org.xeustechnologies.jtar.TarInputStream Maven / Gradle / Ivy
/**
* Copyright 2012 Kamran Zafar
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.xeustechnologies.jtar;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* @author Kamran Zafar
*
*/
public class TarInputStream extends FilterInputStream {
private static final int SKIP_BUFFER_SIZE = 2048;
private TarEntry currentEntry;
private long currentFileSize;
private long bytesRead;
private boolean defaultSkip = false;
public TarInputStream(InputStream in) {
super( in );
currentFileSize = 0;
bytesRead = 0;
}
@Override
public boolean markSupported() {
return false;
}
/**
* Not supported
*
*/
@Override
public synchronized void mark(int readlimit) {
}
/**
* Not supported
*
*/
@Override
public synchronized void reset() throws IOException {
throw new IOException( "mark/reset not supported" );
}
/**
* Read a byte
*
* @see FilterInputStream#read()
*/
@Override
public int read() throws IOException {
byte[] buf = new byte[1];
int res = this.read( buf, 0, 1 );
if (res != -1) {
return buf[0];
}
return res;
}
/**
* Checks if the bytes being read exceed the entry size and adjusts the byte
* array length. Updates the byte counters
*
*
* @see FilterInputStream#read(byte[], int, int)
*/
@Override
public int read(byte[] b, int off, int len) throws IOException {
if (currentEntry != null) {
if (currentFileSize == currentEntry.getSize()) {
return -1;
} else if (( currentEntry.getSize() - currentFileSize ) < len) {
len = (int) ( currentEntry.getSize() - currentFileSize );
}
}
int br = super.read( b, off, len );
if (br != -1) {
if (currentEntry != null) {
currentFileSize += br;
}
bytesRead += br;
}
return br;
}
/**
* Returns the next entry in the tar file
*
* @return TarEntry
* @throws IOException
*/
public TarEntry getNextEntry() throws IOException {
closeCurrentEntry();
byte[] header = new byte[TarConstants.HEADER_BLOCK];
byte[] theader = new byte[TarConstants.HEADER_BLOCK];
int tr = 0;
// Read full header
while (tr < TarConstants.HEADER_BLOCK) {
int res = read( theader, 0, TarConstants.HEADER_BLOCK - tr );
if (res < 0) {
break;
}
System.arraycopy( theader, 0, header, tr, res );
tr += res;
}
// Check if record is null
boolean eof = true;
for (byte b : header) {
if (b != 0) {
eof = false;
break;
}
}
if (!eof) {
bytesRead += header.length;
currentEntry = new TarEntry( header );
}
return currentEntry;
}
/**
* Closes the current tar entry
*
* @throws IOException
*/
protected void closeCurrentEntry() throws IOException {
if (currentEntry != null) {
if (currentEntry.getSize() > currentFileSize) {
// Not fully read, skip rest of the bytes
long bs = 0;
while (bs < currentEntry.getSize() - currentFileSize) {
long res = skip( currentEntry.getSize() - currentFileSize - bs );
if (res == 0 && currentEntry.getSize() - currentFileSize > 0) {
throw new IOException( "Possible tar file corruption" );
}
bs += res;
}
}
currentEntry = null;
currentFileSize = 0L;
skipPad();
}
}
/**
* Skips the pad at the end of each tar entry file content
*
* @throws IOException
*/
protected void skipPad() throws IOException {
if (bytesRead > 0) {
int extra = (int) ( bytesRead % TarConstants.DATA_BLOCK );
if (extra > 0) {
long bs = 0;
while (bs < TarConstants.DATA_BLOCK - extra) {
long res = skip( TarConstants.DATA_BLOCK - extra - bs );
bs += res;
}
}
}
}
/**
* Skips 'n' bytes on the InputStream
* Overrides default implementation of skip
*
*/
@Override
public long skip(long n) throws IOException {
if (defaultSkip) {
// use skip method of parent stream
// may not work if skip not implemented by parent
return super.skip( n );
}
if (n <= 0) {
return 0;
}
long left = n;
byte[] sBuff = new byte[SKIP_BUFFER_SIZE];
while (left > 0) {
int res = read( sBuff, 0, (int) ( left < SKIP_BUFFER_SIZE ? left : SKIP_BUFFER_SIZE ) );
if (res < 0) {
break;
}
left -= res;
}
return n - left;
}
public boolean isDefaultSkip() {
return defaultSkip;
}
public void setDefaultSkip(boolean defaultSkip) {
this.defaultSkip = defaultSkip;
}
}