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 package org.apache.commons.compress.archivers.zip;
019
020 import java.io.IOException;
021 import java.util.Calendar;
022 import java.util.Date;
023 import java.util.zip.CRC32;
024
025 /**
026 * Utility class for handling DOS and Java time conversions.
027 * @Immutable
028 */
029 public abstract class ZipUtil {
030 /**
031 * Smallest date/time ZIP can handle.
032 */
033 private static final byte[] DOS_TIME_MIN = ZipLong.getBytes(0x00002100L);
034
035 /**
036 * Convert a Date object to a DOS date/time field.
037 * @param time the <code>Date</code> to convert
038 * @return the date as a <code>ZipLong</code>
039 */
040 public static ZipLong toDosTime(Date time) {
041 return new ZipLong(toDosTime(time.getTime()));
042 }
043
044 /**
045 * Convert a Date object to a DOS date/time field.
046 *
047 * <p>Stolen from InfoZip's <code>fileio.c</code></p>
048 * @param t number of milliseconds since the epoch
049 * @return the date as a byte array
050 */
051 public static byte[] toDosTime(long t) {
052 Calendar c = Calendar.getInstance();
053 c.setTimeInMillis(t);
054
055 int year = c.get(Calendar.YEAR);
056 if (year < 1980) {
057 return copy(DOS_TIME_MIN); // stop callers from changing the array
058 }
059 int month = c.get(Calendar.MONTH) + 1;
060 long value = ((year - 1980) << 25)
061 | (month << 21)
062 | (c.get(Calendar.DAY_OF_MONTH) << 16)
063 | (c.get(Calendar.HOUR_OF_DAY) << 11)
064 | (c.get(Calendar.MINUTE) << 5)
065 | (c.get(Calendar.SECOND) >> 1);
066 return ZipLong.getBytes(value);
067 }
068
069 /**
070 * Assumes a negative integer really is a positive integer that
071 * has wrapped around and re-creates the original value.
072 * @param i the value to treat as unsigned int.
073 * @return the unsigned int as a long.
074 */
075 public static long adjustToLong(int i) {
076 if (i < 0) {
077 return 2 * ((long) Integer.MAX_VALUE) + 2 + i;
078 } else {
079 return i;
080 }
081 }
082
083 /**
084 * Convert a DOS date/time field to a Date object.
085 *
086 * @param zipDosTime contains the stored DOS time.
087 * @return a Date instance corresponding to the given time.
088 */
089 public static Date fromDosTime(ZipLong zipDosTime) {
090 long dosTime = zipDosTime.getValue();
091 return new Date(dosToJavaTime(dosTime));
092 }
093
094 /**
095 * Converts DOS time to Java time (number of milliseconds since
096 * epoch).
097 */
098 public static long dosToJavaTime(long dosTime) {
099 Calendar cal = Calendar.getInstance();
100 // CheckStyle:MagicNumberCheck OFF - no point
101 cal.set(Calendar.YEAR, (int) ((dosTime >> 25) & 0x7f) + 1980);
102 cal.set(Calendar.MONTH, (int) ((dosTime >> 21) & 0x0f) - 1);
103 cal.set(Calendar.DATE, (int) (dosTime >> 16) & 0x1f);
104 cal.set(Calendar.HOUR_OF_DAY, (int) (dosTime >> 11) & 0x1f);
105 cal.set(Calendar.MINUTE, (int) (dosTime >> 5) & 0x3f);
106 cal.set(Calendar.SECOND, (int) (dosTime << 1) & 0x3e);
107 // CheckStyle:MagicNumberCheck ON
108 return cal.getTime().getTime();
109 }
110
111 /**
112 * If the entry has Unicode*ExtraFields and the CRCs of the
113 * names/comments match those of the extra fields, transfer the
114 * known Unicode values from the extra field.
115 */
116 static void setNameAndCommentFromExtraFields(ZipArchiveEntry ze,
117 byte[] originalNameBytes,
118 byte[] commentBytes) {
119 UnicodePathExtraField name = (UnicodePathExtraField)
120 ze.getExtraField(UnicodePathExtraField.UPATH_ID);
121 String originalName = ze.getName();
122 String newName = getUnicodeStringIfOriginalMatches(name,
123 originalNameBytes);
124 if (newName != null && !originalName.equals(newName)) {
125 ze.setName(newName);
126 }
127
128 if (commentBytes != null && commentBytes.length > 0) {
129 UnicodeCommentExtraField cmt = (UnicodeCommentExtraField)
130 ze.getExtraField(UnicodeCommentExtraField.UCOM_ID);
131 String newComment =
132 getUnicodeStringIfOriginalMatches(cmt, commentBytes);
133 if (newComment != null) {
134 ze.setComment(newComment);
135 }
136 }
137 }
138
139 /**
140 * If the stored CRC matches the one of the given name, return the
141 * Unicode name of the given field.
142 *
143 * <p>If the field is null or the CRCs don't match, return null
144 * instead.</p>
145 */
146 private static
147 String getUnicodeStringIfOriginalMatches(AbstractUnicodeExtraField f,
148 byte[] orig) {
149 if (f != null) {
150 CRC32 crc32 = new CRC32();
151 crc32.update(orig);
152 long origCRC32 = crc32.getValue();
153
154 if (origCRC32 == f.getNameCRC32()) {
155 try {
156 return ZipEncodingHelper
157 .UTF8_ZIP_ENCODING.decode(f.getUnicodeName());
158 } catch (IOException ex) {
159 // UTF-8 unsupported? should be impossible the
160 // Unicode*ExtraField must contain some bad bytes
161
162 // TODO log this anywhere?
163 return null;
164 }
165 }
166 }
167 return null;
168 }
169
170 /**
171 * Create a copy of the given array - or return null if the
172 * argument is null.
173 */
174 static byte[] copy(byte[] from) {
175 if (from != null) {
176 byte[] to = new byte[from.length];
177 System.arraycopy(from, 0, to, 0, to.length);
178 return to;
179 }
180 return null;
181 }
182
183 /**
184 * Whether this library is able to read or write the given entry.
185 */
186 static boolean canHandleEntryData(ZipArchiveEntry entry) {
187 return supportsEncryptionOf(entry) && supportsMethodOf(entry);
188 }
189
190 /**
191 * Whether this library supports the encryption used by the given
192 * entry.
193 *
194 * @return true if the entry isn't encrypted at all
195 */
196 private static boolean supportsEncryptionOf(ZipArchiveEntry entry) {
197 return !entry.getGeneralPurposeBit().usesEncryption();
198 }
199
200 /**
201 * Whether this library supports the compression method used by
202 * the given entry.
203 *
204 * @return true if the compression method is STORED or DEFLATED
205 */
206 private static boolean supportsMethodOf(ZipArchiveEntry entry) {
207 return entry.getMethod() == ZipArchiveEntry.STORED
208 || entry.getMethod() == ZipArchiveEntry.DEFLATED;
209 }
210
211 /**
212 * Checks whether the entry requires features not (yet) supported
213 * by the library and throws an exception if it does.
214 */
215 static void checkRequestedFeatures(ZipArchiveEntry ze)
216 throws UnsupportedZipFeatureException {
217 if (!supportsEncryptionOf(ze)) {
218 throw
219 new UnsupportedZipFeatureException(UnsupportedZipFeatureException
220 .Feature.ENCRYPTION, ze);
221 }
222 if (!supportsMethodOf(ze)) {
223 throw
224 new UnsupportedZipFeatureException(UnsupportedZipFeatureException
225 .Feature.METHOD, ze);
226 }
227 }
228 }