001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 *
017 */
018
019 package com.mucommander.file.impl.zip.provider;
020
021 import java.util.zip.CRC32;
022 import java.util.zip.ZipException;
023
024 /**
025 * Adds Unix file permission and UID/GID fields as well as symbolic
026 * link handling.
027 *
028 * <p>This class uses the ASi extra field in the format:
029 * <pre>
030 * Value Size Description
031 * ----- ---- -----------
032 * (Unix3) 0x756e Short tag for this extra block type
033 * TSize Short total data size for this block
034 * CRC Long CRC-32 of the remaining data
035 * Mode Short file permissions
036 * SizDev Long symlink'd size OR major/minor dev num
037 * UID Short user ID
038 * GID Short group ID
039 * (var.) variable symbolic link filename
040 * </pre>
041 * taken from appnote.iz (Info-ZIP note, 981119) found at <a
042 * href="ftp://ftp.uu.net/pub/archiving/zip/doc/">ftp://ftp.uu.net/pub/archiving/zip/doc/</a></p>
043 *
044 * <p>Short is two bytes and Long is four bytes in big endian byte and
045 * word order, device numbers are currently not supported.</p>
046 *
047 * <p>--------------------------------------------------------------------------------------------------------------<br>
048 * <br>
049 * This class is based off the <code>org.apache.tools.zip</code> package of the <i>Apache Ant</i> project. The Ant
050 * code has been modified under the terms of the Apache License which you can find in the bundled muCommander license
051 * file. It was forked at version 1.7.0 of Ant.</p>
052 *
053 * @author Apache Ant, Maxence Bernard
054 */
055 public class AsiExtraField implements ZipExtraField, UnixStat, Cloneable {
056
057 private static final ZipShort HEADER_ID = new ZipShort(0x756E);
058
059 /**
060 * Standard Unix stat(2) file mode.
061 */
062 private int mode = 0;
063 /**
064 * User ID.
065 */
066 private int uid = 0;
067 /**
068 * Group ID.
069 */
070 private int gid = 0;
071 /**
072 * File this entry points to, if it is a symbolic link.
073 *
074 * <p>empty string - if entry is not a symbolic link.</p>
075 */
076 private String link = "";
077 /**
078 * Is this an entry for a directory?
079 */
080 private boolean dirFlag = false;
081
082 /**
083 * Instance used to calculate checksums.
084 */
085 private CRC32 crc = new CRC32();
086
087 /** Constructor for AsiExtraField. */
088 public AsiExtraField() {
089 }
090
091 /**
092 * The Header-ID.
093 * @return the value for the header id for this extrafield
094 */
095 public ZipShort getHeaderId() {
096 return HEADER_ID;
097 }
098
099 /**
100 * Length of the extra field in the local file data - without
101 * Header-ID or length specifier.
102 * @return a <code>ZipShort</code> for the length of the data of this extra field
103 */
104 public ZipShort getLocalFileDataLength() {
105 return new ZipShort(4 // CRC
106 + 2 // Mode
107 + 4 // SizDev
108 + 2 // UID
109 + 2 // GID
110 + getLinkedFile().getBytes().length);
111 }
112
113 /**
114 * Delegate to local file data.
115 * @return the centralDirectory length
116 */
117 public ZipShort getCentralDirectoryLength() {
118 return getLocalFileDataLength();
119 }
120
121 /**
122 * The actual data to put into local file data - without Header-ID
123 * or length specifier.
124 * @return get the data
125 */
126 public byte[] getLocalFileDataData() {
127 // CRC will be added later
128 byte[] data = new byte[getLocalFileDataLength().getValue() - 4];
129 ZipShort.getBytes(getMode(), data, 0);
130
131 byte[] linkArray = getLinkedFile().getBytes();
132 ZipLong.getBytes(linkArray.length, data, 2);
133 ZipShort.getBytes(getUserId(), data, 6);
134 ZipShort.getBytes(getGroupId(), data, 8);
135 System.arraycopy(linkArray, 0, data, 10, linkArray.length);
136
137 crc.reset();
138 crc.update(data);
139 long checksum = crc.getValue();
140
141 byte[] result = new byte[data.length + 4];
142 ZipLong.getBytes(checksum, result, 0);
143 System.arraycopy(data, 0, result, 4, data.length);
144
145 return result;
146 }
147
148 /**
149 * Delegate to local file data.
