Allow TarOutputStream to append to an existing tar file. This is

achieved by positioning the file pointer before the EOF-padding bytes
and overwriting them.

Additionally, the existing tests were broken and only executable on
kamranzafar's machine. The tests should now work on any machine.

pom.xml

@@ -125,6 +125,6 @@
 	</profiles>
 	
 	<properties>
-		<skipTests>true</skipTests>
+		<skipTests>false</skipTests>
 	</properties>
 </project>

src/main/java/org/kamranzafar/jtar/TarOutputStream.java

@@ -17,25 +17,50 @@
 
 package org.kamranzafar.jtar;
 
-import java.io.FilterOutputStream;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.io.RandomAccessFile;
 
 /**
  * @author Kamran Zafar
  * 
  */
-public class TarOutputStream extends FilterOutputStream {
+public class TarOutputStream extends OutputStream {
+	private final OutputStream out;
     private long bytesWritten;
     private long currentFileSize;
     private TarEntry currentEntry;
 
     public TarOutputStream(OutputStream out) {
-        super( out );
+        this.out = out;
         bytesWritten = 0;
         currentFileSize = 0;
     }
 
+	public TarOutputStream(final File fout) throws FileNotFoundException {
+		// TODO: Wrap bufferedoutputstream
+		this.out = new FileOutputStream(fout);
+		bytesWritten = 0;
+		currentFileSize = 0;
+	}
+
+	/**
+	 * Opens a file for writing. 
+	 */
+	public TarOutputStream(final File fout, final boolean append) throws IOException {
+		@SuppressWarnings("resource")
+		RandomAccessFile raf = new RandomAccessFile(fout, "rw");
+		final long fileSize = fout.length();
+		if (append && fileSize > TarConstants.EOF_BLOCK) {
+			raf.seek(fileSize - TarConstants.EOF_BLOCK);
+		}
+		// TODO: Wrap bufferedoutputstream
+		out = new FileOutputStream(raf.getFD());
+	}
+
     /**
      * Appends the EOF record and closes the stream
      * 
@@ -45,9 +70,8 @@ public class TarOutputStream extends FilterOutputStream {
     public void close() throws IOException {
         closeCurrentEntry();
         write( new byte[TarConstants.EOF_BLOCK] );
-        super.close();
+        out.close();
     }
-
     /**
      * Writes a byte to the stream and updates byte counters
      * 
@@ -55,7 +79,7 @@ public class TarOutputStream extends FilterOutputStream {
      */
     @Override
     public void write(int b) throws IOException {
-        super.write( b );
+        out.write( b );
         bytesWritten += 1;
 
         if (currentEntry != null) {
@@ -78,7 +102,13 @@ public class TarOutputStream extends FilterOutputStream {
             }
         }
 
-        super.write( b, off, len );
+        out.write( b, off, len );
+        
+        bytesWritten += len;
+
+        if (currentEntry != null) {
+            currentFileSize += len;
+        }        
     }
 
