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| 1 | +/* | |
| 2 | + * Copyright (c) 1997, 2008, 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 java.lang.reflect; | |
| 27 | + | |
| 28 | +import java.security.AccessController; | |
| 29 | +import sun.reflect.Reflection; | |
| 30 | +import sun.reflect.ReflectionFactory; | |
| 31 | +import java.lang.annotation.Annotation; | |
| 32 | + | |
| 33 | +/** | |
| 34 | + * The AccessibleObject class is the base class for Field, Method and | |
| 35 | + * Constructor objects. It provides the ability to flag a reflected | |
| 36 | + * object as suppressing default Java language access control checks | |
| 37 | + * when it is used. The access checks--for public, default (package) | |
| 38 | + * access, protected, and private members--are performed when Fields, | |
| 39 | + * Methods or Constructors are used to set or get fields, to invoke | |
| 40 | + * methods, or to create and initialize new instances of classes, | |
| 41 | + * respectively. | |
| 42 | + * | |
| 43 | + * <p>Setting the {@code accessible} flag in a reflected object | |
| 44 | + * permits sophisticated applications with sufficient privilege, such | |
| 45 | + * as Java Object Serialization or other persistence mechanisms, to | |
| 46 | + * manipulate objects in a manner that would normally be prohibited. | |
| 47 | + * | |
| 48 | + * <p>By default, a reflected object is <em>not</em> accessible. | |
| 49 | + * | |
| 50 | + * @see Field | |
| 51 | + * @see Method | |
| 52 | + * @see Constructor | |
| 53 | + * @see ReflectPermission | |
| 54 | + * | |
| 55 | + * @since 1.2 | |
| 56 | + */ | |
| 57 | +public class AccessibleObject implements AnnotatedElement { | |
| 58 | + | |
| 59 | + /** | |
| 60 | + * The Permission object that is used to check whether a client | |
| 61 | + * has sufficient privilege to defeat Java language access | |
| 62 | + * control checks. | |
| 63 | + */ | |
| 64 | + static final private java.security.Permission ACCESS_PERMISSION = | |
| 65 | + new ReflectPermission("suppressAccessChecks"); | |
| 66 | + | |
| 67 | + /** | |
| 68 | + * Convenience method to set the {@code accessible} flag for an | |
| 69 | + * array of objects with a single security check (for efficiency). | |
| 70 | + * | |
| 71 | + * <p>First, if there is a security manager, its | |
| 72 | + * {@code checkPermission} method is called with a | |
| 73 | + * {@code ReflectPermission("suppressAccessChecks")} permission. | |
| 74 | + * | |
| 75 | + * <p>A {@code SecurityException} is raised if {@code flag} is | |
| 76 | + * {@code true} but accessibility of any of the elements of the input | |
| 77 | + * {@code array} may not be changed (for example, if the element | |
| 78 | + * object is a {@link Constructor} object for the class {@link | |
| 79 | + * java.lang.Class}). In the event of such a SecurityException, the | |
| 80 | + * accessibility of objects is set to {@code flag} for array elements | |
| 81 | + * upto (and excluding) the element for which the exception occurred; the | |
| 82 | + * accessibility of elements beyond (and including) the element for which | |
| 83 | + * the exception occurred is unchanged. | |
| 84 | + * | |
| 85 | + * @param array the array of AccessibleObjects | |
| 86 | + * @param flag the new value for the {@code accessible} flag | |
| 87 | + * in each object | |
| 88 | + * @throws SecurityException if the request is denied. | |
| 89 | + * @see SecurityManager#checkPermission | |
| 90 | + * @see java.lang.RuntimePermission | |
| 91 | + */ | |
| 92 | + public static void setAccessible(AccessibleObject[] array, boolean flag) | |
| 93 | + throws SecurityException { | |
| 94 | + SecurityManager sm = System.getSecurityManager(); | |
| 95 | + if (sm != null) sm.checkPermission(ACCESS_PERMISSION); | |
| 96 | + for (int i = 0; i < array.length; i++) { | |
| 97 | + setAccessible0(array[i], flag); | |
| 98 | + } | |
| 99 | + } | |
| 100 | + | |
| 101 | + /** | |
| 102 | + * Set the {@code accessible} flag for this object to | |
| 103 | + * the indicated boolean value. A value of {@code true} indicates that | |
| 104 | + * the reflected object should suppress Java language access | |
| 105 | + * checking when it is used. A value of {@code false} indicates | |
| 106 | + * that the reflected object should enforce Java language access checks. | |
| 107 | + * | |
| 108 | + * <p>First, if there is a security manager, its | |
| 109 | + * {@code checkPermission} method is called with a | |
| 110 | + * {@code ReflectPermission("suppressAccessChecks")} permission. | |
| 111 | + * | |
| 112 | + * <p>A {@code SecurityException} is raised if {@code flag} is | |
| 113 | + * {@code true} but accessibility of this object may not be changed | |
| 114 | + * (for example, if this element object is a {@link Constructor} object for | |
| 115 | + * the class {@link java.lang.Class}). | |
| 116 | + * | |
| 117 | + * <p>A {@code SecurityException} is raised if this object is a {@link | |
| 118 | + * java.lang.reflect.Constructor} object for the class | |
