FreeBSD/Linux Kernel Cross Reference
sys/dev/null/null.c
1 /*-
2 * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen
3 * Copyright (c) 2001-2004 Mark R. V. Murray
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer
11 * in this position and unchanged.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD: releng/8.4/sys/dev/null/null.c 230335 2012-01-19 19:39:41Z gnn $");
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/priv.h>
40 #include <sys/disk.h>
41 #include <sys/bus.h>
42 #include <sys/filio.h>
43
44 #include <machine/bus.h>
45
46 /* For use with destroy_dev(9). */
47 static struct cdev *null_dev;
48 static struct cdev *zero_dev;
49
50 static d_write_t null_write;
51 static d_ioctl_t null_ioctl;
52 static d_ioctl_t zero_ioctl;
53 static d_read_t zero_read;
54
55 static struct cdevsw null_cdevsw = {
56 .d_version = D_VERSION,
57 .d_read = (d_read_t *)nullop,
58 .d_write = null_write,
59 .d_ioctl = null_ioctl,
60 .d_name = "null",
61 };
62
63 static struct cdevsw zero_cdevsw = {
64 .d_version = D_VERSION,
65 .d_read = zero_read,
66 .d_write = null_write,
67 .d_ioctl = zero_ioctl,
68 .d_name = "zero",
69 .d_flags = D_MMAP_ANON,
70 };
71
72 static void *zbuf;
73
74 /* ARGSUSED */
75 static int
76 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
77 {
78 uio->uio_resid = 0;
79
80 return (0);
81 }
82
83 /* ARGSUSED */
84 static int
85 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
86 int flags __unused, struct thread *td)
87 {
88 int error;
89 error = 0;
90
91 switch (cmd) {
92 case DIOCSKERNELDUMP:
93 error = priv_check(td, PRIV_SETDUMPER);
94 if (error == 0)
95 error = set_dumper(NULL);
96 break;
97 case FIONBIO:
98 break;
99 case FIOASYNC:
100 if (*(int *)data != 0)
101 error = EINVAL;
102 break;
103 default:
104 error = ENOIOCTL;
105 }
106 return (error);
107 }
108
109 /* ARGSUSED */
110 static int
111 zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
112 int flags __unused, struct thread *td)
113 {
114 int error;
115 error = 0;
116
117 switch (cmd) {
118 case FIONBIO:
119 break;
120 case FIOASYNC:
121 if (*(int *)data != 0)
122 error = EINVAL;
123 break;
124 default:
125 error = ENOIOCTL;
126 }
127 return (error);
128 }
129
130
131 /* ARGSUSED */
132 static int
133 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused)
134 {
135 int error = 0;
136
137 while (uio->uio_resid > 0 && error == 0)
138 error = uiomove(zbuf, MIN(uio->uio_resid, PAGE_SIZE), uio);
139
140 return (error);
141 }
142
143 /* ARGSUSED */
144 static int
145 null_modevent(module_t mod __unused, int type, void *data __unused)
146 {
147 switch(type) {
148 case MOD_LOAD:
149 if (bootverbose)
150 printf("null: <null device, zero device>\n");
151 zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK | M_ZERO);
152 null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0,
153 NULL, UID_ROOT, GID_WHEEL, 0666, "null");
154 zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0,
155 NULL, UID_ROOT, GID_WHEEL, 0666, "zero");
156 break;
157
158 case MOD_UNLOAD:
159 destroy_dev(null_dev);
160 destroy_dev(zero_dev);
161 free(zbuf, M_TEMP);
162 break;
163
164 case MOD_SHUTDOWN:
165 break;
166
167 default:
168 return (EOPNOTSUPP);
169 }
170
171 return (0);
172 }
173
174 DEV_MODULE(null, null_modevent, NULL);
175 MODULE_VERSION(null, 1);
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