content: package org.apache.lucene.index;
  
  /**
   * 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.
   */
  
  import java.io.EOFException;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.util.HashMap;
  
  import org.apache.lucene.store.BufferedIndexInput;
  import org.apache.lucene.store.Directory;
  import org.apache.lucene.store.IndexInput;
  import org.apache.lucene.store.IndexOutput;
  import org.apache.lucene.store.Lock;
  
  /**
   * Class for accessing a compound stream.
   * This class implements a directory, but is limited to only read operations.
   * Directory methods that would normally modify data throw an exception.
   */
  class CompoundFileReader extends Directory {
    
    private int readBufferSize;
    
    private static final class FileEntry {
      long offset;
      long length;
    }
      
    // Base info
    private Directory directory;
    private String fileName;
    private String fileNamepos;
    HashMap<Long, Long> pos=new HashMap<Long, Long>();
  
    
    private IndexInput stream;
    private HashMap<String,FileEntry> entries = new HashMap<String,FileEntry>();
    
    public CompoundFileReader(Directory dir, String name,String posname) throws IOException {
      this(dir, name,posname, BufferedIndexInput.BUFFER_SIZE);
    }
    
    public CompoundFileReader(Directory dir, String name,String posname, int readBufferSize) throws IOException {
      assert !(dir instanceof CompoundFileReader) : "compound file inside of compound file: " + name;
      directory = dir;
      fileName = name;
      fileNamepos=posname;
      this.readBufferSize = readBufferSize;
      
      boolean success = false;
      
      try {
        stream = dir.openInput(name, readBufferSize);
        
        pos = new HashMap<Long, Long>();
        IndexInput streampos = dir.openInput(fileNamepos, readBufferSize);
        int size = streampos.readInt();
        for (int i = 0; i < size; i++) {
  	Long key = streampos.readLong();
  	Long value = streampos.readLong();
  	pos.put(key, value);
        }
  
        streampos.close();
        
        // read the first VInt. If it is negative, it's the version number
        // otherwise it's the count (pre-3.1 indexes)
        int firstInt = stream.readVInt();
        
        final int count;
        final boolean stripSegmentName;
        if (firstInt < CompoundFileWriter.FORMAT_PRE_VERSION) {
          if (firstInt < CompoundFileWriter.FORMAT_CURRENT) {
            throw new CorruptIndexException("Incompatible format version: "
                + firstInt + " expected " + CompoundFileWriter.FORMAT_CURRENT + " (resource: " + stream + ")");
          }
          // It's a post-3.1 index, read the count.
          count = stream.readVInt();
          stripSegmentName = false;
        } else {
          count = firstInt;
          stripSegmentName = true;
        }
        
        // read the directory and init files
        FileEntry entry = null;
        for (int i=0; i<count; i++) {
  	  long opos=stream.getFilePointer();
  
          long offset = stream.readLong();
          if(pos.containsKey(opos))
          {
              offset=pos.get(opos);
  //            System.out.println("###opos"+opos+","+offset);
          }
          String id = stream.readString();
          
          if (stripSegmentName) {
            // Fix the id to not include the segment names. This is relevant for
            // pre-3.1 indexes.
            id = IndexFileNames.stripSegmentName(id);
          }
          
          if (entry != null) {
            // set length of the previous entry
            entry.length = offset - entry.offset;
          }
          
          entry = new FileEntry();
          entry.offset = offset;
          entries.put(id, entry);
        }
        
        // set the length of the final entry
        if (entry != null) {
          entry.length = stream.length() - entry.offset;
        }
        
        success = true;
        
      } finally {
        if (!success && (stream != null)) {
          try {
            stream.close();
          } catch (IOException e) { }
        }
      }
    }
    
    public Directory getDirectory() {
      return directory;
    }
    
    public String getName() {
      return fileName;
    }
    
    @Override
    public synchronized void close() throws IOException {
      if (stream == null)
        throw new IOException("Already closed");
      
      entries.clear();
      stream.close();
      stream = null;
    }
    
    @Override
    public synchronized IndexInput openInput(String id) throws IOException {
      // Default to readBufferSize passed in when we were opened
      return openInput(id, readBufferSize);
    }
    
    @Override
    public synchronized IndexInput openInput(String id, int readBufferSize) throws IOException {
      if (stream == null)
        throw new IOException("Stream closed");
      
      id = IndexFileNames.stripSegmentName(id);
      FileEntry entry = entries.get(id);
      if (entry == null) {
        throw new IOException("No sub-file with id " + id + " found (fileName=" + fileName + " files: " + entries.keySet() + ")");
      }
      
      return new CSIndexInput(stream, entry.offset, entry.length, readBufferSize);
    }
    
