lib/jtar/org/kamranzafar/jtar/TarOutputStream.java

   1 /**
   2  * Copyright 2012 Kamran Zafar
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *      http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  *
  16  */
  17
  18 package org.kamranzafar.jtar;
  19
  20 import java.io.BufferedOutputStream;
  21 import java.io.File;
  22 import java.io.FileNotFoundException;
  23 import java.io.FileOutputStream;
  24 import java.io.IOException;
  25 import java.io.OutputStream;
  26 import java.io.RandomAccessFile;
  27
  28 /**
  29  * @author Kamran Zafar
  30  *
  31  */
  32 public class TarOutputStream extends OutputStream {
  33         private final OutputStream out;
  34     private long bytesWritten;
  35     private long currentFileSize;
  36     private TarEntry currentEntry;
  37
  38     public TarOutputStream(OutputStream out) {
  39         this.out = out;
  40         bytesWritten = 0;
  41         currentFileSize = 0;
  42     }
  43
  44         public TarOutputStream(final File fout) throws FileNotFoundException {
  45                 this.out = new BufferedOutputStream(new FileOutputStream(fout));
  46                 bytesWritten = 0;
  47                 currentFileSize = 0;
  48         }
  49
  50         /**
  51          * Opens a file for writing.
  52          */
  53         public TarOutputStream(final File fout, final boolean append) throws IOException {
  54                 @SuppressWarnings("resource")
  55                 RandomAccessFile raf = new RandomAccessFile(fout, "rw");
  56                 final long fileSize = fout.length();
  57                 if (append && fileSize > TarConstants.EOF_BLOCK) {
  58                         raf.seek(fileSize - TarConstants.EOF_BLOCK);
  59                 }
  60                 out = new BufferedOutputStream(new FileOutputStream(raf.getFD()));
  61         }
  62
  63     /**
  64      * Appends the EOF record and closes the stream
  65      *
  66      * @see java.io.FilterOutputStream#close()
  67      */
  68     @Override
  69     public void close() throws IOException {
  70         closeCurrentEntry();
  71         write( new byte[TarConstants.EOF_BLOCK] );
  72         out.close();
  73     }
  74     /**
  75      * Writes a byte to the stream and updates byte counters
  76      *
  77      * @see java.io.FilterOutputStream#write(int)
  78      */
  79     @Override
  80     public void write(int b) throws IOException {
  81         out.write( b );
  82         bytesWritten += 1;
  83
  84         if (currentEntry != null) {
  85             currentFileSize += 1;
  86         }
  87     }
  88
  89     /**
  90      * Checks if the bytes being written exceed the current entry size.
  91      *
  92      * @see java.io.FilterOutputStream#write(byte[], int, int)
  93      */
  94     @Override
  95     public void write(byte[] b, int off, int len) throws IOException {
  96         if (currentEntry != null && !currentEntry.isDirectory()) {
  97             if (currentEntry.getSize() < currentFileSize + len) {
  98                 throw new IOException( "The current entry[" + currentEntry.getName() + "] size["
  99                         + currentEntry.getSize() + "] is smaller than the bytes[" + ( currentFileSize + len )
 100                         + "] being written." );
 101             }
 102         }
 103
 104         out.write( b, off, len );
 105
 106         bytesWritten += len;
 107
 108         if (currentEntry != null) {
 109             currentFileSize += len;
 110         }
 111     }
 112
 113     /**
 114      * Writes the next tar entry header on the stream
 115      *
 116      * @param entry
 117      * @throws IOException
 118      */
 119     public void putNextEntry(TarEntry entry) throws IOException {
 120         closeCurrentEntry();
 121
 122         byte[] header = new byte[TarConstants.HEADER_BLOCK];
 123         entry.writeEntryHeader( header );
 124
 125         write( header );
 126
 127         currentEntry = entry;
 128     }
 129
 130     /**
 131      * Closes the current tar entry
 132      *
 133      * @throws IOException
 134      */
 135     protected void closeCurrentEntry() throws IOException {
 136         if (currentEntry != null) {
 137             if (currentEntry.getSize() > currentFileSize) {
 138                 throw new IOException( "The current entry[" + currentEntry.getName() + "] of size["
 139                         + currentEntry.getSize() + "] has not been fully written." );
 140             }
 141
 142             currentEntry = null;
 143             currentFileSize = 0;
 144
 145             pad();
 146         }
 147     }
 148
 149     /**
 150      * Pads the last content block
 151      *
 152      * @throws IOException
 153      */
 154     protected void pad() throws IOException {
 155         if (bytesWritten > 0) {
 156             int extra = (int) ( bytesWritten % TarConstants.DATA_BLOCK );
 157
 158             if (extra > 0) {
 159                 write( new byte[TarConstants.DATA_BLOCK - extra] );
 160             }
 161         }
 162     }
 163 }