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