Allow WAR and JAR files

All ZIP-based zip files like zip, jar and war can be put on the classpath of the project. To avoid UI bugs, only zip files can be opened that are not added to the project's classpath. This commit introduces a check for the classpath.

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/propertytester/ZipFilePropertyTester.java

@@ -24,7 +24,9 @@ public class ZipFilePropertyTester extends ResourcePropertyTester {
 
 	/** Enum representing allowed file extensions for zip files. */
 	private enum ZipFileExtensions {
-		ZIP("zip"); //$NON-NLS-1$
+		ZIP("zip"), //$NON-NLS-1$
+		JAR("jar"), //$NON-NLS-1$
+		WAR("war"); //$NON-NLS-1$
 
 		private final String value;
 

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/resources/ZipFileTransformer.java

@@ -17,6 +17,9 @@
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.zip.ZipException;
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
 import org.eclipse.core.filesystem.EFS;
 import org.eclipse.core.filesystem.IFileStore;
 import org.eclipse.core.filesystem.URIUtil;
@@ -25,6 +28,10 @@
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.w3c.dom.NodeList;
+import org.xml.sax.SAXException;
 
 /**
  * Utility class for opening and closing zip files.
@@ -99,6 +106,11 @@ public static void openZipFile(IFile file, boolean backgroundRefresh)
 					"Nested ZIP files are not allowed to be opened: " + file.getName())); //$NON-NLS-1$
 		}
 
+		if (isOnClasspath(file)) {
+			throw new CoreException(new Status(IStatus.ERROR, ResourcesPlugin.PI_RESOURCES,
+					"ZIP files on classpath are not allowed to be opened: " + file.getName())); //$NON-NLS-1$
+		}
+
 
 		URI zipURI = new URI("zip", null, "/", file.getLocationURI().toString(), null); //$NON-NLS-1$ //$NON-NLS-2$
 		IFolder link = file.getParent().getFolder(IPath.fromOSString(file.getName()));
@@ -112,4 +124,41 @@ public static void openZipFile(IFile file, boolean backgroundRefresh)
 					new Status(IStatus.ERROR, ResourcesPlugin.PI_RESOURCES, "Zip File could not be opened")); //$NON-NLS-1$
 		}
 	}
+
+	/**
+	 * Checks if the given file is on the project's classpath.
+	 *
+	 * @param file The file to check.
+	 * @return true if the file is on the classpath; false otherwise.
+	 * @throws CoreException
+	 */
+	private static boolean isOnClasspath(IFile file) throws CoreException {
+		IProject project = file.getProject();
+		IFile classpathFile = project.getFile(".classpath"); //$NON-NLS-1$
+		if (!classpathFile.exists()) {
+			return false;
+		}
+		try (InputStream inputStream = classpathFile.getContents()) {
+			DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
+			DocumentBuilder builder = factory.newDocumentBuilder();
+			Document document = builder.parse(inputStream);
+			NodeList classpathEntries = document.getElementsByTagName("classpathentry"); //$NON-NLS-1$
+
+			for (int i = 0; i < classpathEntries.getLength(); i++) {
+				Element classpathEntry = (Element) classpathEntries.item(i);
+				String kind = classpathEntry.getAttribute("kind"); //$NON-NLS-1$
+				String path = classpathEntry.getAttribute("path"); //$NON-NLS-1$
+
+				if ("lib".equals(kind) || "src".equals(kind)) { //$NON-NLS-1$//$NON-NLS-2$
+					if (file.exists() && file.getLocation().toString().contains(path)) {
+						return true;
+					}
+				}
+			}
+		} catch (IOException | CoreException | ParserConfigurationException | SAXException e) {
+			throw new CoreException(new Status(IStatus.ERROR, ResourcesPlugin.PI_RESOURCES,
+					"ZIP files on classpath are not allowed to be opened: " + file.getName())); //$NON-NLS-1$
+		}
+		return false;
+	}
 }