EncryptedLOBFile (Apache Derby V10.14 Internals)

java.lang.Object
- org.apache.derby.impl.jdbc.LOBFile
- - org.apache.derby.impl.jdbc.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.

Constructor Summary

Constructors
Constructor Description

EncryptedLOBFile(StorageFile lobFile, DataFactory df)
Constructs the EncryptedLOBFile object with encryption support.

Constructors
Constructor	Description
`EncryptedLOBFile(StorageFile lobFile, DataFactory df)`	Constructs the EncryptedLOBFile object with encryption support.

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 org.apache.derby.impl.jdbc.LOBFile
close, getStorageFile

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

Class EncryptedLOBFile

Field Summary

Constructor Summary

Method Summary

Methods inherited from class org.apache.derby.impl.jdbc.LOBFile

Methods inherited from class java.lang.Object

Field Detail

blockSize

tail

tailSize

currentPos

df

Constructor Detail

EncryptedLOBFile

Method Detail

getBlocks

length

getFilePointer

seek

write

write

write

readByte

read

setLength