/*
 * Copyright (c) 1989, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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.
 */

#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1989, 1993, 1994\n\
	The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)nice.c	8.2 (Berkeley) 4/16/94";
#endif /* not lint */

#include <sys/types.h>
#include <sys/time.h>
#include <sys/param.h>
#include <sys/resource.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <grp.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#define	DEFNICE	10
#define	MEAN_GROUP_NAME	"meanies"

void usage __P((void));

int
main(argc, argv)
	int argc;
	char *argv[];
{
	int niceness = DEFNICE;

	if (argc < 2)
		usage();

	if (argv[1][0] == '-') {
		if (argv[1][1] == '-' || isdigit(argv[1][1])) {
			niceness = atoi(argv[1] + 1);
			++argv;
		} else
			errx(1, "illegal option -- %s", argv[1]);
	}

	if (argv[1] == NULL)
		usage();

	errno = 0;
	niceness += getpriority(PRIO_PROCESS, 0);
	if (errno)
		err(1, "getpriority");
	(void)seteuid(getuid());
	if (setpriority(PRIO_PROCESS, 0, niceness)) {
		struct group *group;
		gid_t gids[NGROUPS_MAX];
		int ngids;

		if (errno != EACCES)
			err(1, "setpriority");
		(void)seteuid(0);
		group = getgrnam(MEAN_GROUP_NAME);
		if (group == NULL)
			errx(1, "cannot find the group \"%s\"",
			    MEAN_GROUP_NAME);
		ngids = getgroups(NGROUPS_MAX, gids);
		if (ngids == -1)
			err(1, "getgroups");
		while (ngids > 0)
			if (gids[--ngids] == group->gr_gid)
				ngids = -42;
		if (ngids != -42)
			errx(1, "must be a member of the group \"%s\"",
			    MEAN_GROUP_NAME);
		if (setpriority(PRIO_PROCESS, 0, niceness))
			err(1, "setpriority");
	}
	(void)setuid(getuid());
	execvp(argv[1], &argv[1]);
	err(1, "%s", argv[1]);
}

void
usage()
{
	(void)fprintf(stderr, "usage: mean [-number] command [arguments]\n");
	exit(1);
}