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My first initial commit with all of mine experimental changes.

Dmitry Kabak (userdima committed 13 years ago

Commit d37b88d1 parent 3f5b46618352 files · +2598093 −-8690Browse files

Showing the changes to java/pkg/sun/invoke/util/VerifyAccess.java (1 of 18352 files). Show all

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java/pkg/sun/invoke/util/VerifyAccess.java+236−0
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1+/*
2+ * Copyright (c) 2008, 2011, Oracle and/or its affiliates. All rights reserved.
3+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4+ *
5+ * This code is free software; you can redistribute it and/or modify it
6+ * under the terms of the GNU General Public License version 2 only, as
7+ * published by the Free Software Foundation. Oracle designates this
8+ * particular file as subject to the "Classpath" exception as provided
9+ * by Oracle in the LICENSE file that accompanied this code.
10+ *
11+ * This code is distributed in the hope that it will be useful, but WITHOUT
12+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14+ * version 2 for more details (a copy is included in the LICENSE file that
15+ * accompanied this code).
16+ *
17+ * You should have received a copy of the GNU General Public License version
18+ * 2 along with this work; if not, write to the Free Software Foundation,
19+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20+ *
21+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22+ * or visit www.oracle.com if you need additional information or have any
23+ * questions.
24+ */
25+
26+package sun.invoke.util;
27+
28+import java.lang.reflect.Modifier;
29+import static java.lang.reflect.Modifier.*;
30+
31+/**
32+ * This class centralizes information about the JVM's linkage access control.
33+ * @author jrose
34+ */
35+public class VerifyAccess {
36+
37+ private VerifyAccess() { } // cannot instantiate
38+
39+ private static final int PACKAGE_ONLY = 0;
40+ private static final int ALL_ACCESS_MODES = (PUBLIC|PRIVATE|PROTECTED|PACKAGE_ONLY);
41+ private static final boolean ALLOW_NESTMATE_ACCESS = false;
42+
43+ /**
44+ * Evaluate the JVM linkage rules for access to the given method
45+ * on behalf of a caller class which proposes to perform the access.
46+ * Return true if the caller class has privileges to invoke a method
47+ * or access a field with the given properties.
48+ * This requires an accessibility check of the referencing class,
49+ * plus an accessibility check of the member within the class,
50+ * which depends on the member's modifier flags.
51+ * <p>
52+ * The relevant properties include the defining class ({@code defc})
53+ * of the member, and its modifier flags ({@code mods}).
54+ * Also relevant is the class used to make the initial symbolic reference
55+ * to the member ({@code refc}). If this latter class is not distinguished,
56+ * the defining class should be passed for both arguments ({@code defc == refc}).
57+ * <h3>JVM Specification, 5.4.4 "Access Control"</h3>
58+ * A field or method R is accessible to a class or interface D if
59+ * and only if any of the following conditions is true:<ul>
60+ * <li>R is public.
61+ * <li>R is protected and is declared in a class C, and D is either
62+ * a subclass of C or C itself. Furthermore, if R is not
63+ * static, then the symbolic reference to R must contain a
64+ * symbolic reference to a class T, such that T is either a
65+ * subclass of D, a superclass of D or D itself.
66+ * <li>R is either protected or has default access (that is,
67+ * neither public nor protected nor private), and is declared
68+ * by a class in the same runtime package as D.
69+ * <li>R is private and is declared in D.
70+ * </ul>
71+ * This discussion of access control omits a related restriction
72+ * on the target of a protected field access or method invocation
73+ * (the target must be of class D or a subtype of D). That
74+ * requirement is checked as part of the verification process
75+ * (5.4.1); it is not part of link-time access control.
76+ * @param refc the class used in the symbolic reference to the proposed member
77+ * @param defc the class in which the proposed member is actually defined
78+ * @param mods modifier flags for the proposed member
79+ * @param lookupClass the class for which the access check is being made
80+ * @return true iff the the accessing class can access such a member
81+ */
82+ public static boolean isMemberAccessible(Class<?> refc, // symbolic ref class
83+ Class<?> defc, // actual def class
84+ int mods, // actual member mods
85+ Class<?> lookupClass) {
86+ // Usually refc and defc are the same, but if they differ, verify them both.
87+ if (refc != defc) {
88+ if (!isClassAccessible(refc, lookupClass)) {
89+ // Note that defc is verified in the switch below.
90+ return false;
91+ }
92+ if ((mods & (ALL_ACCESS_MODES|STATIC)) == (PROTECTED|STATIC)) {
93+ // Apply the special rules for refc here.
94+ if (!isRelatedClass(refc, lookupClass))
95+ return isSamePackage(defc, lookupClass);
