/*
 * play --
 *      play the game
 */
static
play(args)
        char    **args;
{
        if (chdir(GAMEHIDE)) {
                perror("dm: chdir");
                exit(1);
        }
        if (priority && setpriority(PRIO_PROCESS, 0, priority) < 0)
                fputs("dm: unable to set priority!\n", stderr);
        setgid(getgid());       /* we run setgid kmem; lose it */
        execv(game, args);
        perror("dm");
        exit(1);
}

#define lcontrol(buf)   (buf[0] == '%' && buf[1] == '%')
#define lignore(buf)    (buf[0] == '\n' || buf[0] == '#')
/*
 * read_days --
 *      read through days listed in the control file, decide
 *      if current time is an okay play time.
 */
static
read_days()
{
        static char     *days[] = {
                "sunday", "monday", "tuesday", "wednesday",
                "thursday", "friday", "saturday",
        };
        struct tm       *ct;
        register char   *dp;
        int     start, stop;
        char    lbuf[BUFSIZ], f1[40], f2[40], f3[40];
        time_t  time();

        (void)time(&now);
        ct = localtime(&now);
        dp = days[ct->tm_wday];

        while (fgets(lbuf, sizeof(lbuf), cfp)) {
                if (lignore(lbuf))
                        continue;
                if (lcontrol(lbuf))
                        return;
                if (sscanf(lbuf, "%s%s%s", f1, f2, f3) != 3)
                        continue;
                if (!strcasecmp(dp, f1)) {
                        if (!isdigit(*f2) || !isdigit(*f3))
                                continue;
                        start = atoi(f2);
                        stop = atoi(f3);
                        if (ct->tm_hour >= start && ct->tm_hour <= stop) {
                                fputs("dm: Sorry, games are not available from ", stderr);
                                hour(start);
                                fputs(" to ", stderr);
                                hour(stop);
                                fputs(" today.\n", stderr);
                                exit(0);
                        }
                        continue;
                }
        }
}

/*
 * read_ttys --
 *      read through ttys listed in the control file, decide if this
 *      tty can be used for games.
 */
static
read_ttys()
{
        register char   *p_tty;
        char    lbuf[BUFSIZ], f1[40], f2[40],
                *ttyname(), *rindex();

        gametty = ttyname(0);
        if (p_tty = rindex(gametty, '/'))
                ++p_tty;
        while (fgets(lbuf, sizeof(lbuf), cfp)) {
                if (lignore(lbuf))
                        continue;
                if (lcontrol(lbuf))
                        return;
                if (sscanf(lbuf, "%s%s", f1, f2) != 2)
                        continue;
                if (strcasecmp("badtty", f1))
                        continue;
                if (!strcmp(gametty, f2) || p_tty && !strcmp(p_tty, f2)) {
                        fprintf(stderr, "dm: Sorry, you may not play games on %s.\n", gametty);
                        exit(0);
                }
        }
}

/*
 * read_games --
 *      read through games listed in the control file, decide if this
 *      game can be played now.
 */
static
read_games()
{
        char    lbuf[BUFSIZ], f1[40], f2[40], f3[40], f4[40];

        while (fgets(lbuf, sizeof(lbuf), cfp)) {
                if (lignore(lbuf))
                        continue;
                if (lcontrol(lbuf))
                        return;
                if (sscanf(lbuf, "%s%s%s%s", f1, f2, f3, f4) != 4)
                        break;
                if (!strcmp(game, f1) || !strcasecmp("default", f1)) {
                        if (isdigit(*f2) && atoi(f2) < load()) {
                                fputs("dm: Sorry, the load average is too high right now.\n", stderr);
                                exit(0);
                        }
                        if (isdigit(*f3) && atoi(f3) <= users()) {
                                fputs("dm: Sorry, there are too many users logged on right now.\n", stderr);
                                exit(0);
                        }
                        if (isdigit(*f4) || *f4 == '-' || *f4 == '+')
                                priority = atoi(f3);
                        return;
                }
        }
}

static struct   nlist nl[] = {
        { "_avenrun" },
#define X_AVENRUN       0
        { "" },
};

/*
 * load --
 *      return 15 minute load average
 */
static double
load()
{
        double  avenrun[3];
        int     kmem;
        long    lseek();

        if (nlist("/vmunix", nl)) {
                fputs("dm: nlist of /vmunix failed.\n", stderr);
                exit(1);
        }
        if ((kmem = open("/dev/kmem", O_RDONLY, 0)) < 0) {
                perror("dm: /dev/kmem");
                exit(1);
        }
        (void)lseek(kmem, (long)nl[X_AVENRUN].n_value, L_SET);
        (void)read(kmem, avenrun, sizeof(avenrun));
        return(avenrun[2]);
}

/*
 * users --
 *      return current number of users
 */
static
users()
{
        register int    nusers,
                        utmp;
        struct utmp     buf;

        if ((utmp = open("/etc/utmp", O_RDONLY, 0)) < 0) {
                perror("dm: /etc/utmp");
                exit(1);
        }
        for (nusers = 0; read(utmp, (char *)&buf, sizeof(struct utmp)) > 0;)
                if (buf.ut_name[0] != '\0')
                        ++nusers;
        return(nusers);
}

/*
 * nogamefile --
 *      if the file NOGAMING exists, no games allowed.
 *      file may also contain a message for the user.
 */
static
nogamefile()
{
        register int    fd, n;
        char    buf[BUFSIZ];

        if ((fd = open(NOGAMING, O_RDONLY, 0)) >= 0) {
#define MESG    "Sorry, no games right now.\n\n"
                (void)write(2, MESG, sizeof(MESG) - 1);
                while ((n = read(fd, buf, sizeof(buf))) > 0)
                        (void)write(2, buf, n);
                exit(1);
        }
}

/*
 * hour --
 *      print out the hour in human form
 */
static
hour(h)
        int     h;
{
        switch(h) {
        case 0:
                fputs("midnight", stderr);
                break;
        case 12:
                fputs("noon", stderr);
                break;
        default:
                if (h > 12)
                        fprintf(stderr, "%dpm", h - 12);
                else
                        fprintf(stderr, "%dam", h);
        }
}

#ifdef LOG
static
logfile()
{
        struct passwd   *pw, *getpwuid();
        FILE    *lp;
        uid_t   uid;
        int     lock_cnt;
        char    *ctime();

        if (lp = fopen(LOGFILE, "a")) {
                for (lock_cnt = 0;; ++lock_cnt) {
                        if (!flock(fileno(lp), LOCK_EX))
                                break;
                        if (lock_cnt == 4) {
                                perror("dm: log lock");
                                (void)fclose(lp);
                                return;
                        }
                        sleep((u_int)1);
                }
                if (pw = getpwuid(uid = getuid()))
                        fputs(pw->pw_name, lp);
                else
                        fprintf(lp, "%u", uid);
                fprintf(lp, "\t%s\t%s\t%s", game, gametty, ctime(&now));
                (void)fclose(lp);
                (void)flock(fileno(lp), LOCK_UN);
        }
}
#endif