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Java Native Access Platform
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/* Copyright (c) 2015 Goldstein Lyor, All Rights Reserved
 *
 * The contents of this file is dual-licensed under 2
 * alternative Open Source/Free licenses: LGPL 2.1 or later and
 * Apache License 2.0. (starting with JNA version 4.0.0).
 *
 * You can freely decide which license you want to apply to
 * the project.
 *
 * You may obtain a copy of the LGPL License at:
 *
 * http://www.gnu.org/licenses/licenses.html
 *
 * A copy is also included in the downloadable source code package
 * containing JNA, in file "LGPL2.1".
 *
 * You may obtain a copy of the Apache License at:
 *
 * http://www.apache.org/licenses/
 *
 * A copy is also included in the downloadable source code package
 * containing JNA, in file "AL2.0".
 */
package com.sun.jna.platform.unix;

/**
 * Note: we are using this "intermediate" API in order to allow
 * Linux-like O/S-es to implement the same API, but maybe using a different
 * library name
 * @author Lyor Goldstein
 */
public interface LibCAPI extends Reboot, Resource {
    // see man(2) get/set uid/gid
    int getuid();
    int geteuid();
    int getgid();
    int getegid();

    int setuid(int uid);
    int seteuid(int uid);
    int setgid(int gid);
    int setegid(int gid);

    // see man(2) get/set hostname
    int HOST_NAME_MAX = 255; // not including the '\0'
    int gethostname(byte[] name, int len);
    int sethostname(String name, int len);

    // see man(2) get/set domainname
    int getdomainname(byte[] name, int len);
    int setdomainname(String name, int len);

    /**
     * @param name Environment variable name
     * @return Returns the value in the environment, or {@code null} if there
     * is no match for the name
     * @see getenv(3)
     */
    String getenv(String name);

    /**
     * Update or add a variable in the environment of the calling process.
     * @param name Environment variable name
     * @param value Required value
     * @param overwrite  If the environment variable already exists and the
     * value of {@code overwrite} is non-zero, the function shall return
     * success and the environment shall be updated. If the environment
     * variable already exists and the value of {@code overwrite} is zero, the
     * function shall return success and the environment shall remain unchanged.
     * @return Upon successful completion, zero shall be returned. Otherwise,
     * -1 shall be returned, {@code errno} set to indicate the error, and the
     * environment shall be unchanged
     * @see getenv(3)
     */
    int setenv(String name, String value, int overwrite);

    /**
     * @param name Environment variable name - If the named variable does not
     * exist in the current environment, the environment shall be unchanged
     * and the function is considered to have completed successfully.
     * @return Upon successful completion, zero shall be returned. Otherwise,
     * -1 shall be returned, {@code errno} set to indicate the error, and the
     * environment shall be unchanged
     * @see getenv(3)
     */
    int unsetenv(String name);

    /**
     * The getloadavg() function returns the number of processes in the system
     * run queue averaged over various periods of time.  Up to nelem samples are
     * retrieved and assigned to successive elements of loadavg[].  The system
     * imposes a maximum of 3 samples, representing averages over the last 1, 5,
     * and 15 minutes, respectively.
     * @param loadavg An array of doubles which will be filled with the results
     * @param nelem Number of samples to return
     * @return If the load average was unobtainable, -1 is returned; otherwise,
     * the number of samples actually retrieved is returned.
     * @see getloadavg(3)
     */
    int getloadavg(double[] loadavg, int nelem);
}