Allow URL resolution within nested JARs

Update JarURLConnection to allow the resolution of items within a nested
jar, even if the jarFile passed to the connection is several levels up.

This prevent a connection from incorrectly resolving an entry against
the wrong jar file.

See gh-1070

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/Handler.java

@@ -83,7 +83,7 @@ public class Handler extends URLStreamHandler {
 			return new JarURLConnection(url, this.jarFile);
 		}
 		try {
-			return new JarURLConnection(url, getJarFileFromUrl(url));
+			return new JarURLConnection(url, getRootJarFileFromUrl(url));
 		}
 		catch (Exception ex) {
 			return openFallbackConnection(url, ex);
@@ -135,24 +135,14 @@ public class Handler extends URLStreamHandler {
 		return (URLConnection) OPEN_CONNECTION_METHOD.invoke(handler, url);
 	}
 
-	public JarFile getJarFileFromUrl(URL url) throws IOException {
-
+	public JarFile getRootJarFileFromUrl(URL url) throws IOException {
 		String spec = url.getFile();
-
 		int separatorIndex = spec.indexOf(SEPARATOR);
 		if (separatorIndex == -1) {
 			throw new MalformedURLException("Jar URL does not contain !/ separator");
 		}
-
-		JarFile jar = null;
-		while (separatorIndex != -1) {
-			String name = spec.substring(0, separatorIndex);
-			jar = (jar == null ? getRootJarFile(name) : getNestedJarFile(jar, name));
-			spec = spec.substring(separatorIndex + SEPARATOR.length());
-			separatorIndex = spec.indexOf(SEPARATOR);
-		}
-
-		return jar;
+		String name = spec.substring(0, separatorIndex);
+		return getRootJarFile(name);
 	}
 
 	private JarFile getRootJarFile(String name) throws IOException {
@@ -175,15 +165,6 @@ public class Handler extends URLStreamHandler {
 		}
 	}
 
-	private JarFile getNestedJarFile(JarFile jarFile, String name) throws IOException {
-		JarEntry jarEntry = jarFile.getJarEntry(name);
-		if (jarEntry == null) {
-			throw new IOException("Unable to find nested jar '" + name + "' from '"
-					+ jarFile + "'");
-		}
-		return jarFile.getNestedJarFile(jarEntry);
-	}
-
 	/**
 	 * Add the given {@link JarFile} to the root file cache.
 	 * @param sourceFile the source file to add

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarURLConnection.java

@@ -61,8 +61,6 @@ class JarURLConnection extends java.net.JarURLConnection {
 
 	private static ThreadLocal<Boolean> useFastExceptions = new ThreadLocal<Boolean>();
 
-	private final String jarFileUrlSpec;
-
 	private final JarFile jarFile;
 
 	private JarEntryData jarEntryData;
@@ -71,19 +69,26 @@ class JarURLConnection extends java.net.JarURLConnection {
 
 	private JarEntryName jarEntryName;
 
-	protected JarURLConnection(URL url, JarFile jarFile) throws MalformedURLException {
+	protected JarURLConnection(URL url, JarFile jarFile) throws IOException {
 		// What we pass to super is ultimately ignored
 		super(EMPTY_JAR_URL);
 		this.url = url;
+		String spec = url.getFile().substring(jarFile.getUrl().getFile().length());
+		int separator;
+		while ((separator = spec.indexOf(SEPARATOR)) > 0) {
+			jarFile = getNestedJarFile(jarFile, spec.substring(0, separator));
+			spec = spec.substring(separator + SEPARATOR.length());
+		}
 		this.jarFile = jarFile;
-		String spec = url.getFile();
-		int separator = spec.lastIndexOf(SEPARATOR);
-		if (separator == -1) {
-			throw new MalformedURLException("no " + SEPARATOR + " found in url spec:"
-					+ spec);
+		this.jarEntryName = getJarEntryName(spec);
+	}
+
+	private JarFile getNestedJarFile(JarFile jarFile, String name) throws IOException {
+		JarEntry jarEntry = jarFile.getJarEntry(name);
+		if (jarEntry == null) {
+			throwFileNotFound(jarEntry, jarFile);
 		}
-		this.jarFileUrlSpec = spec.substring(0, separator);
-		this.jarEntryName = getJarEntryName(spec.substring(separator + 2));
+		return jarFile.getNestedJarFile(jarEntry);
 	}
 
