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snappy-java: A fast compression/decompression library
/*--------------------------------------------------------------------------
* Copyright 2011 Taro L. Saito
*
* Licensed 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.
*--------------------------------------------------------------------------*/
//--------------------------------------
// XerialJ
//
// SnappyInputStream.java
// Since: 2011/03/31 20:14:56
//
// $URL$
// $Author$
//--------------------------------------
package org.xerial.snappy;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* A stream filter for reading data compressed by {@link SnappyOutputStream}.
*
* @author leo
*/
public class SnappyInputStream
extends InputStream
{
private boolean finishedReading = false;
protected final InputStream in;
private byte[] compressed;
private byte[] uncompressed;
private int uncompressedCursor = 0;
private int uncompressedLimit = 0;
private byte[] header = new byte[SnappyCodec.headerSize()];
/**
* Create a filter for reading compressed data as a uncompressed stream
*
* @param input
* @throws IOException
*/
public SnappyInputStream(InputStream input)
throws IOException
{
this.in = input;
readHeader();
}
/**
* Close the stream
*/
/* (non-Javadoc)
* @see java.io.InputStream#close()
*/
@Override
public void close()
throws IOException
{
compressed = null;
uncompressed = null;
if (in != null) {
in.close();
}
}
protected void readHeader()
throws IOException
{
int readBytes = 0;
while (readBytes < header.length) {
int ret = in.read(header, readBytes, header.length - readBytes);
if (ret == -1) {
break;
}
readBytes += ret;
}
// Quick test of the header
if (readBytes == 0) {
// Snappy produces at least 1-byte result. So the empty input is not a valid input
throw new SnappyIOException(SnappyErrorCode.EMPTY_INPUT, "Cannot decompress empty stream");
}
if (readBytes < header.length || !SnappyCodec.hasMagicHeaderPrefix(header)) {
// do the default uncompression
// (probably) compressed by Snappy.compress(byte[])
readFully(header, readBytes);
return;
}
}
private static boolean isValidHeader(byte[] header)
throws IOException
{
SnappyCodec codec = SnappyCodec.readHeader(new ByteArrayInputStream(header));
if (codec.isValidMagicHeader()) {
// The input data is compressed by SnappyOutputStream
if (codec.version < SnappyCodec.MINIMUM_COMPATIBLE_VERSION) {
throw new SnappyIOException(SnappyErrorCode.INCOMPATIBLE_VERSION, String.format(
"Compressed with an incompatible codec version %d. At least version %d is required",
codec.version, SnappyCodec.MINIMUM_COMPATIBLE_VERSION));
}
return true;
}
else {
return false;
}
}
protected void readFully(byte[] fragment, int fragmentLength)
throws IOException
{
if (fragmentLength == 0) {
finishedReading = true;
return;
}
// read the entire input data to the buffer
compressed = new byte[Math.max(8 * 1024, fragmentLength)]; // 8K
System.arraycopy(fragment, 0, compressed, 0, fragmentLength);
int cursor = fragmentLength;
for (int readBytes = 0; (readBytes = in.read(compressed, cursor, compressed.length - cursor)) != -1; ) {
cursor += readBytes;
if (cursor >= compressed.length) {
byte[] newBuf = new byte[(compressed.length * 2)];
System.arraycopy(compressed, 0, newBuf, 0, compressed.length);
compressed = newBuf;
}
}
finishedReading = true;
// Uncompress
int uncompressedLength = Snappy.uncompressedLength(compressed, 0, cursor);
uncompressed = new byte[uncompressedLength];
Snappy.uncompress(compressed, 0, cursor, uncompressed, 0);
this.uncompressedCursor = 0;
this.uncompressedLimit = uncompressedLength;
}
/**
* Reads up to len bytes of data from the input stream into an array of
* bytes.
