xref: /freebsd/usr.bin/systat/fetch.c (revision 6f2d322192a3949db6e0f0b4bad4c763abc52bed)
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("$FreeBSD$");
37 
38 #ifdef lint
39 static 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 
52 int
53 kvm_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 
64 void 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 
99 char *
100 sysctl_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