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Apache Commons Compress defines an API for working with compression and archive formats. These include bzip2, gzip, pack200, LZMA, XZ, Snappy, traditional Unix Compress, DEFLATE, DEFLATE64, LZ4, Brotli, Zstandard and ar, cpio, jar, tar, zip, dump, 7z, arj.
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/*
 *  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.harmony.pack200;

import org.objectweb.asm.Attribute;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.Label;

/**
 * NewAttribute extends Attribute and manages unknown attributes encountered by ASM that have had a layout
 * definition given to pack200 (e.g. via one of the -C, -M, -F or -D command line options)
 */
public class NewAttribute extends Attribute {

    private boolean contextClass = false;
    private boolean contextMethod = false;
    private boolean contextField = false;
    private boolean contextCode = false;

    private final String layout;
    private byte[] contents;
    private int codeOff;
    private Label[] labels;
    private ClassReader classReader;
    private char[] buf;

    public NewAttribute(final String type, final String layout, final int context) {
        super(type);
        this.layout = layout;
        addContext(context);
    }

    public NewAttribute(final ClassReader classReader, final String type, final String layout, final byte[] contents,
        final char[] buf, final int codeOff, final Label[] labels) {
        super(type);
        this.classReader = classReader;
        this.contents = contents;
        this.layout = layout;
        this.codeOff = codeOff;
        this.labels = labels;
        this.buf = buf;
    }

    public void addContext(final int context) {
        switch (context) {
        case AttributeDefinitionBands.CONTEXT_CLASS:
            contextClass = true;
            break;
        case AttributeDefinitionBands.CONTEXT_METHOD:
            contextMethod = true;
            break;
        case AttributeDefinitionBands.CONTEXT_FIELD:
            contextField = true;
            break;
        case AttributeDefinitionBands.CONTEXT_CODE:
            contextCode = true;
            break;
        }
    }

    public boolean isContextClass() {
        return contextClass;
    }

    public boolean isContextMethod() {
        return contextMethod;
    }

    public boolean isContextField() {
        return contextField;
    }

    public boolean isContextCode() {
        return contextCode;
    }

    public String getLayout() {
        return layout;
    }

    @Override
    public boolean isUnknown() {
        return false;
    }

    @Override
    public boolean isCodeAttribute() {
        return codeOff != -1;
    }

    @Override
    protected Attribute read(final ClassReader cr, final int off, final int len, final char[] buf, final int codeOff,
        final Label[] labels) {
        final byte[] attributeContents = new byte[len];
        System.arraycopy(cr.b, off, attributeContents, 0, len);
        return new NewAttribute(cr, type, layout, attributeContents, buf, codeOff, labels);
    }

    public boolean isUnknown(final int context) {
        switch (context) {
        case AttributeDefinitionBands.CONTEXT_CLASS:
            return !contextClass;
        case AttributeDefinitionBands.CONTEXT_METHOD:
            return !contextMethod;
        case AttributeDefinitionBands.CONTEXT_FIELD:
            return !contextField;
        case AttributeDefinitionBands.CONTEXT_CODE:
            return !contextCode;
        }
        return false;
    }

    public String readUTF8(final int index) {
        return classReader.readUTF8(index, buf);
    }

    public String readClass(final int index) {
        return classReader.readClass(index, buf);
    }

    public Object readConst(final int index) {
        return classReader.readConst(index, buf);
    }

    public byte[] getBytes() {
        return contents;
    }

    public Label getLabel(final int index) {
        return labels[index];
    }

    /**
     * ErrorAttribute extends NewAttribute and manages attributes encountered by ASM that have had an error
     * action specified to pack200 (e.g. via one of the -C, -M, -F or -D command line options such as
     * -Cattribute-name=error)
     */
    public static class ErrorAttribute extends NewAttribute {

        public ErrorAttribute(final String type, final int context) {
            super(type, "", context);
        }

        @Override
        protected Attribute read(final ClassReader cr, final int off, final int len, final char[] buf,
            final int codeOff, final Label[] labels) {
            throw new Error("Attribute " + type + " was found");
        }

    }

    /**
     * StripAttribute extends NewAttribute and manages attributes encountered by ASM that have had an strip
     * action specified to pack200 (e.g. via one of the -C, -M, -F or -D command line options such as
     * -Cattribute-name=strip)
     */
    public static class StripAttribute extends NewAttribute {

        public StripAttribute(final String type, final int context) {
            super(type, "", context);
        }

        @Override
        protected Attribute read(final ClassReader cr, final int off, final int len, final char[] buf,
            final int codeOff, final Label[] labels) {
            // TODO Not sure if this works, can we really strip an attribute if we don't know the layout?
            return null;
        }
    }

    /**
     * PassAttribute extends NewAttribute and manages attributes encountered by ASM that have had an pass
     * action specified to pack200 (e.g. via one of the -C, -M, -F or -D command line options such as
     * -Cattribute-name=pass)
     */
    public static class PassAttribute extends NewAttribute {

        public PassAttribute(final String type, final int context) {
            super(type, "", context);
        }

        @Override
        protected Attribute read(final ClassReader cr, final int off, final int len, final char[] buf,
            final int codeOff, final Label[] labels) {
            throw new Segment.PassException();
        }

    }
}