*/
/* (non-Javadoc)
* @see java.io.InputStream#read(byte[], int, int)
*/
@Override
public int read(byte[] b, int byteOffset, int byteLength)
throws IOException
{
int writtenBytes = 0;
for (; writtenBytes < byteLength; ) {
if (uncompressedCursor >= uncompressedLimit) {
if (hasNextChunk()) {
continue;
}
else {
return writtenBytes == 0 ? -1 : writtenBytes;
}
}
int bytesToWrite = Math.min(uncompressedLimit - uncompressedCursor, byteLength - writtenBytes);
System.arraycopy(uncompressed, uncompressedCursor, b, byteOffset + writtenBytes, bytesToWrite);
writtenBytes += bytesToWrite;
uncompressedCursor += bytesToWrite;
}
return writtenBytes;
}
/**
* Read uncompressed data into the specified array
*
* @param array
* @param byteOffset
* @param byteLength
* @return written bytes
* @throws IOException
*/
public int rawRead(Object array, int byteOffset, int byteLength)
throws IOException
{
int writtenBytes = 0;
for (; writtenBytes < byteLength; ) {
if (uncompressedCursor >= uncompressedLimit) {
if (hasNextChunk()) {
continue;
}
else {
return writtenBytes == 0 ? -1 : writtenBytes;
}
}
int bytesToWrite = Math.min(uncompressedLimit - uncompressedCursor, byteLength - writtenBytes);
Snappy.arrayCopy(uncompressed, uncompressedCursor, bytesToWrite, array, byteOffset + writtenBytes);
writtenBytes += bytesToWrite;
uncompressedCursor += bytesToWrite;
}
return writtenBytes;
}
/**
* Read long array from the stream
*
* @param d input
* @param off offset
* @param len the number of long elements to read
* @return the total number of bytes read into the buffer, or -1 if there is
* no more data because the end of the stream has been reached.
* @throws IOException
*/
public int read(long[] d, int off, int len)
throws IOException
{
return rawRead(d, off * 8, len * 8);
}
/**
* Read long array from the stream
*
* @param d
* @return the total number of bytes read into the buffer, or -1 if there is
* no more data because the end of the stream has been reached.
* @throws IOException
*/
public int read(long[] d)
throws IOException
{
return read(d, 0, d.length);
}
/**
* Read double array from the stream
*
* @param d input
* @param off offset
* @param len the number of double elements to read
* @return the total number of bytes read into the buffer, or -1 if there is
* no more data because the end of the stream has been reached.
* @throws IOException
*/
public int read(double[] d, int off, int len)
throws IOException
{
return rawRead(d, off * 8, len * 8);
}
/**
* Read double array from the stream
*
* @param d
* @return the total number of bytes read into the buffer, or -1 if there is
* no more data because the end of the stream has been reached.
* @throws IOException
*/
public int read(double[] d)
throws IOException
{
return read(d, 0, d.length);
}
/**
* Read int array from the stream
*
* @param d
* @return the total number of bytes read into the buffer, or -1 if there is
* no more data because the end of the stream has been reached.
* @throws IOException
*/
public int read(int[] d)
throws IOException
{
return read(d, 0, d.length);
}
/**
* Read int array from the stream
*
* @param d input
* @param off offset
* @param len the number of int elements to read
* @return the total number of bytes read into the buffer, or -1 if there is
* no more data because the end of the stream has been reached.
* @throws IOException
*/
public int read(int[] d, int off, int len)
throws IOException
{
return rawRead(d, off * 4, len * 4);
}
/**
* Read float array from the stream
*
* @param d input
* @param off offset
* @param len the number of float elements to read
* @return the total number of bytes read into the buffer, or -1 if there is
* no more data because the end of the stream has been reached.
* @throws IOException
*/
public int read(float[] d, int off, int len)
throws IOException
{
return rawRead(d, off * 4, len * 4);
}
/**
* Read float array from the stream
*
* @param d
* @return the total number of bytes read into the buffer, or -1 if there is
* no more data because the end of the stream has been reached.
