fetch.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1980, 1992, 1993
5 *	The Regents of the University of California.  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 * 4. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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
32#include <sys/cdefs.h>
33
34__FBSDID("$FreeBSD: stable/11/usr.bin/systat/fetch.c 330897 2018-03-14 03:19:51Z eadler $");
35
36#ifdef lint
37static const char sccsid[] = "@(#)fetch.c	8.1 (Berkeley) 6/6/93";
38#endif
39
40#include <sys/types.h>
41#include <sys/sysctl.h>
42
43#include <err.h>
44#include <errno.h>
45#include <stdlib.h>
46#include <string.h>
47
48#include "systat.h"
49#include "extern.h"
50
51int
52kvm_ckread(void *a, void *b, int l)
53{
54	if (kvm_read(kd, (u_long)a, b, l) != l) {
55		if (verbose)
56			error("error reading kmem at %p", a);
57		return (0);
58	}
59	else
60		return (1);
61}
62
63void getsysctl(const char *name, void *ptr, size_t len)
64{
65	size_t nlen = len;
66	if (sysctlbyname(name, ptr, &nlen, NULL, 0) != 0) {
67		error("sysctl(%s...) failed: %s", name,
68		    strerror(errno));
69	}
70	if (nlen != len) {
71		error("sysctl(%s...) expected %lu, got %lu", name,
72		    (unsigned long)len, (unsigned long)nlen);
73    }
74}
75
76/*
77 * Read sysctl data with variable size. Try some times (with increasing
78 * buffers), fail if still too small.
79 * This is needed sysctls with possibly raplidly increasing data sizes,
80 * but imposes little overhead in the case of constant sizes.
81 * Returns NULL on error, or a pointer to freshly malloc()'ed memory that holds
82 * the requested data.
83 * If szp is not NULL, the size of the returned data will be written into *szp.
84 */
85
86/* Some defines: Number of tries. */
87#define SD_NTRIES  10
88/* Percent of over-allocation (initial) */
89#define SD_MARGIN  10
90/*
91 * Factor for over-allocation in percent (the margin is increased by this on
92 * any failed try).
93 */
94#define SD_FACTOR  50
95/* Maximum supported MIB depth */
96#define SD_MAXMIB  16
97
98char *
99sysctl_dynread(const char *n, size_t *szp)
100{
101	char   *rv = NULL;
102	int    mib[SD_MAXMIB];
103	size_t mibsz = SD_MAXMIB;
104	size_t mrg = SD_MARGIN;
105	size_t sz;
106	int i;
107
108	/* cache the MIB */
109	if (sysctlnametomib(n, mib, &mibsz) == -1) {
110		if (errno == ENOMEM) {
111			error("XXX: SD_MAXMIB too small, please bump!");
112		}
113		return NULL;
114	}
115	for (i = 0; i < SD_NTRIES; i++) {
116		/* get needed buffer size */
117		if (sysctl(mib, mibsz, NULL, &sz, NULL, 0) == -1)
118			break;
119		sz += sz * mrg / 100;
120		if ((rv = (char *)malloc(sz)) == NULL) {
121			error("Out of memory!");
122			return NULL;
123		}
124		if (sysctl(mib, mibsz, rv, &sz, NULL, 0) == -1) {
125			free(rv);
126			rv = NULL;
127			if (errno == ENOMEM) {
128				mrg += mrg * SD_FACTOR / 100;
129			} else
130				break;
131		} else {
132			/* success */
133			if (szp != NULL)
134				*szp = sz;
135			break;
136		}
137	}
138
139	return rv;
140}
141