     /**

src/test/java/org/kamranzafar/jtar/JTarAppendTest.java

@@ -0,0 +1,124 @@
+/**
+ * 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.kamranzafar.jtar;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.BufferedOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
+import java.nio.file.Files;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class JTarAppendTest {
+	static final int BUFFER = 2048;
+
+	private File dir;
+	private File outDir;
+	private File inDir;
+
+	@Before
+	public void setup() throws IOException {
+		dir = Files.createTempDirectory("apnd").toFile();
+		dir.mkdirs();
+		outDir = new File(dir, "out");
+		outDir.mkdirs();
+		inDir = new File(dir, "in");
+		inDir.mkdirs();
+	}
+
+	@Test
+	public void testSingleOperation() throws IOException {
+		TarOutputStream tar = new TarOutputStream(new FileOutputStream(new File(dir, "tar.tar")));
+		tar.putNextEntry(new TarEntry(TestUtils.writeStringToFile("a", new File(inDir, "afile")), "afile"));
+		copyFileToStream(new File(inDir, "afile"), tar);
+		tar.putNextEntry(new TarEntry(TestUtils.writeStringToFile("b", new File(inDir, "bfile")), "bfile"));
+		copyFileToStream(new File(inDir, "bfile"), tar);
+		tar.putNextEntry(new TarEntry(TestUtils.writeStringToFile("c", new File(inDir, "cfile")), "cfile"));
+		copyFileToStream(new File(inDir, "cfile"), tar);
+		tar.close();
+
+		untar();
+
+		assertInEqualsOut();
+	}
+
+	@Test
+	public void testAppend() throws IOException {
+		TarOutputStream tar = new TarOutputStream(new FileOutputStream(new File(dir, "tar.tar")));
+		tar.putNextEntry(new TarEntry(TestUtils.writeStringToFile("a", new File(inDir, "afile")), "afile"));
+		copyFileToStream(new File(inDir, "afile"), tar);
+		tar.close();
+
+		tar = new TarOutputStream(new File(dir, "tar.tar"), true);
+		tar.putNextEntry(new TarEntry(TestUtils.writeStringToFile("b", new File(inDir, "bfile")), "bfile"));
+		copyFileToStream(new File(inDir, "bfile"), tar);
+		tar.putNextEntry(new TarEntry(TestUtils.writeStringToFile("c", new File(inDir, "cfile")), "cfile"));
+		copyFileToStream(new File(inDir, "cfile"), tar);
+		tar.close();
+
+		untar();
+
+		assertInEqualsOut();
+	}
+
+	private void copyFileToStream(File file, OutputStream out) throws IOException {
+		final byte[] buffer = new byte[BUFFER];
+		int length = 0;
+
+		try (FileInputStream in = new FileInputStream(file)) {
+			while ((length = in.read(buffer)) > 0) {
+				out.write(buffer, 0, length);
+			}
+		}
+	}
+
+	/**
+	 * Make sure that the contents of the input & output dirs are identical.
+	 */
+	private void assertInEqualsOut() throws UnsupportedEncodingException, FileNotFoundException, IOException {
+		assertEquals(inDir.list().length, outDir.list().length);
+		for (File in : inDir.listFiles()) {
+			assertEquals(TestUtils.readFile(in), TestUtils.readFile(new File(outDir, in.getName())));
+		}
+	}
+
+	private void untar() throws FileNotFoundException, IOException {
+		try (TarInputStream in = new TarInputStream(new FileInputStream(new File(dir, "tar.tar")))) {
+			TarEntry entry;
+
+			while ((entry = in.getNextEntry()) != null) {
+				int count;
+				byte data[] = new byte[2048];
+				try (BufferedOutputStream dest = new BufferedOutputStream(new FileOutputStream(outDir + "/" + entry.getName()))) {
+					while ((count = in.read(data)) != -1) {
+						dest.write(data, 0, count);
+					}
+				}
+			}
+		}
+	}
+
+}

src/test/java/org/kamranzafar/jtar/JTarTest.java

@@ -17,23 +17,34 @@
 
 package org.kamranzafar.jtar;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
 import java.io.BufferedInputStream;
 import java.io.BufferedOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
+import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.nio.file.Files;
 import java.util.zip.GZIPInputStream;
 
+import org.junit.Before;
 import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
-import static org.junit.Assert.*;
 
-@RunWith(JUnit4.class)
 public class JTarTest {
 	static final int BUFFER = 2048;
 
+	private File dir;
+
+	@Before
+	public void setup() throws IOException {
+		dir = Files.createTempDirectory("tartest").toFile();
+		dir.mkdirs();
+	}
+
 	/**
 	 * Tar the given folder
 	 * 
@@ -41,15 +52,24 @@ public class JTarTest {
 	 */
 	@Test
 	public void tar() throws IOException {
-		FileOutputStream dest = new FileOutputStream("/home/kamran/tmp/tartest.tar");
+		FileOutputStream dest = new FileOutputStream(dir.getAbsolutePath() + "/tartest.tar");
 		TarOutputStream out = new TarOutputStream(new BufferedOutputStream(dest));
 
-		tarFolder(null, "/home/kamran/tmp/tartest/", out);
+		File tartest = new File(dir.getAbsolutePath(), "tartest");
+		tartest.mkdirs();
+
+		TestUtils.writeStringToFile("HPeX2kD5kSTc7pzCDX", new File(tartest, "one"));
+		TestUtils.writeStringToFile("gTzyuQjfhrnyX9cTBSy", new File(tartest, "two"));
+		TestUtils.writeStringToFile("KG889vdgjPHQXUEXCqrr", new File(tartest, "three"));
+		TestUtils.writeStringToFile("CNBDGjEJNYfms7rwxfkAJ", new File(tartest, "four"));
+		TestUtils.writeStringToFile("tT6mFKuLRjPmUDjcVTnjBL", new File(tartest, "five"));
+		TestUtils.writeStringToFile("jrPYpzLfWB5vZTRsSKqFvVj", new File(tartest, "six"));
+
+		tarFolder(null, dir.getAbsolutePath() + "/tartest/", out);
 
 		out.close();
 
-		System.out.println("Calculated tar size: " + TarUtils.calculateTarSize(new File("/home/kamran/tmp/tartest")));
-		System.out.println("Actual tar size: " + new File("/home/kamran/tmp/tartest.tar").length());
+		assertEquals(TarUtils.calculateTarSize(new File(dir.getAbsolutePath() + "/tartest")), new File(dir.getAbsolutePath() + "/tartest.tar").length());
 	}
 
 	/**
@@ -59,13 +79,17 @@ public class JTarTest {
 	 */
 	@Test
 	public void untarTarFile() throws IOException {
-		String destFolder = "/home/kamran/tmp/untartest";
-		File zf = new File("/home/kamran/tmp/tartest.tar");
+		File destFolder = new File(dir, "untartest");
+		destFolder.mkdirs();
+
+		File zf = new File("src/test/resources/tartest.tar");
 
