Security improvements for games (largely from or inspired by OpenBSD).

[bsdgames-darwin.git] / rogue / machdep.c

/*      $NetBSD: machdep.c,v 1.10 1999/09/12 09:02:23 jsm Exp $ */

/*
 * Copyright (c) 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Timothy C. Stoehr.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)machdep.c   8.1 (Berkeley) 5/31/93";
#else
__RCSID("$NetBSD: machdep.c,v 1.10 1999/09/12 09:02:23 jsm Exp $");
#endif
#endif /* not lint */

/*
 * machdep.c
 *
 * This source herein may be modified and/or distributed by anybody who
 * so desires, with the following restrictions:
 *    1.)  No portion of this notice shall be removed.
 *    2.)  Credit shall not be taken for the creation of this source.
 *    3.)  This code is not to be traded, sold, or used for personal
 *         gain or profit.
 *
 */

/* Included in this file are all system dependent routines.  Extensive use
 * of #ifdef's will be used to compile the appropriate code on each system:
 *
 *    UNIX:        all UNIX systems.
 *    UNIX_BSD4_2: UNIX BSD 4.2 and later, UTEK, (4.1 BSD too?)
 *    UNIX_SYSV:   UNIX system V
 *    UNIX_V7:     UNIX version 7
 *
 * All UNIX code should be included between the single "#ifdef UNIX" at the
 * top of this file, and the "#endif" at the bottom.
 * 
 * To change a routine to include a new UNIX system, simply #ifdef the
 * existing routine, as in the following example:
 *
 *   To make a routine compatible with UNIX system 5, change the first
 *   function to the second:
 *
 *      md_function()
 *      {
 *         code;
 *      }
 *
 *      md_function()
 *      {
 *      #ifdef UNIX_SYSV
 *         sys5code;
 *      #else
 *         code;
 *      #endif
 *      }
 *
 * Appropriate variations of this are of course acceptible.
 * The use of "#elseif" is discouraged because of non-portability.
 * If the correct #define doesn't exist, "UNIX_SYSV" in this case, make it up
 * and insert it in the list at the top of the file.  Alter the CFLAGS
 * in you Makefile appropriately.
 *
 */

#ifdef UNIX

#include <sys/types.h>
#include <sys/wait.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <pwd.h>

#ifdef UNIX_BSD4_2
#include <sys/time.h>
#endif

#ifdef UNIX_SYSV
#include <time.h>
#endif

#include <signal.h>
#include <stdlib.h>
#include <termios.h>
#include <unistd.h>
#include "rogue.h"
#include "pathnames.h"

/* md_slurp:
 *
 * This routine throws away all keyboard input that has not
 * yet been read.  It is used to get rid of input that the user may have
 * typed-ahead.
 *
 * This function is not necessary, so it may be stubbed.  The might cause
 * message-line output to flash by because the game has continued to read
 * input without waiting for the user to read the message.  Not such a
 * big deal.
 */

void
md_slurp()
{
        (void)fpurge(stdin);
}

/* md_heed_signals():
 *
 * This routine tells the program to call particular routines when
 * certain interrupts/events occur:
 *
 *      SIGINT: call onintr() to interrupt fight with monster or long rest.
 *      SIGQUIT: call byebye() to check for game termination.
 *      SIGHUP: call error_save() to save game when terminal hangs up.
 *
 *              On VMS, SIGINT and SIGQUIT correspond to ^C and ^Y.
 *
 * This routine is not strictly necessary and can be stubbed.  This will
 * mean that the game cannot be interrupted properly with keyboard
 * input, this is not usually critical.
 */

void
md_heed_signals()
{
        signal(SIGINT, onintr);
        signal(SIGQUIT, byebye);
        signal(SIGHUP, error_save);
}

/* md_ignore_signals():
 *
 * This routine tells the program to completely ignore the events mentioned
 * in md_heed_signals() above.  The event handlers will later be turned on
 * by a future call to md_heed_signals(), so md_heed_signals() and
 * md_ignore_signals() need to work together.
 *
 * This function should be implemented or the user risks interrupting
 * critical sections of code, which could cause score file, or saved-game
 * file, corruption.
 */

void
md_ignore_signals()
{
        signal(SIGQUIT, SIG_IGN);
        signal(SIGINT, SIG_IGN);
        signal(SIGHUP, SIG_IGN);
}

