| /** |
| * 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.fs; |
| |
| import java.io.*; |
| |
| /**************************************************************** |
| * FSInputStream is a generic old InputStream with a little bit |
| * of RAF-style seek ability. |
| * |
| *****************************************************************/ |
| public abstract class FSInputStream extends InputStream |
| implements Seekable, PositionedReadable { |
| /** |
| * Seek to the given offset from the start of the file. |
| * The next read() will be from that location. Can't |
| * seek past the end of the file. |
| */ |
| public abstract void seek(long pos) throws IOException; |
| |
| /** |
| * Return the current offset from the start of the file |
| */ |
| public abstract long getPos() throws IOException; |
| |
| /** |
| * Seeks a different copy of the data. Returns true if |
| * found a new source, false otherwise. |
| */ |
| public abstract boolean seekToNewSource(long targetPos) throws IOException; |
| |
| public int read(long position, byte[] buffer, int offset, int length) |
| throws IOException { |
| synchronized (this) { |
| long oldPos = getPos(); |
| int nread = -1; |
| try { |
| seek(position); |
| nread = read(buffer, offset, length); |
| } finally { |
| seek(oldPos); |
| } |
| return nread; |
| } |
| } |
| |
| public void readFully(long position, byte[] buffer, int offset, int length) |
| throws IOException { |
| int nread = 0; |
| while (nread < length) { |
| int nbytes = read(position+nread, buffer, offset+nread, length-nread); |
| if (nbytes < 0) { |
| throw new EOFException("End of file reached before reading fully."); |
| } |
| nread += nbytes; |
| } |
| } |
| |
| public void readFully(long position, byte[] buffer) |
| throws IOException { |
| readFully(position, buffer, 0, buffer.length); |
| } |
| } |