/*
 * 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.tar;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

This class represents a sparse entry in a Tar archive.

The C structure for a sparse entry is:

struct posix_header {
struct sparse sp[21]; // TarConstants.SPARSELEN_GNU_SPARSE     - offset 0
char isextended;      // TarConstants.ISEXTENDEDLEN_GNU_SPARSE - offset 504
};
Whereas, "struct sparse" is:
struct sparse {
char offset[12];   // offset 0
char numbytes[12]; // offset 12
};
/** * 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.
/** If an extension sparse header follows. */
private final boolean isExtended; private List<TarArchiveStructSparse> sparseHeaders;
Construct an entry from an archive's header bytes. File is set to null.
Params:
  • headerBuf – The header bytes from a tar archive entry.
Throws:
/** * 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(final byte[] headerBuf) throws IOException { int offset = 0; sparseHeaders = new ArrayList<>(); for(int i = 0; i < SPARSE_HEADERS_IN_EXTENSION_HEADER;i++) { TarArchiveStructSparse sparseHeader = TarUtils.parseSparse(headerBuf, offset + i * (SPARSE_OFFSET_LEN + SPARSE_NUMBYTES_LEN)); // some sparse headers are empty, we need to skip these sparse headers if(sparseHeader.getOffset() > 0 || sparseHeader.getNumbytes() > 0) { sparseHeaders.add(sparseHeader); } } offset += SPARSELEN_GNU_SPARSE; isExtended = TarUtils.parseBoolean(headerBuf, offset); } public boolean isExtended() { return isExtended; }
Obtains information about the configuration for the sparse entry.
Since:1.20
Returns:information about the configuration for the sparse entry.
/** * Obtains information about the configuration for the sparse entry. * @since 1.20 * @return information about the configuration for the sparse entry. */
public List<TarArchiveStructSparse> getSparseHeaders() { return sparseHeaders; } }