Ensure that JarResourceManager correctly handles path without leading /

Previously, JarResourceManager assumed that the path would begin with
a / but this isn't always the case. For example, it may be an empty
string. This could lead to a malformed jar:file: URL that used ! as
the separator rather than the required !/.

This commit updates JarResourceManager to prepend / to any path that
does not being with one before using it to construct the URL.

Closes gh-7717

spring-boot/src/main/java/org/springframework/boot/context/embedded/undertow/JarResourceManager.java

+/*
+ * Copyright 2012-2017 the original author or authors.
+ *
+ * Licensed 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.springframework.boot.context.embedded.undertow;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URL;
+
+import io.undertow.UndertowMessages;
+import io.undertow.server.handlers.resource.Resource;
+import io.undertow.server.handlers.resource.ResourceChangeListener;
+import io.undertow.server.handlers.resource.ResourceManager;
+import io.undertow.server.handlers.resource.URLResource;
+
+/**
+ * {@link ResourceManager} for JAR resources.
+ *
+ * @author Ivan Sopov
+ * @author Andy Wilkinson
+ */
+class JarResourceManager implements ResourceManager {
+
+	private final String jarPath;
+
+	JarResourceManager(File jarFile) {
+		this(jarFile.getAbsolutePath());
+	}
+
+	JarResourceManager(String jarPath) {
+		this.jarPath = jarPath;
+	}
+
+	@Override
+	public Resource getResource(String path) throws IOException {
+		URL url = new URL("jar:file:" + this.jarPath + "!"
+				+ (path.startsWith("/") ? path : "/" + path));
+		URLResource resource = new URLResource(url, url.openConnection(), path);
+		if (resource.getContentLength() < 0) {
+			return null;
+		}
+		return resource;
+	}
+
+	@Override
+	public boolean isResourceChangeListenerSupported() {
+		return false;
+	}
+
+	@Override
+	public void registerResourceChangeListener(ResourceChangeListener listener) {
+		throw UndertowMessages.MESSAGES.resourceChangeListenerNotSupported();
+
+	}
+
+	@Override
+	public void removeResourceChangeListener(ResourceChangeListener listener) {
+		throw UndertowMessages.MESSAGES.resourceChangeListenerNotSupported();
+	}
+
+	@Override
+	public void close() throws IOException {
+
+	}
+
+}

spring-boot/src/main/java/org/springframework/boot/context/embedded/undertow/UndertowEmbeddedServletContainerFactory.java

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,17 +43,13 @@ import javax.servlet.ServletException;
 
 import io.undertow.Undertow;
 import io.undertow.Undertow.Builder;
-import io.undertow.UndertowMessages;
 import io.undertow.server.HandlerWrapper;
 import io.undertow.server.HttpHandler;
 import io.undertow.server.handlers.accesslog.AccessLogHandler;
 import io.undertow.server.handlers.accesslog.AccessLogReceiver;
 import io.undertow.server.handlers.accesslog.DefaultAccessLogReceiver;
 import io.undertow.server.handlers.resource.FileResourceManager;
-import io.undertow.server.handlers.resource.Resource;
-import io.undertow.server.handlers.resource.ResourceChangeListener;
 import io.undertow.server.handlers.resource.ResourceManager;
-import io.undertow.server.handlers.resource.URLResource;
 import io.undertow.server.session.SessionManager;
 import io.undertow.servlet.Servlets;
 import io.undertow.servlet.api.DeploymentInfo;
@@ -601,53 +597,6 @@ public class UndertowEmbeddedServletContainerFactory
 		this.useForwardHeaders = useForwardHeaders;
 	}
 
-	/**
-	 * Undertow {@link ResourceManager} for JAR resources.
-	 */
-	private static class JarResourceManager implements ResourceManager {
-
-		private final String jarPath;
-
-		JarResourceManager(File jarFile) {
-			this(jarFile.getAbsolutePath());
-		}
-
-		JarResourceManager(String jarPath) {
-			this.jarPath = jarPath;
-		}
-
-		@Override
-		public Resource getResource(String path) throws IOException {
-			URL url = new URL("jar:file:" + this.jarPath + "!" + path);
-			URLResource resource = new URLResource(url, url.openConnection(), path);
-			if (resource.getContentLength() < 0) {
-				return null;
-			}
-			return resource;
-		}
-
-		@Override
-		public boolean isResourceChangeListenerSupported() {
-			return false;
-		}
-
-		@Override
-		public void registerResourceChangeListener(ResourceChangeListener listener) {
-			throw UndertowMessages.MESSAGES.resourceChangeListenerNotSupported();
-
-		}
-
-		@Override
-		public void removeResourceChangeListener(ResourceChangeListener listener) {
-			throw UndertowMessages.MESSAGES.resourceChangeListenerNotSupported();
-		}
-
-		@Override
-		public void close() throws IOException {
-		}
-
-	}
-
 	/**
 	 * {@link ServletContainerInitializer} to initialize {@link ServletContextInitializer
 	 * ServletContextInitializers}.

spring-boot/src/test/java/org/springframework/boot/context/embedded/undertow/JarResourceManagerTests.java

+/*
+ * Copyright 2012-2017 the original author or authors.
+ *
+ * Licensed 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.springframework.boot.context.embedded.undertow;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.jar.JarOutputStream;
+import java.util.zip.ZipEntry;
+
+import io.undertow.server.handlers.resource.Resource;
+import io.undertow.server.handlers.resource.ResourceManager;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link JarResourceManager}.
+ *
+ * @author Andy Wilkinson
+ */
+public class JarResourceManagerTests {
+
+	@Rule
+	public TemporaryFolder temp = new TemporaryFolder();
+
+	private ResourceManager resourceManager;
+
+	@Before
+	public void createJar() throws IOException {
+		File jar = this.temp.newFile();
+		JarOutputStream out = new JarOutputStream(new FileOutputStream(jar));
+		out.putNextEntry(new ZipEntry("hello.txt"));
+		out.write("hello".getBytes());
+		out.close();
+		this.resourceManager = new JarResourceManager(jar);
+	}
+
+	@Test
+	public void emptyPathIsHandledCorrectly() throws IOException {
+		Resource resource = this.resourceManager.getResource("");
+		assertThat(resource).isNotNull();
+		assertThat(resource.isDirectory()).isTrue();
+	}
+
+	@Test
+	public void rootPathIsHandledCorrectly() throws IOException {
+		Resource resource = this.resourceManager.getResource("/");
+		assertThat(resource).isNotNull();
+		assertThat(resource.isDirectory()).isTrue();
+	}
+
+	@Test
+	public void resourceIsFoundInJarFile() throws IOException {
+		Resource resource = this.resourceManager.getResource("/hello.txt");
+		assertThat(resource).isNotNull();
+		assertThat(resource.isDirectory()).isFalse();
+		assertThat(resource.getContentLength()).isEqualTo(5);
+	}
+
+	@Test
+	public void resourceIsFoundInJarFileWithoutLeadingSlash() throws IOException {
+		Resource resource = this.resourceManager.getResource("hello.txt");
+		assertThat(resource).isNotNull();
+		assertThat(resource.isDirectory()).isFalse();
+		assertThat(resource.getContentLength()).isEqualTo(5);
+	}
+
+}