fetch.c revision 87715 
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 87715 2001-12-12 00:13:37Z markm $");
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 <err.h>
46#include <errno.h>
47#include <stdlib.h>
48#include <string.h>
49
50#include "systat.h"
51#include "extern.h"
52
53int
54kvm_ckread(a, b, l)
55	void *a, *b;
56	int l;
57{
58	if (kvm_read(kd, (u_long)a, b, l) != l) {
59		if (verbose)
60			error("error reading kmem at %p", a);
61		return (0);
62	}
63	else
64		return (1);
65}
66
67void getsysctl(name, ptr, len)
68	const char *name;
69	void *ptr;
70	size_t len;
71{
72	size_t nlen = len;
73	if (sysctlbyname(name, ptr, &nlen, NULL, 0) != 0) {
74		error("sysctl(%s...) failed: %s", name,
75		    strerror(errno));
76	}
77	if (nlen != len) {
78		error("sysctl(%s...) expected %lu, got %lu", name,
79		    (unsigned long)len, (unsigned long)nlen);
80    }
81}
82
83/*
84 * Read sysctl data with variable size. Try some times (with increasing
85 * buffers), fail if still too small.
86 * This is needed sysctls with possibly raplidly increasing data sizes,
87 * but imposes little overhead in the case of constant sizes.
88 * Returns NULL on error, or a pointer to freshly malloc()'ed memory that holds
89 * the requested data.
90 * If szp is not NULL, the size of the returned data will be written into *szp.
91 */
92
93/* Some defines: Number of tries. */
94#define SD_NTRIES  10
95/* Percent of over-allocation (initial) */
96#define SD_MARGIN  10
97/*
98 * Factor for over-allocation in percent (the margin is increased by this on
99 * any failed try).
100 */
101#define SD_FACTOR  50
102/* Maximum supported MIB depth */
103#define SD_MAXMIB  16
104
105char *
106sysctl_dynread(n, szp)
107	const char *n;
108	size_t *szp;
109{
110	char   *rv = NULL;
111	int    mib[SD_MAXMIB];
112	size_t mibsz = SD_MAXMIB;
113	size_t mrg = SD_MARGIN;
114	size_t sz;
115	int i;
116
117	/* cache the MIB */
118	if (sysctlnametomib(n, mib, &mibsz) == -1) {
119		if (errno == ENOMEM) {
120			error("XXX: SD_MAXMIB too small, please bump!");
121		}
122		return NULL;
123	}
124	for (i = 0; i < SD_NTRIES; i++) {
125		/* get needed buffer size */
126		if (sysctl(mib, mibsz, NULL, &sz, NULL, 0) == -1)
127			break;
128		sz += sz * mrg / 100;
129		if ((rv = (char *)malloc(sz)) == NULL) {
130			error("Out of memory!");
131			return NULL;
132		}
133		if (sysctl(mib, mibsz, rv, &sz, NULL, 0) == -1) {
134			free(rv);
135			rv = NULL;
136			if (errno == ENOMEM) {
137				mrg += mrg * SD_FACTOR / 100;
138			} else
139				break;
140		} else {
141			/* success */
142			if (szp != NULL)
143				*szp = sz;
144			break;
145		}
146	}
147
148	return rv;
149}
150