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
86
87 /* ARGSUSED */
88 static int
89 full_write(struct cdev *dev __unused, struct uio *uio __unused, int flags __unused)
90 {
91
92 return (ENOSPC);
93 }
94
95 /* ARGSUSED */
96 static int
97 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
98 {
99 uio->uio_resid = 0;
100
101 return (0);
102 }
103
104 /* ARGSUSED */
105 static int
106 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
107 int flags __unused, struct thread *td)
108 {
109 int error;
110
111 error = 0;
112 switch (cmd) {
113 #ifdef COMPAT_FREEBSD11
114 case DIOCSKERNELDUMP_FREEBSD11:
115 #endif
116 case DIOCSKERNELDUMP:
117 error = clear_dumper(td);
118 break;
119 case FIONBIO:
120 break;
121 case FIOASYNC:
122 if (*(int *)data != 0)
123 error = EINVAL;
124 break;
125 default:
126 error = ENOIOCTL;
127 }
128 return (error);
129 }
130
131 /* ARGSUSED */
132 static int
133 zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
134 int flags __unused, struct thread *td)
135 {
136 int error;
137 error = 0;
138
139 switch (cmd) {
140 case FIONBIO:
141 break;
142 case FIOASYNC:
143 if (*(int *)data != 0)
144 error = EINVAL;
145 break;
146 default:
147 error = ENOIOCTL;
148 }
149 return (error);
150 }
151
152
153 /* ARGSUSED */
154 static int
155 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused)
156 {
157 void *zbuf;
158 ssize_t len;
159 int error = 0;
160
161 KASSERT(uio->uio_rw == UIO_READ,
162 ("Can't be in %s for write", __func__));
163 zbuf = __DECONST(void *, zero_region);
164 while (uio->uio_resid > 0 && error == 0) {
165 len = uio->uio_resid;
166 if (len > ZERO_REGION_SIZE)
167 len = ZERO_REGION_SIZE;
168 error = uiomove(zbuf, len, uio);
169 }
170
171 return (error);
172 }
173
174 /* ARGSUSED */
175 static int
176 null_modevent(module_t mod __unused, int type, void *data __unused)
177 {
178 switch(type) {
179 case MOD_LOAD:
180 if (bootverbose)
181 printf("null: <full device, null device, zero device>\n");
182 full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0,
183 NULL, UID_ROOT, GID_WHEEL, 0666, "full");
184 null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0,
185 NULL, UID_ROOT, GID_WHEEL, 0666, "null");
186 zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0,
187 NULL, UID_ROOT, GID_WHEEL, 0666, "zero");
188 break;
189
190 case MOD_UNLOAD:
191 destroy_dev(full_dev);
192 destroy_dev(null_dev);
193 destroy_dev(zero_dev);
194 break;
195
196 case MOD_SHUTDOWN:
197 break;
198
199 default:
200 return (EOPNOTSUPP);
201 }
202
203 return (0);
204 }
205
206 DEV_MODULE(null, null_modevent, NULL);
207 MODULE_VERSION(null, 1);
Cache object: 55080bc666c36f37a5f4e86e12554e71
|