https://openjdk.java.net/ 
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 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

package jdk.tools.jaotc.binformat;

import jdk.tools.jaotc.binformat.Symbol.Binding;
import jdk.tools.jaotc.binformat.Symbol.Kind;
import jdk.tools.jaotc.jnilibelf.ELFContainer;

import java.io.ByteArrayOutputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Arrays;


Base class that represents content of all sections with byte-level granularity. The ByteContainer class is backed by a ByteArrayOutputStream. This class supports writing all desired byte content to the container using the method appendBytes and accessing the byte array using the method getByteArray. The method putIntAt updates the content of contentBytes. Changes are not reflected in contentStream. 
/**
 * Base class that represents content of all sections with byte-level granularity. The ByteContainer
 * class is backed by a ByteArrayOutputStream. This class supports writing all desired byte content
 * to the container using the method {@code appendBytes} and accessing the byte array using the
 * method {@code getByteArray}.
 *
 * The method {@code putIntAt} updates the content of {@code contentBytes}. Changes are not
 * reflected in {@code contentStream}.
 */
public class ByteContainer implements ELFContainer {
    
ByteBuffer representation of BinaryContainer. 
/**
     * {@code ByteBuffer} representation of {@code BinaryContainer}.
     */
    private ByteBuffer contentBytes;

    
ByteArrayoutputStream to which all appends are done. 
/**
     * {@code ByteArrayoutputStream} to which all appends are done.
     */
    private ByteArrayOutputStream contentStream;

    
Boolean to indicate if contentBytes was modified.

/**
     * Boolean to indicate if contentBytes was modified.
     */
    private boolean bufferModified;

    
Boolean to indicate if this section contains any relocations.

/**
     * Boolean to indicate if this section contains any relocations.
     */
    private boolean hasRelocations;

    
Name of this container, used as section name.

/**
     * Name of this container, used as section name.
     */
    private String containerName;
    private final SymbolTable symbolTable;

    
Contains a unique id.

/**
     * Contains a unique id.
     */
    private int sectionId = -1;

    
Construct a ByteContainer object. 
/**
     * Construct a {@code ByteContainer} object.
     */
    public ByteContainer(String containerName, SymbolTable symbolTable) {
        this.containerName = containerName;
        this.symbolTable = symbolTable;
        this.contentBytes = null;
        this.bufferModified = false;
        this.hasRelocations = false;
        this.contentStream = new ByteArrayOutputStream();
    }

    
Update byte buffer to reflect the current contents of byte stream.

Throws:
  • InternalError – throws InternalError if buffer byte array was modified
/**
     * Update byte buffer to reflect the current contents of byte stream.
     *
     * @throws InternalError throws {@code InternalError} if buffer byte array was modified
     */
    private void updateByteBuffer() {
        if (!bufferModified) {
            contentBytes = ByteBuffer.wrap(contentStream.toByteArray());
            // Default byte order of ByteBuffer is BIG_ENDIAN.
            // Set it appropriately
            this.contentBytes.order(ByteOrder.nativeOrder());
        } else {
            throw new InternalError("Backing byte buffer no longer in sync with byte stream");
        }
    }

    
Get the byte array of ByteContainer. 
Throws:
  • InternalError – throws InternalError if buffer byte array was modified
Returns:byte array
/**
     * Get the byte array of {@code ByteContainer}.
     *
     * @return byte array
     * @throws InternalError throws {@code InternalError} if buffer byte array was modified
     */
    public byte[] getByteArray() {
        if (!bufferModified) {
            updateByteBuffer();
        }
        return contentBytes.array();
    }

    
Append to byte stream. It is an error to append to stream if the byte buffer version is
changed.

