jdk/src/share/classes/sun/reflect/Reflection.java
changeset 2 90ce3da70b43
child 5506 202f599c92aa
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/sun/reflect/Reflection.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,325 @@
+/*
+ * Copyright 2001-2006 Sun Microsystems, Inc.  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.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package sun.reflect;
+
+import java.lang.reflect.*;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+/** Common utility routines used by both java.lang and
+    java.lang.reflect */
+
+public class Reflection {
+
+    /** Used to filter out fields and methods from certain classes from public
+        view, where they are sensitive or they may contain VM-internal objects.
+        These Maps are updated very rarely. Rather than synchronize on
+        each access, we use copy-on-write */
+    private static volatile Map<Class,String[]> fieldFilterMap;
+    private static volatile Map<Class,String[]> methodFilterMap;
+
+    static {
+        Map<Class,String[]> map = new HashMap<Class,String[]>();
+        map.put(Reflection.class,
+            new String[] {"fieldFilterMap", "methodFilterMap"});
+        map.put(System.class, new String[] {"security"});
+        fieldFilterMap = map;
+
+        methodFilterMap = new HashMap<Class,String[]>();
+    }
+
+    /** Returns the class of the method <code>realFramesToSkip</code>
+        frames up the stack (zero-based), ignoring frames associated
+        with java.lang.reflect.Method.invoke() and its implementation.
+        The first frame is that associated with this method, so
+        <code>getCallerClass(0)</code> returns the Class object for
+        sun.reflect.Reflection. Frames associated with
+        java.lang.reflect.Method.invoke() and its implementation are
+        completely ignored and do not count toward the number of "real"
+        frames skipped. */
+    public static native Class getCallerClass(int realFramesToSkip);
+
+    /** Retrieves the access flags written to the class file. For
+        inner classes these flags may differ from those returned by
+        Class.getModifiers(), which searches the InnerClasses
+        attribute to find the source-level access flags. This is used
+        instead of Class.getModifiers() for run-time access checks due
+        to compatibility reasons; see 4471811. Only the values of the
+        low 13 bits (i.e., a mask of 0x1FFF) are guaranteed to be
+        valid. */
+    private static native int getClassAccessFlags(Class c);
+
+    /** A quick "fast-path" check to try to avoid getCallerClass()
+        calls. */
+    public static boolean quickCheckMemberAccess(Class memberClass,
+                                                 int modifiers)
+    {
+        return Modifier.isPublic(getClassAccessFlags(memberClass) & modifiers);
+    }
+
+    public static void ensureMemberAccess(Class currentClass,
+                                          Class memberClass,
+                                          Object target,
+                                          int modifiers)
+        throws IllegalAccessException
+    {
+        if (currentClass == null || memberClass == null) {
+            throw new InternalError();
+        }
+
+        if (!verifyMemberAccess(currentClass, memberClass, target, modifiers)) {
+            throw new IllegalAccessException("Class " + currentClass.getName() +
+                                             " can not access a member of class " +
+                                             memberClass.getName() +
+                                             " with modifiers \"" +
+                                             Modifier.toString(modifiers) +
+                                             "\"");
+        }
+    }
+
+    public static boolean verifyMemberAccess(Class currentClass,
+                                             // Declaring class of field
+                                             // or method
+                                             Class  memberClass,
+                                             // May be NULL in case of statics
+                                             Object target,
+                                             int    modifiers)
+    {
+        // Verify that currentClass can access a field, method, or
+        // constructor of memberClass, where that member's access bits are
+        // "modifiers".
+
+        boolean gotIsSameClassPackage = false;
+        boolean isSameClassPackage = false;
+
+        if (currentClass == memberClass) {
+            // Always succeeds
+            return true;
+        }
+
+        if (!Modifier.isPublic(getClassAccessFlags(memberClass))) {
+            isSameClassPackage = isSameClassPackage(currentClass, memberClass);
+            gotIsSameClassPackage = true;
+            if (!isSameClassPackage) {
+                return false;
+            }
+        }
+
+        // At this point we know that currentClass can access memberClass.
