fetch.c revision 200420 
1/*-
2 * Copyright (c) 1980, 1992, 1993
3 *	The Regents of the University of California.  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. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <sys/cdefs.h>
35
36__FBSDID("$FreeBSD: head/usr.bin/systat/fetch.c 200420 2009-12-11 23:35:38Z delphij $");
37
38#ifdef lint
39static const char sccsid[] = "@(#)fetch.c	8.1 (Berkeley) 6/6/93";
40#endif
41
42#include <sys/types.h>
43#include <sys/sysctl.h>
44
45#include <errno.h>
46#include <stdlib.h>
47#include <string.h>
48
49#include "systat.h"
50#include "extern.h"
51
52int
53kvm_ckread(void *a, void *b, int l)
54{
55	if (kvm_read(kd, (u_long)a, b, l) != l) {
56		if (verbose)
57			error("error reading kmem at %p", a);
58		return (0);
59	}
60	else
61		return (1);
62}
63
64void getsysctl(const char *name, void *ptr, size_t len)
65{
66	size_t nlen = len;
67	if (sysctlbyname(name, ptr, &nlen, NULL, 0) != 0) {
68		error("sysctl(%s...) failed: %s", name,
69		    strerror(errno));
70	}
71	if (nlen != len) {
72		error("sysctl(%s...) expected %lu, got %lu", name,
73		    (unsigned long)len, (unsigned long)nlen);
74    }
75}
76
77/*
78 * Read sysctl data with variable size. Try some times (with increasing
79 * buffers), fail if still too small.
80 * This is needed sysctls with possibly raplidly increasing data sizes,
81 * but imposes little overhead in the case of constant sizes.
82 * Returns NULL on error, or a pointer to freshly malloc()'ed memory that holds
83 * the requested data.
84 * If szp is not NULL, the size of the returned data will be written into *szp.
85 */
86
87/* Some defines: Number of tries. */
88#define SD_NTRIES  10
89/* Percent of over-allocation (initial) */
90#define SD_MARGIN  10
91/*
92 * Factor for over-allocation in percent (the margin is increased by this on
93 * any failed try).
94 */
95#define SD_FACTOR  50
96/* Maximum supported MIB depth */
97#define SD_MAXMIB  16
98
99char *
100sysctl_dynread(const char *n, size_t *szp)
101{
102	char   *rv = NULL;
103	int    mib[SD_MAXMIB];
104	size_t mibsz = SD_MAXMIB;
105	size_t mrg = SD_MARGIN;
106	size_t sz;
107	int i;
108
109	/* cache the MIB */
110	if (sysctlnametomib(n, mib, &mibsz) == -1) {
111		if (errno == ENOMEM) {
112			error("XXX: SD_MAXMIB too small, please bump!");
113		}
114		return NULL;
115	}
116	for (i = 0; i < SD_NTRIES; i++) {
117		/* get needed buffer size */
118		if (sysctl(mib, mibsz, NULL, &sz, NULL, 0) == -1)
119			break;
120		sz += sz * mrg / 100;
121		if ((rv = (char *)malloc(sz)) == NULL) {
122			error("Out of memory!");
123			return NULL;
124		}
125		if (sysctl(mib, mibsz, rv, &sz, NULL, 0) == -1) {
126			free(rv);
127			rv = NULL;
128			if (errno == ENOMEM) {
129				mrg += mrg * SD_FACTOR / 100;
130			} else
131				break;
132		} else {
133			/* success */
134			if (szp != NULL)
135				*szp = sz;
136			break;
137		}
138	}
139
140	return rv;
141}
142