001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     * http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing,
013     * software distributed under the License is distributed on an
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     * KIND, either express or implied.  See the License for the
016     * specific language governing permissions and limitations
017     * under the License.
018     */
019    package org.apache.commons.compress.archivers.tar;
020    
021    import java.io.IOException;
022    
023    /**
024     * This class represents a sparse entry in a Tar archive.
025     *
026     * <p>
027     * The C structure for a sparse entry is:
028     * <pre>
029     * struct posix_header {
030     * struct sparse sp[21]; // TarConstants.SPARSELEN_GNU_SPARSE     - offset 0
031     * char isextended;      // TarConstants.ISEXTENDEDLEN_GNU_SPARSE - offset 504
032     * };
033     * </pre>
034     * Whereas, "struct sparse" is:
035     * <pre>
036     * struct sparse {
037     * char offset[12];   // offset 0
038     * char numbytes[12]; // offset 12
039     * };
040     * </pre>
041     */
042    
043    public class TarArchiveSparseEntry implements TarConstants {
044        /** If an extension sparse header follows. */
045        private boolean isExtended;
046    
047        /**
048         * Construct an entry from an archive's header bytes. File is set
049         * to null.
050         *
051         * @param headerBuf The header bytes from a tar archive entry.
052         * @throws IOException on unknown format
053         */
054        public TarArchiveSparseEntry(byte[] headerBuf) throws IOException {
055            int offset = 0;
056            offset += SPARSELEN_GNU_SPARSE;
057            isExtended = TarUtils.parseBoolean(headerBuf, offset);
058        }
059    
060        public boolean isExtended() {
061            return isExtended;
062        }
063    }