net.java.truevfs.driver.tar.gzip.TarGZipDriver Maven / Gradle / Ivy

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Provides a file system driver for accessing the GZIP compressed TAR file format. Add the JAR artifact of this module to the run time class path to make its file system drivers available for service location in the client API modules.
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/*
 * Copyright (C) 2005-2015 Schlichtherle IT Services.
 * All rights reserved. Use is subject to license terms.
 */
package net.java.truevfs.driver.tar.gzip;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.zip.Deflater;
import java.util.zip.GZIPInputStream;
import javax.annotation.concurrent.Immutable;
import net.java.truecommons.io.AbstractSink;
import net.java.truecommons.io.AbstractSource;
import net.java.truecommons.io.Streams;
import net.java.truecommons.shed.BitField;
import net.java.truevfs.comp.tardriver.TarDriver;
import net.java.truevfs.comp.tardriver.TarDriverEntry;
import net.java.truevfs.comp.tardriver.TarInputService;
import net.java.truevfs.comp.tardriver.TarOutputService;
import net.java.truevfs.kernel.spec.FsAccessOption;
import static net.java.truevfs.kernel.spec.FsAccessOption.STORE;
import net.java.truevfs.kernel.spec.FsController;
import net.java.truevfs.kernel.spec.FsInputSocketSource;
import net.java.truevfs.kernel.spec.FsModel;
import net.java.truevfs.kernel.spec.FsNodeName;
import net.java.truevfs.kernel.spec.FsOutputSocketSink;
import net.java.truecommons.cio.InputService;
import net.java.truevfs.kernel.spec.cio.MultiplexingOutputService;
import net.java.truecommons.cio.OutputService;

/**
 * An archive driver for GZIP compressed TAR files (TAR.GZIP).
 * 
 * Subclasses must be thread-safe and should be immutable!
 *
 * @author Christian Schlichtherle
 */
@Immutable
public class TarGZipDriver extends TarDriver {

    /**
     * Returns the size of the I/O buffer.
     * 

     * The implementation in the class {@link TarGZipDriver} returns
     * {@link Streams#BUFFER_SIZE}.
     *
     * @return The size of the I/O buffer.
     */
    public int getBufferSize() {
        return Streams.BUFFER_SIZE;
    }

    /**
     * Returns the compression level to use when writing a GZIP sink stream.
     * 
     * The implementation in the class {@link TarGZipDriver} returns
     * {@link Deflater#BEST_COMPRESSION}.
     *
     * @return The compression level to use when writing a GZIP sink stream.
     */
    public int getLevel() {
        return Deflater.BEST_COMPRESSION;
    }

    @Override
    protected InputService newInput(
            final FsModel model,
            final FsInputSocketSource source)
    throws IOException {
        final class Source extends AbstractSource {
            @Override
            public InputStream stream() throws IOException {
                final InputStream in = source.stream();
                try {
                    return new GZIPInputStream(in, getBufferSize());
                } catch(final Throwable ex) {
                    try {
                        in.close();
                    } catch (final Throwable ex2) {
                        ex.addSuppressed(ex2);
                    }
                    throw ex;
                }
            }
        } // Source

        return new TarInputService(model, new Source(), this);
    }

    @Override
    protected OutputService newOutput(
            final FsModel model,
            final FsOutputSocketSink sink,
            final InputService input)
    throws IOException {
        final class Sink extends AbstractSink {
            @Override
            public OutputStream stream() throws IOException {
                final OutputStream out = sink.stream();
                try {
                    return new GZIPOutputStream(out, getBufferSize(), getLevel());
                } catch(final Throwable ex) {
                    try {
                        out.close();
                    } catch (final Throwable ex2) {
                        ex.addSuppressed(ex2);
                    }
                    throw ex;
                }
            }
        } // Sink

        return new MultiplexingOutputService<>(getPool(),
                new TarOutputService(model, new Sink(), this));
    }

    /**
     * Sets {@link FsAccessOption#STORE} in {@code options} before
     * forwarding the call to {@code controller}.
     */
    @Override
    protected FsOutputSocketSink sink(
            BitField options,
            final FsController controller,
            final FsNodeName name) {
        // Leave FsAccessOption.COMPRESS untouched - the driver shall be given
        // opportunity to apply its own preferences to sort out such a conflict.
        options = options.set(STORE);
        return new FsOutputSocketSink(options,
                controller.output(options, name, null));
    }

    /** Extends its super class to set the deflater level. */
    private static final class GZIPOutputStream
    extends java.util.zip.GZIPOutputStream {
        GZIPOutputStream(OutputStream out, int size, int level)
        throws IOException {
            super(out, size);
            def.setLevel(level);
        }
    } // GZIPOutputStream
}