kitaev@213: /*
kitaev@213:  * Copyright (c) 2011 TMate Software Ltd
kitaev@213:  *  
kitaev@213:  * This program is free software; you can redistribute it and/or modify
kitaev@213:  * it under the terms of the GNU General Public License as published by
kitaev@213:  * the Free Software Foundation; version 2 of the License.
kitaev@213:  *
kitaev@213:  * This program is distributed in the hope that it will be useful,
kitaev@213:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
kitaev@213:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
kitaev@213:  * GNU General Public License for more details.
kitaev@213:  *
kitaev@213:  * For information on how to redistribute this software under
kitaev@213:  * the terms of a license other than GNU General Public License
kitaev@213:  * contact TMate Software at support@hg4j.com
kitaev@213:  */
kitaev@213: package org.tmatesoft.hg.internal;
kitaev@213: 
kitaev@213: import java.io.EOFException;
kitaev@213: import java.io.IOException;
kitaev@213: import java.util.zip.DataFormatException;
kitaev@213: import java.util.zip.Inflater;
kitaev@213: import java.util.zip.ZipException;
kitaev@213: 
kitaev@213: import org.tmatesoft.hg.core.HgBadStateException;
kitaev@213: 
kitaev@213: 
kitaev@213: /**
kitaev@213:  * DataAccess counterpart for InflaterInputStream.
kitaev@213:  * XXX is it really needed to be subclass of FilterDataAccess? 
kitaev@213:  *   
kitaev@213:  * @author Artem Tikhomirov
kitaev@213:  * @author TMate Software Ltd.
kitaev@213:  */
kitaev@213: public class InflaterDataAccess extends FilterDataAccess {
kitaev@213: 
kitaev@213: 	private final Inflater inflater;
kitaev@213: 	private final byte[] buffer;
kitaev@213: 	private final byte[] singleByte = new byte[1];
kitaev@213: 	private int decompressedPos = 0;
kitaev@213: 	private int decompressedLength;
kitaev@213: 
kitaev@213: 	public InflaterDataAccess(DataAccess dataAccess, int offset, int compressedLength) {
kitaev@213: 		this(dataAccess, offset, compressedLength, -1, new Inflater(), 512);
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	public InflaterDataAccess(DataAccess dataAccess, int offset, int compressedLength, int actualLength) {
kitaev@213: 		this(dataAccess, offset, compressedLength, actualLength, new Inflater(), 512);
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	public InflaterDataAccess(DataAccess dataAccess, int offset, int compressedLength, int actualLength, Inflater inflater, int bufSize) {
kitaev@213: 		super(dataAccess, offset, compressedLength);
kitaev@213: 		this.inflater = inflater;
kitaev@213: 		this.decompressedLength = actualLength;
kitaev@213: 		buffer = new byte[bufSize];
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	@Override
kitaev@213: 	public InflaterDataAccess reset() throws IOException {
kitaev@213: 		super.reset();
kitaev@213: 		inflater.reset();
kitaev@213: 		decompressedPos = 0;
kitaev@213: 		return this;
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	@Override
kitaev@213: 	protected int available() {
kitaev@213: 		return length() - decompressedPos;
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	@Override
kitaev@213: 	public boolean isEmpty() {
kitaev@213: 		// can't use super.available() <= 0 because even when 0 < super.count < 6(?)
kitaev@213: 		// decompressedPos might be already == length() 
kitaev@213: 		return available() <= 0;
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	@Override
kitaev@213: 	public int length() {
kitaev@213: 		if (decompressedLength != -1) {
kitaev@213: 			return decompressedLength;
kitaev@213: 		}
kitaev@213: 		decompressedLength = 0; // guard to avoid endless loop in case length() would get invoked from below. 
