ping.c revision 1.5 
1/*	$NetBSD: ping.c,v 1.5 2020/04/30 10:55:32 christos Exp $	*/
2
3/*-
4 * Copyright (c) 2015 The NetBSD Foundation, Inc.
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 * 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__KERNEL_RCSID(0, "$NetBSD: ping.c,v 1.5 2020/04/30 10:55:32 christos Exp $");
31
32#include <sys/param.h>
33#include <sys/conf.h>
34#include <sys/device.h>
35#include <sys/kernel.h>
36#include <sys/module.h>
37
38#include "ping.h"
39
40/*
41 * Create a device /dev/ping in order to test this module.
42 *
43 * To use this device you need to do:
44 *     mknod /dev/ping c 351 0
45 *
46 */
47
48dev_type_open(ping_open);
49dev_type_close(ping_close);
50dev_type_ioctl(ping_ioctl);
51
52static struct cdevsw ping_cdevsw = {
53	.d_open = ping_open,
54	.d_close = ping_close,
55	.d_read = noread,
56	.d_write = nowrite,
57	.d_ioctl = ping_ioctl,
58	.d_stop = nostop,
59	.d_tty = notty,
60	.d_poll = nopoll,
61	.d_mmap = nommap,
62	.d_kqfilter = nokqfilter,
63	.d_discard = nodiscard,
64	.d_flag = D_OTHER
65};
66
67
68struct ping_softc {
69	int		refcnt;
70};
71
72static struct ping_softc sc;
73
74int
75ping_open(dev_t self __unused, int flag __unused, int mode __unused,
76          struct lwp *l __unused)
77{
78	if (sc.refcnt > 0)
79		return EBUSY;
80
81	++sc.refcnt;
82
83	return 0;
84}
85
86int
87ping_close(dev_t self __unused, int flag __unused, int mode __unused,
88           struct lwp *l __unused)
89{
90	--sc.refcnt;
91
92	return 0;
93}
94
95int
96ping_ioctl(dev_t self __unused, u_long cmd, void *data, int flag,
97           struct lwp *l __unused)
98{
99	switch(cmd) {
100	case CMD_PING:
101		printf("ping: pong!\n");
102		return 0;
103	default:
104		return ENOTTY;
105	}
106}
107
108MODULE(MODULE_CLASS_MISC, ping, NULL);
109
110static int
111ping_modcmd(modcmd_t cmd, void *arg __unused)
112{
113	/* The major should be verified and changed if needed to avoid
114	 * conflicts with other devices. */
115	int cmajor = 351, bmajor = -1;
116
117	switch (cmd) {
118	case MODULE_CMD_INIT:
119		if (devsw_attach("ping", NULL, &bmajor, &ping_cdevsw, &cmajor))
120			return ENXIO;
121		return 0;
122	case MODULE_CMD_FINI:
123		if (sc.refcnt > 0)
124			return EBUSY;
125
126		devsw_detach(NULL, &ping_cdevsw);
127		return 0;
128	default:
129		return ENOTTY;
130	}
131}
132