537208: Task data filename can get too long

* moved file-related operations to a separate class
* file name is only encoded if required
* file name is trimmed to stay below 255 characters
* encoded file name always used if file already exists
* added unit tests for file-related methods

Change-Id: I8b536b3a3df8168b997aa9be1ec82b9f7e314dfd
Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=537208
Signed-off-by: alexei.trebounskikh <alexei.trebounskikh@tasktop.com>

1 files changed, 128 insertions, 0 deletions

diff --git a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/data/TaskDataFileManager.java b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/data/TaskDataFileManager.java
new file mode 100644
index 000000000..3b8fcc7ef
--- /dev/null
+++ b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/data/TaskDataFileManager.java
@@ -0,0 +1,128 @@
+/*******************************************************************************
+ * Copyright (c) 2018 Tasktop Technologies 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:
+ *     Tasktop Technologies - initial API and implementation
+ *******************************************************************************/
+
+package org.eclipse.mylyn.internal.tasks.core.data;
+
+import java.io.File;
+import java.io.UnsupportedEncodingException;
+import java.net.URLEncoder;
+import java.util.function.Predicate;
+
+import org.eclipse.core.runtime.Assert;
+import org.eclipse.mylyn.commons.core.CoreUtil;
+import org.eclipse.mylyn.tasks.core.ITask;
+
+/**
+ * Encapsulates file-related operations of TaskDataManager
+ */
+public class TaskDataFileManager {
+
+	private static final String ENCODING_UTF_8 = "UTF-8"; //$NON-NLS-1$
+
+	private static final String EXTENSION = ".zip"; //$NON-NLS-1$
+
+	private static final String FOLDER_TASKS = "tasks"; //$NON-NLS-1$
+
+	private static final String FOLDER_DATA = "offline"; //$NON-NLS-1$
+
+	private static final String FOLDER_TASKS_1_0 = "offline"; //$NON-NLS-1$
+
+	private static final int FILENAME_MAX_LEN = 255 - EXTENSION.length(); // 255 is an OS limit for file name
+
+	private String dataPath;
+
+	public String getDataPath() {
+		return dataPath;
+	}
+
+	public void setDataPath(String dataPath) {
+		this.dataPath = dataPath;
+	}
+
+	public File getFile(ITask task, String kind) {
+		return getFile(task.getRepositoryUrl(), task, kind);
+	}
+
+	public File getFile(String repositoryUrl, ITask task, String kind) {
+		File path = getDirectory(repositoryUrl, task);
+		String fileName = getFileName(task, path);
+		return new File(path, fileName + EXTENSION);
+	}
+
+	private File getDirectory(String repositoryUrl, ITask task) {
+		Assert.isNotNull(dataPath);
+		String repositoryPath = task.getConnectorKind() + "-" + CoreUtil.asFileName(repositoryUrl); //$NON-NLS-1$
+		return new File(dataPath + File.separator + FOLDER_TASKS + File.separator + repositoryPath + File.separator
+				+ FOLDER_DATA);
+	}
+
+	private String getFileName(ITask task, File path) {
+		return getFileName(task, filename -> new File(path, filename + EXTENSION).exists());
+	}
+
+	// the method is made protected for unit testing
+	protected String getFileName(ITask task, Predicate<String> fileExists) {
+		String encodedFileName = CoreUtil.asFileName(task.getTaskId());
+
+		// for backwards-compatibility with versions that always encoded file names,
+		// we will use an encoded name if the file with an encoded name already exists
+		if (fileExists.test(encodedFileName)) {
+			return encodedFileName;
+		}
+
+		// if file with encoded name does not exist, we will only encode file name if it is required
+		String fileName;
+		if (requiresEncoding(task.getTaskId())) {
+			fileName = encodedFileName;
+		} else {
+			fileName = task.getTaskId();
+		}
+
+		// trim the file name if it is too long
+		return trimFilenameIfRequired(fileName);
+	}
+
+	/**
+	 * Checks if input contains characters other than ones returned by {@link CoreUtil.asFileName}
+	 *
+	 * @param fileName
+	 * @return true or false
+	 */
+	private boolean requiresEncoding(String fileName) {
+		return !fileName.matches("^[a-zA-Z0-9%\\.]+$"); //$NON-NLS-1$
+	}
+
+	private String trimFilenameIfRequired(String filename) {
+		if (filename.length() > FILENAME_MAX_LEN) {
+			// replace a long file name with a shorter name + the hash
+			String hashCode = getHashCode(filename);
+			return filename.substring(0, FILENAME_MAX_LEN - hashCode.length() - 1) + "." + hashCode; //$NON-NLS-1$
+		}
+
+		return filename;
+	}
+
+	private String getHashCode(String text) {
+		return Integer.toUnsignedString(text.hashCode());
+	}
+
+	public File getFile10(ITask task, String kind) {
+		try {
+			String pathName = URLEncoder.encode(task.getRepositoryUrl(), ENCODING_UTF_8);
+			String fileName = task.getTaskId() + EXTENSION;
+			File path = new File(dataPath + File.separator + FOLDER_TASKS_1_0, pathName);
+			return new File(path, fileName);
+		} catch (UnsupportedEncodingException e) {
+			throw new RuntimeException(e);
+		}
+
+	}
+}