1 /*-
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
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
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.
16 *
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.
27 *
28 */
29
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32
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
84
85 /* ARGSUSED */
86 static int
full_write(struct cdev * dev __unused,struct uio * uio __unused,int flags __unused)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
null_write(struct cdev * dev __unused,struct uio * uio,int flags __unused)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
null_ioctl(struct cdev * dev __unused,u_long cmd,caddr_t data __unused,int flags __unused,struct thread * td)104 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
105 int flags __unused, struct thread *td)
106 {
107 int error;
108 error = 0;
109
110 switch (cmd) {
111 case DIOCSKERNELDUMP:
112 error = set_dumper(NULL, NULL, td);
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
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