/* md_get_file_id():
 *
 * This function returns an integer that uniquely identifies the specified
 * file.  It need not check for the file's existence.  In UNIX, the inode
 * number is used.
 *
 * This function is used to identify saved-game files.
 */

int
md_get_file_id(fname)
        const char *fname;
{
        struct stat sbuf;

        if (stat(fname, &sbuf)) {
                return(-1);
        }
        return((int) sbuf.st_ino);
}

/* md_link_count():
 *
 * This routine returns the number of hard links to the specified file.
 *
 * This function is not strictly necessary.  On systems without hard links
 * this routine can be stubbed by just returning 1.
 */

int
md_link_count(fname)
        const char *fname;
{
        struct stat sbuf;

        stat(fname, &sbuf);
        return((int) sbuf.st_nlink);
}

/* md_gct(): (Get Current Time)
 *
 * This function returns the current year, month(1-12), day(1-31), hour(0-23),
 * minute(0-59), and second(0-59).  This is used for identifying the time
 * at which a game is saved.
 *
 * This function is not strictly necessary.  It can be stubbed by returning
 * zeros instead of the correct year, month, etc.  If your operating
 * system doesn't provide all of the time units requested here, then you
 * can provide only those that it does, and return zeros for the others.
 * If you cannot provide good time values, then users may be able to copy
 * saved-game files and play them.  
 */

void
md_gct(rt_buf)
        struct rogue_time *rt_buf;
{
        struct tm *t;
        time_t seconds;

        time(&seconds);
        t = localtime(&seconds);

        rt_buf->year = t->tm_year;
        rt_buf->month = t->tm_mon + 1;
        rt_buf->day = t->tm_mday;
        rt_buf->hour = t->tm_hour;
        rt_buf->minute = t->tm_min;
        rt_buf->second = t->tm_sec;
}

/* md_gfmt: (Get File Modification Time)
 *
 * This routine returns a file's date of last modification in the same format
 * as md_gct() above.
 *
 * This function is not strictly necessary.  It is used to see if saved-game
 * files have been modified since they were saved.  If you have stubbed the
 * routine md_gct() above by returning constant values, then you may do
 * exactly the same here.
 * Or if md_gct() is implemented correctly, but your system does not provide
 * file modification dates, you may return some date far in the past so
 * that the program will never know that a saved-game file being modified.  
 * You may also do this if you wish to be able to restore games from
 * saved-games that have been modified.
 */

void
md_gfmt(fname, rt_buf)
        const char *fname;
        struct rogue_time *rt_buf;
{
        struct stat sbuf;
        time_t seconds;
        struct tm *t;

        stat(fname, &sbuf);
        seconds = (long) sbuf.st_mtime;
        t = localtime(&seconds);

        rt_buf->year = t->tm_year;
        rt_buf->month = t->tm_mon + 1;
        rt_buf->day = t->tm_mday;
        rt_buf->hour = t->tm_hour;
        rt_buf->minute = t->tm_min;
        rt_buf->second = t->tm_sec;
}

/* md_df: (Delete File)
 *
 * This function deletes the specified file, and returns true (1) if the
 * operation was successful.  This is used to delete saved-game files
 * after restoring games from them.
 *
 * Again, this function is not strictly necessary, and can be stubbed
 * by simply returning 1.  In this case, saved-game files will not be
 * deleted and can be replayed.
 */

boolean
md_df(fname)
        const char *fname;
{
        if (unlink(fname)) {
                return(0);
        }
        return(1);
}

/* md_gln: (Get login name)
 *
 * This routine returns the login name of the user.  This string is
 * used mainly for identifying users in score files.
 *
 * A dummy string may be returned if you are unable to implement this
 * function, but then the score file would only have one name in it.
 */

const char *
md_gln()
{
        struct passwd *p;

        if (!(p = getpwuid(getuid())))
                return((char *)NULL);
        return(p->pw_name);
}

