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 /**
021 * Parser/encoder for the "general purpose bit" field in ZIP's local
022 * file and central directory headers.
023 * @since 1.1
024 * @NotThreadSafe
025 */
026 public final class GeneralPurposeBit {
027 /**
028 * Indicates that the file is encrypted.
029 */
030 private static final int ENCRYPTION_FLAG = 1 << 0;
031
032 /**
033 * Indicates that a data descriptor stored after the file contents
034 * will hold CRC and size information.
035 */
036 private static final int DATA_DESCRIPTOR_FLAG = 1 << 3;
037
038 /**
039 * Indicates strong encryption.
040 */
041 private static final int STRONG_ENCRYPTION_FLAG = 1 << 6;
042
043 /**
044 * Indicates that filenames are written in utf-8.
045 *
046 * <p>The only reason this is public is that {@link
047 * ZipArchiveOutputStream#EFS_FLAG} was public in Apache Commons
048 * Compress 1.0 and we needed a substitute for it.</p>
049 */
050 public static final int UFT8_NAMES_FLAG = 1 << 11;
051
052 private boolean languageEncodingFlag = false;
053 private boolean dataDescriptorFlag = false;
054 private boolean encryptionFlag = false;
055 private boolean strongEncryptionFlag = false;
056
057 public GeneralPurposeBit() {
058 }
059
060 /**
061 * whether the current entry uses UTF8 for file name and comment.
062 */
063 public boolean usesUTF8ForNames() {
064 return languageEncodingFlag;
065 }
066
067 /**
068 * whether the current entry will use UTF8 for file name and comment.
069 */
070 public void useUTF8ForNames(boolean b) {
071 languageEncodingFlag = b;
072 }
073
074 /**
075 * whether the current entry uses the data descriptor to store CRC
076 * and size information
077 */
078 public boolean usesDataDescriptor() {
079 return dataDescriptorFlag;
080 }
081
082 /**
083 * whether the current entry will use the data descriptor to store
084 * CRC and size information
085 */
086 public void useDataDescriptor(boolean b) {
087 dataDescriptorFlag = b;
088 }
089
090 /**
091 * whether the current entry is encrypted
092 */
093 public boolean usesEncryption() {
094 return encryptionFlag;
095 }
096
097 /**
098 * whether the current entry will be encrypted
099 */
100 public void useEncryption(boolean b) {
101 encryptionFlag = b;
102 }
103
104 /**
105 * whether the current entry is encrypted using strong encryption
106 */
107 public boolean usesStrongEncryption() {
108 return encryptionFlag && strongEncryptionFlag;
109 }
110
111 /**
112 * whether the current entry will be encrypted using strong encryption
113 */
114 public void useStrongEncryption(boolean b) {
115 strongEncryptionFlag = b;
116 if (b) {
117 useEncryption(true);
118 }
119 }
120
121 /**
122 * Encodes the set bits in a form suitable for ZIP archives.
123 */
124 public byte[] encode() {
125 return
126 ZipShort.getBytes((dataDescriptorFlag ? DATA_DESCRIPTOR_FLAG : 0)
127 |
128 (languageEncodingFlag ? UFT8_NAMES_FLAG : 0)
129 |
130 (encryptionFlag ? ENCRYPTION_FLAG : 0)
131 |
132 (strongEncryptionFlag ? STRONG_ENCRYPTION_FLAG : 0)
133 );
134 }
135
136 /**
137 * Parses the supported flags from the given archive data.
138 * @param data local file header or a central directory entry.
139 * @param offset offset at which the general purpose bit starts
140 */
141 public static GeneralPurposeBit parse(final byte[] data, final int offset) {
142 final int generalPurposeFlag = ZipShort.getValue(data, offset);
143 GeneralPurposeBit b = new GeneralPurposeBit();
144 b.useDataDescriptor((generalPurposeFlag & DATA_DESCRIPTOR_FLAG) != 0);
145 b.useUTF8ForNames((generalPurposeFlag & UFT8_NAMES_FLAG) != 0);
146 b.useStrongEncryption((generalPurposeFlag & STRONG_ENCRYPTION_FLAG)
147 != 0);
148 b.useEncryption((generalPurposeFlag & ENCRYPTION_FLAG) != 0);
149 return b;
150 }
151
152 @Override
153 public int hashCode() {
154 return 3 * (7 * (13 * (17 * (encryptionFlag ? 1 : 0)
155 + (strongEncryptionFlag ? 1 : 0))
156 + (languageEncodingFlag ? 1 : 0))
157 + (dataDescriptorFlag ? 1 : 0));
158 }
159
160 @Override
161 public boolean equals(Object o) {
162 if (!(o instanceof GeneralPurposeBit)) {
163 return false;
164 }
165 GeneralPurposeBit g = (GeneralPurposeBit) o;
166 return g.encryptionFlag == encryptionFlag
167 && g.strongEncryptionFlag == strongEncryptionFlag
168 && g.languageEncodingFlag == languageEncodingFlag
169 && g.dataDescriptorFlag == dataDescriptorFlag;
170 }
171 }