1 /* $NetBSD: devnull.c,v 1.8 2018/09/03 16:29:37 riastradh Exp $ */
2
3 /*
4 * Copyright (c) 2009 Antti Kantee. 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 * 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 AUTHOR ``AS IS'' AND ANY EXPRESS
16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 /*
29 * /dev/null, the infamous bytesink.
30 *
31 * I can't imagine it being very different in the rump kernel than in
32 * the host kernel. But nonetheless it serves as a simple example.
33 */
34
35 #include <sys/cdefs.h>
36 __KERNEL_RCSID(0, "$NetBSD: devnull.c,v 1.8 2018/09/03 16:29:37 riastradh Exp $");
37
38 #include <sys/param.h>
39 #include <sys/conf.h>
40 #include <sys/device.h>
41 #include <sys/stat.h>
42
43 #include <rump-sys/vfs.h>
44
45 static dev_type_open(rump_devnullopen);
46 static dev_type_read(rump_devnullrw);
47
48 static struct cdevsw null_cdevsw = {
49 .d_open = rump_devnullopen,
50 .d_close = nullclose,
51 .d_read = rump_devnullrw,
52 .d_write = rump_devnullrw,
53 .d_ioctl = noioctl,
54 .d_stop = nostop,
55 .d_tty = notty,
56 .d_poll = nopoll,
57 .d_mmap = nommap,
58 .d_kqfilter = nokqfilter,
59 .d_discard = nodiscard,
60 .d_flag = D_OTHER | D_MPSAFE
61 };
62
63 int
rump_devnull_init()64 rump_devnull_init()
65 {
66 devmajor_t null_bmaj, null_cmaj;
67 int error;
68
69 null_bmaj = null_cmaj = NODEVMAJOR;
70 error = devsw_attach("null", NULL, &null_bmaj, &null_cdevsw,&null_cmaj);
71 KASSERT(error || null_cmaj == 2);
72
73 error = rump_vfs_makeonedevnode(S_IFCHR,
74 "/dev/null", null_cmaj, DEV_NULL);
75 if (error)
76 return error;
77 return rump_vfs_makeonedevnode(S_IFCHR,
78 "/dev/zero", null_cmaj, DEV_ZERO);
79 }
80
81 static int
rump_devnullopen(dev_t dev,int flag,int mode,struct lwp * l)82 rump_devnullopen(dev_t dev, int flag, int mode, struct lwp *l)
83 {
84
85 if (minor(dev) == DEV_ZERO || minor(dev) == DEV_NULL)
86 return 0;
87 return ENXIO;
88 }
89
90 static int
rump_devnullrw(dev_t dev,struct uio * uio,int flags)91 rump_devnullrw(dev_t dev, struct uio *uio, int flags)
92 {
93 char zeros[512];
94 int error;
95
96 switch (minor(dev)) {
97 case DEV_NULL:
98 if (uio->uio_rw == UIO_WRITE)
99 uio->uio_resid = 0;
100 break;
101 case DEV_ZERO:
102 if (uio->uio_rw == UIO_WRITE) {
103 uio->uio_resid = 0;
104 break;
105 }
106 memset(zeros, 0, sizeof(zeros));
107 while (uio->uio_resid > 0) {
108 error = uiomove(zeros,
109 uimin(sizeof(zeros), uio->uio_resid), uio);
110 if (error)
111 return error;
112 }
113 break;
114 default:
115 return ENXIO; /* how? */
116 }
117
118 return 0;
119 }
120