1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2007 Peter Wemm
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 AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD$");
31
32#include <sys/param.h>
33#include <sys/sysctl.h>
34#include <errno.h>
35#include <link.h>
36#include "libc_private.h"
37
38/*
39 * This is private to libc.  It is intended for wrapping syscall stubs in order
40 * to avoid having to put SIGSYS signal handlers in place to test for presence
41 * of new syscalls.  This caches the result in order to be as quick as possible.
42 *
43 * Use getosreldate(3) for public use as it respects the $OSVERSION environment
44 * variable.
45 */
46
47int
48__getosreldate(void)
49{
50	static int osreldate;
51	size_t len;
52	int oid[2];
53	int error, osrel;
54
55	if (osreldate != 0)
56		return (osreldate);
57
58	error = _elf_aux_info(AT_OSRELDATE, &osreldate, sizeof(osreldate));
59	if (error == 0 && osreldate != 0)
60		return (osreldate);
61
62	oid[0] = CTL_KERN;
63	oid[1] = KERN_OSRELDATE;
64	osrel = 0;
65	len = sizeof(osrel);
66	error = sysctl(oid, 2, &osrel, &len, NULL, 0);
67	if (error == 0 && osrel > 0 && len == sizeof(osrel))
68		osreldate = osrel;
69	return (osreldate);
70}
71