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8233272: The Class.forName specification should be updated to match the long-standing implementation with respect to class linking

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Reviewed-by: dholmes, mchung
This commit is contained in:
Brent Christian 2019-11-19 10:02:46 -08:00
parent 6a99789fd5
commit 469cb2b334
4 changed files with 147 additions and 5 deletions
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20
src/java.base/share/classes/java/lang/Class.java
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@ -325,6 +325,10 @@ public final class Class<T> implements java.io.Serializable,
* @throws ExceptionInInitializerError if the initialization provoked
* by this method fails
* @throws ClassNotFoundException if the class cannot be located
*
* @jls 12.2 Loading of Classes and Interfaces
* @jls 12.3 Linking of Classes and Interfaces
* @jls 12.4 Initialization of Classes and Interfaces
*/
@CallerSensitive
public static Class<?> forName(String className)
@ -339,7 +343,7 @@ public final class Class<T> implements java.io.Serializable,
* interface with the given string name, using the given class loader.
* Given the fully qualified name for a class or interface (in the same
* format returned by {@code getName}) this method attempts to
* locate, load, and link the class or interface. The specified class
* locate and load the class or interface. The specified class
* loader is used to load the class or interface. If the parameter
* {@code loader} is null, the class is loaded through the bootstrap
* class loader. The class is initialized only if the
@ -374,7 +378,7 @@ public final class Class<T> implements java.io.Serializable,
* is accessible to its caller.
*
* @param name fully qualified name of the desired class
* @param initialize if {@code true} the class will be initialized.
* @param initialize if {@code true} the class will be initialized (which implies linking).
* See Section 12.4 of <em>The Java Language Specification</em>.
* @param loader class loader from which the class must be loaded
* @return class object representing the desired class
@ -392,6 +396,10 @@ public final class Class<T> implements java.io.Serializable,
*
* @see java.lang.Class#forName(String)
* @see java.lang.ClassLoader
*
* @jls 12.2 Loading of Classes and Interfaces
* @jls 12.3 Linking of Classes and Interfaces
* @jls 12.4 Initialization of Classes and Interfaces
* @since 1.2
*/
@CallerSensitive
@ -427,9 +435,9 @@ public final class Class<T> implements java.io.Serializable,
* Returns the {@code Class} with the given <a href="ClassLoader.html#binary-name">
* binary name</a> in the given module.
*
* <p> This method attempts to locate, load, and link the class or interface.
* It does not run the class initializer. If the class is not found, this
* method returns {@code null}. </p>
* <p> This method attempts to locate and load the class or interface.
* It does not link the class, and does not run the class initializer.
* If the class is not found, this method returns {@code null}. </p>
*
* <p> If the class loader of the given module defines other modules and
* the given name is a class defined in a different module, this method
@ -465,6 +473,8 @@ public final class Class<T> implements java.io.Serializable,
* in a module.</li>
* </ul>
*
* @jls 12.2 Loading of Classes and Interfaces
* @jls 12.3 Linking of Classes and Interfaces
* @since 9
* @spec JPMS
*/

31
test/jdk/java/lang/Class/forName/NonLinking/Container.java Normal file
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@ -0,0 +1,31 @@
/*
* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
public class Container {
public Container(MissingClass m) {}
public Container() {
this(new MissingClass() {});
}
}

24
test/jdk/java/lang/Class/forName/NonLinking/MissingClass.java Normal file
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@ -0,0 +1,24 @@
/*
* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
public class MissingClass {}

77
test/jdk/java/lang/Class/forName/NonLinking/NonLinking.java Normal file
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@ -0,0 +1,77 @@
/*
* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.file.Path;
import java.nio.file.Paths;
/*
* @test
* @bug 8231924 8233091 8233272
* @summary Confirm load (but not link) behavior of Class.forName()
* @library /test/lib
*
* @compile MissingClass.java Container.java
*
* @run driver ClassFileInstaller -jar classes.jar Container Container$1
*
* @run main/othervm NonLinking init
* @run main/othervm NonLinking load
*/
/*
* The @compile and '@main ClassFileInstaller' tasks above create a classes.jar
* file containing the .class file for Container, but not MissingClass.
*/
public class NonLinking {
public static void main(String[] args) throws Throwable {
Path jarPath = Paths.get("classes.jar");
URL url = jarPath.toUri().toURL();
URLClassLoader ucl1 = new URLClassLoader("UCL1",
new URL[] { url },
null); // Don't delegate
switch(args[0]) {
case "init":
try {
// Trying to initialize Container without MissingClass -> NCDFE
Class.forName("Container", true, ucl1);
throw new RuntimeException("Missed expected NoClassDefFoundError");
} catch (NoClassDefFoundError expected) {
final String CLASSNAME = "MissingClass";
Throwable cause = expected.getCause();
if (!cause.getMessage().contains(CLASSNAME)) {
throw new RuntimeException("Cause of NoClassDefFoundError does not contain \"" + CLASSNAME + "\"", cause);
}
}
break;
case "load":
// Loading (but not linking) Container will succeed.
// Before 8233091, this fails with NCDFE due to linking.
Class.forName("Container", false, ucl1);
break;
default:
throw new RuntimeException("Unknown command: " + args[0]);
}
}
}