cmd/badioctl/badioctl.c

	badioctl.c revision 9512fe850e98fdd448c638ca63fdd92a8a510255
/*
 * 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 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#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);
    }
}

void
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);
    }
}