com.day.durbo.io.ChunkedInflaterInputStream Maven / Gradle / Ivy

/*
 * Copyright 1997-2008 Day Management AG
 * Barfuesserplatz 6, 4001 Basel, Switzerland
 * All Rights Reserved.
 *
 * This software is the confidential and proprietary information of
 * Day Management AG, ("Confidential Information"). You shall not
 * disclose such Confidential Information and shall use it only in
 * accordance with the terms of the license agreement you entered into
 * with Day.
 */
package com.day.durbo.io;

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

/**
 * This class implements a stream filter for uncompressing data in the
 * "deflate" compression format. Most of its implementation is copied from the
 * {@link InflaterInputStream} but in addition to its original, this one can
 * handle several chunks of compressed data on the same underlying stream.
 * such streams are for example generated by the
 * {@link ChunkedDeflaterOutputStream}.
 */
public class ChunkedInflaterInputStream extends FilterInputStream {

    /**
     * Decompressor for this stream.
     */
    protected Inflater inf;

    /**
     * Input buffer for decompression.
     */
    protected byte[] buf;

    /**
     * Length of input buffer.
     */
    protected int len;

    /**
     * true if closed
     */
    private boolean closed = false;

    /**
     * this flag is set to true after EOF has reached
     */
    private boolean reachEOF = false;

    /**
     * true if default inflater is used
     */
    boolean usesDefaultInflater = false;

    /**
     * Check to make sure that this stream has not been closed
     *
     * @throws IOException if not open
     */
    private void ensureOpen() throws IOException {
        if (closed) {
            throw new IOException("Stream closed");
        }
    }

    /**
     * Creates a new input stream with the specified decompressor and
     * buffer size.
     *
     * @param in   the input stream
     * @param inf  the decompressor ("inflater")
     * @param size the input buffer size
     * @throws IllegalArgumentException if size is <= 0
     */
    public ChunkedInflaterInputStream(InputStream in, Inflater inf, int size) {
        super(in);
        if (in == null || inf == null) {
            throw new NullPointerException();
        } else if (size <= 0) {
            throw new IllegalArgumentException("buffer size <= 0");
        }
        this.inf = inf;
        buf = new byte[size];
    }

    /**
     * Creates a new input stream with the specified decompressor and a
     * default buffer size.
     *
     * @param in  the input stream
     * @param inf the decompressor ("inflater")
     */
    public ChunkedInflaterInputStream(InputStream in, Inflater inf) {
        this(in, inf, 8192);
    }

    /**
     * Creates a new input stream with a default decompressor and buffer size.
     *
     * @param in the input stream
     */
    public ChunkedInflaterInputStream(InputStream in) {
        this(in, new Inflater());
        usesDefaultInflater = true;
    }

    private byte[] singleByteBuf = new byte[1];

    /**
     * Reads a byte of uncompressed data. This method will block until
     * enough input is available for decompression.
     *
     * @return the byte read, or -1 if end of compressed input is reached
     * @throws IOException if an I/O error has occurred
     */
    public int read() throws IOException {
        ensureOpen();
        return read(singleByteBuf, 0, 1) == -1 ? -1 : singleByteBuf[0] & 0xff;
    }

    /**
     * Reads uncompressed data into an array of bytes. This method will
     * block until some input can be decompressed.
     *
     * @param b   the buffer into which the data is read
     * @param off the start offset of the data
     * @param len the maximum number of bytes read
     * @return the actual number of bytes read, or -1 if the end of the
     *         compressed input is reached or a preset dictionary is needed
     * @throws ZipException if a ZIP format error has occurred
     * @throws IOException  if an I/O error has occurred
     */
    public int read(byte[] b, int off, int len) throws IOException {
        ensureOpen();
        if ((off | len | (off + len) | (b.length - (off + len))) < 0) {
            throw new IndexOutOfBoundsException();
        } else if (len == 0) {
            return 0;
        }
        try {
            int n;
            while ((n = inf.inflate(b, off, len)) == 0) {
                if (inf.finished() || inf.needsDictionary()) {
                    int r = inf.getRemaining();
                    // check if underlying stream would have more data
                    if (r == 0 && in.available() <= 0) {
                        reachEOF = true;
                        return -1;
                    }
                    inf.reset();
                    inf.setInput(buf, this.len - r, r);
                }
                if (inf.needsInput()) {
                    fill();
                }
            }
            return n;
        } catch (DataFormatException e) {
            String s = e.getMessage();
            throw new ZipException(s != null ? s : "Invalid ZLIB data format");
        }
    }

    /**
     * Returns 0 after EOF has reached, otherwise always return 1.
     * 
     * Programs should not count on this method to return the actual number
     * of bytes that could be read without blocking.
     *
     * @return 1 before EOF and 0 after EOF.
     * @throws IOException if an I/O error occurs.
     */
    public int available() throws IOException {
        ensureOpen();
        if (reachEOF) {
            return 0;
        } else {
            return 1;
        }
    }

    private byte[] b = new byte[512];

    /**
     * Skips specified number of bytes of uncompressed data.
     *
     * @param n the number of bytes to skip
     * @return the actual number of bytes skipped.
     * @throws IOException              if an I/O error has occurred
     * @throws IllegalArgumentException if n < 0
     */
    public long skip(long n) throws IOException {
        if (n < 0) {
            throw new IllegalArgumentException("negative skip length");
        }
        ensureOpen();
        int max = (int) Math.min(n, Integer.MAX_VALUE);
        int total = 0;
        while (total < max) {
            int len = max - total;
            if (len > b.length) {
                len = b.length;
            }
            len = read(b, 0, len);
            if (len == -1) {
                reachEOF = true;
                break;
            }
            total += len;
        }
        return total;
    }

    /**
     * Closes the input stream.
     *
     * @throws IOException if an I/O error has occurred
     */
    public void close() throws IOException {
        if (!closed) {
            if (usesDefaultInflater)
                inf.end();
            in.close();
            closed = true;
        }
    }

    /**
     * Fills input buffer with more data to decompress.
     *
     * @throws IOException if an I/O error has occurred
     */
    protected void fill() throws IOException {
        ensureOpen();
        len = in.read(buf, 0, buf.length);
        if (len == -1) {
            throw new EOFException("Unexpected end of ZLIB input stream");
        }
        inf.setInput(buf, 0, len);
    }
}