Handle the case where the file resolver is used with a classloader th…

…at return a URL for directories.

When unpackFromJarURL is called with a directory, the method throws an exception as the entry does not really exist. By checking the length we can detect the case and not try to retrieve the JarFile from the connection.

src/main/java/io/vertx/core/file/impl/FileResolverImpl.java

@@ -30,6 +30,7 @@
 import java.util.ArrayList;
 import java.util.Enumeration;
 import java.util.List;
+import java.util.jar.JarFile;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 
@@ -317,6 +318,17 @@ private File unpackFromJarURL(URL url, String fileName, ClassLoader cl) {
       switch (listOfEntries.size()) {
         case 1: {
           JarURLConnection conn = (JarURLConnection) url.openConnection();
+          if (conn.getContentLength() == -1) {
+            // the entry is a directory, so, it does not really exist.
+            // which means we cannot get the JarFile from the connection.
+
+            // In general, we should not be here, as the URL should be a directory, and we should not have a JarURLConnection.
+            // However, classloader implementation may provide an URL. In this case, we should not try to get the JarFile
+            // as it does not exist (or is not valid), and it will throw an exception.
+
+            // We still retrieve it from the cache if it exists (got unzipped before or concurrently)
+            return cache.getFile(fileName);
+          }
           ZipFile zip = conn.getJarFile();
           try {
             extractFilesFromJarFile(zip, fileName);

src/test/java/io/vertx/core/file/CustomJarFileResolverTest.java

@@ -67,6 +67,16 @@ protected URLConnection openConnection(URL u) throws IOException {
                 public JarFile getJarFile() throws IOException {
                   return new JarFile(files);
                 }
+
+                @Override
+                public int getContentLength() {
+                  try {
+                    return (int) getJarFile().getJarEntry(name).getSize();
+                  } catch (IOException e) {
+                    return -1;
+                  }
+                }
+
                 @Override
                 public void connect() throws IOException {
                 }

src/test/java/io/vertx/core/file/JarFileResolverWithOddClassLoaderTest.java

@@ -0,0 +1,61 @@
+package io.vertx.core.file;
+
+import io.vertx.core.file.impl.FileResolverImpl;
+import io.vertx.core.spi.file.FileResolver;
+import org.assertj.core.api.Assertions;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
+
+public class JarFileResolverWithOddClassLoaderTest {
+
+  @Test
+  public void testWhenClassLoaderReturnUrlsForDirectory() throws IOException {
+    File webjar = new File("src/test/resources/jars/wc-chatbot-0.1.2.jar");
+    Assertions.assertThat(webjar).exists();
+    ClassLoader cl = new DecoratedClassLoader(new URLClassLoader(new URL[]{webjar.toURI().toURL()}, Thread.currentThread().getContextClassLoader()));
+
+    ClassLoader orig = Thread.currentThread().getContextClassLoader();
+    try (FileResolver resolver = new FileResolverImpl()) {
+      Thread.currentThread().setContextClassLoader(cl);
+      String fileName = "META-INF/resources/_static/wc-chatbot/0.1.2/LICENSE";
+      File resolved = resolver.resolveFile(fileName);
+      Assertions.assertThat(resolved).exists();
+    } finally {
+      Thread.currentThread().setContextClassLoader(orig);
+    }
+  }
+
+  /**
+   * A somewhat broken classloader returning an URL even for directory included in the given jars.
+   */
+  private static class DecoratedClassLoader extends ClassLoader {
+    private final URL[] urls;
+
+    public DecoratedClassLoader(URLClassLoader parent) {
+      super(parent);
+      this.urls = parent.getURLs();
+    }
+
+    @Override
+    protected URL findResource(String name) {
+      if (! name.contains("META-INF/resources")) {
+        return super.findResource(name);
+      }
+      for (URL url : urls) {
+        if (url.getFile().endsWith(".jar")) {
+          try {
+            return new URL("jar:" + url + "!/" + name);
+          } catch (MalformedURLException e) {
+            return super.findResource(name);
+          }
+        }
+      }
+      return super.findResource(name);
+    }
+  }
+}