1 /*-
2 * SPDX-License-Identifier: BSD-3-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
53 char *
geom_getxml(void)54 geom_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