2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen
5 * Copyright (c) 2001-2004 Mark R. V. Murray
6 * Copyright (c) 2014 Eitan Adler
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer
14 * in this position and unchanged.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
35 #include "opt_compat.h"
37 #include <sys/param.h>
38 #include <sys/systm.h>
41 #include <sys/kernel.h>
42 #include <sys/malloc.h>
43 #include <sys/module.h>
46 #include <sys/filio.h>
48 #include <machine/bus.h>
49 #include <machine/vmparam.h>
51 /* For use with destroy_dev(9). */
52 static struct cdev *full_dev;
53 static struct cdev *null_dev;
54 static struct cdev *zero_dev;
56 static d_write_t full_write;
57 static d_write_t null_write;
58 static d_ioctl_t null_ioctl;
59 static d_ioctl_t zero_ioctl;
60 static d_read_t zero_read;
62 static struct cdevsw full_cdevsw = {
63 .d_version = D_VERSION,
65 .d_write = full_write,
66 .d_ioctl = zero_ioctl,
70 static struct cdevsw null_cdevsw = {
71 .d_version = D_VERSION,
72 .d_read = (d_read_t *)nullop,
73 .d_write = null_write,
74 .d_ioctl = null_ioctl,
78 static struct cdevsw zero_cdevsw = {
79 .d_version = D_VERSION,
81 .d_write = null_write,
82 .d_ioctl = zero_ioctl,
84 .d_flags = D_MMAP_ANON,
91 full_write(struct cdev *dev __unused, struct uio *uio __unused, int flags __unused)
99 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
108 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
109 int flags __unused, struct thread *td)
115 #ifdef COMPAT_FREEBSD11
116 case DIOCSKERNELDUMP_FREEBSD11:
118 case DIOCSKERNELDUMP:
119 error = set_dumper(NULL, NULL, td, 0, 0, NULL, 0, NULL);
124 if (*(int *)data != 0)
135 zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
136 int flags __unused, struct thread *td)
145 if (*(int *)data != 0)
157 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused)
163 KASSERT(uio->uio_rw == UIO_READ,
164 ("Can't be in %s for write", __func__));
165 zbuf = __DECONST(void *, zero_region);
166 while (uio->uio_resid > 0 && error == 0) {
167 len = uio->uio_resid;
168 if (len > ZERO_REGION_SIZE)
169 len = ZERO_REGION_SIZE;
170 error = uiomove(zbuf, len, uio);
178 null_modevent(module_t mod __unused, int type, void *data __unused)
183 printf("null: <full device, null device, zero device>\n");
184 full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0,
185 NULL, UID_ROOT, GID_WHEEL, 0666, "full");
186 null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0,
187 NULL, UID_ROOT, GID_WHEEL, 0666, "null");
188 zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0,
189 NULL, UID_ROOT, GID_WHEEL, 0666, "zero");
193 destroy_dev(full_dev);
194 destroy_dev(null_dev);
195 destroy_dev(zero_dev);
208 DEV_MODULE(null, null_modevent, NULL);
209 MODULE_VERSION(null, 1);