| /* |
| * 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.taverna.prov; |
| |
| /** |
| * Copied out from net.sf.taverna.t2.workbench.file.impl.SafeFileOutputStream |
| * to avoid dependency on file-impl. |
| * |
| * TODO: Move to taverna utils! |
| * |
| */ |
| |
| import java.io.FileNotFoundException; |
| import java.io.FilterOutputStream; |
| import java.io.IOException; |
| import java.nio.file.Files; |
| import java.nio.file.Path; |
| import java.nio.file.StandardCopyOption; |
| |
| public class SafeFileOutputStream extends FilterOutputStream { |
| |
| private final Path desiredFile; |
| private Path tempFile; |
| boolean desiredAlreadyExisted; |
| |
| public SafeFileOutputStream(Path file) throws IOException { |
| this(file, tempFile(file)); |
| } |
| |
| public SafeFileOutputStream(Path desiredFile, Path tempFile) |
| throws IOException { |
| |
| super(Files.newOutputStream(tempFile)); |
| this.desiredFile = desiredFile; |
| this.tempFile = tempFile; |
| // Some useful things to check that we preferably don't want to fail on |
| // close() |
| desiredAlreadyExisted = Files.exists(desiredFile); |
| Path desiredFolder = this.desiredFile.getParent(); |
| if (desiredAlreadyExisted) { |
| if (!Files.isWritable(desiredFile)) { |
| throw new FileNotFoundException("Can't write to " + desiredFile); |
| } |
| } else { |
| if (!Files.exists(desiredFolder)) { |
| throw new FileNotFoundException("Folder does not exist: " |
| + desiredFolder); |
| } |
| if (!Files.isDirectory(desiredFolder)) { |
| throw new FileNotFoundException("Not a directory: " |
| + desiredFolder); |
| } |
| } |
| if (!Files.isWritable(desiredFolder)) { |
| throw new FileNotFoundException("Can't modify folder " |
| + desiredFolder); |
| } |
| } |
| |
| private static Path tempFile(Path file) throws IOException { |
| return Files.createTempFile(file.getParent(), file.getFileName() |
| .toString(), ".tmp"); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| // If super.close fails - we leave the tempfiles behind |
| super.close(); |
| if (!Files.exists(tempFile)) { |
| // Probably something went wrong before close called, |
| // like rollback() |
| return; |
| } |
| Path beforeDeletion = null; |
| try { |
| if (desiredAlreadyExisted) { |
| // In case renaming goes wrong, we don't want to have already |
| // deleted the |
| // desired file. So we'll rename it to another temporary file |
| // instead which |
| // we can delete on successful rename. |
| beforeDeletion = tempFile(desiredFile); |
| if (!Files.deleteIfExists(beforeDeletion)) { |
| // Should not happen, we just made it! |
| throw new IOException("Can't delete temporary file " |
| + beforeDeletion); |
| } |
| Files.move(desiredFile, beforeDeletion, |
| StandardCopyOption.ATOMIC_MOVE); |
| } |
| try { |
| Files.move(tempFile, desiredFile, |
| StandardCopyOption.ATOMIC_MOVE); |
| } catch (IOException e) { |
| // We'll leave our tempFiles for recovery. |
| tempFile = null; |
| beforeDeletion = null; |
| |
| if (Files.exists(desiredFile)) { |
| // Someone else added or replaced the file afterwards, |
| // kind-a OK |
| return; |
| } |
| throw e; |
| } |
| } finally { |
| if (beforeDeletion != null) { |
| Files.deleteIfExists(beforeDeletion); |
| } |
| if (tempFile != null) { |
| Files.deleteIfExists(tempFile); |
| } |
| } |
| } |
| |
| public void rollback() throws IOException { |
| super.close(); |
| Files.deleteIfExists(tempFile); |
| } |
| |
| } |