Package org.apache.derby.impl.jdbc

Class EncryptedLOBFile

  • class EncryptedLOBFile
extends LOBFile
    This class is a wrapper class on top of StorageRandomAccess to provide common methods to write in encrypted file. This class is NOT thread safe. The user class should take care of synchronization if being used in multi threaded environment.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private int blockSize
      Block size for encryption.
      private long currentPos
      Current file position.
      private DataFactory df
      Factory object used for encryption and decryption.
      private byte[] tail
      Leftover bytes.
      private int tailSize
      Number of actual bytes in tail array.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      private byte[] getBlocks​(long pos, int len)
      Find the blocks containing the data we are interested in.
      (package private) long getFilePointer()
      Returns the currrent position in the file.
      (package private) long length()
      Returns file length.
      (package private) int read​(byte[] buff, int off, int len)
      Reads len or remaining bytes in the file (whichever is lower) bytes into buff starting from off position of the buffer.
      (package private) int readByte()
      Reads one byte from file.
      (package private) void seek​(long pos)
      Sets the current file pointer to specific location.
      (package private) void setLength​(long size)
      Sets the file length to a given size.
      (package private) void write​(byte[] b)
      Write the buffer into file at current position.
      (package private) void write​(byte[] b, int off, int len)
      Writes length number of bytes from buffer starting from off position.
      (package private) void write​(int b)
      Writes one byte into the file.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • blockSize

        private final int blockSize
        Block size for encryption.

      • tail

        private final byte[] tail
        Leftover bytes. Stored in memory until they fill one block .

      • tailSize

        private int tailSize
        Number of actual bytes in tail array.

      • currentPos

        private long currentPos
        Current file position.

      • df

        private final DataFactory df
        Factory object used for encryption and decryption.

    • Constructor Detail

      • EncryptedLOBFile

        EncryptedLOBFile​(StorageFile lobFile,
                 DataFactory df)
          throws java.io.FileNotFoundException
        Constructs the EncryptedLOBFile object with encryption support.
        Parameters:
        lobFile - StorageFile Object for which file will be created
        df - data factory for encryption and decription
        Throws:
        java.io.FileNotFoundException - if the file exists but is a directory or cannot be opened

    • Method Detail

      • getBlocks

        private byte[] getBlocks​(long pos,
                         int len)
                  throws java.io.IOException,
                         StandardException
        Find the blocks containing the data we are interested in.
        Parameters:
        pos - first position we are interested in
        len - number of bytes of interest
        Returns:
        byte array containing all the blocks of data the specified region spans over
        Throws:
        java.io.IOException
        StandardException

      • length

        long length()
     throws java.io.IOException
        Returns file length.
        Overrides:
        length in class LOBFile
        Returns:
        file length
        Throws:
        java.io.IOException - if an I/O error occurs

      • getFilePointer

        long getFilePointer()
        Returns the currrent position in the file.
        Overrides:
        getFilePointer in class LOBFile
        Returns:
        current position of file pointer

      • seek

        void seek​(long pos)
   throws java.io.IOException
        Sets the current file pointer to specific location.
        Overrides:
        seek in class LOBFile
        Parameters:
        pos - new position
        Throws:
        java.io.IOException

      • write

        void write​(int b)
    throws java.io.IOException,
           StandardException
        Writes one byte into the file.
        Overrides:
        write in class LOBFile
        Parameters:
        b - byte value
        Throws:
        java.io.IOException - if disk operation fails
        StandardException - if error occurred during encryption/decryption

      • write

        void write​(byte[] b,
           int off,
           int len)
    throws java.io.IOException,
           StandardException
        Writes length number of bytes from buffer starting from off position.
        Overrides:
        write in class LOBFile
        Parameters:
        b - byte array containing bytes to be written
        off - starting offset of the byte array from where the data should be written to the file
        len - number of bytes to be written
        Throws:
        java.io.IOException - if disk operation fails
        StandardException - if error occurred during encryption/decryption

      • write

        void write​(byte[] b)
    throws java.io.IOException,
           StandardException
        Write the buffer into file at current position. It overwrites the data if current position is in the middle of the file and appends into the file if the total length exceeds the file size.
        Overrides:
        write in class LOBFile
        Parameters:
        b - byte array to be written
        Throws:
        java.io.IOException - if disk operation fails
        StandardException - if error occurred during encryption/decryption

      • readByte

        int readByte()
      throws java.io.IOException,
             StandardException
        Reads one byte from file.
        Overrides:
        readByte in class LOBFile
        Returns:
        byte
        Throws:
        java.io.IOException - if disk operation fails
        StandardException - if error occurred during decryption

      • read

        int read​(byte[] buff,
         int off,
         int len)
  throws java.io.IOException,
         StandardException
        Reads len or remaining bytes in the file (whichever is lower) bytes into buff starting from off position of the buffer.
        Overrides:
        read in class LOBFile
        Parameters:
        buff - byte array to fill read bytes
        off - offset of buff where the byte will be written
        len - number of bytes to be read
        Returns:
        number of bytes read
        Throws:
        java.io.IOException - if disk operation fails
        StandardException - if error occurred during decryption

      • setLength

        void setLength​(long size)
        throws java.io.IOException,
               StandardException
        Sets the file length to a given size. If the new size is smaller than the file length the file is truncated.
        Overrides:
        setLength in class LOBFile
        Parameters:
        size - new file size. Must be lower than file length.
        Throws:
        java.io.IOException - if file i/o fails
        StandardException - if error occurred during decryption