1 /*-
2 * Copyright (c) 2008 Yahoo!, Inc.
3 * All rights reserved.
4 * Written by: John Baldwin <[email protected]>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the author nor the names of any co-contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #ifndef FSTACK
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34 #else
35 #define _GNU_SOURCE
36 #endif
37
38 #include <sys/types.h>
39 #include <sys/sysctl.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <unistd.h>
43
44 #include "compat.h"
45
46 /*
47 * Returns true if the named feature is present in the currently
48 * running kernel. A feature's presence is indicated by an integer
49 * sysctl node called kern.feature.<feature> that is non-zero.
50 */
51 int
feature_present(const char * feature)52 feature_present(const char *feature)
53 {
54 char *mib;
55 size_t len;
56 int i;
57
58 if (asprintf(&mib, "kern.features.%s", feature) < 0)
59 return (0);
60 len = sizeof(i);
61 if (sysctlbyname(mib, &i, &len, NULL, 0) < 0) {
62 free(mib);
63 return (0);
64 }
65 free(mib);
66 if (len != sizeof(i))
67 return (0);
68 return (i != 0);
69 }
70