/**
* This file is part of muCommander, http://www.mucommander.com
* Copyright (C) 2002-2016 Maxence Bernard
*
* muCommander is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* muCommander is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package com.mucommander.commons.file.archive.tar.provider;
import com.mucommander.commons.io.BufferPool;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Arrays;
/**
* 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.
* <p>-----------------------------------</p>
* <p>This class is based off the <code>org.apache.tools.tar</code> package of the <i>Apache Ant</i> project. The Ant
* code has been modified under the terms of the Apache License which you can find in the bundled muCommander license
* file. It was forked at version 1.7.1 of Ant.</p>
*
* @author Apache Ant, Maxence Bernard
*/
public class TarBuffer {
/** Default record size */
public static final int DEFAULT_RCDSIZE = (512);
/** Default block size */
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;
/**
* Constructor for a TarBuffer on an input stream.
* @param inStream the input stream to use
*/
public TarBuffer(InputStream inStream) {
this(inStream, TarBuffer.DEFAULT_BLKSIZE, TarBuffer.DEFAULT_RCDSIZE);
}
/**
* Constructor for a TarBuffer on an input stream.
* @param inStream the input stream to use
* @param blockSize the block size to use
* @param recordSize the record size to use
*/
public TarBuffer(InputStream inStream, int blockSize, int recordSize) {
this.inStream = inStream;
this.outStream = null;
this.initialize(blockSize, recordSize);
}
/**
* Constructor for a TarBuffer on an output stream.
* @param outStream the output stream to use
*/
public TarBuffer(OutputStream outStream) {
this(outStream, TarBuffer.DEFAULT_BLKSIZE, TarBuffer.DEFAULT_RCDSIZE);
}
/**
* Constructor for a TarBuffer on an output stream.
* @param outStream the output stream to use
* @param blockSize the block size to use
* @param recordSize the record size to use
*/
public TarBuffer(OutputStream outStream, int blockSize, int recordSize) {
this.inStream = null;
this.outStream = outStream;
this.initialize(blockSize, recordSize);
}
/**
* Initialization common to all constructors.
*
* @param blockSize the block size to use
* @param recordSize the record size to use
*/
private void initialize(int blockSize, int recordSize) {
this.debug = false;
this.blockSize = blockSize;
this.recordSize = recordSize;
this.recsPerBlock = (this.blockSize / this.recordSize);
this.blockBuffer = BufferPool.getByteArray(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.
* @return the block size
*/
public int getBlockSize() {
return this.blockSize;
}
/**
* Get the TAR Buffer's record size.
* @return the 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.
* @return true if the record data is an End of Archive
*/
public boolean isEOFRecord(byte[] record) {
for (int i = 0, sz = getRecordSize(); i < sz; ++i) {
if (record[i] != 0) {
return false;
}
}
return true;
}
/**
* Skip over a record on the input stream.
*
* @return <code>true</code> if the record has been skipped, <code>false</code> if EOF has been reached
* @throws IOException on error
*/
public boolean skipRecord() throws IOException {
if (debug) {
System.err.println("SkipRecord: recIdx = " + currRecIdx
+ " blkIdx = " + currBlkIdx);
}
if (inStream == null) {
throw new IOException("reading (via skip) from an output buffer");
}
if (currRecIdx >= recsPerBlock) {
if (!readBlock()) {
return false;
}
}
currRecIdx++;
return true;
}
/**
* Read a record from the input stream and stores it into the specified buffer.
*
* @param recordBuf the buffer into which the record will be stored. Its length must be {@link #getRecordSize()}.
* @return <code>true</code> if the record has been read, <code>false</code> if EOF has been reached
* @throws IOException on error
*/
public boolean readRecord(byte[] recordBuf) throws IOException {
if (debug) {
System.err.println("ReadRecord: recIdx = " + currRecIdx
+ " blkIdx = " + currBlkIdx);
}
if(recordBuf.length!=recordSize)
throw new IOException("specified record buffer doesn't match record size: "+recordSize);
if (inStream == null) {
throw new IOException("reading from an output buffer");
}
if (currRecIdx >= recsPerBlock) {
if (!readBlock()) {
return false;
}
}
System.arraycopy(blockBuffer,
(currRecIdx * recordSize), recordBuf, 0,
recordSize);
currRecIdx++;
return true;
}
/**
* Read a block from the input stream and stores it into the block buffer.
*
* @return true if a block was read, false if EOF was reached
* @throws IOException on error
*/
private boolean readBlock() throws IOException {
if (debug) {
System.err.println("ReadBlock: blkIdx = " + currBlkIdx);
}
if (inStream == null) {
throw new IOException("reading from an output buffer");
}
currRecIdx = 0;
int offset = 0;
int bytesNeeded = blockSize;
while (bytesNeeded > 0) {
long numBytes = inStream.read(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) {
if (offset == 0) {
// Ensure that we do not read gigabytes of zeros
// for a corrupt tar file.
