share/examples/kld/dyn_sysctl/dyn_sysctl.c

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