1/*-
2 * Copyright (c) 2009 Alan L. Cox <alc@cs.rice.edu>
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("$FreeBSD$");
29
30#include <sys/param.h>
31#include <sys/mman.h>
32#include <sys/sysctl.h>
33
34#include <errno.h>
35#include <link.h>
36
37#include "libc_private.h"
38
39/*
40 * Retrieves page size information from the system.  Specifically, returns the
41 * number of distinct page sizes that are supported by the system, if
42 * "pagesize" is NULL and "nelem" is 0.  Otherwise, assigns up to "nelem" of
43 * the system-supported page sizes to consecutive elements of the array
44 * referenced by "pagesize", and returns the number of such page sizes that it
45 * assigned to the array.  These page sizes are expressed in bytes.
46 *
47 * The implementation of this function does not directly or indirectly call
48 * malloc(3) or any other dynamic memory allocator that may itself call this
49 * function.
50 */
51int
52getpagesizes(size_t pagesize[], int nelem)
53{
54	static u_long ps[MAXPAGESIZES];
55	static int nops;
56	size_t size;
57	int error, i;
58
59	if (nelem < 0 || (nelem > 0 && pagesize == NULL)) {
60		errno = EINVAL;
61		return (-1);
62	}
63	/* Cache the result of the sysctl(2). */
64	if (nops == 0) {
65		error = _elf_aux_info(AT_PAGESIZES, ps, sizeof(ps));
66		size = sizeof(ps);
67		if (error != 0 || ps[0] == 0) {
68			if (sysctlbyname("hw.pagesizes", ps, &size, NULL, 0)
69			    == -1)
70				return (-1);
71		}
72		/* Count the number of page sizes that are supported. */
73		nops = size / sizeof(ps[0]);
74		while (nops > 0 && ps[nops - 1] == 0)
75			nops--;
76	}
77	if (pagesize == NULL)
78		return (nops);
79	/* Return up to "nelem" page sizes from the cached result. */
80	if (nelem > nops)
81		nelem = nops;
82	for (i = 0; i < nelem; i++)
83		pagesize[i] = ps[i];
84	return (nelem);
85}
86