FreeBSD/Linux Kernel Cross Reference
sys/dev/null/null.c
1 /*-
2 * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer
10 * in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 * $FreeBSD: releng/5.0/sys/dev/null/null.c 103745 2002-09-21 17:28:17Z markm $
27 */
28
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/conf.h>
32 #include <sys/uio.h>
33 #include <sys/kernel.h>
34 #include <sys/malloc.h>
35 #include <sys/module.h>
36 #include <sys/disk.h>
37 #include <sys/bus.h>
38 #include <machine/bus.h>
39 #include <machine/resource.h>
40 #include <sys/rman.h>
41
42 /* For use with destroy_dev(9). */
43 static dev_t null_dev;
44 static dev_t zero_dev;
45
46 static d_write_t null_write;
47 static d_ioctl_t null_ioctl;
48 static d_read_t zero_read;
49
50 #define CDEV_MAJOR 2
51 #define NULL_MINOR 2
52 #define ZERO_MINOR 12
53
54 static struct cdevsw null_cdevsw = {
55 /* open */ (d_open_t *)nullop,
56 /* close */ (d_close_t *)nullop,
57 /* read */ (d_read_t *)nullop,
58 /* write */ null_write,
59 /* ioctl */ null_ioctl,
60 /* poll */ nopoll,
61 /* mmap */ nommap,
62 /* strategy */ nostrategy,
63 /* name */ "null",
64 /* maj */ CDEV_MAJOR,
65 /* dump */ nodump,
66 /* psize */ nopsize,
67 /* flags */ 0,
68 /* kqfilter */ NULL
69 };
70
71 static struct cdevsw zero_cdevsw = {
72 /* open */ (d_open_t *)nullop,
73 /* close */ (d_close_t *)nullop,
74 /* read */ zero_read,
75 /* write */ null_write,
76 /* ioctl */ noioctl,
77 /* poll */ nopoll,
78 /* mmap */ nommap,
79 /* strategy */ nostrategy,
80 /* name */ "zero",
81 /* maj */ CDEV_MAJOR,
82 /* dump */ nodump,
83 /* psize */ nopsize,
84 /* flags */ D_MMAP_ANON,
85 /* kqfilter */ NULL
86 };
87
88 static void *zbuf;
89
90 static int
91 null_write(dev_t dev, struct uio *uio, int flags)
92 {
93 uio->uio_resid = 0;
94 return 0;
95 }
96
97 static int
98 null_ioctl(dev_t dev, u_long cmd, caddr_t data, int flags, struct thread *td)
99 {
100 int error;
101
102 if (cmd != DIOCSKERNELDUMP)
103 return (noioctl(dev, cmd, data, flags, td));
104 error = suser(td);
105 if (error)
106 return (error);
107 return (set_dumper(NULL));
108 }
109
110 static int
111 zero_read(dev_t dev, struct uio *uio, int flags)
112 {
113 u_int c;
114 int error = 0;
115
116 while (uio->uio_resid > 0 && error == 0) {
117 c = min(uio->uio_resid, PAGE_SIZE);
118 error = uiomove(zbuf, c, uio);
119 }
120 return error;
121 }
122
123 static int
124 null_modevent(module_t mod, int type, void *data)
125 {
126 switch(type) {
127 case MOD_LOAD:
128 if (bootverbose)
129 printf("null: <null device, zero device>\n");
130 zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK | M_ZERO);
131 zero_dev = make_dev(&zero_cdevsw, ZERO_MINOR, UID_ROOT,
132 GID_WHEEL, 0666, "zero");
133 null_dev = make_dev(&null_cdevsw, NULL_MINOR, UID_ROOT,
134 GID_WHEEL, 0666, "null");
135 return 0;
136
137 case MOD_UNLOAD:
138 destroy_dev(null_dev);
139 destroy_dev(zero_dev);
140 free(zbuf, M_TEMP);
141 return 0;
142
143 case MOD_SHUTDOWN:
144 return 0;
145
146 default:
147 return EOPNOTSUPP;
148 }
149 }
150
151 DEV_MODULE(null, null_modevent, NULL);
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