/* * $Id: CompressedInputStream.java,v 1.1 2003/10/19 08:51:37 dog Exp $ * Copyright (C) 2003 The Free Software Foundation * * This file is part of GNU inetlib, a library. * * GNU inetlib is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * GNU inetlib is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * As a special exception, if you link this library with other files to * produce an executable, this library does not by itself cause the * resulting executable to be covered by the GNU General Public License. * This exception does not however invalidate any other reasons why the * executable file might be covered by the GNU General Public License. */ package gnu.inet.ftp; import java.io.InputStream; import java.io.IOException; import java.net.ProtocolException; /** * A DTP input stream that implements the FTP compressed transfer mode. * * @author Chris Burdess * @version $Revision: 1.1 $ $Date: 2003/10/19 08:51:37 $ */ class CompressedInputStream extends DTPInputStream { static final int EOF = 64; static final int RAW = 0x00; static final int COMPRESSED = 0x80; static final int FILLER = 0xc0; int descriptor; int max = -1; int count = -1; int state = RAW; // RAW | STATE | FILLER int rep; // the compressed byte int n = 0; // the number of compressed or raw bytes CompressedInputStream(DTP dtp, InputStream in) { super(dtp, in); } public int read() throws IOException { if (transferComplete) return -1; if (count==-1) readHeader(); if (max<1) { close(); return -1; } if (n>0 && (state==COMPRESSED || state==FILLER)) { n--; return rep; } int c = super.read(); if (c==-1) close(); count++; if (count>=max) { count = -1; if (descriptor==EOF) close(); } if (c==-1) return c; while (n==0) // read code header { state = (c & 0xc0); n = (c & 0x3f); c = super.read(); if (c==-1) return -1; } switch (state) { case RAW: break; case COMPRESSED: case FILLER: rep = c; break; default: throw new ProtocolException("Illegal state: "+state); } n--; return c; } public int read(byte[] buf) throws IOException { return read(buf, 0, buf.length); } public int read(byte[] buf, int off, int len) throws IOException { if (transferComplete) return -1; if (count==-1) readHeader(); if (max<1) { close(); return -1; } // TODO improve performance for (int i=off; i=max) { count = -1; if (descriptor==EOF) close(); } return l; */ } /** * Reads the block header. */ void readHeader() throws IOException { descriptor = super.read(); int max_hi = super.read(); int max_lo = super.read(); max = (max_hi<<8) | max_lo; count = 0; } /** * Reads the code header. */ void readCodeHeader() throws IOException { int code = super.read(); state = (code & 0xc0); n = (code & 0x3f); } }