/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1983, 1989, 1993
 *      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. 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 <err.h>
#include <errno.h>
#include <limits.h>
#include <pwd.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static int      donice(int, int, int, bool);
static int      getnum(const char *, const char *, int *);
static void     usage(void);

/*
 * Change the priority (nice) of processes
 * or groups of processes which are already
 * running.
 */
int
main(int argc, char *argv[])
{
        struct passwd *pwd;
        bool havedelim = false, haveprio = false, incr = false;
        int errs = 0, prio = 0, who = 0, which = PRIO_PROCESS;

        for (argc--, argv++; argc > 0; argc--, argv++) {
                if (!havedelim) {
                        /* can occur at any time prior to delimiter */
                        if (strcmp(*argv, "-g") == 0) {
                                which = PRIO_PGRP;
                                continue;
                        }
                        if (strcmp(*argv, "-u") == 0) {
                                which = PRIO_USER;
                                continue;
                        }
                        if (strcmp(*argv, "-p") == 0) {
                                which = PRIO_PROCESS;
                                continue;
                        }
                        if (strcmp(*argv, "--") == 0) {
                                havedelim = true;
                                continue;
                        }
                        if (strcmp(*argv, "-n") == 0) {
                                /* may occur only once, prior to priority */
                                if (haveprio || incr || argc < 2)
                                        usage();
                                incr = true;
                                (void)argc--, argv++;
                                /* fall through to priority */
                        }
                }
                if (!haveprio) {
                        /* must occur exactly once, prior to target */
                        if (getnum("priority", *argv, &prio))
                                return (1);
                        haveprio = true;
                        continue;
                }
                if (which == PRIO_USER) {
                        if ((pwd = getpwnam(*argv)) != NULL)
                                who = pwd->pw_uid;
                        else if (getnum("uid", *argv, &who)) {
                                errs++;
                                continue;
                        } else if (who < 0) {
                                warnx("%s: bad value", *argv);
                                errs++;
                                continue;
                        }
                } else {
                        if (getnum("pid", *argv, &who)) {
                                errs++;
                                continue;
                        }
                        if (who < 0) {
                                warnx("%s: bad value", *argv);
                                errs++;
                                continue;
                        }
                }
                errs += donice(which, who, prio, incr);
        }
        if (!haveprio)
                usage();
        exit(errs != 0);
}

static int
donice(int which, int who, int prio, bool incr)
{
        int oldprio;

        errno = 0;
        oldprio = getpriority(which, who);
        if (oldprio == -1 && errno) {
                warn("%d: getpriority", who);
                return (1);
        }
        if (incr)
                prio = oldprio + prio;
        if (prio > PRIO_MAX)
                prio = PRIO_MAX;
        if (prio < PRIO_MIN)
                prio = PRIO_MIN;
        if (setpriority(which, who, prio) < 0) {
                warn("%d: setpriority", who);
                return (1);
        }
        fprintf(stderr, "%d: old priority %d, new priority %d\n", who,
            oldprio, prio);
        return (0);
}

static int
getnum(const char *com, const char *str, int *val)
{
        long v;
        char *ep;

        errno = 0;
        v = strtol(str, &ep, 10);
        if (v < INT_MIN || v > INT_MAX || errno == ERANGE) {
                warnx("%s argument %s is out of range.", com, str);
                return (1);
        }
        if (ep == str || *ep != '\0' || errno != 0) {
                warnx("%s argument %s is invalid.", com, str);
                return (1);
        }

        *val = (int)v;
        return (0);
}

static void
usage(void)
{
        fprintf(stderr, "%s\n%s\n",
"usage: renice priority [[-p] pid ...] [[-g] pgrp ...] [[-u] user ...]",
"       renice -n increment [[-p] pid ...] [[-g] pgrp ...] [[-u] user ...]");
        exit(1);
}