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/param.h>
33 #include <sys/systm.h>
34 #include <sys/conf.h>
35 #include <sys/uio.h>
36 #include <sys/kernel.h>
37 #include <sys/malloc.h>
38 #include <sys/module.h>
39 #include <sys/disk.h>
40 #include <sys/bus.h>
41 #include <sys/filio.h>
42
43 #include <machine/bus.h>
44 #include <machine/vmparam.h>
45
46 /* For use with destroy_dev(9). */
47 static struct cdev *full_dev;
48 static struct cdev *null_dev;
49 static struct cdev *zero_dev;
50
51 static d_write_t full_write;
52 static d_write_t null_write;
53 static d_ioctl_t null_ioctl;
54 static d_ioctl_t zero_ioctl;
55 static d_read_t zero_read;
56
57 static struct cdevsw full_cdevsw = {
58 .d_version = D_VERSION,
59 .d_read = zero_read,
60 .d_write = full_write,
61 .d_ioctl = zero_ioctl,
62 .d_name = "full",
63 };
64
65 static struct cdevsw null_cdevsw = {
66 .d_version = D_VERSION,
67 .d_read = (d_read_t *)nullop,
68 .d_write = null_write,
69 .d_ioctl = null_ioctl,
70 .d_name = "null",
71 };
72
73 static struct cdevsw zero_cdevsw = {
74 .d_version = D_VERSION,
75 .d_read = zero_read,
76 .d_write = null_write,
77 .d_ioctl = zero_ioctl,
78 .d_name = "zero",
79 .d_flags = D_MMAP_ANON,
80 };
81
82 /* ARGSUSED */
83 static int
full_write(struct cdev * dev __unused,struct uio * uio __unused,int flags __unused)84 full_write(struct cdev *dev __unused, struct uio *uio __unused, int flags __unused)
85 {
86
87 return (ENOSPC);
88 }
89
90 /* ARGSUSED */
91 static int
null_write(struct cdev * dev __unused,struct uio * uio,int flags __unused)92 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
93 {
94 uio->uio_resid = 0;
95
96 return (0);
97 }
98
99 /* ARGSUSED */
100 static int
null_ioctl(struct cdev * dev __unused,u_long cmd,caddr_t data __unused,int flags __unused,struct thread * td)101 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
102 int flags __unused, struct thread *td)
103 {
104 struct diocskerneldump_arg kda;
105 int error;
106
107 error = 0;
108 switch (cmd) {
109 case DIOCSKERNELDUMP:
110 bzero(&kda, sizeof(kda));
111 kda.kda_index = KDA_REMOVE_ALL;
112 error = dumper_remove(NULL, &kda);
113 break;
114 case FIONBIO:
115 break;
116 case FIOASYNC:
117 if (*(int *)data != 0)
118 error = EINVAL;
119 break;
120 default:
121 error = ENOIOCTL;
122 }
123 return (error);
124 }
125
126 /* ARGSUSED */
127 static int
zero_ioctl(struct cdev * dev __unused,u_long cmd,caddr_t data __unused,int flags __unused,struct thread * td)128 zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
129 int flags __unused, struct thread *td)
130 {
131 int error;
132 error = 0;
133
134 switch (cmd) {
135 case FIONBIO:
136 break;
137 case FIOASYNC:
138 if (*(int *)data != 0)
139 error = EINVAL;
140 break;
141 default:
142 error = ENOIOCTL;
143 }
144 return (error);
145 }
146
147 /* ARGSUSED */
148 static int
zero_read(struct cdev * dev __unused,struct uio * uio,int flags __unused)149 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused)
150 {
151 void *zbuf;
152 ssize_t len;
153 int error = 0;
154
155 KASSERT(uio->uio_rw == UIO_READ,
156 ("Can't be in %s for write", __func__));
157 zbuf = __DECONST(void *, zero_region);
158 while (uio->uio_resid > 0 && error == 0) {
159 len = uio->uio_resid;
160 if (len > ZERO_REGION_SIZE)
161 len = ZERO_REGION_SIZE;
162 error = uiomove(zbuf, len, uio);
163 }
164
165 return (error);
166 }
167
168 /* ARGSUSED */
169 static int
null_modevent(module_t mod __unused,int type,void * data __unused)170 null_modevent(module_t mod __unused, int type, void *data __unused)
171 {
172 switch(type) {
173 case MOD_LOAD:
174 if (bootverbose)
175 printf("null: <full device, null device, zero device>\n");
176 full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0,
177 NULL, UID_ROOT, GID_WHEEL, 0666, "full");
178 null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0,
179 NULL, UID_ROOT, GID_WHEEL, 0666, "null");
180 zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0,
181 NULL, UID_ROOT, GID_WHEEL, 0666, "zero");
182 break;
183
184 case MOD_UNLOAD:
185 destroy_dev(full_dev);
186 destroy_dev(null_dev);
187 destroy_dev(zero_dev);
188 break;
189
190 case MOD_SHUTDOWN:
191 break;
192
193 default:
194 return (EOPNOTSUPP);
195 }
196
197 return (0);
198 }
199
200 DEV_MODULE(null, null_modevent, NULL);
201 MODULE_VERSION(null, 1);
202