antliscence/src/main/org/apache/tools/tar/TarArchiveSparseEntry.java

/*
 * 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.tools.tar;

import java.io.IOException;

/**
 * This class represents a sparse entry in a Tar archive.
 *
 * <p>
 * The C structure for a sparse entry is:
 * <pre>
 * struct posix_header {
 * struct sparse sp[21]; // TarConstants.SPARSELEN_GNU_SPARSE     - offset 0
 * char isextended;      // TarConstants.ISEXTENDEDLEN_GNU_SPARSE - offset 504
 * };
 * </pre>
 * Whereas, "struct sparse" is:
 * <pre>
 * struct sparse {
 * char offset[12];   // offset 0
 * char numbytes[12]; // offset 12
 * };
 * </pre>
 */

public class TarArchiveSparseEntry implements TarConstants {
    /** If an extension sparse header follows. */
    private boolean isExtended;

    /**
     * Construct an entry from an archive's header bytes. File is set
     * to null.
     *
     * @param headerBuf The header bytes from a tar archive entry.
     * @throws IOException on unknown format
     */
    public TarArchiveSparseEntry(byte[] headerBuf) throws IOException {
        int offset = 0;
        offset += SPARSELEN_GNU_SPARSE;
        isExtended = TarUtils.parseBoolean(headerBuf, offset);
    }

    public boolean isExtended() {
        return isExtended;
    }
}