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/* Copyright 2017 Google Inc. All Rights Reserved.
Distributed under MIT license.
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/
package org.brotli.wrapper.dec;
import java.io.IOException;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;
import java.util.ArrayList;
/**
* Base class for InputStream / Channel implementations.
*/
public class Decoder {
private static final ByteBuffer EMPTY_BUFFER = ByteBuffer.allocate(0);
private final ReadableByteChannel source;
private final DecoderJNI.Wrapper decoder;
ByteBuffer buffer;
boolean closed;
boolean eager;
/**
* Creates a Decoder wrapper.
*
* @param source underlying source
* @param inputBufferSize read buffer size
*/
public Decoder(ReadableByteChannel source, int inputBufferSize)
throws IOException {
if (inputBufferSize <= 0) {
throw new IllegalArgumentException("buffer size must be positive");
}
if (source == null) {
throw new NullPointerException("source can not be null");
}
this.source = source;
this.decoder = new DecoderJNI.Wrapper(inputBufferSize);
}
private void fail(String message) throws IOException {
try {
close();
} catch (IOException ex) {
/* Ignore */
}
throw new IOException(message);
}
void attachDictionary(ByteBuffer dictionary) throws IOException {
if (!decoder.attachDictionary(dictionary)) {
fail("failed to attach dictionary");
}
}
public void enableEagerOutput() {
this.eager = true;
}
/**
* Continue decoding.
*
* @return -1 if stream is finished, or number of bytes available in read buffer (> 0)
*/
int decode() throws IOException {
while (true) {
if (buffer != null) {
if (!buffer.hasRemaining()) {
buffer = null;
} else {
return buffer.remaining();
}
}
switch (decoder.getStatus()) {
case DONE:
return -1;
case OK:
decoder.push(0);
break;
case NEEDS_MORE_INPUT:
// In "eager" more pulling preempts pushing.
if (eager && decoder.hasOutput()) {
buffer = decoder.pull();
break;
}
ByteBuffer inputBuffer = decoder.getInputBuffer();
((Buffer) inputBuffer).clear();
int bytesRead = source.read(inputBuffer);
if (bytesRead == -1) {
fail("unexpected end of input");
}
if (bytesRead == 0) {
// No input data is currently available.
buffer = EMPTY_BUFFER;
return 0;
}
decoder.push(bytesRead);
break;
case NEEDS_MORE_OUTPUT:
buffer = decoder.pull();
break;
default:
fail("corrupted input");
}
}
}
void discard(int length) {
((Buffer) buffer).position(buffer.position() + length);
if (!buffer.hasRemaining()) {
buffer = null;
}
}
int consume(ByteBuffer dst) {
ByteBuffer slice = buffer.slice();
int limit = Math.min(slice.remaining(), dst.remaining());
((Buffer) slice).limit(limit);
dst.put(slice);
discard(limit);
return limit;
}
void close() throws IOException {
if (closed) {
return;
}
closed = true;
decoder.destroy();
source.close();
}
/** Decodes the given data buffer starting at offset till length. */
public static byte[] decompress(byte[] data, int offset, int length) throws IOException {
DecoderJNI.Wrapper decoder = new DecoderJNI.Wrapper(length);
ArrayList<byte[]> output = new ArrayList<byte[]>();
int totalOutputSize = 0;
try {
decoder.getInputBuffer().put(data, offset, length);
decoder.push(length);
while (decoder.getStatus() != DecoderJNI.Status.DONE) {
switch (decoder.getStatus()) {
case OK:
decoder.push(0);
break;
case NEEDS_MORE_OUTPUT:
ByteBuffer buffer = decoder.pull();
byte[] chunk = new byte[buffer.remaining()];
buffer.get(chunk);
output.add(chunk);
totalOutputSize += chunk.length;
break;
case NEEDS_MORE_INPUT:
// Give decoder a chance to process the remaining of the buffered byte.
decoder.push(0);
// If decoder still needs input, this means that stream is truncated.
if (decoder.getStatus() == DecoderJNI.Status.NEEDS_MORE_INPUT) {
throw new IOException("corrupted input");
}
break;
default:
throw new IOException("corrupted input");
}
}
} finally {
decoder.destroy();
}
if (output.size() == 1) {
return output.get(0);
}
byte[] result = new byte[totalOutputSize];
int resultOffset = 0;
for (byte[] chunk : output) {
System.arraycopy(chunk, 0, result, resultOffset, chunk.length);
resultOffset += chunk.length;
}
return result;
}
/** Decodes the given data buffer. */
public static byte[] decompress(byte[] data) throws IOException {
return decompress(data, 0, data.length);
}
}
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