/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.commons.compress.archivers;

import java.io.IOException;
import java.io.InputStream;

/**
 * Archive input streams <b>MUST</b> override the 
 * {@link #read(byte[], int, int)} - or {@link #read()} -
 * method so that reading from the stream generates EOF for the end of
 * data in each entry as well as at the end of the file proper.
 * <p>
 * The {@link #getNextEntry()} method is used to reset the input stream
 * ready for reading the data from the next entry.
 * <p>
 * The input stream classes must also implement a method with the signature:
 * <pre>
 * public static boolean matches(byte[] signature, int length)
 * </pre>
 * which is used by the {@link ArchiveStreamFactory} to autodetect
 * the archive type from the first few bytes of a stream. 
 */
public abstract class ArchiveInputStream extends InputStream {

    private byte[] SINGLE = new byte[1];
    private static final int BYTE_MASK = 0xFF;

    /**
     * Returns the next Archive Entry in this Stream.
     * @return the next entry
     * @throws IOException if the next entry could not be read
     */
    public abstract ArchiveEntry getNextEntry() throws IOException;

    /*
     * Note that subclasses also implement specific get() methods which
     * return the appropriate class without need for a cast.
     * See SVN revision r743259
     * @return
     * @throws IOException
     */
    // public abstract XXXArchiveEntry getNextXXXEntry() throws IOException;


    /**
     * Reads a byte of data. This method will block until enough input is
     * available.
     * 
     * Simply calls the {@link #read(byte[], int, int)} method.
     * 
     * MUST be overridden if the {@link #read(byte[], int, int)} method
     * is not overridden; may be overridden otherwise.
     * 
     * @return the byte read, or -1 if end of input is reached
     * @throws IOException
     *             if an I/O error has occurred or if a CPIO file error has
     *             occurred
     */
    public int read() throws IOException {
        int num = read(SINGLE, 0, 1);
        return num == -1 ? -1 : SINGLE[0] & BYTE_MASK;
    }
}

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.commons.compress.archivers;

import java.io.IOException;
import java.io.InputStream;

/**
 * Archive input streams <b>MUST</b> override the 
 * {@link #read(byte[], int, int)} - or {@link #read()} -
 * method so that reading from the stream generates EOF for the end of
 * data in each entry as well as at the end of the file proper.
 * <p>
 * The {@link #getNextEntry()} method is used to reset the input stream
 * ready for reading the data from the next entry.
 * <p>
 * The input stream classes must also implement a method with the signature:
 * <pre>
 * public static boolean matches(byte[] signature, int length)
 * </pre>
 * which is used by the {@link ArchiveStreamFactory} to autodetect
 * the archive type from the first few bytes of a stream. 
 */
public abstract class ArchiveInputStream extends InputStream {

    private byte[] SINGLE = new byte[1];
    private static final int BYTE_MASK = 0xFF;

    /**
     * Returns the next Archive Entry in this Stream.
     *
     * @return the next entry,
     *         or <code>null</code> if there are no more entries
     * @throws IOException if the next entry could not be read
     */
    public abstract ArchiveEntry getNextEntry() throws IOException;

    /*
     * Note that subclasses also implement specific get() methods which
     * return the appropriate class without need for a cast.
     * See SVN revision r743259
     * @return
     * @throws IOException
     */
    // public abstract XXXArchiveEntry getNextXXXEntry() throws IOException;


    /**
     * Reads a byte of data. This method will block until enough input is
     * available.
     * 
     * Simply calls the {@link #read(byte[], int, int)} method.
     * 
     * MUST be overridden if the {@link #read(byte[], int, int)} method
     * is not overridden; may be overridden otherwise.
     * 
     * @return the byte read, or -1 if end of input is reached
     * @throws IOException
     *             if an I/O error has occurred or if a CPIO file error has
     *             occurred
     */
    public int read() throws IOException {
        int num = read(SINGLE, 0, 1);
        return num == -1 ? -1 : SINGLE[0] & BYTE_MASK;
    }
}

Document null return value of ArchiveInputStream.getNextEntry