/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/varargs.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <unistd.h>

#define DTRACEIOC       (('d' << 24) | ('t' << 16) | ('r' << 8))
#define DTRACEIOC_MAX   17

void
fatal(char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);

        fprintf(stderr, "%s: ", "badioctl");
        vfprintf(stderr, fmt, ap);

        if (fmt[strlen(fmt) - 1] != '\n')
                fprintf(stderr, ": %s\n", strerror(errno));

        exit(1);
}

void
badioctl(pid_t parent)
{
        int fd = -1, random, ps = sysconf(_SC_PAGESIZE);
        int i = 0, seconds;
        caddr_t addr;
        hrtime_t now, last = 0, end;

        if ((random = open("/dev/random", O_RDONLY)) == -1)
                fatal("couldn't open /dev/random");

        if ((addr = mmap(0, ps, PROT_READ | PROT_WRITE,
            MAP_ANON | MAP_PRIVATE, -1, 0)) == (caddr_t)-1)
                fatal("mmap");

        for (;;) {
                unsigned int ioc;

                if ((now = gethrtime()) - last > NANOSEC) {
                        if (kill(parent, 0) == -1 && errno == ESRCH) {
                                /*
                                 * Our parent died.  We will kill ourselves in
                                 * sympathy.
                                 */
                                exit(0);
                        }

                        /*
                         * Once a second, we'll reopen the device.
                         */
                        if (fd != -1)
                                close(fd);

                        fd = open("/devices/pseudo/dtrace@0:dtrace", O_RDONLY);

                        if (fd == -1)
                                fatal("couldn't open DTrace pseudo device");

                        last = now;
                }


                if ((i++ % 1000) == 0) {
                        /*
                         * Every thousand iterations, change our random gunk.
                         */
                        read(random, addr, ps);
                }

                read(random, &ioc, sizeof (ioc));
                ioc %= DTRACEIOC_MAX;
                ioc++;
                ioctl(fd, DTRACEIOC | ioc, addr);
        }
}

int
main()
{
        pid_t child, parent = getpid();
        int status;

        for (;;) {
                if ((child = fork()) == 0)
                        badioctl(parent);

                while (waitpid(child, &status, WEXITED) != child)
                        continue;

                if (WIFEXITED(status)) {
                        /*
                         * Our child exited by design -- we'll exit with
                         * the same status code.
                         */
                        exit(WEXITSTATUS(status));
                }

                /*
                 * Our child died on a signal.  Respawn it.
                 */
                printf("badioctl: child died on signal %d; respawning.\n",
                    WTERMSIG(status));
                fflush(stdout);
        }

        /* NOTREACHED */
        return (0);
}