 	private JarEntryName getJarEntryName(String spec) {
@@ -99,16 +104,20 @@ class JarURLConnection extends java.net.JarURLConnection {
 			this.jarEntryData = this.jarFile.getJarEntryData(this.jarEntryName
 					.asAsciiBytes());
 			if (this.jarEntryData == null) {
-				if (Boolean.TRUE.equals(useFastExceptions.get())) {
-					throw FILE_NOT_FOUND_EXCEPTION;
-				}
-				throw new FileNotFoundException("JAR entry " + this.jarEntryName
-						+ " not found in " + this.jarFile.getName());
+				throwFileNotFound(this.jarEntryName, this.jarFile);
 			}
 		}
 		this.connected = true;
 	}
 
+	private void throwFileNotFound(Object entry, JarFile jarFile) throws FileNotFoundException {
+		if (Boolean.TRUE.equals(useFastExceptions.get())) {
+			throw FILE_NOT_FOUND_EXCEPTION;
+		}
+		throw new FileNotFoundException("JAR entry " + entry + " not found in "
+				+ jarFile.getName());
+	}
+
 	@Override
 	public Manifest getManifest() throws IOException {
 		try {
@@ -135,10 +144,14 @@ class JarURLConnection extends java.net.JarURLConnection {
 
 	private URL buildJarFileUrl() {
 		try {
-			if (this.jarFileUrlSpec.indexOf(SEPARATOR) == -1) {
-				return new URL(this.jarFileUrlSpec);
+			String spec = this.jarFile.getUrl().getFile();
+			if (spec.endsWith(SEPARATOR)) {
+				spec = spec.substring(0, spec.length() - SEPARATOR.length());
+			}
+			if (spec.indexOf(SEPARATOR) == -1) {
+				return new URL(spec);
 			}
-			return new URL("jar:" + this.jarFileUrlSpec);
+			return new URL("jar:" + spec);
 		}
 		catch (MalformedURLException ex) {
 			throw new IllegalStateException(ex);

spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/LaunchedURLClassLoaderTests.java

@@ -16,21 +16,32 @@
 
 package org.springframework.boot.loader;
 
+import java.io.File;
 import java.net.URL;
 
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+import org.springframework.boot.loader.jar.JarFile;
 
+import static org.hamcrest.Matchers.equalTo;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 
 /**
  * Tests for {@link LaunchedURLClassLoader}.
  * 
  * @author Dave Syer
+ * @author Phillip Webb
  */
+@SuppressWarnings("resource")
 public class LaunchedURLClassLoaderTests {
 
+	@Rule
+	public TemporaryFolder temporaryFolder = new TemporaryFolder();
+
 	@Test
 	public void resolveResourceFromWindowsFilesystem() throws Exception {
 		// This path is invalid - it should return null even on Windows.
@@ -76,4 +87,17 @@ public class LaunchedURLClassLoaderTests {
 		assertTrue(loader.getResources("").hasMoreElements());
 	}
 
+	@Test
+	public void resolveFromNested() throws Exception {
+		File file = this.temporaryFolder.newFile();
+		TestJarCreator.createTestJar(file);
+		JarFile jarFile = new JarFile(file);
+		URL url = jarFile.getUrl();
+		LaunchedURLClassLoader loader = new LaunchedURLClassLoader(new URL[] { url },
+				null);
+		URL resource = loader.getResource("nested.jar!/3.dat");
+		assertThat(resource.toString(), equalTo(url + "nested.jar!/3.dat"));
+		assertThat(resource.openConnection().getInputStream().read(), equalTo(3));
+	}
+
 }

spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/JarFileTests.java

@@ -408,4 +408,16 @@ public class JarFileTests {
 		getEntries();
 		getNestedJarFile();
 	}
+
+	@Test
+	public void cannotLoadMissingJar() throws Exception {
+		// relates to gh-1070
+		JarFile nestedJarFile = this.jarFile.getNestedJarFile(this.jarFile
+				.getEntry("nested.jar"));
+		URL nestedUrl = nestedJarFile.getUrl();
+		URL url = new URL(nestedUrl, nestedJarFile.getUrl() + "missing.jar!/3.dat");
+		this.thrown.expect(FileNotFoundException.class);
+		url.openConnection().getInputStream();
+	}
+
 }