/*
* 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.
*/
package java.util.zip;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import org.apache.harmony.archive.internal.nls.Messages;
/**
* The {@code GZIPInputStream} class is used to read data stored in the GZIP
* format, reading and decompressing GZIP data from the underlying stream into
* its buffer.
*/
public class GZIPInputStream extends InflaterInputStream {
private static final int FCOMMENT = 16;
private static final int FEXTRA = 4;
private static final int FHCRC = 2;
private static final int FNAME = 8;
/**
* The magic header for the GZIP format.
*/
public final static int GZIP_MAGIC = 0x8b1f;
/**
* The checksum algorithm used when handling uncompressed data.
*/
protected CRC32 crc = new CRC32();
/**
* Indicates the end of the input stream.
*/
protected boolean eos = false;
/**
* Construct a {@code GZIPInputStream} to read from GZIP data from the
* underlying stream.
*
* @param is
* the {@code InputStream} to read data from.
* @throws IOException
* if an {@code IOException} occurs.
*/
public GZIPInputStream(InputStream is) throws IOException {
this(is, BUF_SIZE);
}
/**
* Construct a {@code GZIPInputStream} to read from GZIP data from the
* underlying stream. Set the internal buffer size to {@code size}.
*
* @param is
* the {@code InputStream} to read data from.
* @param size
* the internal read buffer size.
* @throws IOException
* if an {@code IOException} occurs.
*/
public GZIPInputStream(InputStream is, int size) throws IOException {
super(is, new Inflater(true), size);
byte[] header = new byte[10];
readFully(header, 0, header.length);
if (getShort(header, 0) != GZIP_MAGIC) {
throw new IOException(Messages.getString("archive.1F")); //$NON-NLS-1$;
}
int flags = header[3];
boolean hcrc = (flags & FHCRC) != 0;
if (hcrc) {
crc.update(header, 0, header.length);
}
if ((flags & FEXTRA) != 0) {
readFully(header, 0, 2);
if (hcrc) {
crc.update(header, 0, 2);
}
int length = getShort(header, 0);
while (length > 0) {
int max = length > buf.length ? buf.length : length;
int result = in.read(buf, 0, max);
if (result == -1) {
throw new EOFException();
}
if (hcrc) {
crc.update(buf, 0, result);
}
length -= result;
}
}
if ((flags & FNAME) != 0) {
readZeroTerminated(hcrc);
}
if ((flags & FCOMMENT) != 0) {
readZeroTerminated(hcrc);
}
if (hcrc) {
readFully(header, 0, 2);
int crc16 = getShort(header, 0);
if ((crc.getValue() & 0xffff) != crc16) {
throw new IOException(Messages.getString("archive.20")); //$NON-NLS-1$
}
crc.reset();
}
}
/**
* Closes this stream and any underlying streams.
*/
@Override
public void close() throws IOException {
eos = true;
super.close();
}
private long getLong(byte[] buffer, int off) {
long l = 0;
l |= (buffer[off] & 0xFF);
l |= (buffer[off + 1] & 0xFF) << 8;
l |= (buffer[off + 2] & 0xFF) << 16;
l |= ((long) (buffer[off + 3] & 0xFF)) << 24;
return l;
}
private int getShort(byte[] buffer, int off) {
return (buffer[off] & 0xFF) | ((buffer[off + 1] & 0xFF) << 8);
}
/**
* Reads and decompresses GZIP data from the underlying stream into the
* given buffer.
*
* @param buffer
* Buffer to receive data
* @param off
* Offset in buffer to store data
* @param nbytes
* Number of bytes to read
*/
@Override
public int read(byte[] buffer, int off, int nbytes) throws IOException {
if (closed) {
throw new IOException(Messages.getString("archive.1E")); //$NON-NLS-1$
}
if (eos) {
return -1;
}
// avoid int overflow, check null buffer
if (off > buffer.length || nbytes < 0 || off < 0
|| buffer.length - off < nbytes) {
throw new ArrayIndexOutOfBoundsException();
}
int bytesRead;
try {
bytesRead = super.read(buffer, off, nbytes);
} finally {
eos = eof; // update eos after every read(), even when it throws
}
if (bytesRead != -1) {
crc.update(buffer, off, bytesRead);
}
if (eos) {
verifyCrc();
}
return bytesRead;
}
private void verifyCrc() throws IOException {
// Get non-compressed bytes read by fill
int size = inf.getRemaining();
final int trailerSize = 8; // crc (4 bytes) + total out (4 bytes)
byte[] b = new byte[trailerSize];
int copySize = (size > trailerSize) ? trailerSize : size;
System.arraycopy(buf, len - size, b, 0, copySize);
readFully(b, copySize, trailerSize - copySize);
if (getLong(b, 0) != crc.getValue()) {
throw new IOException(Messages.getString("archive.20")); //$NON-NLS-1$
}
if ((int) getLong(b, 4) != inf.getTotalOut()) {
throw new IOException(Messages.getString("archive.21")); //$NON-NLS-1$
}
}
private void readFully(byte[] buffer, int offset, int length)
throws IOException {
int result;
while (length > 0) {
result = in.read(buffer, offset, length);
if (result == -1) {
throw new EOFException();
}
offset += result;
length -= result;
}
}
private void readZeroTerminated(boolean hcrc) throws IOException {
int result;
while ((result = in.read()) > 0) {
if (hcrc) {
crc.update(result);
}
}
if (result == -1) {
throw new EOFException();
}
// Add the zero
if (hcrc) {
crc.update(result);
}
}
}