1 /* $NetBSD: sysctl.c,v 1.1 2018/04/13 01:20:28 kamil Exp $ */ 2 3 /*- 4 * Copyright (c) 2018 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: sysctl.c,v 1.1 2018/04/13 01:20:28 kamil Exp $"); 31 32 #include <sys/param.h> 33 #include <sys/module.h> 34 #include <sys/sysctl.h> 35 36 /* 37 * Check if sysctl -A contains an entry 38 * example_subroot1.sysctl_example=0 39 * to test this module 40 * 41 */ 42 43 MODULE(MODULE_CLASS_MISC, sysctl, NULL); 44 45 static int sysctl_example; 46 47 static struct sysctllog *example_sysctl_log; 48 49 static void sysctl_example_setup(struct sysctllog **); 50 51 52 /* 53 * sysctl_example_setup : 54 * It first creates a subtree by adding a node to the tree. 55 * This node is named as example_subroot1. 56 * 57 * It then creates a node in subtree for the example variable which 58 * is an integer and is defined in this file itself. 59 * 60 * ROOT 61 * | 62 * ------- 63 * | 64 * examples_subroot1 65 * | 66 * | 67 * sysctl_example (INT) 68 * 69 */ 70 71 static void 72 sysctl_example_setup(struct sysctllog **clog) 73 { 74 const struct sysctlnode *rnode; 75 76 sysctl_createv(clog, 0, NULL, &rnode, 77 CTLFLAG_PERMANENT, 78 CTLTYPE_NODE, "example_subroot1", 79 NULL, 80 NULL, 0, 81 NULL, 0, 82 CTL_CREATE, CTL_EOL); 83 84 sysctl_createv(clog, 0, &rnode, NULL, 85 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 86 CTLTYPE_INT, "sysctl_example", 87 SYSCTL_DESCR("An example for sysctl_example"), 88 NULL, 0, 89 &sysctl_example, 0, 90 CTL_CREATE, CTL_EOL); 91 } 92 93 /* 94 * The sysctl_example modcmd has two functions. 95 * 1. Call the sysctl_example_setup function to create a sysctl 96 * handle when the module is loaded in the kernel. 97 * 2. Remove the sysctl entry from the kernel once the module 98 * is unloaded. 99 */ 100 101 102 static int 103 sysctl_modcmd(modcmd_t cmd, void *arg) 104 { 105 switch(cmd) { 106 case MODULE_CMD_INIT: 107 printf("sysctl module inserted"); 108 sysctl_example_setup(&example_sysctl_log); 109 break; 110 case MODULE_CMD_FINI: 111 printf("sysctl module unloaded"); 112 sysctl_teardown(&example_sysctl_log); 113 break; 114 default: 115 return ENOTTY; 116 } 117 return 0; 118 } 119