fetch.c revision 225736 
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 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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
30#include <sys/cdefs.h>
31
32__FBSDID("$FreeBSD: stable/9/usr.bin/systat/fetch.c 216370 2010-12-11 08:32:16Z joel $");
33
34#ifdef lint
35static const char sccsid[] = "@(#)fetch.c	8.1 (Berkeley) 6/6/93";
36#endif
37
38#include <sys/types.h>
39#include <sys/sysctl.h>
40
41#include <err.h>
42#include <errno.h>
43#include <stdlib.h>
44#include <string.h>
45
46#include "systat.h"
47#include "extern.h"
48
49int
50kvm_ckread(void *a, void *b, int l)
51{
52	if (kvm_read(kd, (u_long)a, b, l) != l) {
53		if (verbose)
54			error("error reading kmem at %p", a);
55		return (0);
56	}
57	else
58		return (1);
59}
60
61void getsysctl(const char *name, void *ptr, size_t len)
62{
63	size_t nlen = len;
64	if (sysctlbyname(name, ptr, &nlen, NULL, 0) != 0) {
65		error("sysctl(%s...) failed: %s", name,
66		    strerror(errno));
67	}
68	if (nlen != len) {
69		error("sysctl(%s...) expected %lu, got %lu", name,
70		    (unsigned long)len, (unsigned long)nlen);
71    }
72}
73
74/*
75 * Read sysctl data with variable size. Try some times (with increasing
76 * buffers), fail if still too small.
77 * This is needed sysctls with possibly raplidly increasing data sizes,
78 * but imposes little overhead in the case of constant sizes.
79 * Returns NULL on error, or a pointer to freshly malloc()'ed memory that holds
80 * the requested data.
81 * If szp is not NULL, the size of the returned data will be written into *szp.
82 */
83
84/* Some defines: Number of tries. */
85#define SD_NTRIES  10
86/* Percent of over-allocation (initial) */
87#define SD_MARGIN  10
88/*
89 * Factor for over-allocation in percent (the margin is increased by this on
90 * any failed try).
91 */
92#define SD_FACTOR  50
93/* Maximum supported MIB depth */
94#define SD_MAXMIB  16
95
96char *
97sysctl_dynread(const char *n, size_t *szp)
98{
99	char   *rv = NULL;
100	int    mib[SD_MAXMIB];
101	size_t mibsz = SD_MAXMIB;
102	size_t mrg = SD_MARGIN;
103	size_t sz;
104	int i;
105
106	/* cache the MIB */
107	if (sysctlnametomib(n, mib, &mibsz) == -1) {
108		if (errno == ENOMEM) {
109			error("XXX: SD_MAXMIB too small, please bump!");
110		}
111		return NULL;
112	}
113	for (i = 0; i < SD_NTRIES; i++) {
114		/* get needed buffer size */
115		if (sysctl(mib, mibsz, NULL, &sz, NULL, 0) == -1)
116			break;
117		sz += sz * mrg / 100;
118		if ((rv = (char *)malloc(sz)) == NULL) {
119			error("Out of memory!");
120			return NULL;
121		}
122		if (sysctl(mib, mibsz, rv, &sz, NULL, 0) == -1) {
123			free(rv);
124			rv = NULL;
125			if (errno == ENOMEM) {
126				mrg += mrg * SD_FACTOR / 100;
127			} else
128				break;
129		} else {
130			/* success */
131			if (szp != NULL)
132				*szp = sz;
133			break;
134		}
135	}
136
137	return rv;
138}
139