| 1 | /* CompressedOutputStream.java -- |
| 2 | Copyright (C) 2003, 2004 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of GNU Classpath. |
| 5 | |
| 6 | GNU Classpath is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 2, or (at your option) |
| 9 | any later version. |
| 10 | |
| 11 | GNU Classpath is distributed in the hope that it will be useful, but |
| 12 | WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with GNU Classpath; see the file COPYING. If not, write to the |
| 18 | Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 19 | 02110-1301 USA. |
| 20 | |
| 21 | Linking this library statically or dynamically with other modules is |
| 22 | making a combined work based on this library. Thus, the terms and |
| 23 | conditions of the GNU General Public License cover the whole |
| 24 | combination. |
| 25 | |
| 26 | As a special exception, the copyright holders of this library give you |
| 27 | permission to link this library with independent modules to produce an |
| 28 | executable, regardless of the license terms of these independent |
| 29 | modules, and to copy and distribute the resulting executable under |
| 30 | terms of your choice, provided that you also meet, for each linked |
| 31 | independent module, the terms and conditions of the license of that |
| 32 | module. An independent module is a module which is not derived from |
| 33 | or based on this library. If you modify this library, you may extend |
| 34 | this exception to your version of the library, but you are not |
| 35 | obligated to do so. If you do not wish to do so, delete this |
| 36 | exception statement from your version. */ |
| 37 | |
| 38 | |
| 39 | package gnu.java.net.protocol.ftp; |
| 40 | |
| 41 | import java.io.IOException; |
| 42 | import java.io.OutputStream; |
| 43 | |
| 44 | /** |
| 45 | * A DTP output stream that implements the FTP compressed transfer mode. |
| 46 | * |
| 47 | * @author Chris Burdess (dog@gnu.org) |
| 48 | */ |
| 49 | class CompressedOutputStream |
| 50 | extends DTPOutputStream |
| 51 | { |
| 52 | |
| 53 | static final byte RECORD = -128; // 0x80 |
| 54 | static final byte EOF = 64; // 0x40 |
| 55 | |
| 56 | CompressedOutputStream(DTP dtp, OutputStream out) |
| 57 | { |
| 58 | super(dtp, out); |
| 59 | } |
| 60 | |
| 61 | /** |
| 62 | * Just one byte cannot be compressed. |
| 63 | * It takes 5 bytes to transmit - hardly very compressed! |
| 64 | */ |
| 65 | public void write(int c) |
| 66 | throws IOException |
| 67 | { |
| 68 | if (transferComplete) |
| 69 | { |
| 70 | return; |
| 71 | } |
| 72 | byte[] buf = new byte[] |
| 73 | { |
| 74 | RECORD, /* record descriptor */ |
| 75 | 0x00, 0x01, /* one byte */ |
| 76 | 0x01, /* one uncompressed byte */ |
| 77 | (byte) c /* the byte */ |
| 78 | }; |
| 79 | out.write(buf, 0, 5); |
| 80 | } |
| 81 | |
| 82 | public void write(byte[] b) |
| 83 | throws IOException |
| 84 | { |
| 85 | write(b, 0, b.length); |
| 86 | } |
| 87 | |
| 88 | /** |
| 89 | * The larger len is, the better. |
| 90 | */ |
| 91 | public void write(byte[] b, int off, int len) |
| 92 | throws IOException |
| 93 | { |
| 94 | if (transferComplete) |
| 95 | { |
| 96 | return; |
| 97 | } |
| 98 | byte[] buf = compress(b, off, len); |
| 99 | len = buf.length; |
| 100 | buf[0] = RECORD; /* record descriptor */ |
| 101 | buf[1] = (byte) ((len & 0x00ff) >> 8); /* high byte of bytecount */ |
| 102 | buf[2] = (byte) (len & 0xff00); /* low byte of bytecount */ |
| 103 | out.write(buf, 0, len); |
| 104 | } |
| 105 | |
| 106 | /** |
| 107 | * Returns the compressed form of the given byte array. |
