nice.c

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/*
 * 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);
}

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