share/examples/kld/dyn_sysctl/dyn_sysctl.c

   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", 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
 163 static moduledata_t mod_data = {
 164         "dyn_sysctl",
 165         load,
 166         0
 167 };
 168
 169 DECLARE_MODULE(dyn_sysctl, mod_data, SI_SUB_EXEC, SI_ORDER_ANY);