/* md_sleep:
 *
 * This routine causes the game to pause for the specified number of
 * seconds.
 *
 * This routine is not particularly necessary at all.  It is used for
 * delaying execution, which is useful to this program at some times.
 */

void
md_sleep(nsecs)
        int nsecs;
{
        (void) sleep(nsecs);
}

/* md_getenv()
 *
 * This routine gets certain values from the user's environment.  These
 * values are strings, and each string is identified by a name.  The names
 * of the values needed, and their use, is as follows:
 *
 *   TERMCAP
 *     The name of the users's termcap file, NOT the termcap entries
 *     themselves.  This is used ONLY if the program is compiled with
 *     CURSES defined (-DCURSES).  Even in this case, the program need
 *     not find a string for TERMCAP.  If it does not, it will use the
 *     default termcap file as returned by md_gdtcf();
 *   TERM
 *     The name of the users's terminal.  This is used ONLY if the program
 *     is compiled with CURSES defined (-DCURSES).  In this case, the string
 *     value for TERM must be found, or the routines in curses.c cannot
 *     function, and the program will quit.
 *   ROGUEOPTS
 *     A string containing the various game options.  This need not be
 *     defined.
 *   HOME
 *     The user's home directory.  This is only used when the user specifies
 *     '~' as the first character of a saved-game file.  This string need
 *     not be defined.
 *   SHELL
 *     The user's favorite shell.  If not found, "/bin/sh" is assumed.
 *
 * If your system does not provide a means of searching for these values,
 * you will have to do it yourself.  None of the values above really need
 * to be defined except TERM when the program is compiled with CURSES
 * defined.  In this case, as a bare minimum, you can check the 'name'
 * parameter, and if it is "TERM" find the terminal name and return that,
 * else return zero.  If the program is not compiled with CURSES, you can
 * get by with simply always returning zero.  Returning zero indicates
 * that their is no defined value for the given string.
 */

char *
md_getenv(name)
        const char *name;
{
        char *value;

        value = getenv(name);

        return(value);
}

/* md_malloc()
 *
 * This routine allocates, and returns a pointer to, the specified number
 * of bytes.  This routines absolutely MUST be implemented for your
 * particular system or the program will not run at all.  Return zero
 * when no more memory can be allocated.
 */

char *
md_malloc(n)
        int n;
{
        char *t;

        t = malloc(n);
        return(t);
}

/* md_gseed() (Get Seed)
 *
 * This function returns a seed for the random number generator (RNG).  This
 * seed causes the RNG to begin generating numbers at some point in it's
 * sequence.  Without a random seed, the RNG will generate the same set
 * of numbers, and every game will start out exactly the same way.  A good
 * number to use is the process id, given by getpid() on most UNIX systems.
 *
 * You need to find some single random integer, such as:
 *   process id.
 *   current time (minutes + seconds) returned from md_gct(), if implemented.
 *   
 * It will not help to return "get_rand()" or "rand()" or the return value of
 * any pseudo-RNG.  If you don't have a random number, you can just return 1,
 * but this means your games will ALWAYS start the same way, and will play
 * exactly the same way given the same input.
 */

int
md_gseed()
{
        time_t seconds;

        time(&seconds);
        return((int) seconds);
}

/* md_exit():
 *
 * This function causes the program to discontinue execution and exit.
 * This function must be implemented or the program will continue to
 * hang when it should quit.
 */

void
md_exit(status)
        int status;
{
        exit(status);
}

/* md_lock():
 *
 * This function is intended to give the user exclusive access to the score
 * file.  It does so by flock'ing the score file.  The full path name of the
 * score file should be defined for any particular site in rogue.h.  The
 * constants _PATH_SCOREFILE defines this file name.
 *
 * When the parameter 'l' is non-zero (true), a lock is requested.  Otherwise
 * the lock is released.
 */

void
md_lock(l)
        boolean l;
{
        static int fd;
        short tries;

        if (l) {
                setegid(egid);
                if ((fd = open(_PATH_SCOREFILE, O_RDONLY)) < 1) {
                        setegid(gid);
                        message("cannot lock score file", 0);
                        return;
                }
                setegid(gid);
                for (tries = 0; tries < 5; tries++)
                        if (!flock(fd, LOCK_EX|LOCK_NB))
                                return;
        } else {
                (void)flock(fd, LOCK_NB);
                (void)close(fd);
        }
}

