HADOOP-11012. hadoop fs -text of zero-length file causes EOFException. Contributed by Eric Payne

(cherry picked from commit 01e8f056d9b7245193e6050f9830ca058db02a6e)

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -397,6 +397,9 @@ Release 2.6.0 - UNRELEASED
 
     HADOOP-11036. Add build directory to .gitignore (Tsuyoshi OZAWA via aw)
 
+    HADOOP-11012. hadoop fs -text of zero-length file causes EOFException
+    (Eric Payne via jlowe)
+
 Release 2.5.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/shell/Display.java

@@ -18,6 +18,7 @@
 package org.apache.hadoop.fs.shell;
 
 import java.io.ByteArrayOutputStream;
+import java.io.EOFException;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
@@ -126,8 +127,17 @@ class Display extends FsCommand {
     protected InputStream getInputStream(PathData item) throws IOException {
       FSDataInputStream i = (FSDataInputStream)super.getInputStream(item);
 
+      // Handle 0 and 1-byte files
+      short leadBytes;
+      try {
+        leadBytes = i.readShort();
+      } catch (EOFException e) {
+        i.seek(0);
+        return i;
+      }
+
       // Check type of stream first
-      switch(i.readShort()) {
+      switch(leadBytes) {
         case 0x1f8b: { // RFC 1952
           // Must be gzip
           i.seek(0);

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/shell/TestTextCommand.java

@@ -42,29 +42,14 @@ public class TestTextCommand {
     System.getProperty("test.build.data", "build/test/data/") + "/testText";
   private static final String AVRO_FILENAME =
     new Path(TEST_ROOT_DIR, "weather.avro").toUri().getPath();
+  private static final String TEXT_FILENAME =
+    new Path(TEST_ROOT_DIR, "testtextfile.txt").toUri().getPath();
 
   /**
    * Tests whether binary Avro data files are displayed correctly.
    */
   @Test (timeout = 30000)
   public void testDisplayForAvroFiles() throws Exception {
-    // Create a small Avro data file on the local file system.
-    createAvroFile(generateWeatherAvroBinaryData());
-
-    // Prepare and call the Text command's protected getInputStream method
-    // using reflection.
-    Configuration conf = new Configuration();
-    URI localPath = new URI(AVRO_FILENAME);
-    PathData pathData = new PathData(localPath, conf);
-    Display.Text text = new Display.Text();
-    text.setConf(conf);
-    Method method = text.getClass().getDeclaredMethod(
-      "getInputStream", PathData.class);
-    method.setAccessible(true);
-    InputStream stream = (InputStream) method.invoke(text, pathData);
-    String output = inputStreamToString(stream);
-
-    // Check the output.
     String expectedOutput =
       "{\"station\":\"011990-99999\",\"time\":-619524000000,\"temp\":0}" +
       System.getProperty("line.separator") +
@@ -77,18 +62,72 @@ public class TestTextCommand {
       "{\"station\":\"012650-99999\",\"time\":-655509600000,\"temp\":78}" +
       System.getProperty("line.separator");
 
+    String output = readUsingTextCommand(AVRO_FILENAME,
+                                         generateWeatherAvroBinaryData());
     assertEquals(expectedOutput, output);
   }
 
+  /**
+   * Tests that a zero-length file is displayed correctly.
+   */
+  @Test (timeout = 30000)
+  public void testEmptyTextFil() throws Exception {
+    byte[] emptyContents = { };
+    String output = readUsingTextCommand(TEXT_FILENAME, emptyContents);
+    assertTrue("".equals(output));
+  }
+
+  /**
+   * Tests that a one-byte file is displayed correctly.
+   */
+  @Test (timeout = 30000)
+  public void testOneByteTextFil() throws Exception {
+    byte[] oneByteContents = { 'x' };
+    String output = readUsingTextCommand(TEXT_FILENAME, oneByteContents);
+    assertTrue(new String(oneByteContents).equals(output));
+  }
+
+  /**
+   * Tests that a one-byte file is displayed correctly.
+   */
+  @Test (timeout = 30000)
+  public void testTwoByteTextFil() throws Exception {
+    byte[] twoByteContents = { 'x', 'y' };
+    String output = readUsingTextCommand(TEXT_FILENAME, twoByteContents);
+    assertTrue(new String(twoByteContents).equals(output));
+  }
+
+  // Create a file on the local file system and read it using
+  // the Display.Text class.
+  private String readUsingTextCommand(String fileName, byte[] fileContents)
+          throws Exception {
+    createFile(fileName, fileContents);
+
+    // Prepare and call the Text command's protected getInputStream method
+    // using reflection.
+    Configuration conf = new Configuration();
+    URI localPath = new URI(fileName);
+    PathData pathData = new PathData(localPath, conf);
+    Display.Text text = new Display.Text() {
+      @Override
+      public InputStream getInputStream(PathData item) throws IOException {
+        return super.getInputStream(item);
+      }
+    };
+    text.setConf(conf);
+    InputStream stream = (InputStream) text.getInputStream(pathData);
+    return inputStreamToString(stream);
+  }
+
   private String inputStreamToString(InputStream stream) throws IOException {
     StringWriter writer = new StringWriter();
     IOUtils.copy(stream, writer);
     return writer.toString();
   }
 
-  private void createAvroFile(byte[] contents) throws IOException {
+  private void createFile(String fileName, byte[] contents) throws IOException {
     (new File(TEST_ROOT_DIR)).mkdir();
-    File file = new File(AVRO_FILENAME);
+    File file = new File(fileName);
     file.createNewFile();
     FileOutputStream stream = new FileOutputStream(file);
     stream.write(contents);