1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
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
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
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.
18 *
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.
29 *
30 */
31
32 #include <sys/cdefs.h>
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/conf.h>
36 #include <sys/uio.h>
37 #include <sys/kernel.h>
38 #include <sys/malloc.h>
39 #include <sys/module.h>
40 #include <sys/disk.h>
41 #include <sys/bus.h>
42 #include <sys/filio.h>
43
44 #include <machine/bus.h>
45 #include <machine/vmparam.h>
46
47 /* For use with destroy_dev(9). */
48 static struct cdev *full_dev;
49 static struct cdev *null_dev;
50 static struct cdev *zero_dev;
51
52 static d_write_t full_write;
53 static d_write_t null_write;
54 static d_ioctl_t null_ioctl;
55 static d_ioctl_t zero_ioctl;
56 static d_read_t zero_read;
57
58 static struct cdevsw full_cdevsw = {
59 .d_version = D_VERSION,
60 .d_read = zero_read,
61 .d_write = full_write,
62 .d_ioctl = zero_ioctl,
63 .d_name = "full",
64 };
65
66 static struct cdevsw null_cdevsw = {
67 .d_version = D_VERSION,
68 .d_read = (d_read_t *)nullop,
69 .d_write = null_write,
70 .d_ioctl = null_ioctl,
71 .d_name = "null",
72 };
73
74 static struct cdevsw zero_cdevsw = {
75 .d_version = D_VERSION,
76 .d_read = zero_read,
77 .d_write = null_write,
78 .d_ioctl = zero_ioctl,
79 .d_name = "zero",
80 .d_flags = D_MMAP_ANON,
81 };
82
83 /* ARGSUSED */
84 static int
full_write(struct cdev * dev __unused,struct uio * uio __unused,int flags __unused)85 full_write(struct cdev *dev __unused, struct uio *uio __unused, int flags __unused)
86 {
87
88 return (ENOSPC);
89 }
90
91 /* ARGSUSED */
92 static int
null_write(struct cdev * dev __unused,struct uio * uio,int flags __unused)93 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
94 {
95 uio->uio_resid = 0;
96
97 return (0);
98 }
99
100 /* ARGSUSED */
101 static int
null_ioctl(struct cdev * dev __unused,u_long cmd,caddr_t data __unused,int flags __unused,struct thread * td)102 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
103 int flags __unused, struct thread *td)
104 {
105 struct diocskerneldump_arg kda;
106 int error;
107
108 error = 0;
109 switch (cmd) {
110 case DIOCSKERNELDUMP:
111 bzero(&kda, sizeof(kda));
112 kda.kda_index = KDA_REMOVE_ALL;
113 error = dumper_remove(NULL, &kda);
114 break;
115 case FIONBIO:
116 break;
117 case FIOASYNC:
118 if (*(int *)data != 0)
119 error = EINVAL;
120 break;
121 default:
122 error = ENOIOCTL;
123 }
124 return (error);
125 }
126
127 /* ARGSUSED */
128 static int
zero_ioctl(struct cdev * dev __unused,u_long cmd,caddr_t data __unused,int flags __unused,struct thread * td)129 zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
130 int flags __unused, struct thread *td)
131 {
132 int error;
133 error = 0;
134
135 switch (cmd) {
136 case FIONBIO:
137 break;
138 case FIOASYNC:
139 if (*(int *)data != 0)
140 error = EINVAL;
141 break;
142 default:
143 error = ENOIOCTL;
144 }
145 return (error);
146 }
147
148 /* ARGSUSED */
149 static int
zero_read(struct cdev * dev __unused,struct uio * uio,int flags __unused)150 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused)
151 {
152 void *zbuf;
153 ssize_t len;
154 int error = 0;
155
156 KASSERT(uio->uio_rw == UIO_READ,
157 ("Can't be in %s for write", __func__));
158 zbuf = __DECONST(void *, zero_region);
159 while (uio->uio_resid > 0 && error == 0) {
160 len = uio->uio_resid;
161 if (len > ZERO_REGION_SIZE)
162 len = ZERO_REGION_SIZE;
163 error = uiomove(zbuf, len, uio);
164 }
165
166 return (error);
167 }
168
169 /* ARGSUSED */
170 static int
null_modevent(module_t mod __unused,int type,void * data __unused)171 null_modevent(module_t mod __unused, int type, void *data __unused)
172 {
173 switch(type) {
174 case MOD_LOAD:
175 if (bootverbose)
176 printf("null: <full device, null device, zero device>\n");
177 full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0,
178 NULL, UID_ROOT, GID_WHEEL, 0666, "full");
179 null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0,
180 NULL, UID_ROOT, GID_WHEEL, 0666, "null");
181 zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0,
182 NULL, UID_ROOT, GID_WHEEL, 0666, "zero");
183 break;
184
185 case MOD_UNLOAD:
186 destroy_dev(full_dev);
187 destroy_dev(null_dev);
188 destroy_dev(zero_dev);
189 break;
190
191 case MOD_SHUTDOWN:
192 break;
193
194 default:
195 return (EOPNOTSUPP);
196 }
197
198 return (0);
199 }
200
201 DEV_MODULE(null, null_modevent, NULL);
202 MODULE_VERSION(null, 1);
203