1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 2003 Poul-Henning Kamp
5 * All rights reserved.
6 * Copyright (c) 2022 Alexander Motin <mav@FreeBSD.org>
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. The names of the authors may not be used to endorse or promote
17 *    products derived from this software without specific prior written
18 *    permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#include <sys/types.h>
34#include <sys/sysctl.h>
35#include <errno.h>
36#include <stdlib.h>
37#include <string.h>
38#include "libgeom.h"
39
40/*
41 * Amount of extra space we allocate to try and anticipate the size of
42 * confxml.
43 */
44#define	GEOM_GETXML_SLACK	4096
45
46/*
47 * Number of times to retry in the face of the size of confxml exceeding
48 * that of our buffer.
49 */
50#define	GEOM_GETXML_RETRIES	4
51
52/*
53 * Size of confxml buffer to request via getxml control request.  It is
54 * expected to be sufficient for single geom and its parents.  In case of
55 * overflow fall back to requesting full confxml via sysctl interface.
56 */
57#define	GEOM_GETXML_BUFFER	65536
58
59char *
60geom_getxml(void)
61{
62	char *p;
63	size_t l = 0;
64	int mib[3];
65	size_t sizep;
66	int retries;
67
68	sizep = sizeof(mib) / sizeof(*mib);
69	if (sysctlnametomib("kern.geom.confxml", mib, &sizep) != 0)
70		return (NULL);
71	if (sysctl(mib, sizep, NULL, &l, NULL, 0) != 0)
72		return (NULL);
73	l += GEOM_GETXML_SLACK;
74
75	for (retries = 0; retries < GEOM_GETXML_RETRIES; retries++) {
76		p = malloc(l);
77		if (p == NULL)
78			return (NULL);
79		if (sysctl(mib, sizep, p, &l, NULL, 0) == 0)
80			return (reallocf(p, strlen(p) + 1));
81
82		free(p);
83
84		if (errno != ENOMEM)
85			return (NULL);
86
87		/*
88		 * Our buffer wasn't big enough. Make it bigger and
89		 * try again.
90		 */
91		l *= 2;
92	}
93
94	return (NULL);
95}
96
97char *
98geom_getxml_geom(const char *class, const char *geom, int parents)
99{
100	struct gctl_req *r;
101	char *p;
102	const char *errstr;
103	int nargs = 0;
104
105	p = malloc(GEOM_GETXML_BUFFER);
106	if (p == NULL)
107		return (NULL);
108	r = gctl_get_handle();
109	gctl_ro_param(r, "class", -1, class);
110	gctl_ro_param(r, "verb", -1, "getxml");
111	gctl_ro_param(r, "parents", sizeof(parents), &parents);
112	if (geom) {
113		gctl_ro_param(r, "arg0", -1, geom);
114		nargs = 1;
115	}
116	gctl_ro_param(r, "nargs", sizeof(nargs), &nargs);
117	p[0] = '\0';
118	gctl_add_param(r, "output", GEOM_GETXML_BUFFER, p,
119	    GCTL_PARAM_WR | GCTL_PARAM_ASCII);
120	errstr = gctl_issue(r);
121	if (errstr != NULL && errstr[0] != '\0') {
122		gctl_free(r);
123		free(p);
124		return (geom_getxml());
125	}
126	gctl_free(r);
127	return (p);
128}
129