96+ // If refc == defc, the call to isPublicSuperClass will do
97+ // the whole job, since in that case refc (as defc) will be
98+ // a superclass of the lookup class.
99+ }
100+ }
101+ if (defc == lookupClass)
102+ return true; // easy check; all self-access is OK
103+ switch (mods & ALL_ACCESS_MODES) {
104+ case PUBLIC:
105+ if (refc != defc) return true; // already checked above
106+ return isClassAccessible(refc, lookupClass);
107+ case PROTECTED:
108+ return isSamePackage(defc, lookupClass) || isPublicSuperClass(defc, lookupClass);
109+ case PACKAGE_ONLY:
110+ return isSamePackage(defc, lookupClass);
111+ case PRIVATE:
112+ // Loosened rules for privates follows access rules for inner classes.
113+ return (ALLOW_NESTMATE_ACCESS &&
114+ isSamePackageMember(defc, lookupClass));
115+ default:
116+ throw new IllegalArgumentException("bad modifiers: "+Modifier.toString(mods));
117+ }
118+ }
119+
120+ static boolean isRelatedClass(Class<?> refc, Class<?> lookupClass) {
121+ return (refc == lookupClass ||
122+ refc.isAssignableFrom(lookupClass) ||
123+ lookupClass.isAssignableFrom(refc));
124+ }
125+
126+ static boolean isPublicSuperClass(Class<?> defc, Class<?> lookupClass) {
127+ return isPublic(defc.getModifiers()) && defc.isAssignableFrom(lookupClass);
128+ }
129+
130+ /**
131+ * Evaluate the JVM linkage rules for access to the given class on behalf of caller.
132+ * <h3>JVM Specification, 5.4.4 "Access Control"</h3>
133+ * A class or interface C is accessible to a class or interface D
134+ * if and only if either of the following conditions are true:<ul>
135+ * <li>C is public.
136+ * <li>C and D are members of the same runtime package.
137+ * </ul>
138+ * @param refc the symbolic reference class to which access is being checked (C)
139+ * @param lookupClass the class performing the lookup (D)
140+ */
141+ public static boolean isClassAccessible(Class<?> refc, Class<?> lookupClass) {
142+ int mods = refc.getModifiers();
143+ if (isPublic(mods))
144+ return true;
145+ if (isSamePackage(lookupClass, refc))
146+ return true;
147+ return false;
148+ }
149+
150+ /**
151+ * Test if two classes have the same class loader and package qualifier.
152+ * @param class1
153+ * @param class2
154+ * @return whether they are in the same package
155+ */
156+ public static boolean isSamePackage(Class<?> class1, Class<?> class2) {
157+ assert(!class1.isArray() && !class2.isArray());
158+ if (class1 == class2)
159+ return true;
160+ if (!loadersAreRelated(class1.getClassLoader(), class2.getClassLoader(), false))
161+ return false;
162+ String name1 = class1.getName(), name2 = class2.getName();
163+ int dot = name1.lastIndexOf('.');
164+ if (dot != name2.lastIndexOf('.'))
165+ return false;
166+ for (int i = 0; i < dot; i++) {
167+ if (name1.charAt(i) != name2.charAt(i))
168+ return false;
169+ }
170+ return true;
171+ }
172+
173+ /** Return the package name for this class.
174+ */
175+ public static String getPackageName(Class<?> cls) {
176+ assert(!cls.isArray());
177+ String name = cls.getName();
178+ int dot = name.lastIndexOf('.');
179+ if (dot < 0) return "";
180+ return name.substring(0, dot);
181+ }
182+
183+ /**
184+ * Test if two classes are defined as part of the same package member (top-level class).
185+ * If this is true, they can share private access with each other.
186+ * @param class1
187+ * @param class2
188+ * @return whether they are identical or nested together
189+ */
190+ public static boolean isSamePackageMember(Class<?> class1, Class<?> class2) {
191+ if (class1 == class2)
192+ return true;
193+ if (!isSamePackage(class1, class2))
194+ return false;
195+ if (getOutermostEnclosingClass(class1) != getOutermostEnclosingClass(class2))
196+ return false;
197+ return true;
198+ }
199+
200+ private static Class<?> getOutermostEnclosingClass(Class<?> c) {
201+ Class<?> pkgmem = c;
202+ for (Class<?> enc = c; (enc = enc.getEnclosingClass()) != null; )
203+ pkgmem = enc;
204+ return pkgmem;
205+ }
206+
207+ private static boolean loadersAreRelated(ClassLoader loader1, ClassLoader loader2,
208+ boolean loader1MustBeParent) {
209+ if (loader1 == loader2 || loader1 == null
210+ || (loader2 == null && !loader1MustBeParent)) {
211+ return true;
212+ }
213+ for (ClassLoader scan2 = loader2;
214+ scan2 != null; scan2 = scan2.getParent()) {
215+ if (scan2 == loader1) return true;
216+ }
217+ if (loader1MustBeParent) return false;
218+ // see if loader2 is a parent of loader1:
219+ for (ClassLoader scan1 = loader1;
220+ scan1 != null; scan1 = scan1.getParent()) {
221+ if (scan1 == loader2) return true;
222+ }
223+ return false;
224+ }
225+
226+ /**
227+ * Is the class loader of parentClass identical to, or an ancestor of,
228+ * the class loader of childClass?
229+ * @param parentClass
230+ * @param childClass
231+ * @return whether parentClass precedes or equals childClass in class loader order
232+ */
233+ public static boolean classLoaderIsAncestor(Class<?> parentClass, Class<?> childClass) {
234+ return loadersAreRelated(parentClass.getClassLoader(), childClass.getClassLoader(), true);
235+ }
236+}