 		TarInputStream tis = new TarInputStream(new BufferedInputStream(new FileInputStream(zf)));
-		untar(tis, destFolder);
+		untar(tis, destFolder.getAbsolutePath());
 
 		tis.close();
+
+		assertFileContents(destFolder);
 	}
 
 	/**
@@ -75,15 +99,19 @@ public class JTarTest {
 	 */
 	@Test
 	public void untarTarFileDefaultSkip() throws IOException {
-		String destFolder = "/home/kamran/tmp/untartest/default";
-		File zf = new File("/home/kamran/tmp/tartest.tar");
+		File destFolder = new File(dir, "untartest/skip");
+		destFolder.mkdirs();
+
+		File zf = new File("src/test/resources/tartest.tar");
 
 		TarInputStream tis = new TarInputStream(new BufferedInputStream(new FileInputStream(zf)));
 		tis.setDefaultSkip(true);
-
-		untar(tis, destFolder);
+		untar(tis, destFolder.getAbsolutePath());
 
 		tis.close();
+
+		assertFileContents(destFolder);
+
 	}
 
 	/**
@@ -93,14 +121,16 @@ public class JTarTest {
 	 */
 	@Test
 	public void untarTGzFile() throws IOException {
-		String destFolder = "/home/kamran/tmp/untargztest";
-		File zf = new File("/home/kamran/tmp/tartest.tar.gz");
+		File destFolder = new File(dir, "untargztest");
+		File zf = new File("src/test/resources/tartest.tar.gz");
 
 		TarInputStream tis = new TarInputStream(new BufferedInputStream(new GZIPInputStream(new FileInputStream(zf))));
 
-		untar(tis, destFolder);
+		untar(tis, destFolder.getAbsolutePath());
 
 		tis.close();
+
+		assertFileContents(destFolder);
 	}
 
 	private void untar(TarInputStream tis, String destFolder) throws IOException {
@@ -169,7 +199,6 @@ public class JTarTest {
 
 			FileInputStream fi = new FileInputStream(fe);
 			origin = new BufferedInputStream(fi);
-
 			TarEntry entry = new TarEntry(fe, parent + files[i]);
 			out.putNextEntry(entry);
 
@@ -187,7 +216,6 @@ public class JTarTest {
 
 	@Test
 	public void fileEntry() throws IOException {
-
 		String fileName = "file.txt";
 		long fileSize = 14523;
 		long modTime = System.currentTimeMillis() / 1000;
@@ -209,4 +237,13 @@ public class JTarTest {
 		TarEntry createdEntry = new TarEntry(headerBuf);
 		assertTrue(fileEntry.equals(createdEntry));
 	}
+
+	private void assertFileContents(File destFolder) throws UnsupportedEncodingException, FileNotFoundException, IOException {
+		assertEquals("HPeX2kD5kSTc7pzCDX", TestUtils.readFile(new File(destFolder, "tartest/one")));
+		assertEquals("gTzyuQjfhrnyX9cTBSy", TestUtils.readFile(new File(destFolder, "tartest/two")));
+		assertEquals("KG889vdgjPHQXUEXCqrr", TestUtils.readFile(new File(destFolder, "tartest/three")));
+		assertEquals("CNBDGjEJNYfms7rwxfkAJ", TestUtils.readFile(new File(destFolder, "tartest/four")));
+		assertEquals("tT6mFKuLRjPmUDjcVTnjBL", TestUtils.readFile(new File(destFolder, "tartest/five")));
+		assertEquals("jrPYpzLfWB5vZTRsSKqFvVj", TestUtils.readFile(new File(destFolder, "tartest/six")));
+	}
 }

src/test/java/org/kamranzafar/jtar/TestUtils.java

@@ -0,0 +1,43 @@
+package org.kamranzafar.jtar;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.io.Reader;
+import java.io.UnsupportedEncodingException;
+
+public class TestUtils {
+
+	private static final int BUFFER = 2048;
+
+	public static File writeStringToFile(String string, File file) throws UnsupportedEncodingException, FileNotFoundException, IOException {
+		try (OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream(file), "UTF-8")) {
+			writer.write(string);
+		}
+
+		return file;
+	}
+
+	public static String readFile(File file) throws UnsupportedEncodingException, FileNotFoundException, IOException {
+		final char[] buffer = new char[BUFFER];
+		final StringBuilder out = new StringBuilder();
+		try (final Reader in = new InputStreamReader(new FileInputStream(file), "UTF-8")) {
+			return readFromStream(buffer, out, in);
+		}
+	}
+
+	public static String readFromStream(final char[] buffer, final StringBuilder out, final Reader in) throws IOException {
+		while (true) {
+			final int read = in.read(buffer, 0, BUFFER);
+			if (read <= 0) {
+				break;
+			}
+			out.append(buffer, 0, read);
+		}
+		return out.toString();
+	}
+}