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8257596: Clarify trusted final fields for record classes

Browse source 
Reviewed-by: hseigel, chegar, psandoz
This commit is contained in:
Mandy Chung 2020-12-11 22:44:48 +00:00
parent b1afed7501
commit 2001da3dd4
4 changed files with 44 additions and 29 deletions
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6
src/hotspot/share/oops/instanceKlass.cpp
View file

@ -739,6 +739,12 @@ void InstanceKlass::deallocate_contents(ClassLoaderData* loader_data) {
}
}
bool InstanceKlass::is_record() const {
return _record_components != NULL &&
is_final() &&
java_super() == SystemDictionary::Record_klass();
}
bool InstanceKlass::is_sealed() const {
return _permitted_subclasses != NULL &&
_permitted_subclasses != Universe::the_empty_short_array();

2
src/hotspot/share/oops/instanceKlass.hpp
View file

@ -473,7 +473,7 @@ class InstanceKlass: public Klass {
void set_record_components(Array<RecordComponent*>* record_components) {
_record_components = record_components;
}
bool is_record() const { return _record_components != NULL; }
bool is_record() const;
// permitted subclasses
Array<u2>* permitted_subclasses() const { return _permitted_subclasses; }

17
src/hotspot/share/prims/jvm.cpp
View file

@ -1851,6 +1851,9 @@ JVM_ENTRY(jobjectArray, JVM_GetClassDeclaredFields(JNIEnv *env, jclass ofClass,
}
JVM_END
// A class is a record if and only if it is final and a direct subclass of
// java.lang.Record and has a Record attribute; otherwise, it is not a record.
JVM_ENTRY(jboolean, JVM_IsRecord(JNIEnv *env, jclass cls))
{
JVMWrapper("JVM_IsRecord");
@ -1864,6 +1867,11 @@ JVM_ENTRY(jboolean, JVM_IsRecord(JNIEnv *env, jclass cls))
}
JVM_END
// Returns an array containing the components of the Record attribute,
// or NULL if the attribute is not present.
//
// Note that this function returns the components of the Record attribute
// even if the class is not a record.
JVM_ENTRY(jobjectArray, JVM_GetRecordComponents(JNIEnv* env, jclass ofClass))
{
JVMWrapper("JVM_GetRecordComponents");
@ -1871,10 +1879,8 @@ JVM_ENTRY(jobjectArray, JVM_GetRecordComponents(JNIEnv* env, jclass ofClass))
assert(c->is_instance_klass(), "must be");
InstanceKlass* ik = InstanceKlass::cast(c);
if (ik->is_record()) {
Array<RecordComponent*>* components = ik->record_components();
assert(components != NULL, "components should not be NULL");
{
if (components != NULL) {
JvmtiVMObjectAllocEventCollector oam;
constantPoolHandle cp(THREAD, ik->constants());
int length = components->length();
@ -1891,11 +1897,8 @@ JVM_ENTRY(jobjectArray, JVM_GetRecordComponents(JNIEnv* env, jclass ofClass))
}
return (jobjectArray)JNIHandles::make_local(THREAD, components_h());
}
}
// Return empty array if ofClass is not a record.
objArrayOop result = oopFactory::new_objArray(SystemDictionary::RecordComponent_klass(), 0, CHECK_NULL);
return (jobjectArray)JNIHandles::make_local(THREAD, result);
return NULL;
}
JVM_END

16
src/java.base/share/classes/java/lang/Class.java
View file

@ -2383,11 +2383,7 @@ public final class Class<T> implements java.io.Serializable,
if (!isRecord()) {
return null;
}
RecordComponent[] recordComponents = getRecordComponents0();
if (recordComponents == null) {
return new RecordComponent[0];
}
return recordComponents;
return getRecordComponents0();
}
/**
@ -3578,6 +3574,14 @@ public final class Class<T> implements java.io.Serializable,
private native Method[] getDeclaredMethods0(boolean publicOnly);
private native Constructor<T>[] getDeclaredConstructors0(boolean publicOnly);
private native Class<?>[] getDeclaredClasses0();
/*
* Returns an array containing the components of the Record attribute,
* or null if the attribute is not present.
*
* Note that this method returns non-null array on a class with
* the Record attribute even if this class is not a record.
*/
private native RecordComponent[] getRecordComponents0();
private native boolean isRecord0();
@ -3706,6 +3710,8 @@ public final class Class<T> implements java.io.Serializable,
* @since 16
*/
public boolean isRecord() {
// this superclass and final modifier check is not strictly necessary
// they are intrinsified and serve as a fast-path check
return getSuperclass() == java.lang.Record.class &&
(this.getModifiers() & Modifier.FINAL) != 0 &&
isRecord0();