* @throws IOException
*/
public int read(float[] d)
throws IOException
{
return read(d, 0, d.length);
}
/**
* Read short array from the stream
*
* @param d input
* @param off offset
* @param len the number of short elements to read
* @return the total number of bytes read into the buffer, or -1 if there is
* no more data because the end of the stream has been reached.
* @throws IOException
*/
public int read(short[] d, int off, int len)
throws IOException
{
return rawRead(d, off * 2, len * 2);
}
/**
* Read short array from the stream
*
* @param d
* @return the total number of bytes read into the buffer, or -1 if there is
* no more data because the end of the stream has been reached.
* @throws IOException
*/
public int read(short[] d)
throws IOException
{
return read(d, 0, d.length);
}
/**
* Read next len bytes
*
* @param dest
* @param offset
* @param len
* @return read bytes
*/
private int readNext(byte[] dest, int offset, int len)
throws IOException
{
int readBytes = 0;
while (readBytes < len) {
int ret = in.read(dest, readBytes + offset, len - readBytes);
if (ret == -1) {
finishedReading = true;
return readBytes;
}
readBytes += ret;
}
return readBytes;
}
protected boolean hasNextChunk()
throws IOException
{
if (finishedReading) {
return false;
}
uncompressedCursor = 0;
uncompressedLimit = 0;
int readBytes = readNext(header, 0, 4);
if (readBytes < 4) {
return false;
}
int chunkSize = SnappyOutputStream.readInt(header, 0);
if (chunkSize == SnappyCodec.MAGIC_HEADER_HEAD) {
// Concatenated data
int remainingHeaderSize = SnappyCodec.headerSize() - 4;
readBytes = readNext(header, 4, remainingHeaderSize);
if(readBytes < remainingHeaderSize) {
throw new SnappyIOException(SnappyErrorCode.FAILED_TO_UNCOMPRESS, String.format("Insufficient header size in a concatenated block"));
}
if (isValidHeader(header)) {
return hasNextChunk();
}
else {
return false;
}
}
// extend the compressed data buffer size
if (compressed == null || chunkSize > compressed.length) {
compressed = new byte[chunkSize];
}
readBytes = 0;
while (readBytes < chunkSize) {
int ret = in.read(compressed, readBytes, chunkSize - readBytes);
if (ret == -1) {
break;
}
readBytes += ret;
}
if (readBytes < chunkSize) {
throw new IOException("failed to read chunk");
}
int uncompressedLength = Snappy.uncompressedLength(compressed, 0, chunkSize);
if (uncompressed == null || uncompressedLength > uncompressed.length) {
uncompressed = new byte[uncompressedLength];
}
int actualUncompressedLength = Snappy.uncompress(compressed, 0, chunkSize, uncompressed, 0);
if (uncompressedLength != actualUncompressedLength) {
throw new SnappyIOException(SnappyErrorCode.INVALID_CHUNK_SIZE, String.format("expected %,d bytes, but decompressed chunk has %,d bytes", uncompressedLength, actualUncompressedLength));
}
uncompressedLimit = actualUncompressedLength;
return true;
}
/**
* Reads the next byte of uncompressed data from the input stream. The value
* byte is returned as an int in the range 0 to 255. If no byte is available
* because the end of the stream has been reached, the value -1 is returned.
* This method blocks until input data is available, the end of the stream
* is detected, or an exception is thrown.
*/
/* (non-Javadoc)
* @see java.io.InputStream#read()
*/
@Override
public int read()
throws IOException
{
if (uncompressedCursor < uncompressedLimit) {
return uncompressed[uncompressedCursor++] & 0xFF;
}
else {
if (hasNextChunk()) {
return read();
}
else {
return -1;
}
}
}
/* (non-Javadoc)
* @see java.io.InputStream#available()
*/
@Override
public int available()
throws IOException
{
if (uncompressedCursor < uncompressedLimit) {
return uncompressedLimit - uncompressedCursor;
}
else {
if (hasNextChunk()) {
return uncompressedLimit - uncompressedCursor;
}
else {
return 0;
}
}
}
}
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