xref: /freebsd/share/examples/kld/dyn_sysctl/dyn_sysctl.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
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  *     $FreeBSD$
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 */
38 static long a = 100;
39 static int b = 200;
40 static char *c = "hi there from dyn_sysctl";
41 static struct sysctl_oid *a_root, *a_root1, *b_root;
42 static struct sysctl_ctx_list clist, clist1, clist2;
43 
44 static int
45 sysctl_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  */
55 static int
56 load (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", CTLFLAG_RD, 0, 0,
104 		 sysctl_dyn_sysctl_test, "A", "I can be here, too");
105 		printf("   (%p)	/kern		  dyn_sysctl\n", &clist);
106 
107 		/* Overlap second tree with the first. */
108 		b_root = SYSCTL_ADD_NODE(&clist1, SYSCTL_CHILDREN(a_root),
109 		 OID_AUTO, "nextlevel", CTLFLAG_RD, 0, "one level down");
110 		SYSCTL_ADD_STRING(&clist1, SYSCTL_CHILDREN(b_root),
111 		 OID_AUTO, "string_c1", CTLFLAG_RD, c, 0, "just to try 2");
112 		printf("2. (%p)	/		  dyn_sysctl	(overlapping #1)\n", &clist1);
113 
114 		/*
115 		 * And now do something stupid. Connect another subtree to
116 		 * dynamic oid.
117 		 * WARNING: this is an example of WRONG use of dynamic sysctls.
118 		 */
119 		b_root=SYSCTL_ADD_NODE(&clist2, SYSCTL_CHILDREN(a_root1),
120 		 OID_AUTO, "bad", CTLFLAG_RW, 0, "dependent node");
121 		SYSCTL_ADD_STRING(&clist2, SYSCTL_CHILDREN(b_root),
122 		 OID_AUTO, "string_c", CTLFLAG_RD, c, 0, "shouldn't panic");
123 		printf("3. (%p)	/kern/dyn_sysctl  bad		(WRONG!)\n", &clist2);
124 		break;
125 	case MOD_UNLOAD :
126 		printf("1. Try to free ctx1 (%p): ", &clist);
127 		if(sysctl_ctx_free(&clist))
128 			printf("failed: expected. Need to remove ctx3 first.\n");
129 		else
130 			printf("HELP! sysctl_ctx_free(%p) succeeded. EXPECT PANIC!!!\n", &clist);
131 		printf("2. Try to free ctx3 (%p): ", &clist2);
132 		if(sysctl_ctx_free(&clist2)) {
133 			printf("sysctl_ctx_free(%p) failed!\n", &clist2);
134 			/* Remove subtree forcefully... */
135 			sysctl_remove_oid(b_root, 1, 1);
136 			printf("sysctl_remove_oid(%p) succeeded\n", b_root);
137 		} else
138 			printf("Ok\n");
139 		printf("3. Try to free ctx1 (%p) again: ", &clist);
140 		if(sysctl_ctx_free(&clist)) {
141 			printf("sysctl_ctx_free(%p) failed!\n", &clist);
142 			/* Remove subtree forcefully... */
143 			sysctl_remove_oid(a_root1, 1, 1);
144 			printf("sysctl_remove_oid(%p) succeeded\n", a_root1);
145 		} else
146 			printf("Ok\n");
147 		printf("4. Try to free ctx2 (%p): ", &clist1);
148 		if(sysctl_ctx_free(&clist1)) {
149 			printf("sysctl_ctx_free(%p) failed!\n", &clist1);
150 			/* Remove subtree forcefully... */
151 			sysctl_remove_oid(a_root, 1, 1);
152 		} else
153 			printf("Ok\n");
154 		break;
155 	default :
156 		error = EOPNOTSUPP;
157 		break;
158 	}
159 	return error;
160 }
161 
162 static moduledata_t mod_data= {
163 	"dyn_sysctl",
164 	load,
165 	0
166 };
167 
168 DECLARE_MODULE(dyn_sysctl, mod_data, SI_SUB_EXEC, SI_ORDER_ANY);
169