1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2003 Poul-Henning Kamp
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 * 3. The names of the authors may not be used to endorse or promote
16 *    products derived from this software without specific prior written
17 *    permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * $FreeBSD$
32 */
33
34#include <sys/types.h>
35#include <sys/sysctl.h>
36#include <errno.h>
37#include <stdlib.h>
38#include <string.h>
39#include "libgeom.h"
40
41/*
42 * Amount of extra space we allocate to try and anticipate the size of
43 * confxml.
44 */
45#define	GEOM_GETXML_SLACK	4096
46
47/*
48 * Number of times to retry in the face of the size of confxml exceeding
49 * that of our buffer.
50 */
51#define	GEOM_GETXML_RETRIES	4
52
53char *
54geom_getxml(void)
55{
56	char *p;
57	size_t l = 0;
58	int mib[3];
59	size_t sizep;
60	int retries;
61
62	sizep = sizeof(mib) / sizeof(*mib);
63	if (sysctlnametomib("kern.geom.confxml", mib, &sizep) != 0)
64		return (NULL);
65	if (sysctl(mib, sizep, NULL, &l, NULL, 0) != 0)
66		return (NULL);
67	l += GEOM_GETXML_SLACK;
68
69	for (retries = 0; retries < GEOM_GETXML_RETRIES; retries++) {
70		p = malloc(l);
71		if (p == NULL)
72			return (NULL);
73		if (sysctl(mib, sizep, p, &l, NULL, 0) == 0)
74			return (reallocf(p, strlen(p) + 1));
75
76		free(p);
77
78		if (errno != ENOMEM)
79			return (NULL);
80
81		/*
82		 * Our buffer wasn't big enough. Make it bigger and
83		 * try again.
84		 */
85		l *= 2;
86	}
87
88	return (NULL);
89}
90