    /** Returns an array of strings, one for each file in the directory. */
    @Override
    public String[] listAll() {
      String[] res = entries.keySet().toArray(new String[entries.size()]);
      // Add the segment name
      String seg = fileName.substring(0, fileName.indexOf('.'));
      for (int i = 0; i < res.length; i++) {
        res[i] = seg + res[i];
      }
      return res;
    }
    
    /** Returns true iff a file with the given name exists. */
    @Override
    public boolean fileExists(String name) {
      return entries.containsKey(IndexFileNames.stripSegmentName(name));
    }
    
    /** Returns the time the compound file was last modified. */
    @Override
    public long fileModified(String name) throws IOException {
      return directory.fileModified(fileName);
    }
    
    /** Set the modified time of the compound file to now.
     *  @deprecated Lucene never uses this API; it will be
     *  removed in 4.0. */
    @Override
    @Deprecated
    public void touchFile(String name) throws IOException {
      directory.touchFile(fileName);
    }
    
    /** Not implemented
     * @throws UnsupportedOperationException */
    @Override
    public void deleteFile(String name) {
      throw new UnsupportedOperationException();
    }
    
    /** Not implemented
     * @throws UnsupportedOperationException */
    public void renameFile(String from, String to) {
      throw new UnsupportedOperationException();
    }
    
    /** Returns the length of a file in the directory.
     * @throws IOException if the file does not exist */
    @Override
    public long fileLength(String name) throws IOException {
      FileEntry e = entries.get(IndexFileNames.stripSegmentName(name));
      if (e == null)
        throw new FileNotFoundException(name);
      return e.length;
    }
    
    /** Not implemented
     * @throws UnsupportedOperationException */
    @Override
    public IndexOutput createOutput(String name) {
      throw new UnsupportedOperationException();
    }
    
    /** Not implemented
     * @throws UnsupportedOperationException */
    @Override
    public Lock makeLock(String name) {
      throw new UnsupportedOperationException();
    }
    
    /** Implementation of an IndexInput that reads from a portion of the
     *  compound file. The visibility is left as "package" *only* because
     *  this helps with testing since JUnit test cases in a different class
     *  can then access package fields of this class.
     */
    static final class CSIndexInput extends BufferedIndexInput {
      IndexInput base;
      long fileOffset;
      long length;
      
      CSIndexInput(final IndexInput base, final long fileOffset, final long length) {
        this(base, fileOffset, length, BufferedIndexInput.BUFFER_SIZE);
      }
      
      CSIndexInput(final IndexInput base, final long fileOffset, final long length, int readBufferSize) {
        super(readBufferSize);
        this.base = (IndexInput)base.clone();
        this.fileOffset = fileOffset;
        this.length = length;
      }
      
      @Override
      public Object clone() {
        CSIndexInput clone = (CSIndexInput)super.clone();
        clone.base = (IndexInput)base.clone();
        clone.fileOffset = fileOffset;
        clone.length = length;
        return clone;
      }
      
      /** Expert: implements buffer refill.  Reads bytes from the current
       *  position in the input.
       * @param b the array to read bytes into
       * @param offset the offset in the array to start storing bytes
       * @param len the number of bytes to read
       */
      @Override
      protected void readInternal(byte[] b, int offset, int len) throws IOException {
        long start = getFilePointer();
        if(start + len > length)
          throw new EOFException("read past EOF (resource: " + base + ")");
        base.seek(fileOffset + start);
        base.readBytes(b, offset, len, false);
      }
      
      /** Expert: implements seek.  Sets current position in this file, where
       *  the next {@link #readInternal(byte[],int,int)} will occur.
       * @see #readInternal(byte[],int,int)
       */
      @Override
      protected void seekInternal(long pos) {}
      
      /** Closes the stream to further operations. */
      @Override
      public void close() throws IOException {
        base.close();
      }
      
      @Override
      public long length() {
        return length;
      }
      
      @Override
      public void copyBytes(IndexOutput out, long numBytes) throws IOException {
        // Copy first whatever is in the buffer
        numBytes -= flushBuffer(out, numBytes);
        
        // If there are more bytes left to copy, delegate the copy task to the
        // base IndexInput, in case it can do an optimized copy.
        if (numBytes > 0) {
          long start = getFilePointer();
          if (start + numBytes > length) {
            throw new EOFException("read past EOF (resource: " + base + ")");
          }
          base.seek(fileOffset + start);
          base.copyBytes(out, numBytes);
        }
      }
    }
  }
  