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 */
019package org.apache.commons.compress.archivers.tar;
020
021import 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
043public class TarArchiveSparseEntry implements TarConstants {
044    /** If an extension sparse header follows. */
045    private final 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(final 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}