path: root/games/rogue/machdep.c

/*	$OpenBSD: machdep.c,v 1.11 2006/03/08 09:44:35 otto Exp $	*/
/*	$NetBSD: machdep.c,v 1.5 1995/04/28 23:49:22 mycroft 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. 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.
 */

#ifndef lint
#if 0
static char sccsid[] = "@(#)machdep.c	8.1 (Berkeley) 5/31/93";
#else
static const char rcsid[] = "$OpenBSD: machdep.c,v 1.11 2006/03/08 09:44:35 otto 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. */

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

#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)
{
	(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(void)
{
	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(void)
{
	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(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(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(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(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(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.
 */

char *
md_gln(void)
{
	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(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:
 *
 *   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.  You can get by simply always returning zero, which
 * indicates that there is no defined value for the given string.
 */

char *
md_getenv(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(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(void)
{
	return(getpid());
}

/* 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(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(boolean l)
{
	extern gid_t gid, egid;
	static int fd;
	short tries;

	if (l) {
		setegid(egid);
		if ((fd = open(_PATH_SCOREFILE, O_RDONLY)) < 1) {
			setegid(gid);
			messagef(0, "cannot lock score file");
			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.
 *
 * It is important that the game not give the shell the privileges the
 * game uses to access the scores file. This version of the game runs
 * with privileges low by default; only the saved gid (if setgid) or uid
 * (if setuid) will be privileged, but that privilege is discarded by
 * exec().
 */

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

	pid = fork();
	switch(pid) {
	case -1:
		break;
	case 0:
		execl(shell, shell, (char *)NULL);
		_exit(255);
	default:
		waitpid(pid, &w, 0);
		break;
	}
}