/*
** Authored by Timothy Gerard Endres
** <mailto:[email protected]> <http://www.trustice.com>
**
** This work has been placed into the public domain.
** You may use this work in any way and for any purpose you wish.
**
** THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND,
** NOT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR
** OF THIS SOFTWARE, ASSUMES _NO_ RESPONSIBILITY FOR ANY
** CONSEQUENCE RESULTING FROM THE USE, MODIFICATION, OR
** REDISTRIBUTION OF THIS SOFTWARE.
**
*/
package installer;
import java.io.*;
/**
* The TarBuffer class implements the tar archive concept
* of a buffered input stream. This concept goes back to the
* days of blocked tape drives and special io devices. In the
* Java universe, the only real function that this class
* performs is to ensure that files have the correct "block"
* size, or other tars will complain.
* <p>
* You should never have a need to access this class directly.
* TarBuffers are created by Tar IO Streams.
*
* @version $Revision: 12504 $
* @author Timothy Gerard Endres,
* <a href="mailto:[email protected]">[email protected]</a>.
* @see TarArchive
*/
public class
TarBuffer extends Object
{
public static final int DEFAULT_RCDSIZE = ( 512 );
public static final int DEFAULT_BLKSIZE = ( DEFAULT_RCDSIZE * 20 );
private InputStream inStream;
private OutputStream outStream;
private byte[] blockBuffer;
private int currBlkIdx;
private int currRecIdx;
private int blockSize;
private int recordSize;
private int recsPerBlock;
private boolean debug;
public
TarBuffer( InputStream inStream )
{
this( inStream, TarBuffer.DEFAULT_BLKSIZE );
}
public
TarBuffer( InputStream inStream, int blockSize )
{
this( inStream, blockSize, TarBuffer.DEFAULT_RCDSIZE );
}
public
TarBuffer( InputStream inStream, int blockSize, int recordSize )
{
this.inStream = inStream;
this.outStream = null;
this.initialize( blockSize, recordSize );
}
public
TarBuffer( OutputStream outStream )
{
this( outStream, TarBuffer.DEFAULT_BLKSIZE );
}
public
TarBuffer( OutputStream outStream, int blockSize )
{
this( outStream, blockSize, TarBuffer.DEFAULT_RCDSIZE );
}
public
TarBuffer( OutputStream outStream, int blockSize, int recordSize )
{
this.inStream = null;
this.outStream = outStream;
this.initialize( blockSize, recordSize );
}
/**
* Initialization common to all constructors.
*/
private void
initialize( int blockSize, int recordSize )
{
this.debug = false;
this.blockSize = blockSize;
this.recordSize = recordSize;
this.recsPerBlock = ( this.blockSize / this.recordSize );
this.blockBuffer = new byte[ this.blockSize ];
if ( this.inStream != null )
{
this.currBlkIdx = -1;
this.currRecIdx = this.recsPerBlock;
}
else
{
this.currBlkIdx = 0;
this.currRecIdx = 0;
}
}
/**
* Get the TAR Buffer's block size. Blocks consist of multiple records.
*/
public int
getBlockSize()
{
return this.blockSize;
}
/**
* Get the TAR Buffer's record size.
*/
public int
getRecordSize()
{
return this.recordSize;
}
/**
* Set the debugging flag for the buffer.
*
* @param debug If true, print debugging output.
*/
public void
setDebug( boolean debug )
{
this.debug = debug;
}
/**
* Determine if an archive record indicate End of Archive. End of
* archive is indicated by a record that consists entirely of null bytes.
*
* @param record The record data to check.
*/
public boolean
isEOFRecord( byte[] record )
{
for ( int i = 0, sz = this.getRecordSize() ; i < sz ; ++i )
if ( record[i] != 0 )
return false;
return true;
}
/**
* Skip over a record on the input stream.
*/
public void
skipRecord()
throws IOException
{
if ( this.debug )
{
System.err.println
( "SkipRecord: recIdx = " + this.currRecIdx
+ " blkIdx = " + this.currBlkIdx );
}
if ( this.inStream == null )
throw new IOException
( "reading (via skip) from an output buffer" );
if ( this.currRecIdx >= this.recsPerBlock )
{
if ( ! this.readBlock() )
return; // UNDONE
}
this.currRecIdx++;
}
/**
* Read a record from the input stream and return the data.
*
* @return The record data.
