/*
 * Copyright (c) 1980, 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.
 *
 * @(#)swapon.c 8.1 (Berkeley) 6/5/93
 * $FreeBSD: src/sbin/dumpon/dumpon.c,v 1.10.2.2 2001/07/30 10:30:05 dd Exp $
 */

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include <fstab.h>
#include <sys/param.h>
#include <sys/sysctl.h>
#include <sys/stat.h>
#include <sysexits.h>

static const char *sc_name = "kern.dumpdev";

static struct stat *get_dumpdev(void);
static void usage(void) __dead2;

int
main(int argc, char **argv)
{
        int ch;
        struct stat stab;
        struct stat *stab_old;
        char *path, *p;
        bool is_dumpoff;

        if (strstr((p = strrchr(argv[0], '/')) ? p+1 : argv[0],
                   "dumpoff") != 0) {
                is_dumpoff = true;
        } else {
                is_dumpoff = false;
        }

        while ((ch = getopt(argc, argv, "v")) != -1) {
                switch (ch) {
                case 'v':
                        /* backward compatibility only */
                        break;
                case '?':
                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        if ((is_dumpoff && argc != 0) || (!is_dumpoff && argc != 1))
                usage();

        path = argv[0];
        if (is_dumpoff || strcmp(path, "off") == 0) {
                stab.st_rdev = NODEV;
        } else {
                path = getdevpath(path, 0);
                if (stat(path, &stab) != 0)
                        err(EX_OSFILE, "%s", path);

                if (!S_ISCHR(stab.st_mode)) {
                        errx(EX_USAGE,
                             "%s: must specify a character disk device",
                             path);
                }
        }

        stab_old = get_dumpdev();

        if (stab.st_rdev == stab_old->st_rdev) {
                if (stab.st_rdev == NODEV) {
                        printf("dumpon: crash dumps already disabled.\n");
                } else {
                        printf("dumpon: crash dumps already configured "
                               "to the given device.\n");
                }
        } else if (stab.st_rdev == NODEV || stab_old->st_rdev == NODEV) {
                if (sysctlbyname(sc_name, NULL, NULL,
                                 &stab.st_rdev, sizeof stab.st_rdev) != 0) {
                        err(EX_OSERR, "sysctl: %s", sc_name);
                }
                if (stab.st_rdev == NODEV) {
                        printf("dumpon: crash dumps disabled\n");
                } else {
                        printf("dumpon: crash dumps to %s (%lu, %#lx)\n",
                               path,
                               (unsigned long)major(stab.st_rdev),
                               (unsigned long)minor(stab.st_rdev));
                }
        } else {
                warnx("crash dumps already configured "
                      "to another device (%lu, %#lx)",
                      (unsigned long)major(stab.st_rdev),
                      (unsigned long)minor(stab.st_rdev));
                errx(EX_USAGE, "you need to run 'dumpoff' first.");
        }

        return 0;
}


static struct stat *
get_dumpdev(void)
{
        struct stat *stab;
        size_t len;

        if ((stab = malloc(sizeof(*stab))) == NULL)
                err(EX_OSERR, "malloc");

        memset(stab, 0, sizeof(*stab));
        len = sizeof(stab->st_rdev);
        if (sysctlbyname(sc_name, &stab->st_rdev, &len, NULL, 0) != 0)
                err(EX_OSERR, "sysctl: %s", sc_name);

        return stab;
}

static void
usage(void)
{
        fprintf(stderr,
                "usage: dumpon [-v] special_file\n"
                "       dumpon [-v] off\n"
                "       dumpoff [-v]\n");
        exit(EX_USAGE);
}