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/*
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* Copyright (c) 1996, 2006, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.util.zip;
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import java.io.FilterInputStream;
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import java.io.InputStream;
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import java.io.IOException;
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import java.io.EOFException;
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/**
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* This class implements a stream filter for uncompressing data in the
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* "deflate" compression format. It is also used as the basis for other
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* decompression filters, such as GZIPInputStream.
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*
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* @see Inflater
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* @author David Connelly
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*/
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public
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class InflaterInputStream extends FilterInputStream {
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/**
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* Decompressor for this stream.
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*/
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protected Inflater inf;
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/**
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* Input buffer for decompression.
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*/
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protected byte[] buf;
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/**
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* Length of input buffer.
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*/
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protected int len;
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private boolean closed = false;
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// this flag is set to true after EOF has reached
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private boolean reachEOF = false;
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/**
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* Check to make sure that this stream has not been closed
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*/
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private void ensureOpen() throws IOException {
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if (closed) {
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throw new IOException("Stream closed");
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}
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}
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/**
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* Creates a new input stream with the specified decompressor and
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* buffer size.
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* @param in the input stream
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* @param inf the decompressor ("inflater")
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* @param size the input buffer size
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* @exception IllegalArgumentException if size is <= 0
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*/
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public InflaterInputStream(InputStream in, Inflater inf, int size) {
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super(in);
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if (in == null || inf == null) {
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throw new NullPointerException();
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} else if (size <= 0) {
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throw new IllegalArgumentException("buffer size <= 0");
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}
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this.inf = inf;
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buf = new byte[size];
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}
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/**
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* Creates a new input stream with the specified decompressor and a
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* default buffer size.
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* @param in the input stream
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* @param inf the decompressor ("inflater")
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*/
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public InflaterInputStream(InputStream in, Inflater inf) {
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this(in, inf, 512);
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}
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boolean usesDefaultInflater = false;
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/**
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* Creates a new input stream with a default decompressor and buffer size.
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* @param in the input stream
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*/
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public InflaterInputStream(InputStream in) {
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this(in, new Inflater());
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usesDefaultInflater = true;
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}
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private byte[] singleByteBuf = new byte[1];
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/**
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* Reads a byte of uncompressed data. This method will block until
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* enough input is available for decompression.
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* @return the byte read, or -1 if end of compressed input is reached
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* @exception IOException if an I/O error has occurred
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*/
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public int read() throws IOException {
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ensureOpen();
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return read(singleByteBuf, 0, 1) == -1 ? -1 : singleByteBuf[0] & 0xff;
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}
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/**
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* Reads uncompressed data into an array of bytes. If <code>len</code> is not
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* zero, the method will block until some input can be decompressed; otherwise,
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* no bytes are read and <code>0</code> is returned.
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* @param b the buffer into which the data is read
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* @param off the start offset in the destination array <code>b</code>
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* @param len the maximum number of bytes read
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* @return the actual number of bytes read, or -1 if the end of the
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* compressed input is reached or a preset dictionary is needed
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* @exception NullPointerException If <code>b</code> is <code>null</code>.
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* @exception IndexOutOfBoundsException If <code>off</code> is negative,
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* <code>len</code> is negative, or <code>len</code> is greater than
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* <code>b.length - off</code>
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* @exception ZipException if a ZIP format error has occurred
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* @exception IOException if an I/O error has occurred
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*/
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public int read(byte[] b, int off, int len) throws IOException {
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ensureOpen();
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if (b == null) {
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throw new NullPointerException();
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} else if (off < 0 || len < 0 || len > b.length - off) {
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throw new IndexOutOfBoundsException();
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} else if (len == 0) {
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return 0;
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}
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try {
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int n;
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while ((n = inf.inflate(b, off, len)) == 0) {
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if (inf.finished() || inf.needsDictionary()) {
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reachEOF = true;
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return -1;
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}
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if (inf.needsInput()) {
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fill();
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}
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}
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return n;
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} catch (DataFormatException e) {
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String s = e.getMessage();
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throw new ZipException(s != null ? s : "Invalid ZLIB data format");
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}
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}
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/**
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* Returns 0 after EOF has been reached, otherwise always return 1.
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* <p>
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* Programs should not count on this method to return the actual number
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* of bytes that could be read without blocking.
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*
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* @return 1 before EOF and 0 after EOF.
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* @exception IOException if an I/O error occurs.
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*
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*/
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public int available() throws IOException {
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ensureOpen();
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if (reachEOF) {
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return 0;
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} else {
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return 1;
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}
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}
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private byte[] b = new byte[512];
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/**
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* Skips specified number of bytes of uncompressed data.
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* @param n the number of bytes to skip
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* @return the actual number of bytes skipped.
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* @exception IOException if an I/O error has occurred
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* @exception IllegalArgumentException if n < 0
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*/
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public long skip(long n) throws IOException {
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if (n < 0) {
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throw new IllegalArgumentException("negative skip length");
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}
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ensureOpen();
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int max = (int)Math.min(n, Integer.MAX_VALUE);
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int total = 0;
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while (total < max) {
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int len = max - total;
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if (len > b.length) {
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len = b.length;
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}
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len = read(b, 0, len);
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if (len == -1) {
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reachEOF = true;
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break;
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}
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total += len;
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}
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return total;
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}
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/**
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* Closes this input stream and releases any system resources associated
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* with the stream.
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* @exception IOException if an I/O error has occurred
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*/
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public void close() throws IOException {
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if (!closed) {
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if (usesDefaultInflater)
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inf.end();
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in.close();
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closed = true;
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}
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}
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/**
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* Fills input buffer with more data to decompress.
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* @exception IOException if an I/O error has occurred
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*/
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protected void fill() throws IOException {
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ensureOpen();
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len = in.read(buf, 0, buf.length);
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if (len == -1) {
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throw new EOFException("Unexpected end of ZLIB input stream");
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}
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inf.setInput(buf, 0, len);
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}
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/**
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* Tests if this input stream supports the <code>mark</code> and
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* <code>reset</code> methods. The <code>markSupported</code>
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* method of <code>InflaterInputStream</code> returns
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* <code>false</code>.
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*
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* @return a <code>boolean</code> indicating if this stream type supports
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* the <code>mark</code> and <code>reset</code> methods.
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* @see java.io.InputStream#mark(int)
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* @see java.io.InputStream#reset()
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*/
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public boolean markSupported() {
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return false;
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}
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/**
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* Marks the current position in this input stream.
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*
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* <p> The <code>mark</code> method of <code>InflaterInputStream</code>
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* does nothing.
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*
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* @param readlimit the maximum limit of bytes that can be read before
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* the mark position becomes invalid.
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* @see java.io.InputStream#reset()
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*/
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public synchronized void mark(int readlimit) {
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}
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/**
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* Repositions this stream to the position at the time the
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* <code>mark</code> method was last called on this input stream.
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*
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* <p> The method <code>reset</code> for class
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* <code>InflaterInputStream</code> does nothing except throw an
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* <code>IOException</code>.
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*
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* @exception IOException if this method is invoked.
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* @see java.io.InputStream#mark(int)
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* @see java.io.IOException
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*/
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public synchronized void reset() throws IOException {
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throw new IOException("mark/reset not supported");
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}
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}
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