Adobe-Consulting-Services/acs-aem-commons

/*
 * ACS AEM Commons
 *
 * Copyright (C) 2013 - 2023 Adobe
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package ch.randelshofer.media.io;

import java.io.IOException;
import java.nio.ByteOrder;
import javax.imageio.stream.ImageInputStreamImpl;

/**
 * {@code ImageInputStreamImpl2} fixes bugs in ImageInputStreamImpl.
 * <p>
 * ImageInputStreamImpl uses read(byte[]) instead of readFully(byte[]) inside of
 * readShort. This results in corrupt data input if the underlying stream can
 * not fulfill the read operation in a single step.
 *
 * @author Werner Randelshofer
 * @version $Id: ImageInputStreamImpl2.java 134 2011-12-02 16:23:00Z werner $
 */
public abstract class ImageInputStreamImpl2 extends ImageInputStreamImpl {
    // Length of the buffer used for readFully(type[], int, int)
    private static final int BYTE_BUF_LENGTH = 8192;
    /**
     * Byte buffer used for readFully(type[], int, int).  Note that this
     * array is also used for bulk reads in readShort(), readInt(), etc, so
     * it should be large enough to hold a primitive value (i.e. >= 8 bytes).
     * Also note that this array is package protected, so that it can be
     * used by ImageOutputStreamImpl in a similar manner.
     */
    byte[] byteBuf = new byte[BYTE_BUF_LENGTH];

    @Override
        public short readShort() throws IOException {
        readFully(byteBuf, 0, 2);

        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            return (short)
                (((byteBuf[0] & 0xff) << 8) | ((byteBuf[1] & 0xff) << 0));
        } else {
            return (short)
                (((byteBuf[1] & 0xff) << 8) | ((byteBuf[0] & 0xff) << 0));
        }
    }
    public int readInt() throws IOException {
        readFully(byteBuf, 0, 4);

        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            return
                (((byteBuf[0] & 0xff) << 24) | ((byteBuf[1] & 0xff) << 16) |
                 ((byteBuf[2] & 0xff) <<  8) | ((byteBuf[3] & 0xff) <<  0));
        } else {
            return
                (((byteBuf[3] & 0xff) << 24) | ((byteBuf[2] & 0xff) << 16) |
                 ((byteBuf[1] & 0xff) <<  8) | ((byteBuf[0] & 0xff) <<  0));
        }
    }

}