+
+        if (Modifier.isPublic(modifiers)) {
+            return true;
+        }
+
+        boolean successSoFar = false;
+
+        if (Modifier.isProtected(modifiers)) {
+            // See if currentClass is a subclass of memberClass
+            if (isSubclassOf(currentClass, memberClass)) {
+                successSoFar = true;
+            }
+        }
+
+        if (!successSoFar && !Modifier.isPrivate(modifiers)) {
+            if (!gotIsSameClassPackage) {
+                isSameClassPackage = isSameClassPackage(currentClass,
+                                                        memberClass);
+                gotIsSameClassPackage = true;
+            }
+
+            if (isSameClassPackage) {
+                successSoFar = true;
+            }
+        }
+
+        if (!successSoFar) {
+            return false;
+        }
+
+        if (Modifier.isProtected(modifiers)) {
+            // Additional test for protected members: JLS 6.6.2
+            Class targetClass = (target == null ? memberClass : target.getClass());
+            if (targetClass != currentClass) {
+                if (!gotIsSameClassPackage) {
+                    isSameClassPackage = isSameClassPackage(currentClass, memberClass);
+                    gotIsSameClassPackage = true;
+                }
+                if (!isSameClassPackage) {
+                    if (!isSubclassOf(targetClass, currentClass)) {
+                        return false;
+                    }
+                }
+            }
+        }
+
+        return true;
+    }
+
+    private static boolean isSameClassPackage(Class c1, Class c2) {
+        return isSameClassPackage(c1.getClassLoader(), c1.getName(),
+                                  c2.getClassLoader(), c2.getName());
+    }
+
+    /** Returns true if two classes are in the same package; classloader
+        and classname information is enough to determine a class's package */
+    private static boolean isSameClassPackage(ClassLoader loader1, String name1,
+                                              ClassLoader loader2, String name2)
+    {
+        if (loader1 != loader2) {
+            return false;
+        } else {
+            int lastDot1 = name1.lastIndexOf('.');
+            int lastDot2 = name2.lastIndexOf('.');
+            if ((lastDot1 == -1) || (lastDot2 == -1)) {
+                // One of the two doesn't have a package.  Only return true
+                // if the other one also doesn't have a package.
+                return (lastDot1 == lastDot2);
+            } else {
+                int idx1 = 0;
+                int idx2 = 0;
+
+                // Skip over '['s
+                if (name1.charAt(idx1) == '[') {
+                    do {
+                        idx1++;
+                    } while (name1.charAt(idx1) == '[');
+                    if (name1.charAt(idx1) != 'L') {
+                        // Something is terribly wrong.  Shouldn't be here.
+                        throw new InternalError("Illegal class name " + name1);
+                    }
+                }
+                if (name2.charAt(idx2) == '[') {
+                    do {
+                        idx2++;
+                    } while (name2.charAt(idx2) == '[');
+                    if (name2.charAt(idx2) != 'L') {
+                        // Something is terribly wrong.  Shouldn't be here.
+                        throw new InternalError("Illegal class name " + name2);
+                    }
+                }
+
+                // Check that package part is identical
+                int length1 = lastDot1 - idx1;
+                int length2 = lastDot2 - idx2;
+
+                if (length1 != length2) {
+                    return false;
+                }
+                return name1.regionMatches(false, idx1, name2, idx2, length1);
+            }
+        }
+    }
+
+    static boolean isSubclassOf(Class queryClass,
+                                Class ofClass)
+    {
+        while (queryClass != null) {
+            if (queryClass == ofClass) {
+                return true;
+            }
+            queryClass = queryClass.getSuperclass();
+        }
+        return false;
+    }
+
+    // fieldNames must contain only interned Strings
+    public static synchronized void registerFieldsToFilter(Class containingClass,
+                                              String ... fieldNames) {
+        fieldFilterMap =
+            registerFilter(fieldFilterMap, containingClass, fieldNames);
+    }
+
+    // methodNames must contain only interned Strings
+    public static synchronized void registerMethodsToFilter(Class containingClass,
+                                              String ... methodNames) {
+        methodFilterMap =
+            registerFilter(methodFilterMap, containingClass, methodNames);
+    }
+
+    private static Map<Class,String[]> registerFilter(Map<Class,String[]> map,
+            Class containingClass, String ... names) {
+        if (map.get(containingClass) != null) {
+            throw new IllegalArgumentException
+                            ("Filter already registered: " + containingClass);
+        }
+        map = new HashMap<Class,String[]>(map);
+        map.put(containingClass, names);
+        return map;
+    }
+
+    public static Field[] filterFields(Class containingClass,
+                                       Field[] fields) {
+        if (fieldFilterMap == null) {
+            // Bootstrapping
+            return fields;
+        }
+        return (Field[])filter(fields, fieldFilterMap.get(containingClass));
+    }
+
+    public static Method[] filterMethods(Class containingClass, Method[] methods) {
+        if (methodFilterMap == null) {
+            // Bootstrapping
+            return methods;
+        }
+        return (Method[])filter(methods, methodFilterMap.get(containingClass));
+    }
+
+    private static Member[] filter(Member[] members, String[] filteredNames) {
+        if ((filteredNames == null) || (members.length == 0)) {
+            return members;
+        }
+        int numNewMembers = 0;
+        for (Member member : members) {
+            boolean shouldSkip = false;
+            for (String filteredName : filteredNames) {
+                if (member.getName() == filteredName) {
+                    shouldSkip = true;
+                    break;
+                }
+            }
+            if (!shouldSkip) {
+                ++numNewMembers;
+            }
+        }
+        Member[] newMembers =
+            (Member[])Array.newInstance(members[0].getClass(), numNewMembers);
+        int destIdx = 0;
+        for (Member member : members) {
+            boolean shouldSkip = false;
+            for (String filteredName : filteredNames) {
+                if (member.getName() == filteredName) {
+                    shouldSkip = true;
+                    break;
+                }
+            }
+            if (!shouldSkip) {
+                newMembers[destIdx++] = member;
+            }
+        }
+        return newMembers;
+    }
+}