org.bouncycastle.openpgp.PGPCompressedData.java Source code

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Here is the source code for org.bouncycastle.openpgp.PGPCompressedData.java

Source

package org.bouncycastle.openpgp;

import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;

import org.bouncycastle.apache.bzip2.CBZip2InputStream;
import org.bouncycastle.bcpg.BCPGInputStream;
import org.bouncycastle.bcpg.CompressedDataPacket;
import org.bouncycastle.bcpg.CompressionAlgorithmTags;
import org.bouncycastle.bcpg.Packet;
import org.bouncycastle.bcpg.PacketTags;

/**
 * A PGP compressed data object.
 */
public class PGPCompressedData implements CompressionAlgorithmTags {
    CompressedDataPacket data;

    /**
     * Construct a compressed data object, reading a single {@link PacketTags#COMPRESSED_DATA}
     * packet from the stream.
     *
     * @param pIn a PGP input stream, with a compressed data packet as the current packet.
     * @throws IOException if an error occurs reading the packet from the stream.
     */
    public PGPCompressedData(BCPGInputStream pIn) throws IOException {

        Packet packet = pIn.readPacket();
        if (!(packet instanceof CompressedDataPacket)) {
            throw new IOException("unexpected packet in stream: " + packet);
        }
        data = (CompressedDataPacket) packet;
    }

    /**
     * Return the {@link CompressionAlgorithmTags compression algorithm} used for this packet.
     *
     * @return the compression algorithm code
     */
    public int getAlgorithm() {
        return data.getAlgorithm();
    }

    /**
     * Return the raw input stream contained in the object.
     * <p>
     * Note that this stream is shared with the decompression stream, so consuming the returned
     * stream will affect decompression.
     * </p>
     * @return the raw data in the compressed data packet.
     */
    public InputStream getInputStream() {
        return data.getInputStream();
    }

    /**
     * Return an input stream that decompresses and returns data in the compressed packet.
     *
     * @return a stream over the uncompressed data.
     * @throws PGPException if an error occurs constructing the decompression stream.
     */
    public InputStream getDataStream() throws PGPException {
        if (this.getAlgorithm() == UNCOMPRESSED) {
            return this.getInputStream();
        }
        if (this.getAlgorithm() == ZIP) {
            return new InflaterInputStream(this.getInputStream(), new Inflater(true)) {
                // If the "nowrap" inflater option is used the stream can
                // apparently overread - we override fill() and provide
                // an extra byte for the end of the input stream to get
                // around this.
                //
                // Totally weird...
                //
                protected void fill() throws IOException {
                    if (eof) {
                        throw new EOFException("Unexpected end of ZIP input stream");
                    }

                    len = this.in.read(buf, 0, buf.length);

                    if (len == -1) {
                        buf[0] = 0;
                        len = 1;
                        eof = true;
                    }

                    inf.setInput(buf, 0, len);
                }

                private boolean eof = false;
            };
        }
        if (this.getAlgorithm() == ZLIB) {
            return new InflaterInputStream(this.getInputStream()) {
                // If the "nowrap" inflater option is used the stream can
                // apparently overread - we override fill() and provide
                // an extra byte for the end of the input stream to get
                // around this.
                //
                // Totally weird...
                //
                protected void fill() throws IOException {
                    if (eof) {
                        throw new EOFException("Unexpected end of ZIP input stream");
                    }

                    len = this.in.read(buf, 0, buf.length);

                    if (len == -1) {
                        buf[0] = 0;
                        len = 1;
                        eof = true;
                    }

                    inf.setInput(buf, 0, len);
                }

                private boolean eof = false;
            };
        }
        if (this.getAlgorithm() == BZIP2) {
            try {
                return new CBZip2InputStream(this.getInputStream());
            } catch (IOException e) {
                throw new PGPException("I/O problem with stream: " + e, e);
            }
        }

        throw new PGPException("can't recognise compression algorithm: " + this.getAlgorithm());
    }
}