org.apache.tools.zip.GeneralPurposeBit Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.apache.tools.zip;
/**
* Parser/encoder for the "general purpose bit" field in ZIP's local
* file and central directory headers.
*
* @since Ant 1.9.0
*/
public final class GeneralPurposeBit {
/**
* Indicates that the file is encrypted.
*/
private static final int ENCRYPTION_FLAG = 1 << 0;
/**
* Indicates that a data descriptor stored after the file contents
* will hold CRC and size information.
*/
private static final int DATA_DESCRIPTOR_FLAG = 1 << 3;
/**
* Indicates strong encryption.
*/
private static final int STRONG_ENCRYPTION_FLAG = 1 << 6;
/**
* Indicates that filenames are written in utf-8.
*
* The only reason this is public is that {@link
* ZipOutputStream#EFS_FLAG} was public in several versions of
* Apache Ant and we needed a substitute for it.
*/
public static final int UFT8_NAMES_FLAG = 1 << 11;
private boolean languageEncodingFlag = false;
private boolean dataDescriptorFlag = false;
private boolean encryptionFlag = false;
private boolean strongEncryptionFlag = false;
public GeneralPurposeBit() {
}
/**
* whether the current entry uses UTF8 for file name and comment.
*/
public boolean usesUTF8ForNames() {
return languageEncodingFlag;
}
/**
* whether the current entry will use UTF8 for file name and comment.
*/
public void useUTF8ForNames(boolean b) {
languageEncodingFlag = b;
}
/**
* whether the current entry uses the data descriptor to store CRC
* and size information
*/
public boolean usesDataDescriptor() {
return dataDescriptorFlag;
}
/**
* whether the current entry will use the data descriptor to store
* CRC and size information
*/
public void useDataDescriptor(boolean b) {
dataDescriptorFlag = b;
}
/**
* whether the current entry is encrypted
*/
public boolean usesEncryption() {
return encryptionFlag;
}
/**
* whether the current entry will be encrypted
*/
public void useEncryption(boolean b) {
encryptionFlag = b;
}
/**
* whether the current entry is encrypted using strong encryption
*/
public boolean usesStrongEncryption() {
return encryptionFlag && strongEncryptionFlag;
}
/**
* whether the current entry will be encrypted using strong encryption
*/
public void useStrongEncryption(boolean b) {
strongEncryptionFlag = b;
if (b) {
useEncryption(true);
}
}
/**
* Encodes the set bits in a form suitable for ZIP archives.
*/
public byte[] encode() {
return
ZipShort.getBytes((dataDescriptorFlag ? DATA_DESCRIPTOR_FLAG : 0)
|
(languageEncodingFlag ? UFT8_NAMES_FLAG : 0)
|
(encryptionFlag ? ENCRYPTION_FLAG : 0)
|
(strongEncryptionFlag ? STRONG_ENCRYPTION_FLAG : 0)
);
}
/**
* Parses the supported flags from the given archive data.
* @param data local file header or a central directory entry.
* @param offset offset at which the general purpose bit starts
*/
public static GeneralPurposeBit parse(final byte[] data, final int offset) {
final int generalPurposeFlag = ZipShort.getValue(data, offset);
GeneralPurposeBit b = new GeneralPurposeBit();
b.useDataDescriptor((generalPurposeFlag & DATA_DESCRIPTOR_FLAG) != 0);
b.useUTF8ForNames((generalPurposeFlag & UFT8_NAMES_FLAG) != 0);
b.useStrongEncryption((generalPurposeFlag & STRONG_ENCRYPTION_FLAG)
!= 0);
b.useEncryption((generalPurposeFlag & ENCRYPTION_FLAG) != 0);
return b;
}
@Override
public int hashCode() {
return 3 * (7 * (13 * (17 * (encryptionFlag ? 1 : 0)
+ (strongEncryptionFlag ? 1 : 0))
+ (languageEncodingFlag ? 1 : 0))
+ (dataDescriptorFlag ? 1 : 0));
}
@Override
public boolean equals(Object o) {
if (!(o instanceof GeneralPurposeBit)) {
return false;
}
GeneralPurposeBit g = (GeneralPurposeBit) o;
return g.encryptionFlag == encryptionFlag
&& g.strongEncryptionFlag == strongEncryptionFlag
&& g.languageEncodingFlag == languageEncodingFlag
&& g.dataDescriptorFlag == dataDescriptorFlag;
}
}