content: /*
   *  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.zip.CRC32;
  import java.util.zip.ZipException;
  
  /**
   * Adds Unix file permission and UID/GID fields as well as symbolic
   * link handling.
   *
   * <p>This class uses the ASi extra field in the format:
   * <pre>
   *         Value         Size            Description
   *         -----         ----            -----------
   * (Unix3) 0x756e        Short           tag for this extra block type
   *         TSize         Short           total data size for this block
   *         CRC           Long            CRC-32 of the remaining data
   *         Mode          Short           file permissions
   *         SizDev        Long            symlink'd size OR major/minor dev num
   *         UID           Short           user ID
   *         GID           Short           group ID
   *         (var.)        variable        symbolic link filename
   * </pre>
   * taken from appnote.iz (Info-ZIP note, 981119) found at <a
   * href="ftp://ftp.uu.net/pub/archiving/zip/doc/">ftp://ftp.uu.net/pub/archiving/zip/doc/</a></p>
  
   *
   * <p>Short is two bytes and Long is four bytes in big endian byte and
   * word order, device numbers are currently not supported.</p>
   *
   * <p>Since the documentation this class is based upon doesn't mention
   * the character encoding of the file name at all, it is assumed that
   * it uses the current platform's default encoding.</p>
   */
  public class AsiExtraField implements ZipExtraField, UnixStat, Cloneable {
  
      private static final ZipShort HEADER_ID = new ZipShort(0x756E);
      private static final int      WORD = 4;
      /**
       * Standard Unix stat(2) file mode.
       *
       * @since 1.1
       */
      private int mode = 0;
      /**
       * User ID.
       *
       * @since 1.1
       */
      private int uid = 0;
      /**
       * Group ID.
       *
       * @since 1.1
       */
      private int gid = 0;
      /**
       * File this entry points to, if it is a symbolic link.
       *
       * <p>empty string - if entry is not a symbolic link.</p>
       *
       * @since 1.1
       */
      private String link = "";
      /**
       * Is this an entry for a directory?
       *
       * @since 1.1
       */
      private boolean dirFlag = false;
  
      /**
       * Instance used to calculate checksums.
       *
       * @since 1.1
       */
      private CRC32 crc = new CRC32();
  
      /** Constructor for AsiExtraField. */
      public AsiExtraField() {
      }
  
      /**
       * The Header-ID.
       * @return the value for the header id for this extrafield
       * @since 1.1
       */
      public ZipShort getHeaderId() {
          return HEADER_ID;
      }
  
      /**
       * Length of the extra field in the local file data - without
       * Header-ID or length specifier.
       * @return a <code>ZipShort</code> for the length of the data of this extra field
       * @since 1.1
       */
      public ZipShort getLocalFileDataLength() {
          return new ZipShort(WORD         // CRC
                            + 2         // Mode
                            + WORD         // SizDev
                            + 2         // UID
                            + 2         // GID
                            + getLinkedFile().getBytes().length);
                            // Uses default charset - see class Javadoc
      }
  
      /**
       * Delegate to local file data.
       * @return the centralDirectory length
       * @since 1.1
       */
      public ZipShort getCentralDirectoryLength() {
          return getLocalFileDataLength();
      }
  
      /**
       * The actual data to put into local file data - without Header-ID
       * or length specifier.
       * @return get the data
       * @since 1.1
       */
      public byte[] getLocalFileDataData() {
          // CRC will be added later
          byte[] data = new byte[getLocalFileDataLength().getValue() - WORD];
          System.arraycopy(ZipShort.getBytes(getMode()), 0, data, 0, 2);
  
          byte[] linkArray = getLinkedFile().getBytes(); // Uses default charset - see class Javadoc
          // CheckStyle:MagicNumber OFF
          System.arraycopy(ZipLong.getBytes(linkArray.length),
                           0, data, 2, WORD);
  
          System.arraycopy(ZipShort.getBytes(getUserId()),
                           0, data, 6, 2);
          System.arraycopy(ZipShort.getBytes(getGroupId()),
                           0, data, 8, 2);
  
          System.arraycopy(linkArray, 0, data, 10, linkArray.length);
          // CheckStyle:MagicNumber ON
  
          crc.reset();
          crc.update(data);
          long checksum = crc.getValue();
  
          byte[] result = new byte[data.length + WORD];
          System.arraycopy(ZipLong.getBytes(checksum), 0, result, 0, WORD);
          System.arraycopy(data, 0, result, WORD, data.length);
          return result;
      }
  
