/*      $NetBSD: renice.c,v 1.20 2020/10/23 16:16:10 wiz Exp $  */

/*
* 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/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1983, 1989, 1993\
The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
/*static char sccsid[] = "from: @(#)renice.c    8.1 (Berkeley) 6/9/93";*/
__RCSID("$NetBSD: renice.c,v 1.20 2020/10/23 16:16:10 wiz Exp $");
#endif /* not lint */

#include <sys/resource.h>

#include <err.h>
#include <errno.h>
#include <limits.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>

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

/*
* Change the priority (nice) of processes
* or groups of processes which are already
* running.
*/
int
main(int argc, char **argv)
{
       int which = PRIO_PROCESS;
       int prio, errs = 0, incr = 0;
       id_t who = 0;

       argc--, argv++;
       if (argc < 2)
               usage();
       if (strcmp(*argv, "-n") == 0) {
               incr = 1;
               argc--, argv++;
               if (argc < 2)
                       usage();
       }
       if (getnum("priority", *argv, &prio))
               return 1;
       argc--, argv++;
       for (; argc > 0; argc--, argv++) {
               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 (which == PRIO_USER) {
                       struct passwd *pwd = getpwnam(*argv);

                       if (pwd == NULL) {
                               warnx("%s: unknown user", *argv);
                               errs++;
                               continue;
                       }
                       who = (id_t)pwd->pw_uid;
               } else {
                       int twho;
                       if (getnum("pid", *argv, &twho)) {
                               errs++;
                               continue;
                       }
                       if (twho < 0) {
                               warnx("%s: bad value", *argv);
                               errs++;
                               continue;
                       }
                       who = (id_t)twho;
               }
               errs += donice(which, who, prio, incr);
       }
       return errs == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
}

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

       errno = 0;
       v = strtol(str, &ep, 0);

       if (*ep) {
               warnx("Bad %s argument: %s", com, str);
               return 1;
       }
       if ((v == LONG_MIN || v == LONG_MAX) && errno == ERANGE) {
               warn("Invalid %s argument: %s", com, str);
               return 1;
       }

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

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

       errno = 0;
       if ((oldprio = getpriority(which, who)) == -1 && errno != 0) {
               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) == -1) {
               warn("%d: setpriority", who);
               return 1;
       }
       (void)printf("%d: old priority %d, new priority %d\n",
           who, oldprio, prio);
       return 0;
}

static void
usage(void)
{

       (void)fprintf(stderr, "Usage: %s [<priority> | -n <incr>] ",
           getprogname());
       (void)fprintf(stderr, "[[-gpu] who ...] ...\n");
       exit(1);
}