HADOOP-12677. DecompressorStream throws IndexOutOfBoundsException when calling skip(long)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/DecompressorStream.java

@@ -199,9 +199,10 @@ public long skip(long n) throws IOException {
     checkStream();
 
     // Read 'n' bytes
-    int skipped = 0;
+    long skipped = 0;
     while (skipped < n) {
-      int len = Math.min(((int)n - skipped), skipBytes.length);
+      // len is between 0 and skipBytes.length, so downcast is safe
+      int len = (int)Math.min((n - skipped), skipBytes.length);
       len = read(skipBytes, 0, len);
       if (len == -1) {
         eof = true;

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/compress/TestBlockDecompressorStream.java

@@ -23,6 +23,7 @@
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
+import java.io.EOFException;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
@@ -48,6 +49,26 @@ public void testRead2() throws IOException {
     testRead(4);
   }
 
+  @Test
+  public void testDecompressorStreamSkipOutOfBound() throws IOException {
+    ByteArrayInputStream bytesIn;
+    DecompressorStream decompStream;
+    int bufLen = 4;
+    bytesOut = new ByteArrayOutputStream();
+    bytesOut.write(ByteBuffer.allocate(bufLen).putInt(1024).array(), 0, bufLen);
+    buf = bytesOut.toByteArray();
+    bytesIn = new ByteArrayInputStream(buf);
+
+    decompStream = new DecompressorStream(bytesIn, new FakeDecompressor());
+    try {
+      // check that skipping a length longer than Integer.MAX_VALUE does not
+      // throw IndexOutOfBoundsException
+      decompStream.skip((long)Integer.MAX_VALUE + 1);
+    } catch (EOFException e) {
+      // expected exception, because the input is not that long
+    }
+  }
+
   private void testRead(int bufLen) throws IOException {
     // compress empty stream
     bytesOut = new ByteArrayOutputStream();