| 108 | * The first 3 bytes are left free for header information. |
| 109 | */ |
| 110 | byte[] compress(byte[] b, int off, int len) |
| 111 | { |
| 112 | byte[] buf = new byte[len]; |
| 113 | byte last = 0; |
| 114 | int pos = 0, raw_count = 0, rep_count = 1; |
| 115 | for (int i = off; i < len; i++) |
| 116 | { |
| 117 | byte c = b[i]; |
| 118 | if (i > off && c == last) // compress |
| 119 | { |
| 120 | if (raw_count > 0) // flush raw bytes to buf |
| 121 | { |
| 122 | // need to add raw_count+1 bytes |
| 123 | if (pos + (raw_count + 1) > buf.length) |
| 124 | { |
| 125 | buf = realloc(buf, len); |
| 126 | } |
| 127 | pos = flush_raw(buf, pos, b, (i - raw_count) - 1, |
| 128 | raw_count); |
| 129 | raw_count = 0; |
| 130 | } |
| 131 | rep_count++; // keep looking for same byte |
| 132 | } |
| 133 | else |
| 134 | { |
| 135 | if (rep_count > 1) // flush compressed bytes to buf |
| 136 | { |
| 137 | // need to add 2 bytes |
| 138 | if (pos + 2 > buf.length) |
| 139 | { |
| 140 | buf = realloc(buf, len); |
| 141 | } |
| 142 | pos = flush_compressed(buf, pos, rep_count, last); |
| 143 | rep_count = 1; |
| 144 | } |
| 145 | raw_count++; // keep looking for raw bytes |
| 146 | } |
| 147 | if (rep_count == 127) // flush compressed bytes |
| 148 | { |
| 149 | // need to add 2 bytes |
| 150 | if (pos + 2 > buf.length) |
| 151 | { |
| 152 | buf = realloc(buf, len); |
| 153 | } |
| 154 | pos = flush_compressed(buf, pos, rep_count, last); |
| 155 | rep_count = 1; |
| 156 | } |
| 157 | if (raw_count == 127) // flush raw bytes |
| 158 | { |
| 159 | // need to add raw_count+1 bytes |
| 160 | if (pos + (raw_count + 1) > buf.length) |
| 161 | { |
| 162 | buf = realloc(buf, len); |
| 163 | } |
| 164 | pos = flush_raw(buf, pos, b, (i - raw_count), raw_count); |
| 165 | raw_count = 0; |
| 166 | } |
| 167 | last = c; |
| 168 | } |
| 169 | if (rep_count > 1) // flush compressed bytes |
| 170 | { |
| 171 | // need to add 2 bytes |
| 172 | if (pos + 2 > buf.length) |
| 173 | { |
| 174 | buf = realloc(buf, len); |
| 175 | } |
| 176 | pos = flush_compressed(buf, pos, rep_count, last); |
| 177 | rep_count = 1; |
| 178 | } |
| 179 | if (raw_count > 0) // flush raw bytes |
| 180 | { |
| 181 | // need to add raw_count+1 bytes |
| 182 | if (pos + (raw_count + 1) > buf.length) |
| 183 | { |
| 184 | buf = realloc(buf, len); |
| 185 | } |
| 186 | pos = flush_raw(buf, pos, b, (len - raw_count), raw_count); |
| 187 | raw_count = 0; |
| 188 | } |
| 189 | byte[] ret = new byte[pos + 3]; |
| 190 | System.arraycopy(buf, 0, ret, 3, pos); |
| 191 | return ret; |
| 192 | } |
| 193 | |
| 194 | int flush_compressed(byte[] buf, int pos, int count, byte c) |
| 195 | { |
| 196 | buf[pos++] = (byte) (0x80 | count); |
| 197 | buf[pos++] = c; |
| 198 | return pos; |
| 199 | } |
| 200 | |
| 201 | int flush_raw(byte[] buf, int pos, byte[] src, int off, int len) |
| 202 | { |
| 203 | buf[pos++] = (byte) len; |
| 204 | System.arraycopy(src, off, buf, pos, len); |
| 205 | return pos + len; |
| 206 | } |
| 207 | |
| 208 | byte[] realloc(byte[] buf, int len) |
| 209 | { |
| 210 | byte[] ret = new byte[buf.length + len]; |
| 211 | System.arraycopy(buf, 0, ret, 0, buf.length); |
| 212 | return ret; |
| 213 | } |
| 214 | |
| 215 | public void close() |
| 216 | throws IOException |
| 217 | { |
| 218 | byte[] buf = new byte[] |
| 219 | { |
| 220 | EOF, /* eof descriptor */ |
| 221 | 0x00, 0x00 /* no bytes */ |
| 222 | }; |
| 223 | out.write(buf, 0, 3); |
| 224 | out.close(); |
| 225 | } |
| 226 | |
| 227 | } |
| 228 | |