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TrueZIP is a Java based Virtual File System (VFS) to enable transparent, multi-threaded read/write access to archive files (ZIP, TAR etc.) as if they were directories. Archive files may be arbitrarily nested and the nesting level is only limited by heap and file system size.

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/*
 * Copyright (C) 2007-2010 Schlichtherle IT Services
 *
 * Licensed 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 de.schlichtherle.util.zip;

/**
 * Default implementation for an Extra Field in a Local or Central Header of a
 * ZIP archive.
 * 
 * This class is not thread-safe.
 *
 * @author Christian Schlichtherle
 * @version $Id$
 * @since TrueZIP 6.7
 */
final class DefaultExtraField extends ExtraField {

    private final int headerID;
    private byte[] data;

    /**
     * Creates a new instance of the default Extra Field implementation.
     * 
     * @param headerID An unsigned short integer (two bytes) indicating the
     *        type of the Extra Field.
     * @throws IllegalArgumentException If 
     */
    DefaultExtraField(final int headerID) {
        UShort.check(headerID, "Header ID out of range", null);
        this.headerID = headerID;
    }

    public int getHeaderID() {
        return headerID;
    }

    int getDataSize() {
        return data != null ? data.length : 0;
    }

    void readFrom(final byte[] data, final int off, final int size) {
        UShort.check(size, "Data Size out of range", null);
        this.data = new byte[size];
        System.arraycopy(data, off, this.data, 0, size);
    }

    void writeTo(byte[] data, int off) {
        if (this.data != null)
            System.arraycopy(this.data, 0, data, off, this.data.length);
    }
}