/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Rick Macklem at The University of Guelph.
 *
 * 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/param.h>
#include <sys/syslog.h>
#include <sys/wait.h>
#include <sys/linker.h>
#include <sys/mount.h>
#include <sys/sysctl.h>

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define MAXNFSDCNT      20

static void
usage(void)
{
        (void)fprintf(stderr, "usage: nfsiod [-n num_servers]\n");
        exit(1);
}

int
main(int argc, char *argv[])
{
        int ch;
        struct xvfsconf vfc;
        int error;
        unsigned int iodmin, iodmax, num_servers;
        size_t len;

        error = getvfsbyname("nfs", &vfc);
        if (error) {
                if (kldload("nfs") == -1)
                        err(1, "kldload(nfs)");
                error = getvfsbyname("nfs", &vfc);
        }
        if (error)
                errx(1, "NFS support is not available in the running kernel");

        num_servers = 0;
        while ((ch = getopt(argc, argv, "n:")) != -1)
                switch (ch) {
                case 'n':
                        num_servers = atoi(optarg);
                        if (num_servers < 1) {
                                warnx("nfsiod count %u; reset to %d",
                                    num_servers, 1);
                                num_servers = 1;
                        }
                        if (num_servers > MAXNFSDCNT) {
                                warnx("nfsiod count %u; reset to %d",
                                    num_servers, MAXNFSDCNT);
                                num_servers = MAXNFSDCNT;
                        }
                        break;
                case '?':
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;

        if (argc > 0)
                usage();

        len = sizeof iodmin;
        error = sysctlbyname("vfs.nfs.iodmin", &iodmin, &len, NULL, 0);
        if (error < 0)
                err(1, "sysctlbyname(\"vfs.nfs.iodmin\")");
        len = sizeof iodmax;
        error = sysctlbyname("vfs.nfs.iodmax", &iodmax, &len, NULL, 0);
        if (error < 0)
                err(1, "sysctlbyname(\"vfs.nfs.iodmax\")");
        if (num_servers == 0) {         /* no change */
                printf("vfs.nfs.iodmin=%u\nvfs.nfs.iodmax=%u\n",
                    iodmin, iodmax);
                exit(0);
        }
        /* Catch the case where we're lowering num_servers below iodmin */
        if (iodmin > num_servers) {
                iodmin = num_servers;
                error = sysctlbyname("vfs.nfs.iodmin", NULL, 0, &iodmin,
                    sizeof iodmin);
                if (error < 0)
                        err(1, "sysctlbyname(\"vfs.nfs.iodmin\")");
        }
        iodmax = num_servers;
        error = sysctlbyname("vfs.nfs.iodmax", NULL, 0, &iodmax, sizeof iodmax);
        if (error < 0)
                err(1, "sysctlbyname(\"vfs.nfs.iodmax\")");
        exit (0);
}