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.util.ArrayList;
021    import java.util.HashMap;
022    import java.util.List;
023    import java.util.Map;
024    import java.util.zip.ZipException;
025    
026    /**
027     * ZipExtraField related methods
028     * @NotThreadSafe because the HashMap is not synch.
029     */
030    // CheckStyle:HideUtilityClassConstructorCheck OFF (bc)
031    public class ExtraFieldUtils {
032    
033        private static final int WORD = 4;
034    
035        /**
036         * Static registry of known extra fields.
037         */
038        private static final Map implementations;
039    
040        static {
041            implementations = new HashMap();
042            register(AsiExtraField.class);
043            register(JarMarker.class);
044            register(UnicodePathExtraField.class);
045            register(UnicodeCommentExtraField.class);
046        }
047    
048        /**
049         * Register a ZipExtraField implementation.
050         *
051         * <p>The given class must have a no-arg constructor and implement
052         * the {@link ZipExtraField ZipExtraField interface}.</p>
053         * @param c the class to register
054         */
055        public static void register(Class c) {
056            try {
057                ZipExtraField ze = (ZipExtraField) c.newInstance();
058                implementations.put(ze.getHeaderId(), c);
059            } catch (ClassCastException cc) {
060                throw new RuntimeException(c + " doesn\'t implement ZipExtraField");
061            } catch (InstantiationException ie) {
062                throw new RuntimeException(c + " is not a concrete class");
063            } catch (IllegalAccessException ie) {
064                throw new RuntimeException(c + "\'s no-arg constructor is not public");
065            }
066        }
067    
068        /**
069         * Create an instance of the approriate ExtraField, falls back to
070         * {@link UnrecognizedExtraField UnrecognizedExtraField}.
071         * @param headerId the header identifier
072         * @return an instance of the appropiate ExtraField
073         * @exception InstantiationException if unable to instantiate the class
074         * @exception IllegalAccessException if not allowed to instatiate the class
075         */
076        public static ZipExtraField createExtraField(ZipShort headerId)
077            throws InstantiationException, IllegalAccessException {
078            Class c = (Class) implementations.get(headerId);
079            if (c != null) {
080                return (ZipExtraField) c.newInstance();
081            }
082            UnrecognizedExtraField u = new UnrecognizedExtraField();
083            u.setHeaderId(headerId);
084            return u;
085        }
086    
087        /**
088         * Split the array into ExtraFields and populate them with the
089         * given data as local file data.
090         * @param data an array of bytes as it appears in local file data
091         * @return an array of ExtraFields
092         * @throws ZipException on error
093         */
094        public static ZipExtraField[] parse(byte[] data) throws ZipException {
095            return parse(data, true);
096        }
097    
098        /**
099         * Split the array into ExtraFields and populate them with the
100         * given data.
101         * @param data an array of bytes
102         * @param local whether data originates from the local file data
103         * or the central directory
104         * @return an array of ExtraFields
105         * @throws ZipException on error
106         */
107        public static ZipExtraField[] parse(byte[] data, boolean local)
108            throws ZipException {
109            List v = new ArrayList();
110            int start = 0;
111            while (start <= data.length - WORD) {
112                ZipShort headerId = new ZipShort(data, start);
113                int length = (new ZipShort(data, start + 2)).getValue();
114                if (start + WORD + length > data.length) {
115                    throw new ZipException("data starting at " + start
116                        + " is in unknown format");
117                }
118                try {
119                    ZipExtraField ze = createExtraField(headerId);
120                    if (local) {
121                        ze.parseFromLocalFileData(data, start + WORD, length);
122                    } else {
123                        ze.parseFromCentralDirectoryData(data, start + WORD,
124                                                         length);
125                    }
126                    v.add(ze);
127                } catch (InstantiationException ie) {
128                    throw new ZipException(ie.getMessage());
129                } catch (IllegalAccessException iae) {
130                    throw new ZipException(iae.getMessage());
131                }
132                start += (length + WORD);
133            }
134    
135            ZipExtraField[] result = new ZipExtraField[v.size()];
136            return (ZipExtraField[]) v.toArray(result);
137        }
138    
139        /**
140         * Merges the local file data fields of the given ZipExtraFields.
141         * @param data an array of ExtraFiles
142         * @return an array of bytes
143         */
144        public static byte[] mergeLocalFileDataData(ZipExtraField[] data) {
145            int sum = WORD * data.length;
146            for (int i = 0; i < data.length; i++) {
147                sum += data[i].getLocalFileDataLength().getValue();
148            }
149            byte[] result = new byte[sum];
150            int start = 0;
151            for (int i = 0; i < data.length; i++) {
152                System.arraycopy(data[i].getHeaderId().getBytes(),
153                                 0, result, start, 2);
154                System.arraycopy(data[i].getLocalFileDataLength().getBytes(),
155                                 0, result, start + 2, 2);
156                byte[] local = data[i].getLocalFileDataData();
157                System.arraycopy(local, 0, result, start + WORD, local.length);
158                start += (local.length + WORD);
159            }
160            return result;
161        }
162    
163        /**
164         * Merges the central directory fields of the given ZipExtraFields.
165         * @param data an array of ExtraFields
166         * @return an array of bytes
167         */
168        public static byte[] mergeCentralDirectoryData(ZipExtraField[] data) {
169            int sum = WORD * data.length;
170            for (int i = 0; i < data.length; i++) {
171                sum += data[i].getCentralDirectoryLength().getValue();
172            }
173            byte[] result = new byte[sum];
174            int start = 0;
175            for (int i = 0; i < data.length; i++) {
176                System.arraycopy(data[i].getHeaderId().getBytes(),
177                                 0, result, start, 2);
178                System.arraycopy(data[i].getCentralDirectoryLength().getBytes(),
179                                 0, result, start + 2, 2);
180                byte[] local = data[i].getCentralDirectoryData();
181                System.arraycopy(local, 0, result, start + WORD, local.length);
182                start += (local.length + WORD);
183            }
184            return result;
185        }
186    }