Add missing file to previous commit.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1213593 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/BlockReaderUtil.java

@@ -0,0 +1,54 @@
+/**
+ * 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
+ *
+ *     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.apache.hadoop.hdfs;
+
+import java.io.IOException;
+
+/**
+ * For sharing between the local and remote block reader implementations.
+ */
+class BlockReaderUtil {
+
+  /* See {@link BlockReader#readAll(byte[], int, int)} */
+  public static int readAll(BlockReader reader,
+      byte[] buf, int offset, int len) throws IOException {
+    int n = 0;
+    for (;;) {
+      int nread = reader.read(buf, offset + n, len - n);
+      if (nread <= 0)
+        return (n == 0) ? nread : n;
+      n += nread;
+      if (n >= len)
+        return n;
+    }
+  }
+
+  /* See {@link BlockReader#readFully(byte[], int, int)} */
+  public static void readFully(BlockReader reader,
+      byte[] buf, int off, int len) throws IOException {
+    int toRead = len;
+    while (toRead > 0) {
+      int ret = reader.read(buf, off, toRead);
+      if (ret < 0) {
+        throw new IOException("Premature EOF from inputStream");
+      }
+      toRead -= ret;
+      off += ret;
+    }
+  }
+}