// See http://issues.apache.org/bugzilla/show_bug.cgi?id=39924
return false;
}
// However, just leaving the unread portion of the buffer dirty does
// cause problems in some cases. This problem is described in
// http://issues.apache.org/bugzilla/show_bug.cgi?id=29877
//
// The solution is to fill the unused portion of the buffer with zeros.
Arrays.fill(blockBuffer, offset, offset + bytesNeeded, (byte) 0);
break;
}
offset += numBytes;
bytesNeeded -= numBytes;
if (numBytes != blockSize) {
if (debug) {
System.err.println("ReadBlock: INCOMPLETE READ "
+ numBytes + " of " + blockSize
+ " bytes read.");
}
}
}
currBlkIdx++;
return true;
}
/**
* Skip over a block on the input stream.
*
* @return true if a block was read, false if EOF was reached
* @throws IOException on error
*/
public boolean skipBlock() throws IOException {
int bytesToSkip = blockSize;
while (bytesToSkip > 0) {
long numBytes = inStream.skip(bytesToSkip);
// Adopt the same 'generous' behavior as #readBlock(), i.e. allow a premature EOF only if at least
// a byte was properly skipped.
if(numBytes==-1) {
return bytesToSkip != blockSize;
}
bytesToSkip -= numBytes;
}
currBlkIdx++;
currRecIdx = recsPerBlock;
return true;
}
/**
* Get the current block number, zero based.
*
* @return The current zero based block number.
*/
public int getCurrentBlockNum() {
return currBlkIdx;
}
/**
* Sets the current block number, zero based.
*
* @param blockNum the current block number, zero based
*/
public void setCurrentBlockNum(int blockNum) {
this.currBlkIdx = blockNum;
}
/**
* 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 currRecIdx - 1;
}
/**
* Returns the number of records per block.
*
* @return the number of records per block
*/
public int getRecordsPerBlock() {
return recsPerBlock;
}
/**
* Write an archive record to the archive.
*
* @param record The record data to write to the archive.
* @throws IOException on error
*/
public void writeRecord(byte[] record) throws IOException {
if (debug) {
System.err.println("WriteRecord: recIdx = " + currRecIdx
+ " blkIdx = " + currBlkIdx);
}
if (outStream == null) {
throw new IOException("writing to an input buffer");
}
if (record.length != recordSize) {
throw new IOException("record to write has length '"
+ record.length
+ "' which is not the record size of '"
+ recordSize + "'");
}
if (currRecIdx >= recsPerBlock) {
writeBlock();
}
System.arraycopy(record, 0, blockBuffer,
(currRecIdx * recordSize),
recordSize);
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.
* @throws IOException on error
*/
public void writeRecord(byte[] buf, int offset) throws IOException {
if (debug) {
System.err.println("WriteRecord: recIdx = " + currRecIdx
+ " blkIdx = " + currBlkIdx);
}
if (outStream == null) {
throw new IOException("writing to an input buffer");
}
if ((offset + recordSize) > buf.length) {
throw new IOException("record has length '" + buf.length
+ "' with offset '" + offset
+ "' which is less than the record size of '"
+ recordSize + "'");
}
if (currRecIdx >= recsPerBlock) {
writeBlock();
}
System.arraycopy(buf, offset, blockBuffer,
(currRecIdx * recordSize),
recordSize);
currRecIdx++;
}
/**
* Write a TarBuffer block to the archive.
*/
private void writeBlock() throws IOException {
if (debug) {
System.err.println("WriteBlock: blkIdx = " + currBlkIdx);
}
if (outStream == null) {
throw new IOException("writing to an input buffer");
}
outStream.write(blockBuffer, 0, blockSize);
outStream.flush();
currRecIdx = 0;
currBlkIdx++;
}
/**
* Flush the current data block if it has any data in it.
*/
private void flushBlock() throws IOException {
if (debug) {
System.err.println("TarBuffer.flushBlock() called.");
}
if (outStream == null) {
throw new IOException("writing to an input buffer");
}
if (currRecIdx > 0) {
writeBlock();
}
}
/**
* Close the TarBuffer. If this is an output buffer, also flush the
* current block before closing.
* @throws IOException on error
*/
public void close() throws IOException {
if (debug) {
System.err.println("TarBuffer.closeBuffer().");
}
try {
if (outStream != null) {
flushBlock();
if (outStream != System.out
&& outStream != System.err) {
outStream.close();
outStream = null;
}
} else if (inStream != null) {
if (inStream != System.in) {
inStream.close();
inStream = null;
}
}
}
finally {
if(blockBuffer!=null) {
BufferPool.releaseByteArray(blockBuffer);
blockBuffer = null;
}
}
}
}