| /******************************************************************************* |
| * Copyright (c) 2003, 2008 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| |
| package org.eclipse.osgi.framework.internal.reliablefile; |
| |
| import java.io.*; |
| |
| /** |
| * A ReliableFile FileInputStream replacement class. |
| * This class can be used just like FileInputStream. The class |
| * is in partnership with ReliableFileOutputStream to avoid losing |
| * file data by using multiple files. |
| * |
| * @see ReliableFileOutputStream |
| */ |
| public class ReliableFileInputStream extends FilterInputStream { |
| /** |
| * ReliableFile object for this file. |
| */ |
| private ReliableFile reliable; |
| |
| /** |
| * size of crc and signature |
| */ |
| private int sigSize; |
| |
| /** |
| * current position reading from file |
| */ |
| private int readPos; |
| |
| /** |
| * total file length available for reading |
| */ |
| private int length; |
| |
| /** |
| * Constructs a new ReliableFileInputStream on the file named <code>name</code>. If the |
| * file does not exist, the <code>FileNotFoundException</code> is thrown. |
| * The <code>name</code> may be absolute or relative |
| * to the System property <code>"user.dir"</code>. |
| * |
| * @param name the file on which to stream reads. |
| * @exception java.io.IOException If an error occurs opening the file. |
| */ |
| public ReliableFileInputStream(String name) throws IOException { |
| this(ReliableFile.getReliableFile(name), ReliableFile.GENERATION_LATEST, ReliableFile.OPEN_BEST_AVAILABLE); |
| } |
| |
| /** |
| * Constructs a new ReliableFileInputStream on the File <code>file</code>. If the |
| * file does not exist, the <code>FileNotFoundException</code> is thrown. |
| * |
| * @param file the File on which to stream reads. |
| * @exception java.io.IOException If an error occurs opening the file. |
| */ |
| public ReliableFileInputStream(File file) throws IOException { |
| this(ReliableFile.getReliableFile(file), ReliableFile.GENERATION_LATEST, ReliableFile.OPEN_BEST_AVAILABLE); |
| } |
| |
| /** |
| * Constructs a new ReliableFileInputStream on the File <code>file</code>. If the |
| * file does not exist, the <code>FileNotFoundException</code> is thrown. |
| * |
| * @param file the File on which to stream reads. |
| * @param generation a specific generation requested. |
| * @param openMask mask used to open data. |
| * are invalid (corrupt, missing, etc). |
| * @exception java.io.IOException If an error occurs opening the file. |
| */ |
| public ReliableFileInputStream(File file, int generation, int openMask) throws IOException { |
| this(ReliableFile.getReliableFile(file), generation, openMask); |
| } |
| |
| /** |
| * |
| * @param reliable The ReliableFile on which to read. |
| * @param generation a specific generation requested. |
| * @param openMask mask used to open data. |
| * are invalid (corrupt, missing, etc). |
| * @throws IOException If an error occurs opening the file. |
| */ |
| private ReliableFileInputStream(ReliableFile reliable, int generation, int openMask) throws IOException { |
| super(reliable.getInputStream(generation, openMask)); |
| |
| this.reliable = reliable; |
| sigSize = reliable.getSignatureSize(); |
| readPos = 0; |
| length = super.available(); |
| if (sigSize > length) |
| length = 0; // shouldn't ever happen |
| else |
| length -= sigSize; |
| } |
| |
| /** |
| * Closes this input stream and releases any system resources associated |
| * with the stream. |
| * |
| * @exception java.io.IOException If an error occurs closing the file. |
| */ |
| public synchronized void close() throws IOException { |
| if (reliable != null) { |
| try { |
| super.close(); |
| } finally { |
| reliable.closeInputFile(); |
| reliable = null; |
| } |
| } |
| } |
| |
| /** |
| * Override default FilterInputStream method. |
| * @see FilterInputStream#read(byte[], int, int) |
| */ |
| public synchronized int read(byte b[], int off, int len) throws IOException { |
| if (readPos >= length) { |
| return -1; |
| } |
| int num = super.read(b, off, len); |
| |
| if (num != -1) { |
| if (num + readPos > length) { |
| num = length - readPos; |
| } |
| readPos += num; |
| } |
| return num; |
| } |
| |
| /** |
| * Override default FilterInputStream method. |
| * @see FilterInputStream#read(byte[]) |
| */ |
| public synchronized int read(byte b[]) throws IOException { |
| return read(b, 0, b.length); |
| } |
| |
| /** |
| * Override default FilterInputStream method. |
| * @see FilterInputStream#read() |
| */ |
| public synchronized int read() throws IOException { |
| if (readPos >= length) { |
| return -1; |
| } |
| int num = super.read(); |
| |
| if (num != -1) { |
| readPos++; |
| } |
| return num; |
| } |
| |
| /** |
| * Override default available method. |
| * @see FilterInputStream#available() |
| */ |
| public synchronized int available() throws IOException { |
| if (readPos < length) // just in case |
| return (length - readPos); |
| return 0; |
| } |
| |
| /** |
| * Override default skip method. |
| * @see FilterInputStream#skip(long) |
| */ |
| public synchronized long skip(long n) throws IOException { |
| long len = super.skip(n); |
| if (readPos + len > length) |
| len = length - readPos; |
| readPos += len; |
| return len; |
| } |
| |
| /** |
| * Override default markSupported method. |
| * @see FilterInputStream#markSupported() |
| */ |
| public boolean markSupported() { |
| return false; |
| } |
| |
| /** |
| * Override default mark method. |
| * @see FilterInputStream#mark(int) |
| */ |
| public void mark(int readlimit) { |
| //ignore |
| } |
| |
| /** |
| * Override default reset method. |
| * @see FilterInputStream#reset() |
| */ |
| public void reset() throws IOException { |
| throw new IOException("reset not supported."); //$NON-NLS-1$ |
| } |
| } |