| /* CompressedOutputStream.java -- |
| Copyright (C) 2003, 2004 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath 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, or (at your option) |
| any later version. |
| |
| GNU Classpath 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 GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package gnu.java.net.protocol.ftp; |
| |
| import java.io.IOException; |
| import java.io.OutputStream; |
| |
| /** |
| * A DTP output stream that implements the FTP compressed transfer mode. |
| * |
| * @author Chris Burdess (dog@gnu.org) |
| */ |
| class CompressedOutputStream |
| extends DTPOutputStream |
| { |
| |
| static final byte RECORD = -128; // 0x80 |
| static final byte EOF = 64; // 0x40 |
| |
| CompressedOutputStream(DTP dtp, OutputStream out) |
| { |
| super(dtp, out); |
| } |
| |
| /** |
| * Just one byte cannot be compressed. |
| * It takes 5 bytes to transmit - hardly very compressed! |
| */ |
| public void write(int c) |
| throws IOException |
| { |
| if (transferComplete) |
| { |
| return; |
| } |
| byte[] buf = new byte[] |
| { |
| RECORD, /* record descriptor */ |
| 0x00, 0x01, /* one byte */ |
| 0x01, /* one uncompressed byte */ |
| (byte) c /* the byte */ |
| }; |
| out.write(buf, 0, 5); |
| } |
| |
| public void write(byte[] b) |
| throws IOException |
| { |
| write(b, 0, b.length); |
| } |
| |
| /** |
| * The larger len is, the better. |
| */ |
| public void write(byte[] b, int off, int len) |
| throws IOException |
| { |
| if (transferComplete) |
| { |
| return; |
| } |
| byte[] buf = compress(b, off, len); |
| len = buf.length; |
| buf[0] = RECORD; /* record descriptor */ |
| buf[1] = (byte) ((len & 0x00ff) >> 8); /* high byte of bytecount */ |
| buf[2] = (byte) (len & 0xff00); /* low byte of bytecount */ |
| out.write(buf, 0, len); |
| } |
| |
| /** |
| * Returns the compressed form of the given byte array. |
| * The first 3 bytes are left free for header information. |
| */ |
| byte[] compress(byte[] b, int off, int len) |
| { |
| byte[] buf = new byte[len]; |
| byte last = 0; |
| int pos = 0, raw_count = 0, rep_count = 1; |
| for (int i = off; i < len; i++) |
| { |
| byte c = b[i]; |
| if (i > off && c == last) // compress |
| { |
| if (raw_count > 0) // flush raw bytes to buf |
| { |
| // need to add raw_count+1 bytes |
| if (pos + (raw_count + 1) > buf.length) |
| { |
| buf = realloc(buf, len); |
| } |
| pos = flush_raw(buf, pos, b, (i - raw_count) - 1, |
| raw_count); |
| raw_count = 0; |
| } |
| rep_count++; // keep looking for same byte |
| } |
| else |
| { |
| if (rep_count > 1) // flush compressed bytes to buf |
| { |
| // need to add 2 bytes |
| if (pos + 2 > buf.length) |
| { |
| buf = realloc(buf, len); |
| } |
| pos = flush_compressed(buf, pos, rep_count, last); |
| rep_count = 1; |
| } |
| raw_count++; // keep looking for raw bytes |
| } |
| if (rep_count == 127) // flush compressed bytes |
| { |
| // need to add 2 bytes |
| if (pos + 2 > buf.length) |
| { |
| buf = realloc(buf, len); |
| } |
| pos = flush_compressed(buf, pos, rep_count, last); |
| rep_count = 1; |
| } |
| if (raw_count == 127) // flush raw bytes |
| { |
| // need to add raw_count+1 bytes |
| if (pos + (raw_count + 1) > buf.length) |
| { |
| buf = realloc(buf, len); |
| } |
| pos = flush_raw(buf, pos, b, (i - raw_count), raw_count); |
| raw_count = 0; |
| } |
| last = c; |
| } |
| if (rep_count > 1) // flush compressed bytes |
| { |
| // need to add 2 bytes |
| if (pos + 2 > buf.length) |
| { |
| buf = realloc(buf, len); |
| } |
| pos = flush_compressed(buf, pos, rep_count, last); |
| rep_count = 1; |
| } |
| if (raw_count > 0) // flush raw bytes |
| { |
| // need to add raw_count+1 bytes |
| if (pos + (raw_count + 1) > buf.length) |
| { |
| buf = realloc(buf, len); |
| } |
| pos = flush_raw(buf, pos, b, (len - raw_count), raw_count); |
| raw_count = 0; |
| } |
| byte[] ret = new byte[pos + 3]; |
| System.arraycopy(buf, 0, ret, 3, pos); |
| return ret; |
| } |
| |
| int flush_compressed(byte[] buf, int pos, int count, byte c) |
| { |
| buf[pos++] = (byte) (0x80 | count); |
| buf[pos++] = c; |
| return pos; |
| } |
| |
| int flush_raw(byte[] buf, int pos, byte[] src, int off, int len) |
| { |
| buf[pos++] = (byte) len; |
| System.arraycopy(src, off, buf, pos, len); |
| return pos + len; |
| } |
| |
| byte[] realloc(byte[] buf, int len) |
| { |
| byte[] ret = new byte[buf.length + len]; |
| System.arraycopy(buf, 0, ret, 0, buf.length); |
| return ret; |
| } |
| |
| public void close() |
| throws IOException |
| { |
| byte[] buf = new byte[] |
| { |
| EOF, /* eof descriptor */ |
| 0x00, 0x00 /* no bytes */ |
| }; |
| out.write(buf, 0, 3); |
| out.close(); |
| } |
| |
| } |
| |