xref: /freebsd/usr.bin/systat/fetch.c (revision 342e2faa0928473d8d765096665d84711eb9f674)
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  * $FreeBSD$
34  */
35 
36 #ifndef lint
37 static char sccsid[] = "@(#)fetch.c	8.1 (Berkeley) 6/6/93";
38 #endif /* not lint */
39 
40 #include <sys/types.h>
41 #include <sys/sysctl.h>
42 
43 #include <errno.h>
44 #include <err.h>
45 #include <string.h>
46 #include <stdlib.h>
47 
48 #include "systat.h"
49 #include "extern.h"
50 
51 int
52 kvm_ckread(a, b, l)
53 	void *a, *b;
54 	int l;
55 {
56 	if (kvm_read(kd, (u_long)a, b, l) != l) {
57 		if (verbose)
58 			error("error reading kmem at %x", a);
59 		return (0);
60 	}
61 	else
62 		return (1);
63 }
64 
65 void getsysctl(name, ptr, len)
66 	char *name;
67 	void *ptr;
68 	size_t len;
69 {
70 	int err;
71 	size_t nlen = len;
72 	if ((err = sysctlbyname(name, ptr, &nlen, NULL, 0)) != 0) {
73 		error("sysctl(%s...) failed: %s", name,
74 		    strerror(errno));
75 	}
76 	if (nlen != len) {
77 		error("sysctl(%s...) expected %d, got %d", name,
78 		    len, nlen);
79     }
80 }
81 
82 /*
83  * Read sysctl data with variable size. Try some times (with increasing
84  * buffers), fail if still too small.
85  * This is needed sysctls with possibly raplidly increasing data sizes,
86  * but imposes little overhead in the case of constant sizes.
87  * Returns NULL on error, or a pointer to freshly malloc()'ed memory that holds
88  * the requested data.
89  * If szp is not NULL, the size of the returned data will be written into *szp.
90  */
91 
92 /* Some defines: Number of tries. */
93 #define SD_NTRIES  10
94 /* Percent of over-allocation (initial) */
95 #define SD_MARGIN  10
96 /*
97  * Factor for over-allocation in percent (the margin is increased by this on
98  * any failed try).
99  */
100 #define SD_FACTOR  50
101 /* Maximum supported MIB depth */
102 #define SD_MAXMIB  16
103 
104 char *
105 sysctl_dynread(n, szp)
106 	char *n;
107 	size_t *szp;
108 {
109 	char   *rv = NULL;
110 	int    mib[SD_MAXMIB];
111 	size_t mibsz = SD_MAXMIB;
112 	size_t mrg = SD_MARGIN;
113 	size_t sz;
114 	int i;
115 
116 	/* cache the MIB */
117 	if (sysctlnametomib(n, mib, &mibsz) == -1) {
118 		if (errno == ENOMEM) {
119 			error("XXX: SD_MAXMIB too small, please bump!");
120 		}
121 		return NULL;
122 	}
123 	for (i = 0; i < SD_NTRIES; i++) {
124 		/* get needed buffer size */
125 		if (sysctl(mib, mibsz, NULL, &sz, NULL, 0) == -1)
126 			break;
127 		sz += sz * mrg / 100;
128 		if ((rv = (char *)malloc(sz)) == NULL) {
129 			error("Out of memory!");
130 			return NULL;
131 		}
132 		if (sysctl(mib, mibsz, rv, &sz, NULL, 0) == -1) {
133 			free(rv);
134 			rv = NULL;
135 			if (errno == ENOMEM) {
136 				mrg += mrg * SD_FACTOR / 100;
137 			} else
138 				break;
139 		} else {
140 			/* success */
141 			if (szp != NULL)
142 				*szp = sz;
143 			break;
144 		}
145 	}
146 
147 	return rv;
148 }
149