/*
** Authored by Timothy Gerard Endres
** <mailto:time@gjt.org> <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 org.jboss.shrinkwrap.impl.base.io.tar;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* 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: 1.10 $
* @author Timothy Gerard Endres, <a href="mailto:time@gjt.org">time@trustice.com</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 'Yohann.Roussel@alcatel.fr' 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");
}
// Thanks to 'Todd Kofford <tkofford@bigfoot.com>' for this patch.
// Use a buffer initialized with 0s to initialize everything in the
// blockBuffer after the last current, complete record. This prevents
// any previous data that might have previously existed in the
// blockBuffer from being written to the file.
if (this.currRecIdx > 0) {
int offset = this.currRecIdx * this.recordSize;
byte[] zeroBuffer = new byte[this.blockSize - offset];
System.arraycopy(zeroBuffer, 0, this.blockBuffer, offset, zeroBuffer.length);
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;
}
}
}
}