getpagesize.c revision 85868 
1/*
2 * Copyright (c) 1989, 1993
3 *	The Regents of the University of California.  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 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * $FreeBSD: head/lib/libc/gen/getpagesize.c 85868 2001-11-02 11:30:42Z phk $
34 */
35
36#if defined(LIBC_SCCS) && !defined(lint)
37static char sccsid[] = "@(#)getpagesize.c	8.1 (Berkeley) 6/4/93";
38#endif /* LIBC_SCCS and not lint */
39
40#include <sys/param.h>
41#include <sys/sysctl.h>
42
43/*
44 * This is unlikely to change over the running time of any
45 * program, so we cache the result to save some syscalls.
46 *
47 * NB: This function may be called from malloc(3) at initialization
48 * NB: so must not result in a malloc(3) related call!
49 */
50
51int
52getpagesize()
53{
54	int mib[2];
55	static int value;
56	size_t size;
57
58	if (!value) {
59		mib[0] = CTL_HW;
60		mib[1] = HW_PAGESIZE;
61		size = sizeof value;
62		if (sysctl(mib, 2, &value, &size, NULL, 0) == -1)
63			return (-1);
64	}
65	return (value);
66}
67