usr.bin/systat/fetch.c

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