Params:
  • newBytes – new content
  • off – offset start offset in newBytes
  • len – length of data to write
Throws:
  • InternalError – throws InternalError if buffer byte array was modified
/**
     * Append to byte stream. It is an error to append to stream if the byte buffer version is
     * changed.
     *
     * @param newBytes new content
     * @param off offset start offset in {@code newBytes}
     * @param len length of data to write
     * @throws InternalError throws {@code InternalError} if buffer byte array was modified
     */
    public ByteContainer appendBytes(byte[] newBytes, int off, int len) {
        if (bufferModified) {
            throw new InternalError("Backing byte buffer no longer in sync with byte stream");
        }
        contentStream.write(newBytes, off, len);
        return this;
    }

    public ByteContainer appendBytes(byte[] newBytes) {
        appendBytes(newBytes, 0, newBytes.length);
        return this;
    }

    public ByteContainer appendInt(int i) {
        if (bufferModified) {
            throw new InternalError("Backing byte buffer no longer in sync with byte stream");
        }
        ByteBuffer b = ByteBuffer.allocate(Integer.BYTES);
        b.order(ByteOrder.nativeOrder());
        b.putInt(i);
        byte[] result = b.array();
        contentStream.write(result, 0, result.length);
        return this;
    }

    public ByteContainer appendInts(int[] newInts) {
        if (bufferModified) {
            throw new InternalError("Backing byte buffer no longer in sync with byte stream");
        }
        ByteBuffer b = ByteBuffer.allocate(Integer.BYTES * newInts.length).order(ByteOrder.nativeOrder());
        Arrays.stream(newInts).forEach(i -> b.putInt(i));
        byte[] result = b.array();
        contentStream.write(result, 0, result.length);
        return this;
    }

    public void appendLong(long l) {
        if (bufferModified) {
            throw new InternalError("Backing byte buffer no longer in sync with byte stream");
        }
        ByteBuffer b = ByteBuffer.allocate(8);
        b.order(ByteOrder.nativeOrder());
        b.putLong(l);
        byte[] result = b.array();
        contentStream.write(result, 0, result.length);
    }

    
Return the current size of byte stream backing the BinaryContainer.

Returns:size of buffer stream
/**
     * Return the current size of byte stream backing the BinaryContainer.
     *
     * @return size of buffer stream
     */
    public int getByteStreamSize() {
        return contentStream.size();
    }

    
Return the name of this container.

Returns:string containing name
/**
     * Return the name of this container.
     *
     * @return string containing name
     */
    public String getContainerName() {
        return containerName;
    }

    
Modify the byte buffer version of the byte output stream. Note that after calling this method
all further updates to BinaryContainer will be out of sync with byte buffer content.

Params:
  • index – index of byte to be changed
  • value – new value
/**
     * Modify the byte buffer version of the byte output stream. Note that after calling this method
     * all further updates to BinaryContainer will be out of sync with byte buffer content.
     *
     * @param index index of byte to be changed
     * @param value new value
     */
    public void putIntAt(int index, int value) {
        if (!bufferModified) {
            updateByteBuffer();
        }
        contentBytes.putInt(index, value);
        bufferModified = true;
    }

    public void putLongAt(int index, long value) {
        if (!bufferModified) {
            updateByteBuffer();
        }
        contentBytes.putLong(index, value);
        bufferModified = true;
    }

    public void setSectionId(int id) {
        if (sectionId != -1) {
            throw new InternalError("Assigning new sectionId (old: " + sectionId + ", new: " + id + ")");
        }
        sectionId = id;
    }

    public int getSectionId() {
        if (sectionId == -1) {
            throw new InternalError("Using sectionId before assigned");
        }
        return sectionId;
    }

    public Symbol createSymbol(int offset, Kind kind, Binding binding, int size, String name) {
        Symbol symbol = new Symbol(offset, kind, binding, this, size, name);
        symbolTable.addSymbol(symbol);
        return symbol;
    }

    public GotSymbol createGotSymbol(String name) {
        GotSymbol symbol = new GotSymbol(Kind.OBJECT, Binding.LOCAL, this, name);
        symbolTable.addSymbol(symbol);
        return symbol;
    }

    public GotSymbol createGotSymbol(int offset, String name) {
        GotSymbol symbol = new GotSymbol(offset, Kind.OBJECT, Binding.LOCAL, this, name);
        symbolTable.addSymbol(symbol);
        return symbol;
    }

    public void clear() {
        this.contentBytes = null;
        this.contentStream = null;
    }

    public void setHasRelocations() {
        this.hasRelocations = true;
    }

    public boolean hasRelocations() {
        return this.hasRelocations;
    }
}