BsdSysctlUtil.java

/**
 * Oshi (https://github.com/oshi/oshi)
 *
 * Copyright (c) 2010 - 2017 The Oshi Project Team
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Maintainers:
 * dblock[at]dblock[dot]org
 * widdis[at]gmail[dot]com
 * enrico.bianchi[at]gmail[dot]com
 *
 * Contributors:
 * https://github.com/oshi/oshi/graphs/contributors
 */
package oshi.util.platform.unix.freebsd;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.sun.jna.Memory;
import com.sun.jna.Native;
import com.sun.jna.Pointer;
import com.sun.jna.Structure;
import com.sun.jna.ptr.IntByReference;

import oshi.jna.platform.unix.freebsd.Libc;

/**
 * Provides access to sysctl calls on FreeBSD
 *
 * @author widdis[at]gmail[dot]com
 */
public class BsdSysctlUtil {
    private static final Logger LOG = LoggerFactory.getLogger(BsdSysctlUtil.class);

    private static final String SYSCTL_FAIL = "Failed syctl call: {}, Error code: {}";

    private BsdSysctlUtil() {
    }

    /**
     * Executes a sysctl call with an int result
     *
     * @param name
     *            name of the sysctl
     * @param def
     *            default int value
     * @return The int result of the call if successful; the default otherwise
     */
    public static int sysctl(String name, int def) {
        IntByReference size = new IntByReference(Libc.INT_SIZE);
        Pointer p = new Memory(size.getValue());
        if (0 != Libc.INSTANCE.sysctlbyname(name, p, size, null, 0)) {
            LOG.error("Failed sysctl call: {}, Error code: {}", name, Native.getLastError());
            return def;
        }
        return p.getInt(0);
    }

    /**
     * Executes a sysctl call with a long result
     *
     * @param name
     *            name of the sysctl
     * @param def
     *            default long value
     * @return The long result of the call if successful; the default otherwise
     */
    public static long sysctl(String name, long def) {
        IntByReference size = new IntByReference(Libc.UINT64_SIZE);
        Pointer p = new Memory(size.getValue());
        if (0 != Libc.INSTANCE.sysctlbyname(name, p, size, null, 0)) {
            LOG.error(SYSCTL_FAIL, name, Native.getLastError());
            return def;
        }
        return p.getLong(0);
    }

    /**
     * Executes a sysctl call with a String result
     *
     * @param name
     *            name of the sysctl
     * @param def
     *            default String value
     * @return The String result of the call if successful; the default
     *         otherwise
     */
    public static String sysctl(String name, String def) {
        // Call first time with null pointer to get value of size
        IntByReference size = new IntByReference();
        if (0 != Libc.INSTANCE.sysctlbyname(name, null, size, null, 0)) {
            LOG.error(SYSCTL_FAIL, name, Native.getLastError());
            return def;
        }
        // Add 1 to size for null terminated string
        Pointer p = new Memory(size.getValue() + 1);
        if (0 != Libc.INSTANCE.sysctlbyname(name, p, size, null, 0)) {
            LOG.error(SYSCTL_FAIL, name, Native.getLastError());
            return def;
        }
        return p.getString(0);
    }

    /**
     * Executes a sysctl call with a Structure result
     *
     * @param name
     *            name of the sysctl
     * @param struct
     *            structure for the result
     * @return True if structure is successfuly populated, false otherwise
     */
    public static boolean sysctl(String name, Structure struct) {
        if (0 != Libc.INSTANCE.sysctlbyname(name, struct.getPointer(), new IntByReference(struct.size()), null, 0)) {
            LOG.error(SYSCTL_FAIL, name, Native.getLastError());
            return false;
        }
        struct.read();
        return true;
    }
}