HDDS-2784. Read to ByteBuffer uses wrong offset

hadoop-ozone/ozonefs/src/main/java/org/apache/hadoop/fs/ozone/OzoneFSInputStream.java

@@ -104,11 +104,10 @@ public int read(ByteBuffer buf) throws IOException {
       throw new ReadOnlyBufferException();
     }
 
-    int bufInitPos = buf.position();
     int readLen = Math.min(buf.remaining(), available());
 
     byte[] readData = new byte[readLen];
-    int bytesRead = read(readData, bufInitPos, readLen);
+    int bytesRead = read(readData, 0, readLen);
     buf.put(readData);
 
     return bytesRead;

hadoop-ozone/ozonefs/src/test/java/org/apache/hadoop/fs/ozone/contract/TestOzoneFSInputStreamUnit.java

@@ -0,0 +1,101 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.apache.hadoop.fs.ozone.contract;
+
+import org.apache.commons.lang3.RandomUtils;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.ozone.OzoneFSInputStream;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+
+// TODO rename to TestOzoneFSInputStream after HDDS-2785
+/**
+ * Tests for {@link OzoneFSInputStream}.
+ */
+public class TestOzoneFSInputStreamUnit {
+
+  @Test
+  public void readToByteBuffer() throws IOException {
+    for (int streamLength = 1; streamLength <= 10; streamLength++) {
+      for (int bufferCapacity = 0; bufferCapacity <= 10; bufferCapacity++) {
+        testReadToByteBuffer(streamLength, bufferCapacity, 0);
+        if (bufferCapacity > 1) {
+          testReadToByteBuffer(streamLength, bufferCapacity, 1);
+          if (bufferCapacity > 2) {
+            testReadToByteBuffer(streamLength, bufferCapacity,
+                bufferCapacity - 1);
+          }
+        }
+        testReadToByteBuffer(streamLength, bufferCapacity, bufferCapacity);
+      }
+    }
+  }
+
+  private static void testReadToByteBuffer(int streamLength, int bufferCapacity,
+      int bufferPosition) throws IOException {
+    final byte[] source = RandomUtils.nextBytes(streamLength);
+    final InputStream input = new ByteArrayInputStream(source);
+    final OzoneFSInputStream subject = createStream(input);
+
+    final int expectedReadLength = Math.min(bufferCapacity - bufferPosition,
+        input.available());
+    final byte[] expectedContent = Arrays.copyOfRange(source, 0,
+        expectedReadLength);
+
+    final ByteBuffer buf = ByteBuffer.allocate(bufferCapacity);
+    buf.position(bufferPosition);
+
+    final int bytesRead = subject.read(buf);
+
+    assertEquals(expectedReadLength, bytesRead);
+
+    final byte[] content = new byte[bytesRead];
+    buf.position(bufferPosition);
+    buf.get(content);
+    assertArrayEquals(expectedContent, content);
+  }
+
+  @Test
+  public void readEmptyStreamToByteBuffer() throws IOException {
+    final OzoneFSInputStream subject = emptyStream();
+    final ByteBuffer buf = ByteBuffer.allocate(1);
+
+    final int bytesRead = subject.read(buf);
+
+    assertEquals(-1, bytesRead);
+    assertEquals(0, buf.position());
+  }
+
+  private static OzoneFSInputStream createStream(InputStream input) {
+    return new OzoneFSInputStream(input,
+        new FileSystem.Statistics("test"));
+  }
+
+  private static OzoneFSInputStream emptyStream() {
+    return createStream(new ByteArrayInputStream(new byte[0]));
+  }
+
+}