[FELIX-6430] Felix uses sun.misc.Unsafe, crashed on JDK 17

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: framework-7.0.0
• Fix Version/s: framework-7.0.1
• Assignee: Karl Pauls
• Reporter: Arjan Tijms
• Created: 10/Jun/21 14:28
• Updated: 21/Jun/21 21:35
• Resolved: 10/Jun/21 20:44

Description

When running on JDK 17, Felix crashes with the following exception:

java.lang.NoSuchMethodException: sun.misc.Unsafe.defineAnonymousClass(java.lang.Class,[B,[Ljava.lang.Object;)
 at java.base/java.lang.Class.getMethod(Class.java:2227)
 at org.apache.felix.framework.util.SecureAction.getAccessor(SecureAction.java:1134)
 at org.apache.felix.framework.util.SecureAction.<clinit>(SecureAction.java:86)
 at org.apache.felix.framework.Felix.<clinit>(Felix.java:114)
 at org.apache.felix.framework.FrameworkFactory.newFramework(FrameworkFactory.java:30)

The offending code in question reflectively uses sun.misc.Unsafe

private static Consumer<AccessibleObject[]> getAccessor(Class clazz) {
    String packageName = clazz.getPackage().getName();
    
    if ("java.net".equals(packageName) || "jdk.internal.loader".equals(packageName)) {
        if (m_accessorCache == null) {
            try {
                // Use reflection on Unsafe to avoid having to compile against it
                Class<?> unsafeClass = Class.forName("sun.misc.Unsafe");
                Field theUnsafe = unsafeClass.getDeclaredField("theUnsafe");
                
                // NOTE: deep reflection is allowed on sun.misc package for java 9.
                theUnsafe.setAccessible(true);
                Object unsafe = theUnsafe.get(null);
                
                // using defineAnonymousClass here because it seems more simple 
                // to get what we need
                Method defineAnonymousClass = 
                    unsafeClass.getMethod("defineAnonymousClass", 
                        Class.class, 
                        byte[].class, 
                        Object[].class);
                
                // The bytes stored in a resource to avoid real loading of it 
                // (see accessible.src for source).
                Class<Consumer<AccessibleObject[]>> result =
                   (Class<Consumer<AccessibleObject[]>>) 
                   defineAnonymousClass.invoke(
                        unsafe, URL.class,
                        accessor, null);
                m_accessorCache = result.getConstructor().newInstance();
            } catch (Throwable t) {
                t.printStackTrace();
                m_accessorCache = 
                    objects -> AccessibleObject.setAccessible(objects, true);
            }
        }
        
        return m_accessorCache;
    }
    
    return objects -> AccessibleObject.setAccessible(objects, true);
}

For JDK 17+ it may be needed to stop using sun.misc.Unsafe and use a JDK replacement?

Issue Links

• fixes: FELIX-6432 NoSuchMethodException: sun.misc.Unsafe.defineAnonymousClass with Felix 7.0.0 and JDK17b25
• is cloned by: FELIX-6433 Felix 6.0.4 doesn't work on JDK 17
• links to: GitHub Pull Request #79
• links to: GitHub Pull Request #80