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/*
* 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;
import java.util.Hashtable;
import java.util.Vector;
import java.util.zip.ZipException;
/**
* ZipExtraField related methods
*
*/
public class ExtraFieldUtils {
/**
* Static registry of known extra fields.
*
* @since 1.1
*/
private static Hashtable implementations;
static {
implementations = new Hashtable();
register(AsiExtraField.class);
register(JarMarker.class);
}
/**
* Register a ZipExtraField implementation.
*
* <p>The given class must have a no-arg constructor and implement
* the {@link ZipExtraField ZipExtraField interface}.</p>
* @param c the class to register
*
* @since 1.1
*/
public static void register(Class c) {
try {
ZipExtraField ze = (ZipExtraField) c.newInstance();
implementations.put(ze.getHeaderId(), c);
} catch (ClassCastException cc) {
throw new RuntimeException(c + " doesn\'t implement ZipExtraField");
} catch (InstantiationException ie) {
throw new RuntimeException(c + " is not a concrete class");
} catch (IllegalAccessException ie) {
throw new RuntimeException(c + "\'s no-arg constructor is not public");
}
}
/**
* Create an instance of the approriate ExtraField, falls back to
* {@link UnrecognizedExtraField UnrecognizedExtraField}.
* @param headerId the header identifier
* @return an instance of the appropiate ExtraField
* @exception InstantiationException if unable to instantiate the class
* @exception IllegalAccessException if not allowed to instatiate the class
* @since 1.1
*/
public static ZipExtraField createExtraField(ZipShort headerId)
throws InstantiationException, IllegalAccessException {
Class c = (Class) implementations.get(headerId);
if (c != null) {
return (ZipExtraField) c.newInstance();
}
UnrecognizedExtraField u = new UnrecognizedExtraField();
u.setHeaderId(headerId);
return u;
}
/**
* Split the array into ExtraFields and populate them with the
* give data.
* @param data an array of bytes
* @return an array of ExtraFields
* @since 1.1
* @throws ZipException on error
*/
public static ZipExtraField[] parse(byte[] data) throws ZipException {
Vector v = new Vector();
int start = 0;
while (start <= data.length - 4) {
ZipShort headerId = new ZipShort(data, start);
int length = (new ZipShort(data, start + 2)).getValue();
if (start + 4 + length > data.length) {
throw new ZipException("data starting at " + start
+ " is in unknown format");
}
try {
ZipExtraField ze = createExtraField(headerId);
ze.parseFromLocalFileData(data, start + 4, length);
v.addElement(ze);
} catch (InstantiationException ie) {
throw new ZipException(ie.getMessage());
} catch (IllegalAccessException iae) {
throw new ZipException(iae.getMessage());
}
start += (length + 4);
}
if (start != data.length) { // array not exhausted
throw new ZipException("data starting at " + start
+ " is in unknown format");
}
ZipExtraField[] result = new ZipExtraField[v.size()];
v.copyInto(result);
return result;
}
/**
* Merges the local file data fields of the given ZipExtraFields.
* @param data an array of ExtraFiles
* @return an array of bytes
* @since 1.1
*/
public static byte[] mergeLocalFileDataData(ZipExtraField[] data) {
int sum = 4 * data.length;
for (int i = 0; i < data.length; i++) {
sum += data[i].getLocalFileDataLength().getValue();
}
byte[] result = new byte[sum];
int start = 0;
for (int i = 0; i < data.length; i++) {
System.arraycopy(data[i].getHeaderId().getBytes(),
0, result, start, 2);
System.arraycopy(data[i].getLocalFileDataLength().getBytes(),
0, result, start + 2, 2);
byte[] local = data[i].getLocalFileDataData();
System.arraycopy(local, 0, result, start + 4, local.length);
start += (local.length + 4);
}
return result;
}
/**
* Merges the central directory fields of the given ZipExtraFields.
* @param data an array of ExtraFields
* @return an array of bytes
* @since 1.1
*/
public static byte[] mergeCentralDirectoryData(ZipExtraField[] data) {
int sum = 4 * data.length;
for (int i = 0; i < data.length; i++) {
sum += data[i].getCentralDirectoryLength().getValue();
}
byte[] result = new byte[sum];
int start = 0;
for (int i = 0; i < data.length; i++) {
System.arraycopy(data[i].getHeaderId().getBytes(),
0, result, start, 2);
System.arraycopy(data[i].getCentralDirectoryLength().getBytes(),
0, result, start + 2, 2);
byte[] local = data[i].getCentralDirectoryData();
System.arraycopy(local, 0, result, start + 4, local.length);
start += (local.length + 4);
}
return result;
}
}
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