*/
public byte[]
readRecord()
throws IOException
{
if ( this.debug )
{
System.err.println
( "ReadRecord: recIdx = " + this.currRecIdx
+ " blkIdx = " + this.currBlkIdx );
}
if ( this.inStream == null )
throw new IOException
( "reading from an output buffer" );
if ( this.currRecIdx >= this.recsPerBlock )
{
if ( ! this.readBlock() )
return null;
}
byte[] result = new byte[ this.recordSize ];
System.arraycopy(
this.blockBuffer, (this.currRecIdx * this.recordSize),
result, 0, this.recordSize );
this.currRecIdx++;
return result;
}
/**
* @return false if End-Of-File, else true
*/
private boolean
readBlock()
throws IOException
{
if ( this.debug )
{
System.err.println
( "ReadBlock: blkIdx = " + this.currBlkIdx );
}
if ( this.inStream == null )
throw new IOException
( "reading from an output buffer" );
this.currRecIdx = 0;
int offset = 0;
int bytesNeeded = this.blockSize;
for ( ; bytesNeeded > 0 ; )
{
long numBytes =
this.inStream.read
( this.blockBuffer, offset, bytesNeeded );
//
// NOTE
// We have fit EOF, and the block is not full!
//
// This is a broken archive. It does not follow the standard
// blocking algorithm. However, because we are generous, and
// it requires little effort, we will simply ignore the error
// and continue as if the entire block were read. This does
// not appear to break anything upstream. We used to return
// false in this case.
//
// Thanks to '[email protected]' for this fix.
//
if ( numBytes == -1 )
break;
offset += numBytes;
bytesNeeded -= numBytes;
if ( numBytes != this.blockSize )
{
if ( this.debug )
{
System.err.println
( "ReadBlock: INCOMPLETE READ " + numBytes
+ " of " + this.blockSize + " bytes read." );
}
}
}
this.currBlkIdx++;
return true;
}
/**
* Get the current block number, zero based.
*
* @return The current zero based block number.
*/
public int
getCurrentBlockNum()
{
return this.currBlkIdx;
}
/**
* Get the current record number, within the current block, zero based.
* Thus, current offset = (currentBlockNum * recsPerBlk) + currentRecNum.
*
* @return The current zero based record number.
*/
public int
getCurrentRecordNum()
{
return this.currRecIdx - 1;
}
/**
* Write an archive record to the archive.
*
* @param record The record data to write to the archive.
*/
public void
writeRecord( byte[] record )
throws IOException
{
if ( this.debug )
{
System.err.println
( "WriteRecord: recIdx = " + this.currRecIdx
+ " blkIdx = " + this.currBlkIdx );
}
if ( this.outStream == null )
throw new IOException
( "writing to an input buffer" );
if ( record.length != this.recordSize )
throw new IOException
( "record to write has length '" + record.length
+ "' which is not the record size of '"
+ this.recordSize + "'" );
if ( this.currRecIdx >= this.recsPerBlock )
{
this.writeBlock();
}
System.arraycopy(
record, 0,
this.blockBuffer, (this.currRecIdx * this.recordSize),
this.recordSize );
this.currRecIdx++;
}
/**
* Write an archive record to the archive, where the record may be
* inside of a larger array buffer. The buffer must be "offset plus
* record size" long.
*
* @param buf The buffer containing the record data to write.
* @param offset The offset of the record data within buf.
*/
public void
writeRecord( byte[] buf, int offset )
throws IOException
{
if ( this.debug )
{
System.err.println
( "WriteRecord: recIdx = " + this.currRecIdx
+ " blkIdx = " + this.currBlkIdx );
}
if ( this.outStream == null )
throw new IOException
( "writing to an input buffer" );
if ( (offset + this.recordSize) > buf.length )
throw new IOException
( "record has length '" + buf.length
+ "' with offset '" + offset
+ "' which is less than the record size of '"
+ this.recordSize + "'" );
if ( this.currRecIdx >= this.recsPerBlock )
{
this.writeBlock();
}
System.arraycopy(
buf, offset,
this.blockBuffer, (this.currRecIdx * this.recordSize),
this.recordSize );
this.currRecIdx++;
}
/**
* Write a TarBuffer block to the archive.
*/
private void
writeBlock()
throws IOException
{
if ( this.debug )
{
System.err.println
( "WriteBlock: blkIdx = " + this.currBlkIdx );
}
if ( this.outStream == null )
throw new IOException
( "writing to an input buffer" );
this.outStream.write( this.blockBuffer, 0, this.blockSize );
this.outStream.flush();
this.currRecIdx = 0;
this.currBlkIdx++;
}
/**
* Flush the current data block if it has any data in it.
*/
private void
flushBlock()
throws IOException
{
if ( this.debug )
{
System.err.println( "TarBuffer.flushBlock() called." );
}
if ( this.outStream == null )
throw new IOException
( "writing to an input buffer" );
if ( this.currRecIdx > 0 )
{
this.writeBlock();
}
}
/**
* Close the TarBuffer. If this is an output buffer, also flush the
* current block before closing.
*/
public void
close()
throws IOException
{
if ( this.debug )
{
System.err.println( "TarBuffer.closeBuffer()." );
}
if ( this.outStream != null )
{
this.flushBlock();
if ( this.outStream != System.out
&& this.outStream != System.err )
{
this.outStream.close();
this.outStream = null;
}
}
else if ( this.inStream != null )
{
if ( this.inStream != System.in )
{
this.inStream.close();
this.inStream = null;
}
}
}
}
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