/* md_shell():
 *
 * This function spawns a shell for the user to use.  When this shell is
 * terminated, the game continues.  Since this program may often be run
 * setuid to gain access to privileged files, care is taken that the shell
 * is run with the user's REAL user id, and not the effective user id.
 * The effective user id is restored after the shell completes.
 */

void
md_shell(shell)
        const char *shell;
{
        int w;

        if (!fork()) {
                execl(shell, shell, 0);
        }
        wait(&w);
}

/* If you have a viable curses/termlib library, then use it and don't bother
 * implementing the routines below.  And don't compile with -DCURSES.
 */

#ifdef CURSES

/* md_cbreak_no_echo_nonl:
 *
 * This routine sets up some terminal characteristics.  The tty-driver
 * must be told to:
 *   1.)  Not echo input.
 *   2.)  Transmit input characters immediately upon typing. (cbreak mode)
 *   3.)  Move the cursor down one line, without changing column, and
 *        without generating a carriage-return, when it
 *        sees a line-feed.  This is only necessary if line-feed is ever
 *        used in the termcap 'do' (cursor down) entry, in which case,
 *        your system should must have a way of accomplishing this.
 *
 * When the parameter 'on' is true, the terminal is set up as specified
 * above.  When this parameter is false, the terminal is restored to the
 * original state.
 *
 * Raw mode should not to be used.  Keyboard signals/events/interrupts should
 * be sent, although they are not strictly necessary.  See notes in
 * md_heed_signals().
 *
 * This function must be implemented for rogue to run properly if the
 * program is compiled with CURSES defined to use the enclosed curses
 * emulation package.  If you are not using this, then this routine is
 * totally unnecessary.
 * 
 * Notice that information is saved between calls.  This is used to
 * restore the terminal to an initial saved state.
 *
 */

void
md_cbreak_no_echo_nonl(on)
        boolean on;
{
        struct termios tty_buf;
        static struct termios tty_save;

        if (on) {
                tcgetattr(0, &tty_buf);
                tty_save = tty_buf;
                tty_buf.c_lflag &= ~(ICANON | ECHO);
                tty_buf.c_oflag &= ~ONLCR;
                tty_buf.c_cc[VMIN] = 1;
                tty_buf.c_cc[VTIME] = 2;
                tcsetattr(0, TCSADRAIN, &tty_buf);
        } else {
                tcsetattr(0, TCSADRAIN, &tty_save);
        }
}

/* md_gdtcf(): (Get Default Termcap File)
 *
 * This function is called ONLY when the program is compiled with CURSES
 * defined.  If you use your system's curses/termlib library, this function
 * won't be called.  On most UNIX systems, "/etc/termcap" suffices.
 *
 * If their is no such termcap file, then return 0, but in that case, you
 * must have a TERMCAP file returned from md_getenv("TERMCAP").  The latter
 * will override the value returned from md_gdtcf().  If the program is
 * compiled with CURSES defined, and md_gdtcf() returns 0, and
 * md_getenv("TERMCAP") returns 0, the program will have no terminal
 * capability information and will quit.
 */

char *
md_gdtcf()
{
        return("/etc/termcap");
}

/* md_tstp():
 *
 * This function puts the game to sleep and returns to the shell.  This
 * only applies to UNIX 4.2 and 4.3.  For other systems, the routine should
 * be provided as a do-nothing routine.  md_tstp() will only be referenced
 * in the code when compiled with CURSES defined.
 *
 */

void
md_tstp()
{
#ifdef UNIX_BSD4_2
        kill(0, SIGTSTP);
#endif
}

#endif

#endif