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/*-
* Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen
* Copyright (c) 2001-2004 Mark R. V. Murray
* 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
* in this position and unchanged.
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHOR 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>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/uio.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/priv.h>
#include <sys/disk.h>
#include <sys/bus.h>
#include <machine/bus.h>
/* For use with destroy_dev(9). */
static struct cdev *null_dev;
static struct cdev *zero_dev;
static d_write_t null_write;
static d_ioctl_t null_ioctl;
static d_read_t zero_read;
static struct cdevsw null_cdevsw = {
.d_version = D_VERSION,
.d_read = (d_read_t *)nullop,
.d_write = null_write,
.d_ioctl = null_ioctl,
.d_name = "null",
};
static struct cdevsw zero_cdevsw = {
.d_version = D_VERSION,
.d_read = zero_read,
.d_write = null_write,
.d_name = "zero",
.d_flags = D_MMAP_ANON,
};
static void *zbuf;
/* ARGSUSED */
static int
null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
{
uio->uio_resid = 0;
return (0);
}
/* ARGSUSED */
static int
null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
int flags __unused, struct thread *td)
{
int error;
if (cmd != DIOCSKERNELDUMP)
return (ENOIOCTL);
error = priv_check(td, PRIV_SETDUMPER);
if (error)
return (error);
return (set_dumper(NULL));
}
/* ARGSUSED */
static int
zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused)
{
int error = 0;
while (uio->uio_resid > 0 && error == 0)
error = uiomove(zbuf, MIN(uio->uio_resid, PAGE_SIZE), uio);
return (error);
}
/* ARGSUSED */
static int
null_modevent(module_t mod __unused, int type, void *data __unused)
{
switch(type) {
case MOD_LOAD:
if (bootverbose)
printf("null: <null device, zero device>\n");
zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK | M_ZERO);
null_dev = make_dev(&null_cdevsw, 0, UID_ROOT, GID_WHEEL,
0666, "null");
zero_dev = make_dev(&zero_cdevsw, 0, UID_ROOT, GID_WHEEL,
0666, "zero");
break;
case MOD_UNLOAD:
destroy_dev(null_dev);
destroy_dev(zero_dev);
free(zbuf, M_TEMP);
break;
case MOD_SHUTDOWN:
break;
default:
return (EOPNOTSUPP);
}
return (0);
}
DEV_MODULE(null, null_modevent, NULL);
MODULE_VERSION(null, 1);
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