bsnmp-sysctl/sysctl_sup.c

/*
 * Copyright (c) 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright 2011 John-Mark Gurney
 *
 * 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.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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/types.h>
#include <sys/sysctl.h>

#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include "sysctl_sup.h"

int
sysctl_alloc(int *name, u_int namelen, void **oldp, size_t *oldlenp,
	    void *newp, size_t newlen)
{
	void *buf;
	size_t curr, prev;
	int r;

	buf = NULL;

	if (sysctl(name, namelen, NULL, &curr, NULL, 0) == -1 &&
	    errno != ENOMEM)
		return -1;

	for (;;) {
		buf = realloc(buf, curr);
		prev = curr;

		if (((r = sysctl(name, namelen, buf, &curr, newp, newlen)) ==
		    -1 && errno != ENOMEM) || r == 0) {
			if (r == 0) {
				*oldlenp = curr;
				*oldp = realloc(buf, *oldlenp);
			}

			return r;
		}

		/* previous estimate was short, try again. */
		if (curr <= prev)
			curr = prev + 16;
	}
}

int
sysctl_oidfmt(int *oid, int len, char **fmt, u_int *kind)
{
	int qoid[CTL_MAXNAME+2];
	void *buf;
	u_char *fmtstart;
	int i;
	size_t j;

	qoid[0] = 0;
	qoid[1] = 4;
	memcpy(qoid + 2, oid, len * sizeof(int));

	i = sysctl_alloc(qoid, len + 2, &buf, &j, NULL, 0);
	if (i)
		return i;

	if (kind)
		*kind = *(u_int *)buf;

	if (fmt) {
		fmtstart = (char *)buf + sizeof(u_int);
		*fmt = malloc(strlen(fmtstart) + 1);
		if (*fmt == NULL) {
			free(buf);
			errno = ENOMEM;
			return -1;
		}
		strcpy(*fmt, fmtstart);
	}

	free(buf);

	return (0);
}