2 * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen
3 * Copyright (c) 2001-2004 Mark R. V. Murray
4 * Copyright (c) 2014 Eitan Adler
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer
12 * in this position and unchanged.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
33 #include <sys/param.h>
34 #include <sys/systm.h>
37 #include <sys/kernel.h>
38 #include <sys/malloc.h>
39 #include <sys/module.h>
43 #include <sys/filio.h>
45 #include <machine/bus.h>
46 #include <machine/vmparam.h>
48 /* For use with destroy_dev(9). */
49 static struct cdev *full_dev;
50 static struct cdev *null_dev;
51 static struct cdev *zero_dev;
53 static d_write_t full_write;
54 static d_write_t null_write;
55 static d_ioctl_t null_ioctl;
56 static d_ioctl_t zero_ioctl;
57 static d_read_t zero_read;
59 static struct cdevsw full_cdevsw = {
60 .d_version = D_VERSION,
62 .d_write = full_write,
63 .d_ioctl = zero_ioctl,
67 static struct cdevsw null_cdevsw = {
68 .d_version = D_VERSION,
69 .d_read = (d_read_t *)nullop,
70 .d_write = null_write,
71 .d_ioctl = null_ioctl,
75 static struct cdevsw zero_cdevsw = {
76 .d_version = D_VERSION,
78 .d_write = null_write,
79 .d_ioctl = zero_ioctl,
81 .d_flags = D_MMAP_ANON,
88 full_write(struct cdev *dev __unused, struct uio *uio __unused, int flags __unused)
96 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
105 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
106 int flags __unused, struct thread *td)
112 case DIOCSKERNELDUMP:
113 error = priv_check(td, PRIV_SETDUMPER);
115 error = set_dumper(NULL, NULL);
120 if (*(int *)data != 0)
131 zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
132 int flags __unused, struct thread *td)
141 if (*(int *)data != 0)
153 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused)
159 KASSERT(uio->uio_rw == UIO_READ,
160 ("Can't be in %s for write", __func__));
161 zbuf = __DECONST(void *, zero_region);
162 while (uio->uio_resid > 0 && error == 0) {
163 len = uio->uio_resid;
164 if (len > ZERO_REGION_SIZE)
165 len = ZERO_REGION_SIZE;
166 error = uiomove(zbuf, len, uio);
174 null_modevent(module_t mod __unused, int type, void *data __unused)
179 printf("null: <full device, null device, zero device>\n");
180 full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0,
181 NULL, UID_ROOT, GID_WHEEL, 0666, "full");
182 null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0,
183 NULL, UID_ROOT, GID_WHEEL, 0666, "null");
184 zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0,
185 NULL, UID_ROOT, GID_WHEEL, 0666, "zero");
189 destroy_dev(full_dev);
190 destroy_dev(null_dev);
191 destroy_dev(zero_dev);
204 DEV_MODULE(null, null_modevent, NULL);
205 MODULE_VERSION(null, 1);