1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2009 Alan L. Cox <alc@cs.rice.edu>
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/mman.h>
34#include <sys/sysctl.h>
35
36#include <errno.h>
37#include <link.h>
38
39#include "libc_private.h"
40
41/*
42 * Retrieves page size information from the system.  Specifically, returns the
43 * number of distinct page sizes that are supported by the system, if
44 * "pagesize" is NULL and "nelem" is 0.  Otherwise, assigns up to "nelem" of
45 * the system-supported page sizes to consecutive elements of the array
46 * referenced by "pagesize", and returns the number of such page sizes that it
47 * assigned to the array.  These page sizes are expressed in bytes.
48 *
49 * The implementation of this function does not directly or indirectly call
50 * malloc(3) or any other dynamic memory allocator that may itself call this
51 * function.
52 */
53int
54getpagesizes(size_t pagesize[], int nelem)
55{
56	static u_long ps[MAXPAGESIZES];
57	static int nops;
58	size_t size;
59	int error, i;
60
61	if (nelem < 0 || (nelem > 0 && pagesize == NULL)) {
62		errno = EINVAL;
63		return (-1);
64	}
65	/* Cache the result of the sysctl(2). */
66	if (nops == 0) {
67		error = _elf_aux_info(AT_PAGESIZES, ps, sizeof(ps));
68		size = sizeof(ps);
69		if (error != 0 || ps[0] == 0) {
70			if (sysctlbyname("hw.pagesizes", ps, &size, NULL, 0)
71			    == -1)
72				return (-1);
73		}
74		/* Count the number of page sizes that are supported. */
75		nops = size / sizeof(ps[0]);
76		while (nops > 0 && ps[nops - 1] == 0)
77			nops--;
78	}
79	if (pagesize == NULL)
80		return (nops);
81	/* Return up to "nelem" page sizes from the cached result. */
82	if (nelem > nops)
83		nelem = nops;
84	for (i = 0; i < nelem; i++)
85		pagesize[i] = ps[i];
86	return (nelem);
87}
88