text: /*
   *  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 com.alimama.mdrill.utils.zip;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.zip.ZipException;
  
  /**
   * ZipExtraField related methods
   *
   */
  // CheckStyle:HideUtilityClassConstructorCheck OFF (bc)
  public class ExtraFieldUtils {
  
      private static final int WORD = 4;
  
      /**
       * Static registry of known extra fields.
       *
       * @since 1.1
       */
      private static final Map<ZipShort, Class<?>> implementations;
  
      static {
          implementations = new ConcurrentHashMap<ZipShort, Class<?>>();
          register(AsiExtraField.class);
          register(JarMarker.class);
          register(UnicodePathExtraField.class);
          register(UnicodeCommentExtraField.class);
          register(Zip64ExtendedInformationExtraField.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 appropriate ExtraField, falls back to
       * {@link UnrecognizedExtraField UnrecognizedExtraField}.
       * @param headerId the header identifier
       * @return an instance of the appropriate ExtraField
       * @exception InstantiationException if unable to instantiate the class
       * @exception IllegalAccessException if not allowed to instantiate the class
       * @since 1.1
       */
      public static ZipExtraField createExtraField(ZipShort headerId)
          throws InstantiationException, IllegalAccessException {
          Class<?> c = 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
       * given data as local file data, throwing an exception if the
       * data cannot be parsed.
       * @param data an array of bytes as it appears in local file data
       * @return an array of ExtraFields
       * @throws ZipException on error
       */
      public static ZipExtraField[] parse(byte[] data) throws ZipException {
          return parse(data, true, UnparseableExtraField.THROW);
      }
  
      /**
       * Split the array into ExtraFields and populate them with the
       * given data, throwing an exception if the data cannot be parsed.
       * @param data an array of bytes
       * @param local whether data originates from the local file data
       * or the central directory
       * @return an array of ExtraFields
       * @since 1.1
       * @throws ZipException on error
       */
      public static ZipExtraField[] parse(byte[] data, boolean local)
          throws ZipException {
          return parse(data, local, UnparseableExtraField.THROW);
      }
  
      /**
       * Split the array into ExtraFields and populate them with the
       * given data.
       * @param data an array of bytes
       * @param local whether data originates from the local file data
       * or the central directory
       * @param onUnparseableData what to do if the extra field data
       * cannot be parsed.
       * @return an array of ExtraFields
       * @throws ZipException on error
       * @since Ant 1.8.1
       */
      public static ZipExtraField[] parse(byte[] data, boolean local,
                                          UnparseableExtraField onUnparseableData)
          throws ZipException {
          List<ZipExtraField> v = new ArrayList<ZipExtraField>();
          int start = 0;
          LOOP:
          while (start <= data.length - WORD) {
              ZipShort headerId = new ZipShort(data, start);
              int length = (new ZipShort(data, start + 2)).getValue();
              if (start + WORD + length > data.length) {
                  switch(onUnparseableData.getKey()) {
                  case UnparseableExtraField.THROW_KEY:
                      throw new ZipException("bad extra field starting at "
                                             + start + ".  Block length of "
                                             + length + " bytes exceeds remaining"
                                             + " data of "
                                             + (data.length - start - WORD)
                                             + " bytes.");
                  case UnparseableExtraField.READ_KEY:
                      UnparseableExtraFieldData field =
                          new UnparseableExtraFieldData();
                      if (local) {
                          field.parseFromLocalFileData(data, start,
                                                       data.length - start);
                      } else {
                          field.parseFromCentralDirectoryData(data, start,
                                                              data.length - start);
                      }
                      v.add(field);
                      //$FALL-THROUGH$
                  case UnparseableExtraField.SKIP_KEY:
                      // since we cannot parse the data we must assume
                      // the extra field consumes the whole rest of the
                      // available data
                      break LOOP;
                  default:
                      throw new ZipException("unknown UnparseableExtraField key: "
                                             + onUnparseableData.getKey());
                  }
              }
              try {
                  ZipExtraField ze = createExtraField(headerId);
                  if (local
                      || !(ze instanceof CentralDirectoryParsingZipExtraField)) {
                      ze.parseFromLocalFileData(data, start + WORD, length);
                  } else {
                      ((CentralDirectoryParsingZipExtraField) ze)
                          .parseFromCentralDirectoryData(data, start + WORD,
                                                         length);
                  }
                  v.add(ze);
              } catch (InstantiationException ie) {
                  throw new ZipException(ie.getMessage());
              } catch (IllegalAccessException iae) {
                  throw new ZipException(iae.getMessage());
              }
              start += (length + WORD);
          }
  
          ZipExtraField[] result = new ZipExtraField[v.size()];
          return v.toArray(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) {
          final boolean lastIsUnparseableHolder = data.length > 0
              && data[data.length - 1] instanceof UnparseableExtraFieldData;
          int regularExtraFieldCount =
              lastIsUnparseableHolder ? data.length - 1 : data.length;
  
          int sum = WORD * regularExtraFieldCount;
          for (ZipExtraField element : data) {
              sum += element.getLocalFileDataLength().getValue();
          }
  
          byte[] result = new byte[sum];
          int start = 0;
          for (int i = 0; i < regularExtraFieldCount; 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 + WORD, local.length);
              start += (local.length + WORD);
          }
          if (lastIsUnparseableHolder) {
              byte[] local = data[data.length - 1].getLocalFileDataData();
              System.arraycopy(local, 0, result, start, local.length);
          }
          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) {
          final boolean lastIsUnparseableHolder = data.length > 0
              && data[data.length - 1] instanceof UnparseableExtraFieldData;
          int regularExtraFieldCount =
              lastIsUnparseableHolder ? data.length - 1 : data.length;
  
          int sum = WORD * regularExtraFieldCount;
          for (ZipExtraField element : data) {
              sum += element.getCentralDirectoryLength().getValue();
          }
          byte[] result = new byte[sum];
          int start = 0;
          for (int i = 0; i < regularExtraFieldCount; 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 + WORD, local.length);
              start += (local.length + WORD);
          }
          if (lastIsUnparseableHolder) {
              byte[] local = data[data.length - 1].getCentralDirectoryData();
              System.arraycopy(local, 0, result, start, local.length);
          }
          return result;
      }
  
      /**
       * "enum" for the possible actions to take if the extra field
       * cannot be parsed.
       */
      public static final class UnparseableExtraField {
          /**
           * Key for "throw an exception" action.
           */
          public static final int THROW_KEY = 0;
          /**
           * Key for "skip" action.
           */
          public static final int SKIP_KEY = 1;
          /**
           * Key for "read" action.
           */
          public static final int READ_KEY = 2;
  
          /**
           * Throw an exception if field cannot be parsed.
           */
          public static final UnparseableExtraField THROW
              = new UnparseableExtraField(THROW_KEY);
  
          /**
           * Skip the extra field entirely and don't make its data
           * available - effectively removing the extra field data.
           */
          public static final UnparseableExtraField SKIP
              = new UnparseableExtraField(SKIP_KEY);
  
          /**
           * Read the extra field data into an instance of {@link
           * UnparseableExtraFieldData UnparseableExtraFieldData}.
           */
          public static final UnparseableExtraField READ
              = new UnparseableExtraField(READ_KEY);
  
          private final int key;
  
          private UnparseableExtraField(int k) {
              key = k;
          }
  
          /**
           * Key of the action to take.
           */
          public int getKey() { return key; }
      }
  }
  