NetBSD/lib/libc/gen/asysctl.c
joerg 3adc1c7681 Add asysctl(3) and asysctlbyname(3) wrappers for the common idiom of
fetching dynamically sized data via sysctl.
2014-06-13 15:45:05 +00:00

93 lines
2.6 KiB
C

/* $NetBSD: asysctl.c,v 1.1 2014/06/13 15:45:05 joerg Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Joerg Sonnenberger.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: asysctl.c,v 1.1 2014/06/13 15:45:05 joerg Exp $");
#include "namespace.h"
#include <sys/sysctl.h>
#include <errno.h>
#include <limits.h>
#include <stdlib.h>
__weak_alias(asysctl,_asysctl)
__weak_alias(asysctlbyname,_asysctlbyname)
void *
asysctl(const int *oids, size_t oidlen, size_t *len)
{
void *data;
*len = 0;
data = NULL;
for (;;) {
if (sysctl(oids, oidlen, data, len, NULL, 0) == 0) {
if (*len == 0) {
free(data);
return NULL;
}
if (data != NULL)
return data;
errno = ENOMEM;
}
free(data);
if (errno == ENOMEM && *len != SIZE_MAX) {
if (*len > SIZE_MAX / 2)
*len = SIZE_MAX;
else
*len *= 2;
data = malloc(*len);
if (data == NULL) {
*len = SIZE_MAX;
return NULL;
}
continue;
}
*len = SIZE_MAX;
return NULL;
}
}
void *
asysctlbyname(const char *gname, size_t *len)
{
int name[CTL_MAXNAME];
u_int namelen;
if (sysctlgetmibinfo(gname, &name[0], &namelen, NULL, NULL, NULL,
SYSCTL_VERSION)) {
*len = SIZE_MAX;
return NULL;
}
return asysctl(&name[0], namelen, len);
}