# MemoryBuffer.java

    /*
    ** Module   : MemoryBuffer.java
    ** Abstract : Representation of a memptr value, when used from non-P2J code.
    **
    ** Copyright (c) 2013-2020, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ---------------------------------Description----------------------------------
    ** 001 CA  20130626 Created initial version.
    ** 002 IAS 20200908 Rework (de)serialization.
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program is distributed in the hope that it will be useful,
    ** but WITHOUT ANY WARRANTY; without even the implied warranty of
    ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ** GNU Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
    **   2. No Misrepresentation of Affiliation.
    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.util;

    import static com.goldencode.util.NativeTypeSerializer.*;
    import java.io.*;
    import java.util.*;

    /**
     * Provides a byte buffer to be used from non-P2J code, when performing remote appserver calls.
     * Instances of this class will be sent when the remote side expectes a memptr instance.
     * <p>
     * The remote side will be responsible of converting instances of this class to a {@link memptr}
     * instance when it receives a {@link MemoryBuffer} instance and also to send back to the
     * requester a {@link MemoryBuffer} instance, in case OUTPUT or INPUT-OUTPUT mode is used for the
     * parameter.
     */
    public final class MemoryBuffer
    implements Externalizable
    {
       /** Stores the state of this instance as an array of bytes. */
       private byte[] value;

       /**
        * Default c'tor, needed for deserialization purposes; not for public use.
        */
       public MemoryBuffer()
       {
       }

       /**
        * Construct a new instance of this class, by saving a copy of the passed byte array.
        * <p>
        * Any changes made to the passed array will not be reflected in this instance.
        *
        * @param    value
        *           The array of bytes representing the state of this instance.
        *           May be <code>null</code>.
        */
       public MemoryBuffer(byte[] value)
       {
          this.value = getCopy(value);
       }

       /**
        * Change the {@link #value array of bytes} of this instance by saving a copy of the passed
        * array.
        * <p>
        * Any changes made to the passed array will not be reflected in this instance.
        *
        * @param    value
        *           The array of bytes representing the new state of this instance.
        *           May be <code>null</code>.
        */
       public void setValue(byte[] value)
       {
          this.value = getCopy(value);
       }

       /**
        * Get the array of bytes for this instance, as a copy.
        * <p>
        * Any changes made to the returned array will not be reflected in this instance.
        *
        * @return   See above.
        */
       public byte[] getValue()
       {
          return getCopy(value);
       }

       /**
        * Write the state of this instance to the specified stream.
        *
        * @param    out
        *           The stream where the state of this instance will be sent.
        * @throws IOException
        */
       public void writeExternal(ObjectOutput out)
       throws IOException
       {
          writeByteArray(out, value);
       }

       /**
        * Initialize this instance by reading its state from the specified stream.
        *
        * @param    in
        *           The stream from where the state of this instance will be read.
        * @throws IOException
        * @throws ClassNotFoundException
        */
       public void readExternal(ObjectInput in)
       throws IOException,
              ClassNotFoundException
       {
          value = readByteArray(in);
       }

       /**
        * Create a copy of the given array of bytes.
        *
        * @param    bytes
        *           The array of bytes for which a copy is needed.  May be <code>null</code>.
        *
        * @return   If the given byte array is <code>null</code>, return <code>null</code>. Else,
        *           return a copy of the array.
        */
       private byte[] getCopy(byte[] bytes)
       {
          byte[] copy = null;

          if (bytes != null)
          {
             copy = Arrays.copyOf(bytes, bytes.length);
          }

          return copy;
       }
    }