Package org.openjdk.jmc.agent.util

Class AccessUtils

java.lang.Object

org.openjdk.jmc.agent.util.AccessUtils

public final class AccessUtils
extends Object

Helper methods for checking accessibility, implied as modifiers, from various contexts.

Constructor Summary

Constructors

Modifier	Constructor	Description
private	AccessUtils()

Method Summary

Modifier and Type	Method	Description
static boolean	areNestMates(Class<?> lhs, Class<?> rhs)	Polyfill Class.isNestMateOf() for pre-11 runtime.
static int	getClassAccessFlags(Class<?> c)	Polyfill for Reflection.getClassAccessFlags(Classinvalid input: '<'?>) as jdk.internal.reflect.Reflection is not exported.
static Field	getFieldOnHierarchy(Class<?> clazz, String name)	Like Class.getDeclaredField, but also gets fields declared by ancestors and interfaces.
static Class<?>	getNestHost(Class<?> clazz)	Polyfill Class.getNestHost() for pre-11 runtime.
static Class<?>[]	getNestMembers(Class<?> clazz)	Polyfill Class.getNestMembers() for pre-11 runtime.
static String	getPackageName(Class<?> clazz)	polyfill for Class.getPackageName(Classinvalid input: '<'?>) for pre-9 Java.
static boolean	isAccessible(Class<?> targetClass, Field field, Class<?> currentClass)	Checks whether a field can be accessed from a caller context.
static boolean	isSameClassPackage(Class<?> lhs, Class<?> rhs)	Check whether the two classes exist in the same package
static boolean	isSubclassOf(Class<?> queryClass, Class<?> ofClass)	Check whether a class is a subclass of the other
static boolean	verifyMemberAccess(Class<?> targetClass, Class<?> memberClass, Class<?> currentClass, int modifiers)	Checks whether the field/method/inner class modifier allows access from a caller context
static boolean	verifyModuleAccess(Class<?> targetClass, Class<?> callerClass)	Check whether the module has the class exported for the caller to access.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

AccessUtils

private AccessUtils()

Method Details

getFieldOnHierarchy

public static Field getFieldOnHierarchy(Class<?> clazz,
 String name)
                                 throws NoSuchFieldException

Like Class.getDeclaredField, but also gets fields declared by ancestors and interfaces.

Parameters:

clazz - the class to lookup from

name - the name of the field

Returns:

the Field object for the specified field in this class

Throws:

NoSuchFieldException - if a field with the specified name is not found.

isAccessible

public static boolean isAccessible(Class<?> targetClass,
 Field field,
 Class<?> currentClass)

Checks whether a field can be accessed from a caller context.

Parameters:

targetClass - the class being referenced

field - the field being accessed

currentClass - the caller class

Returns:

whether the field is accessible from given context

verifyMemberAccess

public static boolean verifyMemberAccess(Class<?> targetClass,
 Class<?> memberClass,
 Class<?> currentClass,
 int modifiers)

Checks whether the field/method/inner class modifier allows access from a caller context

Parameters:

targetClass - the class being referenced

memberClass - the class declaring the field/method/inner class

currentClass - the caller class

modifiers - member access modifiers in bit flags as a integer

Returns:

verifyModuleAccess

public static boolean verifyModuleAccess(Class<?> targetClass,
 Class<?> callerClass)

Check whether the module has the class exported for the caller to access. For Pre-9 Java runtime, this function always returns true.

Parameters:

targetClass - the class being accessed

callerClass - the caller class

Returns:

whether the class is accessible

getPackageName

public static String getPackageName(Class<?> clazz)

polyfill for Class.getPackageName(Classinvalid input: '<'?>) for pre-9 Java.

Parameters:

clazz - the class to lookup the package name against

Returns:

the name of the package containing the class

getClassAccessFlags

public static int getClassAccessFlags(Class<?> c)

Polyfill for Reflection.getClassAccessFlags(Classinvalid input: '<'?>) as jdk.internal.reflect.Reflection is not exported.

Parameters:

c - the class being inspected

Returns:

the access flags written to the class file

isSameClassPackage

public static boolean isSameClassPackage(Class<?> lhs,
 Class<?> rhs)

Check whether the two classes exist in the same package

Parameters:

lhs - the first class

rhs - the second class

Returns:

whether the given classes exist in the same package

isSubclassOf

public static boolean isSubclassOf(Class<?> queryClass,
 Class<?> ofClass)

Check whether a class is a subclass of the other

Parameters:

queryClass - the subclass

ofClass - the superclass

Returns:

whether it's a subclass-superclass relationship

getNestMembers

public static Class<?>[] getNestMembers(Class<?> clazz)

Polyfill Class.getNestMembers() for pre-11 runtime. This function does not fully respect the definition of nesting from JVM's perspective. It's only used for validating access.

Parameters:

clazz - the class to inspect against

Returns:

an array of all nest members

areNestMates

public static boolean areNestMates(Class<?> lhs,
 Class<?> rhs)

Polyfill Class.isNestMateOf() for pre-11 runtime. This function does not fully respect the definition of nesting from JVM's perspective. It's only used for validating access.

Parameters:

lhs - the first class

rhs - the second class

Returns:

whether the given classes are nestmates

getNestHost

public static Class<?> getNestHost(Class<?> clazz)

Polyfill Class.getNestHost() for pre-11 runtime. This function does not fully respect the definition of nesting from JVM's perspective. It's only used for validating access.

Parameters:

clazz - the class the inspect against

Returns:

the nesthost of the class