      /**
       * Delegate to local file data.
       * @return the local file data
       * @since 1.1
       */
      public byte[] getCentralDirectoryData() {
          return getLocalFileDataData();
      }
  
      /**
       * Set the user id.
       * @param uid the user id
       * @since 1.1
       */
      public void setUserId(int uid) {
          this.uid = uid;
      }
  
      /**
       * Get the user id.
       * @return the user id
       * @since 1.1
       */
      public int getUserId() {
          return uid;
      }
  
      /**
       * Set the group id.
       * @param gid the group id
       * @since 1.1
       */
      public void setGroupId(int gid) {
          this.gid = gid;
      }
  
      /**
       * Get the group id.
       * @return the group id
       * @since 1.1
       */
      public int getGroupId() {
          return gid;
      }
  
      /**
       * Indicate that this entry is a symbolic link to the given filename.
       *
       * @param name Name of the file this entry links to, empty String
       *             if it is not a symbolic link.
       *
       * @since 1.1
       */
      public void setLinkedFile(String name) {
          link = name;
          mode = getMode(mode);
      }
  
      /**
       * Name of linked file
       *
       * @return name of the file this entry links to if it is a
       *         symbolic link, the empty string otherwise.
       *
       * @since 1.1
       */
      public String getLinkedFile() {
          return link;
      }
  
      /**
       * Is this entry a symbolic link?
       * @return true if this is a symbolic link
       * @since 1.1
       */
      public boolean isLink() {
          return getLinkedFile().length() != 0;
      }
  
      /**
       * File mode of this file.
       * @param mode the file mode
       * @since 1.1
       */
      public void setMode(int mode) {
          this.mode = getMode(mode);
      }
  
      /**
       * File mode of this file.
       * @return the file mode
       * @since 1.1
       */
      public int getMode() {
          return mode;
      }
  
      /**
       * Indicate whether this entry is a directory.
       * @param dirFlag if true, this entry is a directory
       * @since 1.1
       */
      public void setDirectory(boolean dirFlag) {
          this.dirFlag = dirFlag;
          mode = getMode(mode);
      }
  
      /**
       * Is this entry a directory?
       * @return true if this entry is a directory
       * @since 1.1
       */
      public boolean isDirectory() {
          return dirFlag && !isLink();
      }
  
      /**
       * Populate data from this array as if it was in local file data.
       * @param data an array of bytes
       * @param offset the start offset
       * @param length the number of bytes in the array from offset
       * @since 1.1
       * @throws ZipException on error
       */
      public void parseFromLocalFileData(byte[] data, int offset, int length)
          throws ZipException {
  
          long givenChecksum = ZipLong.getValue(data, offset);
          byte[] tmp = new byte[length - WORD];
          System.arraycopy(data, offset + WORD, tmp, 0, length - WORD);
          crc.reset();
          crc.update(tmp);
          long realChecksum = crc.getValue();
          if (givenChecksum != realChecksum) {
              throw new ZipException("bad CRC checksum "
                                     + Long.toHexString(givenChecksum)
                                     + " instead of "
                                     + Long.toHexString(realChecksum));
          }
  
          int newMode = ZipShort.getValue(tmp, 0);
          // CheckStyle:MagicNumber OFF
          byte[] linkArray = new byte[(int) ZipLong.getValue(tmp, 2)];
          uid = ZipShort.getValue(tmp, 6);
          gid = ZipShort.getValue(tmp, 8);
  
          if (linkArray.length == 0) {
              link = "";
          } else {
              System.arraycopy(tmp, 10, linkArray, 0, linkArray.length);
              link = new String(linkArray); // Uses default charset - see class Javadoc
          }
          // CheckStyle:MagicNumber ON
          setDirectory((newMode & DIR_FLAG) != 0);
          setMode(newMode);
      }
  
      /**
       * Get the file mode for given permissions with the correct file type.
       * @param mode the mode
       * @return the type with the mode
       * @since 1.1
       */
      protected int getMode(int mode) {
          int type = FILE_FLAG;
          if (isLink()) {
              type = LINK_FLAG;
          } else if (isDirectory()) {
              type = DIR_FLAG;
          }
          return type | (mode & PERM_MASK);
      }
  
      @Override
      public Object clone() {
          try {
              AsiExtraField cloned = (AsiExtraField) super.clone();
              cloned.crc = new CRC32();
              return cloned;
          } catch (CloneNotSupportedException cnfe) {
              // impossible
              throw new RuntimeException(cnfe);
          }
      }
  }
  