FreeBSD/Linux Kernel Cross Reference
sys/dev/null/null.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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 __FBSDID("$FreeBSD$");
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/conf.h>
38 #include <sys/uio.h>
39 #include <sys/kernel.h>
40 #include <sys/malloc.h>
41 #include <sys/module.h>
42 #include <sys/disk.h>
43 #include <sys/bus.h>
44 #include <sys/filio.h>
45
46 #include <machine/bus.h>
47 #include <machine/vmparam.h>
48
49 /* For use with destroy_dev(9). */
50 static struct cdev *full_dev;
51 static struct cdev *null_dev;
52 static struct cdev *zero_dev;
53
54 static d_write_t full_write;
55 static d_write_t null_write;
56 static d_ioctl_t null_ioctl;
57 static d_ioctl_t zero_ioctl;
58 static d_read_t zero_read;
59
60 static struct cdevsw full_cdevsw = {
61 .d_version = D_VERSION,
62 .d_read = zero_read,
63 .d_write = full_write,
64 .d_ioctl = zero_ioctl,
65 .d_name = "full",
66 };
67
68 static struct cdevsw null_cdevsw = {
69 .d_version = D_VERSION,
70 .d_read = (d_read_t *)nullop,
71 .d_write = null_write,
72 .d_ioctl = null_ioctl,
73 .d_name = "null",
74 };
75
76 static struct cdevsw zero_cdevsw = {
77 .d_version = D_VERSION,
78 .d_read = zero_read,
79 .d_write = null_write,
80 .d_ioctl = zero_ioctl,
81 .d_name = "zero",
82 .d_flags = D_MMAP_ANON,
83 };
84
85 /* ARGSUSED */
86 static int
87 full_write(struct cdev *dev __unused, struct uio *uio __unused, int flags __unused)
88 {
89
90 return (ENOSPC);
91 }
92
93 /* ARGSUSED */
94 static int
95 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
96 {
97 uio->uio_resid = 0;
98
99 return (0);
100 }
101
102 /* ARGSUSED */
103 static int
104 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
105 int flags __unused, struct thread *td)
106 {
107 struct diocskerneldump_arg kda;
108 int error;
109
110 error = 0;
111 switch (cmd) {
112 #ifdef COMPAT_FREEBSD11
113 case DIOCSKERNELDUMP_FREEBSD11:
114 gone_in(13, "FreeBSD 11.x ABI compat");
115 /* FALLTHROUGH */
116 #endif
117 #ifdef COMPAT_FREEBSD12
118 case DIOCSKERNELDUMP_FREEBSD12:
119 if (cmd == DIOCSKERNELDUMP_FREEBSD12)
120 gone_in(14, "FreeBSD 12.x ABI compat");
121 /* FALLTHROUGH */
122 #endif
123 case DIOCSKERNELDUMP:
124 bzero(&kda, sizeof(kda));
125 kda.kda_index = KDA_REMOVE_ALL;
126 error = dumper_remove(NULL, &kda);
127 break;
128 case FIONBIO:
129 break;
130 case FIOASYNC:
131 if (*(int *)data != 0)
132 error = EINVAL;
133 break;
134 default:
135 error = ENOIOCTL;
136 }
137 return (error);
138 }
139
140 /* ARGSUSED */
141 static int
142 zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
143 int flags __unused, struct thread *td)
144 {
145 int error;
146 error = 0;
147
148 switch (cmd) {
149 case FIONBIO:
150 break;
151 case FIOASYNC:
152 if (*(int *)data != 0)
153 error = EINVAL;
154 break;
155 default:
156 error = ENOIOCTL;
157 }
158 return (error);
159 }
160
161 /* ARGSUSED */
162 static int
163 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused)
164 {
165 void *zbuf;
166 ssize_t len;
167 int error = 0;
168
169 KASSERT(uio->uio_rw == UIO_READ,
170 ("Can't be in %s for write", __func__));
171 zbuf = __DECONST(void *, zero_region);
172 while (uio->uio_resid > 0 && error == 0) {
173 len = uio->uio_resid;
174 if (len > ZERO_REGION_SIZE)
175 len = ZERO_REGION_SIZE;
176 error = uiomove(zbuf, len, uio);
177 }
178
179 return (error);
180 }
181
182 /* ARGSUSED */
183 static int
184 null_modevent(module_t mod __unused, int type, void *data __unused)
185 {
186 switch(type) {
187 case MOD_LOAD:
188 if (bootverbose)
189 printf("null: <full device, null device, zero device>\n");
190 full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0,
191 NULL, UID_ROOT, GID_WHEEL, 0666, "full");
192 null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0,
193 NULL, UID_ROOT, GID_WHEEL, 0666, "null");
194 zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0,
195 NULL, UID_ROOT, GID_WHEEL, 0666, "zero");
196 break;
197
198 case MOD_UNLOAD:
199 destroy_dev(full_dev);
200 destroy_dev(null_dev);
201 destroy_dev(zero_dev);
202 break;
203
204 case MOD_SHUTDOWN:
205 break;
206
207 default:
208 return (EOPNOTSUPP);
209 }
210
211 return (0);
212 }
213
214 DEV_MODULE(null, null_modevent, NULL);
215 MODULE_VERSION(null, 1);
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