/*
* 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.
*/
/*
* Imported by CG 20080603 based on Apache Harmony ("enhanced") revision 768128.
*/
package java.util.zip;
import java.io.EOFException;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* This class provides an implementation of {@code FilterInputStream} that
* uncompresses data that was compressed using the <i>DEFLATE</i> algorithm
* (see <a href="http://www.gzip.org/algorithm.txt">specification</a>).
* Basically it wraps the {@code Inflater} class and takes care of the
* buffering.
*
* @see Inflater
* @see DeflaterOutputStream
*/
public class InflaterInputStream extends FilterInputStream {
/**
* The inflater used for this stream.
*/
protected Inflater inf;
/**
* The input buffer used for decompression.
*/
protected byte[] buf;
/**
* The length of the buffer.
*/
protected int len;
boolean closed;
boolean eof;
static final int BUF_SIZE = 512;
/**
* This is the most basic constructor. You only need to pass the {@code
* InputStream} from which the compressed data is to be read from. Default
* settings for the {@code Inflater} and internal buffer are be used. In
* particular the Inflater expects a ZLIB header from the input stream.
*
* @param is
* the {@code InputStream} to read data from.
*/
public InflaterInputStream(InputStream is) {
this(is, new Inflater(), BUF_SIZE);
}
/**
* This constructor lets you pass a specifically initialized Inflater,
* for example one that expects no ZLIB header.
*
* @param is
* the {@code InputStream} to read data from.
* @param inf
* the specific {@code Inflater} for uncompressing data.
*/
public InflaterInputStream(InputStream is, Inflater inf) {
this(is, inf, BUF_SIZE);
}
/**
* This constructor lets you specify both the {@code Inflater} as well as
* the internal buffer size to be used.
*
* @param is
* the {@code InputStream} to read data from.
* @param inf
* the specific {@code Inflater} for uncompressing data.
* @param bsize
* the size to be used for the internal buffer.
*/
public InflaterInputStream(InputStream is, Inflater inf, int bsize) {
super(is);
if (is == null || inf == null) {
throw new NullPointerException();
}
if (bsize <= 0) {
throw new IllegalArgumentException();
}
this.inf = inf;
buf = new byte[bsize];
}
/**
* Reads a single byte of decompressed data.
*
* @return the byte read.
* @throws IOException
* if an error occurs reading the byte.
*/
public int read() throws IOException {
byte[] b = new byte[1];
if (read(b, 0, 1) == -1) {
return -1;
}
return b[0] & 0xff;
}
/**
* Reads up to {@code nbytes} of decompressed data and stores it in
* {@code buffer} starting at {@code off}.
*
* @param buffer
* the buffer to write data to.
* @param off
* offset in buffer to start writing.
* @param nbytes
* number of bytes to read.
* @return Number of uncompressed bytes read
* @throws IOException
* if an IOException occurs.
*/
public int read(byte[] buffer, int off, int nbytes) throws IOException {
if (closed) {
throw new IOException("stream is closed");
}
if (null == buffer) {
throw new NullPointerException();
}
if (off < 0 || nbytes < 0 || off + nbytes > buffer.length) {
throw new IndexOutOfBoundsException();
}
if (nbytes == 0) {
return 0;
}
if (inf.finished()) {
eof = true;
return -1;
}
// avoid int overflow, check null buffer
if (off <= buffer.length && nbytes >= 0 && off >= 0
&& buffer.length - off >= nbytes) {
do {
if (inf.needsInput()) {
fill();
}
int result;
try {
result = inf.inflate(buffer, off, nbytes);
} catch (DataFormatException e) {
if (len == -1) {
throw new EOFException();
}
throw (IOException) (new IOException().initCause(e));
}
if (result > 0) {
return result;
} else if (inf.finished()) {
eof = true;
return -1;
} else if (inf.needsDictionary()) {
return -1;
} else if (len == -1) {
throw new EOFException();
// If result == 0, fill() and try again
}
} while (true);
}
throw new ArrayIndexOutOfBoundsException();
}
/**
* Fills the input buffer with data to be decompressed.
*
* @throws IOException
* if an {@code IOException} occurs.
*/
protected void fill() throws IOException {
if (closed) {
throw new IOException("stream is closed");
}
if ((len = in.read(buf)) > 0) {
inf.setInput(buf, 0, len);
}
}
/**
* Skips up to n bytes of uncompressed data.
*
* @param nbytes
* the number of bytes to skip.
* @return the number of uncompressed bytes skipped.
* @throws IOException
* if an error occurs skipping.
*/
public long skip(long nbytes) throws IOException {
if (nbytes >= 0) {
long count = 0, rem = 0;
while (count < nbytes) {
int x = read(buf, 0,
(rem = nbytes - count) > buf.length ? buf.length
: (int) rem);
if (x == -1) {
eof = true;
return count;
}
count += x;
}
return count;
}
throw new IllegalArgumentException();
}
/**
* Returns whether data can be read from this stream.
*
* @return 0 if this stream has been closed, 1 otherwise.
* @throws IOException
* If an error occurs.
*/
public int available() throws IOException {
if (closed) {
throw new IOException("stream is closed");
}
if (eof) {
return 0;
}
return 1;
}
/**
* Closes the input stream.
*
* @throws IOException
* If an error occurs closing the input stream.
*/
public void close() throws IOException {
if (!closed) {
inf.end();
closed = true;
eof = true;
super.close();
// [CG 20090603] help GC to clean up
in = null;
}
}
}