__getosreldate.c revision 171219 
1/*-
2 * Copyright (c) 2007 Peter Wemm
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
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/lib/libc/gen/__getosreldate.c 171219 2007-07-04 23:27:38Z peter $");
29
30#include <sys/param.h>
31#include <sys/sysctl.h>
32
33/*
34 * This is private to libc.  It is intended for wrapping syscall stubs in order
35 * to avoid having to put SIGSYS signal handlers in place to test for presence
36 * of new syscalls.  This caches the result in order to be as quick as possible.
37 *
38 * Use getosreldate(3) for public use as it respects the $OSVERSION environment
39 * variable.
40 */
41
42int
43__getosreldate(void)
44{
45	static int osreldate;
46	size_t len;
47	int oid[2];
48	int error, osrel;
49
50	if (osreldate != 0)
51		return (osreldate);
52
53	oid[0] = CTL_KERN;
54	oid[1] = KERN_OSRELDATE;
55	osrel = 0;
56	len = sizeof(osrel);
57	error = sysctl(oid, 2, &osrel, &len, NULL, 0);
58	if (error == 0 && osrel > 0 && len == sizeof(osrel))
59		osreldate = osrel;
60	return (osreldate);
61}
62