/*
 * Copyright (c) 1998, 2007 Sun Microsystems, Inc. 
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 * modification, are permitted provided that the following conditions 
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 * notice, this list of conditions and the following disclaimer in the
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 * Neither the name of Sun Microsystems, Inc. or the names of contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
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package com.sun.nfs;

import com.sun.rpc.*;

/**
 *
 * NFS file attributes
 *
 * This is essentially a container class that holds
 * the attributes, but it also has methods to encode
 * and decode the attributes in an Xdr buffer.
 *
 * Note that the time at which the attributes were
 * retrieved is automatically updated and the cache
 * time varies according to the frequency of file
 * modification.
 *
 * There are two subclasses: Fattr2 for NFS v2
 * attributes and Fattr3 for v3.
 *
 * @see Nfs
 * @see Fattr2
 * @see Fattr3
 * @author Brent Callaghan
 */
public abstract class Fattr {

    long validtime;			// time when attrs were new
    long cachetime;			// max cache duration in ms
    static final int ACMIN = 3  * 1000;	// 3 sec - min cache time
    static final int ACMAX = 60 * 1000;	// 1 min - max cache time

    static final int NOBODY = 60001;	// Svr4 UID/GID "nobody"
    static final int NFS_NOBODY = -2;	// NFS  UID/GID "nobody"


    /**
     * Check if the attributes are "fresh" enough.
     *
     * If not, then the caller will likely update
     * the attributes with an NFS getattr request.
     *
     * @returns	true if the attributes are valid
     */
    boolean valid() {
        long timenow = System.currentTimeMillis();

        return (timenow <= validtime + cachetime);
    }
        
    abstract void putFattr(Xdr x);

    abstract void getFattr(Xdr x);
}