commands/nice/nice.c
/*
 * 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.
 */

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

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

#define	DEFNICE	10

void usage(void);

int
main(int argc, char *argv[])
{
	long niceness = DEFNICE;
	int ch;
	char *ep;
	char arg1[10];

	/* Obsolescent syntax: -number, --number */
	if (argc >= 2 && argv[1][0] == '-' && (argv[1][1] == '-' ||
	    isdigit((unsigned char)argv[1][1])) && strcmp(argv[1], "--") != 0) {
		snprintf(arg1, sizeof(arg1), "-n%s", argv[1] + 1);
		argv[1] = arg1;
	}

	while ((ch = getopt(argc, argv, "n:")) != -1) {
		switch (ch) {
		case 'n':
			errno = 0;
			niceness = strtol(optarg, &ep, 10);
			if (ep == optarg || *ep != '\0' || errno ||
			    niceness < INT_MIN || niceness > INT_MAX) {
				fprintf(stderr, "%s: invalid nice value", optarg);
				return 1;
			}
			break;
		default:
			usage();
		}
	}
	argc -= optind;
	argv += optind;

	if (argc == 0)
		usage();

	errno = 0;
	niceness += getpriority(PRIO_PROCESS, 0);
	if (errno) {
		perror("getpriority");
		return 1;
	}
	if (setpriority(PRIO_PROCESS, 0, (int)niceness)) {
		perror("setpriority");
		return 1;
	}
	errno = 0;
	execvp(*argv, argv);
	perror("execvp");
	return 1;
}

void
usage(void)
{

	(void)fprintf(stderr, "usage: nice [-n incr] utility [arguments]\n");
	exit(1);
}
