From 3896d9ed0a87c77330f3f2c998a6fdafe272e2d6 Mon Sep 17 00:00:00 2001
From: tedyu <yuzhihong@gmail.com>
Date: Sun, 25 Sep 2016 06:37:40 -0700
Subject: [PATCH] HBASE-16692 Make ByteBufferUtils#equals safer and correct
 (binlijin)

---
 .../hadoop/hbase/util/ByteBufferUtils.java    |  9 ++++++
 .../hbase/util/TestByteBufferUtils.java       | 29 +++++++++++++++++++
 2 files changed, 38 insertions(+)
 rename {hbase-server => hbase-common}/src/test/java/org/apache/hadoop/hbase/util/TestByteBufferUtils.java (93%)

diff --git a/hbase-common/src/main/java/org/apache/hadoop/hbase/util/ByteBufferUtils.java b/hbase-common/src/main/java/org/apache/hadoop/hbase/util/ByteBufferUtils.java
index d788c701d96..c491fe12fb5 100644
--- a/hbase-common/src/main/java/org/apache/hadoop/hbase/util/ByteBufferUtils.java
+++ b/hbase-common/src/main/java/org/apache/hadoop/hbase/util/ByteBufferUtils.java
@@ -17,6 +17,7 @@
 package org.apache.hadoop.hbase.util;
 
 import java.io.ByteArrayOutputStream;
+import java.io.DataInput;
 import java.io.DataInputStream;
 import java.io.IOException;
 import java.io.InputStream;
@@ -573,6 +574,10 @@ public final class ByteBufferUtils {
   }
 
   public static boolean equals(ByteBuffer buf1, int o1, int l1, ByteBuffer buf2, int o2, int l2) {
+    if ((l1 == 0) || (l2 == 0)) {
+      // both 0 length, return true, or else false
+      return l1 == l2;
+    }
     // Since we're often comparing adjacent sorted data,
     // it's usual to have equal arrays except for the very last byte
     // so check that first
@@ -627,6 +632,10 @@ public final class ByteBufferUtils {
   }
 
   public static boolean equals(ByteBuffer buf1, int o1, int l1, byte[] buf2, int o2, int l2) {
+    if ((l1 == 0) || (l2 == 0)) {
+      // both 0 length, return true, or else false
+      return l1 == l2;
+    }
     // Since we're often comparing adjacent sorted data,
     // it's usual to have equal arrays except for the very last byte
     // so check that first
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/util/TestByteBufferUtils.java b/hbase-common/src/test/java/org/apache/hadoop/hbase/util/TestByteBufferUtils.java
similarity index 93%
rename from hbase-server/src/test/java/org/apache/hadoop/hbase/util/TestByteBufferUtils.java
rename to hbase-common/src/test/java/org/apache/hadoop/hbase/util/TestByteBufferUtils.java
index 8ef07d235e7..dfbc015aea7 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/util/TestByteBufferUtils.java
+++ b/hbase-common/src/test/java/org/apache/hadoop/hbase/util/TestByteBufferUtils.java
@@ -34,6 +34,7 @@ import java.util.Set;
 import java.util.SortedSet;
 import java.util.TreeSet;
 
+import org.apache.hadoop.hbase.HConstants;
 import org.apache.hadoop.hbase.testclassification.MiscTests;
 import org.apache.hadoop.hbase.testclassification.SmallTests;
 import org.apache.hadoop.io.WritableUtils;
@@ -398,6 +399,34 @@ public class TestByteBufferUtils {
     assertTrue(result < 0);
   }
 
+  @Test
+  public void testEquals() {
+    byte[] a = Bytes.toBytes("http://A");
+    ByteBuffer bb = ByteBuffer.wrap(a);
+
+    assertTrue(ByteBufferUtils.equals(HConstants.EMPTY_BYTE_BUFFER, 0, 0,
+        HConstants.EMPTY_BYTE_BUFFER, 0, 0));
+
+    assertFalse(ByteBufferUtils.equals(HConstants.EMPTY_BYTE_BUFFER, 0, 0, bb,
+        0, a.length));
+
+    assertFalse(ByteBufferUtils.equals(bb, 0, 0, HConstants.EMPTY_BYTE_BUFFER,
+        0, a.length));
+
+    assertTrue(ByteBufferUtils.equals(bb, 0, a.length, bb, 0, a.length));
+
+    assertTrue(ByteBufferUtils.equals(HConstants.EMPTY_BYTE_BUFFER, 0, 0,
+        HConstants.EMPTY_BYTE_ARRAY, 0, 0));
+
+    assertFalse(ByteBufferUtils.equals(HConstants.EMPTY_BYTE_BUFFER, 0, 0, a,
+        0, a.length));
+
+    assertFalse(ByteBufferUtils.equals(bb, 0, a.length,
+        HConstants.EMPTY_BYTE_ARRAY, 0, 0));
+
+    assertTrue(ByteBufferUtils.equals(bb, 0, a.length, a, 0, a.length));
+  }
+
   private static void fillBB(ByteBuffer bb, byte b) {
     for (int i = bb.position(); i < bb.limit(); i++) {
       bb.put(i, b);