150 * @return the local file data
151 */
152 public byte[] getCentralDirectoryData() {
153 return getLocalFileDataData();
154 }
155
156 /**
157 * Set the user id.
158 * @param uid the user id
159 */
160 public void setUserId(int uid) {
161 this.uid = uid;
162 }
163
164 /**
165 * Get the user id.
166 * @return the user id
167 */
168 public int getUserId() {
169 return uid;
170 }
171
172 /**
173 * Set the group id.
174 * @param gid the group id
175 */
176 public void setGroupId(int gid) {
177 this.gid = gid;
178 }
179
180 /**
181 * Get the group id.
182 * @return the group id
183 */
184 public int getGroupId() {
185 return gid;
186 }
187
188 /**
189 * Indicate that this entry is a symbolic link to the given filename.
190 *
191 * @param name Name of the file this entry links to, empty String
192 * if it is not a symbolic link.
193 */
194 public void setLinkedFile(String name) {
195 link = name;
196 mode = getMode(mode);
197 }
198
199 /**
200 * Name of linked file
201 *
202 * @return name of the file this entry links to if it is a
203 * symbolic link, the empty string otherwise.
204 */
205 public String getLinkedFile() {
206 return link;
207 }
208
209 /**
210 * Is this entry a symbolic link?
211 * @return true if this is a symbolic link
212 */
213 public boolean isLink() {
214 return getLinkedFile().length() != 0;
215 }
216
217 /**
218 * File mode of this file.
219 * @param mode the file mode
220 */
221 public void setMode(int mode) {
222 this.mode = getMode(mode);
223 }
224
225 /**
226 * File mode of this file.
227 * @return the file mode
228 */
229 public int getMode() {
230 return mode;
231 }
232
233 /**
234 * Indicate whether this entry is a directory.
235 * @param dirFlag if true, this entry is a directory
236 */
237 public void setDirectory(boolean dirFlag) {
238 this.dirFlag = dirFlag;
239 mode = getMode(mode);
240 }
241
242 /**
243 * Is this entry a directory?
244 * @return true if this entry is a directory
245 */
246 public boolean isDirectory() {
247 return dirFlag && !isLink();
248 }
249
250 /**
251 * Populate data from this array as if it was in local file data.
252 * @param data an array of bytes
253 * @param offset the start offset
254 * @param length the number of bytes in the array from offset
255 * @throws ZipException on error
256 */
257 public void parseFromLocalFileData(byte[] data, int offset, int length)
258 throws ZipException {
259
260 long givenChecksum = ZipLong.getValue(data, offset);
261 byte[] tmp = new byte[length - 4];
262 System.arraycopy(data, offset + 4, tmp, 0, length - 4);
263 crc.reset();
264 crc.update(tmp);
265 long realChecksum = crc.getValue();
266 if (givenChecksum != realChecksum) {
267 throw new ZipException("bad CRC checksum "
268 + Long.toHexString(givenChecksum)
269 + " instead of "
270 + Long.toHexString(realChecksum));
271 }
272
273 int newMode = ZipShort.getValue(tmp, 0);
274 byte[] linkArray = new byte[(int) ZipLong.getValue(tmp, 2)];
275 uid = ZipShort.getValue(tmp, 6);
276 gid = ZipShort.getValue(tmp, 8);
277
278 if (linkArray.length == 0) {
279 link = "";
280 } else {
281 System.arraycopy(tmp, 10, linkArray, 0, linkArray.length);
282 link = new String(linkArray);
283 }
284 setDirectory((newMode & DIR_FLAG) != 0);
285 setMode(newMode);
286 }
287
288 /**
289 * Get the file mode for given permissions with the correct file type.
290 * @param mode the mode
291 * @return the type with the mode
292 */
293 protected int getMode(int mode) {
294 int type = FILE_FLAG;
295 if (isLink()) {
296 type = LINK_FLAG;
297 } else if (isDirectory()) {
298 type = DIR_FLAG;
299 }
300 return type | (mode & PERM_MASK);
301 }
302
303 }