dyn_sysctl.c revision 239428 
1/*-
2 * Copyright (c) 2000 Andrzej Bialecki <abial@freebsd.org>
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 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 *     $FreeBSD: stable/9/share/examples/kld/dyn_sysctl/dyn_sysctl.c 239428 2012-08-20 14:34:30Z emaste $
27 */
28
29#include <sys/types.h>
30#include <sys/param.h>
31#include <sys/systm.h>
32#include <sys/module.h>
33#include <sys/sysctl.h>
34#include <sys/kernel.h>
35
36
37/* Some example data */
38static long a = 100;
39static int b = 200;
40static char *c = "hi there from dyn_sysctl";
41static struct sysctl_oid *a_root, *a_root1, *b_root;
42static struct sysctl_ctx_list clist, clist1, clist2;
43
44static int
45sysctl_dyn_sysctl_test(SYSCTL_HANDLER_ARGS)
46{
47	char *buf = "let's produce some text...";
48
49	return (sysctl_handle_string(oidp, buf, strlen(buf), req));
50}
51
52/*
53 * The function called at load/unload.
54 */
55static int
56load(module_t mod, int cmd, void *arg)
57{
58	int error;
59
60	error = 0;
61	switch (cmd) {
62	case MOD_LOAD:
63		/* Initialize the contexts */
64		printf("Initializing contexts and creating subtrees.\n\n");
65		sysctl_ctx_init(&clist);
66		sysctl_ctx_init(&clist1);
67		sysctl_ctx_init(&clist2);
68		/*
69		 * Create two partially overlapping subtrees, belonging
70		 * to different contexts.
71		 */
72		printf("TREE		ROOT		  NAME\n");
73		a_root = SYSCTL_ADD_NODE(&clist,
74			SYSCTL_STATIC_CHILDREN(/* top of sysctl tree */),
75			OID_AUTO, "dyn_sysctl", CTLFLAG_RW, 0,
76			"dyn_sysctl root node");
77		a_root = SYSCTL_ADD_NODE(&clist1,
78			SYSCTL_STATIC_CHILDREN(/* top of sysctl tree */),
79			OID_AUTO, "dyn_sysctl", CTLFLAG_RW, 0,
80			"dyn_sysctl root node");
81		if (a_root == NULL) {
82			printf("SYSCTL_ADD_NODE failed!\n");
83			return (EINVAL);
84		}
85		SYSCTL_ADD_LONG(&clist, SYSCTL_CHILDREN(a_root),
86		    OID_AUTO, "long_a", CTLFLAG_RW, &a, "just to try");
87		SYSCTL_ADD_INT(&clist, SYSCTL_CHILDREN(a_root),
88		    OID_AUTO, "int_b", CTLFLAG_RW, &b, 0, "just to try 1");
89		a_root1 = SYSCTL_ADD_NODE(&clist, SYSCTL_CHILDREN(a_root),
90		    OID_AUTO, "nextlevel", CTLFLAG_RD, 0, "one level down");
91		SYSCTL_ADD_STRING(&clist, SYSCTL_CHILDREN(a_root1),
92		    OID_AUTO, "string_c", CTLFLAG_RD, c, 0, "just to try 2");
93		printf("1. (%p)	/		  dyn_sysctl\n", &clist);
94
95		/* Add a subtree under already existing category */
96		a_root1 = SYSCTL_ADD_NODE(&clist, SYSCTL_STATIC_CHILDREN(_kern),
97		    OID_AUTO, "dyn_sysctl", CTLFLAG_RW, 0, "dyn_sysctl root node");
98		if (a_root1 == NULL) {
99			printf("SYSCTL_ADD_NODE failed!\n");
100			return (EINVAL);
101		}
102		SYSCTL_ADD_PROC(&clist, SYSCTL_CHILDREN(a_root1),
103		    OID_AUTO, "procedure", CTLTYPE_STRING | CTLFLAG_RD,
104		    NULL, 0, sysctl_dyn_sysctl_test, "A",
105		    "I can be here, too");
106		printf("   (%p)	/kern		  dyn_sysctl\n", &clist);
107
108		/* Overlap second tree with the first. */
109		b_root = SYSCTL_ADD_NODE(&clist1, SYSCTL_CHILDREN(a_root),
110		    OID_AUTO, "nextlevel", CTLFLAG_RD, 0, "one level down");
111		SYSCTL_ADD_STRING(&clist1, SYSCTL_CHILDREN(b_root),
112		    OID_AUTO, "string_c1", CTLFLAG_RD, c, 0, "just to try 2");
113		printf("2. (%p)	/		  dyn_sysctl	(overlapping #1)\n", &clist1);
114
115		/*
116		 * And now do something stupid. Connect another subtree to
117		 * dynamic oid.
118		 * WARNING: this is an example of WRONG use of dynamic sysctls.
119		 */
120		b_root=SYSCTL_ADD_NODE(&clist2, SYSCTL_CHILDREN(a_root1),
121		    OID_AUTO, "bad", CTLFLAG_RW, 0, "dependent node");
122		SYSCTL_ADD_STRING(&clist2, SYSCTL_CHILDREN(b_root),
123		    OID_AUTO, "string_c", CTLFLAG_RD, c, 0, "shouldn't panic");
124		printf("3. (%p)	/kern/dyn_sysctl  bad		(WRONG!)\n", &clist2);
125		break;
126	case MOD_UNLOAD:
127		printf("1. Try to free ctx1 (%p): ", &clist);
128		if (sysctl_ctx_free(&clist) != 0)
129			printf("failed: expected. Need to remove ctx3 first.\n");
130		else
131			printf("HELP! sysctl_ctx_free(%p) succeeded. EXPECT PANIC!!!\n", &clist);
132		printf("2. Try to free ctx3 (%p): ", &clist2);
133		if (sysctl_ctx_free(&clist2) != 0) {
134			printf("sysctl_ctx_free(%p) failed!\n", &clist2);
135			/* Remove subtree forcefully... */
136			sysctl_remove_oid(b_root, 1, 1);
137			printf("sysctl_remove_oid(%p) succeeded\n", b_root);
138		} else
139			printf("Ok\n");
140		printf("3. Try to free ctx1 (%p) again: ", &clist);
141		if (sysctl_ctx_free(&clist) != 0) {
142			printf("sysctl_ctx_free(%p) failed!\n", &clist);
143			/* Remove subtree forcefully... */
144			sysctl_remove_oid(a_root1, 1, 1);
145			printf("sysctl_remove_oid(%p) succeeded\n", a_root1);
146		} else
147			printf("Ok\n");
148		printf("4. Try to free ctx2 (%p): ", &clist1);
149		if (sysctl_ctx_free(&clist1) != 0) {
150			printf("sysctl_ctx_free(%p) failed!\n", &clist1);
151			/* Remove subtree forcefully... */
152			sysctl_remove_oid(a_root, 1, 1);
153		} else
154			printf("Ok\n");
155		break;
156	default:
157		error = EOPNOTSUPP;
158		break;
159	}
160	return (error);
161}
162
163static moduledata_t mod_data = {
164	"dyn_sysctl",
165	load,
166	0
167};
168
169DECLARE_MODULE(dyn_sysctl, mod_data, SI_SUB_EXEC, SI_ORDER_ANY);
170