desruisseaux commented on code in PR #508: URL: https://github.com/apache/maven-jar-plugin/pull/508#discussion_r3892127127
########## src/main/java/org/apache/maven/plugins/jar/TimestampCheck.java: ########## @@ -0,0 +1,237 @@ +/* + * 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.maven.plugins.jar; + +import java.io.IOException; +import java.nio.file.FileVisitResult; +import java.nio.file.Files; +import java.nio.file.Path; +import java.nio.file.SimpleFileVisitor; +import java.nio.file.attribute.BasicFileAttributes; +import java.nio.file.attribute.FileTime; +import java.util.Collection; +import java.util.Enumeration; +import java.util.HashSet; +import java.util.Set; +import java.util.zip.ZipEntry; +import java.util.zip.ZipFile; + +import org.apache.maven.api.plugin.Log; + +/** + * Checks file timestamps in order to determine if anything changed compared to an existing <abbr>JAR</abbr> file. + * This class may scan directories, but only if they have not already been visited by {@link FileCollector}. + * Note that the latter can occur only if {@link FileCollector} has no {@code PathMatcher}. + * Therefore, this class uses no {@code PathMatcher} neither. + * + * <h2>Ignore files</h2> + * The {@code META-INF/MANIFEST.MF} file and the {@code META-INF/maven/} directory are ignored. + * See {@link #isIgnored(Path)} for the rational. + */ +final class TimestampCheck extends SimpleFileVisitor<Path> { + /** + * The base directory of archived files. + */ + private final Path classesDir; + + /** + * Path to the existing <abbr>JAR</abbr> file. + */ + private final Path jarFile; + + /** + * The last modified time of the <abbr>JAR</abbr> file. + */ + private final FileTime jarFileTime; + + /** + * Where to send non-fatal error messages. + */ + private final Log logger; + + /** + * Entries of the <abbr>JAR</abbr> file. Note that getting elements from this enumeration can be costly. + * Therefore, we do not fetch all elements in advance but only when needed. + */ + private Enumeration<? extends ZipEntry> entries; + + /** + * Files found in the <abbr>JAR</abbr> file but not yet traversed by the file visitor. + * Files are added lazily only when needed, and removed as soon as they have been traversed. + * Path are absolute (resolved with {@link #classesDir}). + */ + private final Set<Path> filesInJAR; + + /** + * Some of the files in the build directory. This list contains only the files for which we have already + * verified the timestamp. We store them in a separated list for avoiding to check the timestamp twice. + * We need this list because we still need to verify if the files are in the {@link #jarFile}. + */ + private final Set<Path> filesInBuild; + + /** + * Whether at least one file is more recent than the <abbr>JAR</abbr> file. + * The scan of files will stop quickly after this flag become {@code true}. + */ + private boolean hasUpdates; + + /** + * Creates a new visitor for checking the validity of a <abbr>JAR</abbr> file. + * + * @param jarFile the existing <abbr>JAR</abbr> file + * @param jarFileTime the last modified time of the <abbr>JAR</abbr> file + * @param classesDir base directory of archived files + * @param logger where to send a warning if an error occurred while checking an existing <abbr>JAR</abbr> file + * @throws IOException if an error occurred while fetching the <abbr>JAR</abbr> file modification time + */ + TimestampCheck(final Path jarFile, final Path classesDir, final Log logger) throws IOException { + this.classesDir = classesDir; + this.jarFile = jarFile; + this.logger = logger; + jarFileTime = Files.getLastModifiedTime(jarFile); + filesInJAR = new HashSet<>(); + filesInBuild = new HashSet<>(); + } + + /** + * Returns {@code true} if the given file is more recent that the <abbr>JAR</abbr> file. + * + * @param file the file to check + * @param attributes the file's basic attributes + * @param isDirectory whether the file is a directory + * @return whether the modification time is more recent that the <abbr>JAR</abbr> file + */ + boolean isUpdated(final Path file, final BasicFileAttributes attributes, final boolean isDirectory) { + if (jarFileTime.compareTo(attributes.lastModifiedTime()) < 0) { + return true; + } + if (!isDirectory) { + filesInBuild.add(file); + } + return false; + } + + /** + * Checks if the <abbr>JAR</abbr> file contains all the given files, no extra entry, and no outdated entry. + * + * @param fileSets pairs of base directory and files potentially relative to the base directory + * @return whether the <abbr>JAR</abbr> file is up-to-date + */ + boolean isUpToDateJAR(final Collection<Archive.FileSet> fileSets) { + // No need to use JarFile because no need to handle META-INF in a special way. + try (ZipFile jar = new ZipFile(jarFile.toFile())) { + entries = jar.entries(); + for (Path file : filesInBuild) { + if (!isFoundInJAR(file)) { + return false; + } + } + for (Archive.FileSet fileSet : fileSets) { + final Path baseDir = fileSet.directory; + for (Path file : fileSet.files) { + file = baseDir.resolve(file); + if (!filesInBuild.remove(file)) { // For skipping the files already verified by above loop. + Files.walkFileTree(file, this); + if (hasUpdates) { + return false; + } + } + } + } + // Check for remaining files in the JAR which were not in the build directory. + for (Path file : filesInJAR) { + if (!isIgnored(classesDir.relativize(file))) { + return false; + } + } + while (entries.hasMoreElements()) { + ZipEntry entry = entries.nextElement(); + if (!(entry.isDirectory() || isIgnored(Path.of(entry.getName())))) { + return false; + } + } + } catch (IOException e) { + logger.warn(e); + return false; + } finally { + entries = null; + } + return true; + } + + /** + * Returns whether the given file in a <abbr>JAR</abbr> file should be ignored. + * We have to ignore the files that are generated in a temporary directory + * because they do not exist yet when the directory is traversed. Furthermore, + * their timestamp would always be newer then the <abbr>JAR</abbr> file anyway. + * + * @param file path to a file relative to the root of the <abbr>JAR</abbr> file + */ + private static boolean isIgnored(Path file) { + if (file.startsWith(MetadataFiles.META_INF)) { + file = file.subpath(1, file.getNameCount()); + if (file.startsWith(MetadataFiles.MANIFEST)) { + return file.getNameCount() == 1; + } else if (file.startsWith(MetadataFiles.MAVEN_DIR)) { + return true; // Ignore all subdirectories. + } + } + return false; + } + + /** + * Checks if the given file is new or more recent than the <abbr>JAR</abbr> file. + * Checks also if the file exists in the <abbr>JAR</abbr> file. + * + * @param file the traversed file + * @param attributes the file's basic attributes + */ + @Override + public FileVisitResult visitFile(final Path file, final BasicFileAttributes attributes) { + if (jarFileTime.compareTo(attributes.lastModifiedTime()) >= 0 && isFoundInJAR(file)) { + return FileVisitResult.CONTINUE; + } else { + hasUpdates = true; + return FileVisitResult.TERMINATE; + } + } + + /** + * Returns whether the given file is found in the <abbr>JAR</abbr> file. + * + * @param file the file to check + * @return whether the given file was found in the <abbr>JAR</abbr> file + */ + private boolean isFoundInJAR(final Path file) { + if (filesInJAR.remove(file)) { Review Comment: Renamed. -- This is an automated message from the Apache Git Service. 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