kitaev@213: 		int c = 0;
kitaev@213: 		try {
kitaev@213: 			int oldPos = decompressedPos;
kitaev@213: 			byte[] dummy = new byte[buffer.length];
kitaev@213: 			int toRead;
kitaev@213: 			while ((toRead = super.available()) > 0) {
kitaev@213: 				if (toRead > buffer.length) {
kitaev@213: 					toRead = buffer.length;
kitaev@213: 				}
kitaev@213: 				super.readBytes(buffer, 0, toRead);
kitaev@213: 				inflater.setInput(buffer, 0, toRead);
kitaev@213: 				try {
kitaev@213: 					while (!inflater.needsInput()) {
kitaev@213: 						c += inflater.inflate(dummy, 0, dummy.length);
kitaev@213: 					}
kitaev@213: 				} catch (DataFormatException ex) {
kitaev@213: 					throw new HgBadStateException(ex);
kitaev@213: 				}
kitaev@213: 			}
kitaev@213: 			decompressedLength = c + oldPos;
kitaev@213: 			reset();
kitaev@213: 			seek(oldPos);
kitaev@213: 			return decompressedLength;
kitaev@213: 		} catch (IOException ex) {
kitaev@213: 			decompressedLength = -1; // better luck next time?
kitaev@213: 			throw new HgBadStateException(ex); // XXX perhaps, checked exception
kitaev@213: 		}
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	@Override
kitaev@213: 	public void seek(int localOffset) throws IOException {
kitaev@213: 		if (localOffset < 0 /* || localOffset >= length() */) {
kitaev@213: 			throw new IllegalArgumentException();
kitaev@213: 		}
kitaev@213: 		if (localOffset >= decompressedPos) {
kitaev@213: 			skip((int) (localOffset - decompressedPos));
kitaev@213: 		} else {
kitaev@213: 			reset();
kitaev@213: 			skip((int) localOffset);
kitaev@213: 		}
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	@Override
kitaev@213: 	public void skip(int bytes) throws IOException {
kitaev@213: 		if (bytes < 0) {
kitaev@213: 			bytes += decompressedPos;
kitaev@213: 			if (bytes < 0) {
kitaev@213: 				throw new IOException("Underflow. Rewind past start of the slice.");
kitaev@213: 			}
kitaev@213: 			reset();
kitaev@213: 			// fall-through
kitaev@213: 		}
kitaev@213: 		while (!isEmpty() && bytes > 0) {
kitaev@213: 			readByte();
kitaev@213: 			bytes--;
kitaev@213: 		}
kitaev@213: 		if (bytes != 0) {
kitaev@213: 			throw new IOException("Underflow. Rewind past end of the slice");
kitaev@213: 		}
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	@Override
kitaev@213: 	public byte readByte() throws IOException {
kitaev@213: 		readBytes(singleByte, 0, 1);
kitaev@213: 		return singleByte[0];
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	@Override
kitaev@213: 	public void readBytes(byte[] b, int off, int len) throws IOException {
kitaev@213: 		try {
kitaev@213: 		    int n;
kitaev@213: 		    while (len > 0) {
kitaev@213: 			    while ((n = inflater.inflate(b, off, len)) == 0) {
kitaev@213: 			    	// FIXME few last bytes (checksum?) may be ignored by inflater, thus inflate may return 0 in
kitaev@213: 			    	// perfectly legal conditions (when all data already expanded, but there are still some bytes
kitaev@213: 			    	// in the input stream
kitaev@213: 					if (inflater.finished() || inflater.needsDictionary()) {
kitaev@213: 	                    throw new EOFException();
kitaev@213: 					}
kitaev@213: 					if (inflater.needsInput()) {
kitaev@213: 						// fill:
kitaev@213: 						int toRead = super.available();
kitaev@213: 						if (toRead > buffer.length) {
kitaev@213: 							toRead = buffer.length;
kitaev@213: 						}
kitaev@213: 						super.readBytes(buffer, 0, toRead);
kitaev@213: 						inflater.setInput(buffer, 0, toRead);
kitaev@213: 					}
kitaev@213: 			    }
kitaev@213: 				off += n;
kitaev@213: 				len -= n;
kitaev@213: 				decompressedPos += n;
kitaev@213: 				if (len == 0) {
kitaev@213: 					return; // filled
kitaev@213: 				}
kitaev@213: 		    }
kitaev@213: 		} catch (DataFormatException e) {
kitaev@213: 		    String s = e.getMessage();
kitaev@213: 		    throw new ZipException(s != null ? s : "Invalid ZLIB data format");
kitaev@213: 		}
kitaev@213:     }
kitaev@213: }