feature_present.c revision 175220
1175220Sjhb/*- 2175220Sjhb * Copyright (c) 2008 Yahoo!, Inc. 3175220Sjhb * All rights reserved. 4175220Sjhb * Written by: John Baldwin <jhb@FreeBSD.org> 5175220Sjhb * 6175220Sjhb * Redistribution and use in source and binary forms, with or without 7175220Sjhb * modification, are permitted provided that the following conditions 8175220Sjhb * are met: 9175220Sjhb * 1. Redistributions of source code must retain the above copyright 10175220Sjhb * notice, this list of conditions and the following disclaimer. 11175220Sjhb * 2. Redistributions in binary form must reproduce the above copyright 12175220Sjhb * notice, this list of conditions and the following disclaimer in the 13175220Sjhb * documentation and/or other materials provided with the distribution. 14175220Sjhb * 3. Neither the name of the author nor the names of any co-contributors 15175220Sjhb * may be used to endorse or promote products derived from this software 16175220Sjhb * without specific prior written permission. 17175220Sjhb * 18175220Sjhb * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19175220Sjhb * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20175220Sjhb * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21175220Sjhb * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22175220Sjhb * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23175220Sjhb * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24175220Sjhb * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25175220Sjhb * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26175220Sjhb * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27175220Sjhb * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28175220Sjhb * SUCH DAMAGE. 29175220Sjhb */ 30175220Sjhb 31175220Sjhb#include <sys/cdefs.h> 32175220Sjhb__FBSDID("$FreeBSD: head/lib/libc/gen/feature_present.c 175220 2008-01-10 22:11:21Z jhb $"); 33175220Sjhb 34175220Sjhb#include <sys/types.h> 35175220Sjhb#include <sys/sysctl.h> 36175220Sjhb#include <stdio.h> 37175220Sjhb#include <stdlib.h> 38175220Sjhb 39175220Sjhb/* 40175220Sjhb * Returns true if the named feature is present in the currently 41175220Sjhb * running kernel. A feature's presence is indicated by an integer 42175220Sjhb * sysctl node called kern.feature.<feature> that is non-zero. 43175220Sjhb */ 44175220Sjhbint 45175220Sjhbfeature_present(const char *feature) 46175220Sjhb{ 47175220Sjhb char *mib; 48175220Sjhb size_t len; 49175220Sjhb int i; 50175220Sjhb 51175220Sjhb if (asprintf(&mib, "kern.features.%s", feature) < 0) 52175220Sjhb return (0); 53175220Sjhb len = sizeof(i); 54175220Sjhb if (sysctlbyname(mib, &i, &len, NULL, 0) < 0) { 55175220Sjhb free(mib); 56175220Sjhb return (0); 57175220Sjhb } 58175220Sjhb free(mib); 59175220Sjhb if (len != sizeof(i)) 60175220Sjhb return (0); 61175220Sjhb return (i != 0); 62175220Sjhb} 63