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8266496: WBIsKlassAliveClosure.do_klass() fails for hidden classes
Reviewed-by: dholmes, coleenp, mseledtsov, lfoltan
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Harold Seigel committed May 6, 2021
1 parent 51f5adf commit eb3b96d86b7fd21d444bb09c032b424e61bc5d6f
Showing with 92 additions and 0 deletions.
  1. +19 −0 src/hotspot/share/prims/whitebox.cpp
  2. +73 −0 test/hotspot/jtreg/runtime/whitebox/TestHiddenClassIsAlive.java
@@ -180,6 +180,25 @@ class WBIsKlassAliveClosure : public LockedClassesDo {
Symbol* ksym = k->name();
if (ksym->fast_compare(_name) == 0) {
_count++;
} else if (k->is_instance_klass()) {
// Need special handling for hidden classes because the JVM
// appends "+<hex-address>" to hidden class names.
InstanceKlass *ik = InstanceKlass::cast(k);
if (ik->is_hidden()) {
ResourceMark rm;
char* k_name = ksym->as_C_string();
// Find the first '+' char and truncate the string at that point.
// NOTE: This will not work correctly if the original hidden class
// name contains a '+'.
char* plus_char = strchr(k_name, '+');
if (plus_char != NULL) {
*plus_char = 0;
char* c_name = _name->as_C_string();
if (strcmp(c_name, k_name) == 0) {
_count++;
}
}
}
}
}

@@ -0,0 +1,73 @@
/*
* Copyright (c) 2021, 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.
*/

/*
* @test
* @bug 8266496
* @summary Test that Whitebox.isClassAlive() works with hidden classes.
* @library /test/lib
* @build sun.hotspot.WhiteBox
* @run driver jdk.test.lib.helpers.ClassFileInstaller sun.hotspot.WhiteBox
* @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestHiddenClassIsAlive
*/

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandles.Lookup;
import java.lang.invoke.MethodType;

import sun.hotspot.WhiteBox;

final class MyClass {
MyClass() {}
public Object get(int i) { return null; }
}

public class TestHiddenClassIsAlive {


public static void main(String[] args) throws Throwable {
byte[] classBytes = readClassFile("MyClass.class");
Lookup lookup = MethodHandles.lookup();
Class<?> c = lookup.defineHiddenClass(classBytes, true).lookupClass();
if (!WhiteBox.getWhiteBox().isClassAlive("MyClass")) {
throw new RuntimeException("Hidden class should be alive");
}
}

static byte[] readClassFile(String classFileName) throws Exception {
File classFile = new File(System.getProperty("test.classes") + File.separator + classFileName);
try (FileInputStream in = new FileInputStream(classFile);
ByteArrayOutputStream out = new ByteArrayOutputStream())
{
int b;
while ((b = in.read()) != -1) {
out.write(b);
}
return out.toByteArray();
}
}
}

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