core/org.eclipse.cdt.core/utils/org/eclipse/cdt/utils/ERandomAccessFile.java

/*******************************************************************************
 * Copyright (c) 2000, 2009 QNX Software Systems and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     QNX Software Systems - Initial API and implementation
 *******************************************************************************/
package org.eclipse.cdt.utils;

import java.io.EOFException;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteOrder;

/**
 * @noextend This class is not intended to be subclassed by clients.
 */
public class ERandomAccessFile extends RandomAccessFile {
	private boolean isle;
	private long ptr_offset;
	int val[] = new int[4];
	private final String path;

	public ERandomAccessFile(String file, String mode) throws IOException {
		super(file, mode);
		path = file;
	}

	public ERandomAccessFile(File file, String mode) throws IOException {
		this(file.getPath(), mode);
	}

	public void setEndian(boolean le) {
		isle = le;
	}

	public final short readShortE() throws IOException {
		val[0] = read();
		val[1] = read();
		if ((val[0] | val[1]) < 0)
			throw new EOFException();
		if (isle) {
			return (short) ((val[1] << 8) + val[0]);
		}
		return (short) ((val[0] << 8) + val[1]);
	}

	public final long readIntE() throws IOException {
		val[0] = read();
		val[1] = read();
		val[2] = read();
		val[3] = read();
		if ((val[0] | val[1] | val[2] | val[3]) < 0)
			throw new EOFException();
		long value;
		if (isle) {
			value = ((val[3] << 24) + (val[2] << 16) + (val[1] << 8) + val[0]);
		} else {
			value = ((val[0] << 24) + (val[1] << 16) + (val[2] << 8) + val[3]);
		}
		return value & 0x00000000ffffffffL;

	}

	public final long readLongE() throws IOException {
		byte[] bytes = new byte[8];
		long result = 0;
		super.readFully(bytes);
		int shift = 0;
		if (isle)
			for (int i = 7; i >= 0; i--) {
				shift = i * 8;
				result += (((long) bytes[i]) << shift) & (0xffL << shift);
			}
		else
			for (int i = 0; i <= 7; i++) {
				shift = (7 - i) * 8;
				result += (((long) bytes[i]) << shift) & (0xffL << shift);
			}
		return result;
	}

	public final void readFullyE(byte[] bytes) throws IOException {
		super.readFully(bytes);
		byte tmp = 0;
		if (isle)
			for (int i = 0; i < (bytes.length / 2); i++) {
				tmp = bytes[i];
				bytes[i] = bytes[bytes.length - i - 1];
				bytes[bytes.length - i - 1] = tmp;
			}
	}

	public void setFileOffset(long offset) throws IOException {
		ptr_offset = offset;
		super.seek(offset);
	}

	/**
	 * Get the path of the file reader
	 * @since 7.0
	 */
	public String getPath() {
		return path;
	}

	@Override
	public long getFilePointer() throws IOException {
		long ptr = super.getFilePointer();
		ptr = ptr - ptr_offset;
		return ptr;
	}

	@Override
	public void seek(long pos) throws IOException {
		long real_pos = pos + ptr_offset;
		super.seek(real_pos);
	}

	/**
	 * Get the byte order of the file
	 * @return {@link ByteOrder#LITTLE_ENDIAN} or {@link ByteOrder#BIG_ENDIAN}
	 * @since 7.0
	 */
	public ByteOrder order() {
		return isle ? ByteOrder.LITTLE_ENDIAN : ByteOrder.BIG_ENDIAN;
	}
}