| 119 | + * {@code java.lang.Class}, and {@code flag} is true. | |
| 120 | + * | |
| 121 | + * @param flag the new value for the {@code accessible} flag | |
| 122 | + * @throws SecurityException if the request is denied. | |
| 123 | + * @see SecurityManager#checkPermission | |
| 124 | + * @see java.lang.RuntimePermission | |
| 125 | + */ | |
| 126 | + public void setAccessible(boolean flag) throws SecurityException { | |
| 127 | + SecurityManager sm = System.getSecurityManager(); | |
| 128 | + if (sm != null) sm.checkPermission(ACCESS_PERMISSION); | |
| 129 | + setAccessible0(this, flag); | |
| 130 | + } | |
| 131 | + | |
| 132 | + /* Check that you aren't exposing java.lang.Class.<init>. */ | |
| 133 | + private static void setAccessible0(AccessibleObject obj, boolean flag) | |
| 134 | + throws SecurityException | |
| 135 | + { | |
| 136 | + if (obj instanceof Constructor && flag == true) { | |
| 137 | + Constructor<?> c = (Constructor<?>)obj; | |
| 138 | + if (c.getDeclaringClass() == Class.class) { | |
| 139 | + throw new SecurityException("Can not make a java.lang.Class" + | |
| 140 | + " constructor accessible"); | |
| 141 | + } | |
| 142 | + } | |
| 143 | + obj.override = flag; | |
| 144 | + } | |
| 145 | + | |
| 146 | + /** | |
| 147 | + * Get the value of the {@code accessible} flag for this object. | |
| 148 | + * | |
| 149 | + * @return the value of the object's {@code accessible} flag | |
| 150 | + */ | |
| 151 | + public boolean isAccessible() { | |
| 152 | + return override; | |
| 153 | + } | |
| 154 | + | |
| 155 | + /** | |
| 156 | + * Constructor: only used by the Java Virtual Machine. | |
| 157 | + */ | |
| 158 | + protected AccessibleObject() {} | |
| 159 | + | |
| 160 | + // Indicates whether language-level access checks are overridden | |
| 161 | + // by this object. Initializes to "false". This field is used by | |
| 162 | + // Field, Method, and Constructor. | |
| 163 | + // | |
| 164 | + // NOTE: for security purposes, this field must not be visible | |
| 165 | + // outside this package. | |
| 166 | + boolean override; | |
| 167 | + | |
| 168 | + // Reflection factory used by subclasses for creating field, | |
| 169 | + // method, and constructor accessors. Note that this is called | |
| 170 | + // very early in the bootstrapping process. | |
| 171 | + static final ReflectionFactory reflectionFactory = | |
| 172 | + AccessController.doPrivileged( | |
| 173 | + new sun.reflect.ReflectionFactory.GetReflectionFactoryAction()); | |
| 174 | + | |
| 175 | + /** | |
| 176 | + * @throws NullPointerException {@inheritDoc} | |
| 177 | + * @since 1.5 | |
| 178 | + */ | |
| 179 | + public <T extends Annotation> T getAnnotation(Class<T> annotationClass) { | |
| 180 | + throw new AssertionError("All subclasses should override this method"); | |
| 181 | + } | |
| 182 | + | |
| 183 | + /** | |
| 184 | + * @throws NullPointerException {@inheritDoc} | |
| 185 | + * @since 1.5 | |
| 186 | + */ | |
| 187 | + public boolean isAnnotationPresent( | |
| 188 | + Class<? extends Annotation> annotationClass) { | |
| 189 | + return getAnnotation(annotationClass) != null; | |
| 190 | + } | |
| 191 | + | |
| 192 | + /** | |
| 193 | + * @since 1.5 | |
| 194 | + */ | |
| 195 | + public Annotation[] getAnnotations() { | |
| 196 | + return getDeclaredAnnotations(); | |
| 197 | + } | |
| 198 | + | |
| 199 | + /** | |
| 200 | + * @since 1.5 | |
| 201 | + */ | |
| 202 | + public Annotation[] getDeclaredAnnotations() { | |
| 203 | + throw new AssertionError("All subclasses should override this method"); | |
| 204 | + } | |
| 205 | + | |
| 206 | + | |
| 207 | + // Shared access checking logic. | |
| 208 | + | |
| 209 | + // For non-public members or members in package-private classes, | |
| 210 | + // it is necessary to perform somewhat expensive security checks. | |
| 211 | + // If the security check succeeds for a given class, it will | |
| 212 | + // always succeed (it is not affected by the granting or revoking | |
| 213 | + // of permissions); we speed up the check in the common case by | |
| 214 | + // remembering the last Class for which the check succeeded. | |
| 215 | + // | |
| 216 | + // The simple security check for Constructor is to see if | |
| 217 | + // the caller has already been seen, verified, and cached. | |
| 218 | + // (See also Class.newInstance(), which uses a similar method.) | |
| 219 | + // | |
| 220 | + // A more complicated security check cache is needed for Method and Field | |
| 221 | + // The cache can be either null (empty cache), a 2-array of {caller,target}, | |
| 222 | + // or a caller (with target implicitly equal to this.clazz). | |
| 223 | + // In the 2-array case, the target is always different from the clazz. | |
| 224 | + volatile Object securityCheckCache; | |
| 225 | + | |
| 226 | + void checkAccess(Class<?> caller, Class<?> clazz, Object obj, int modifiers) | |
| 227 | + throws IllegalAccessException | |
| 228 | + { | |
| 229 | + if (caller == clazz) { // quick check | |
| 230 | + return; // ACCESS IS OK | |
| 231 | + } | |
| 232 | + Object cache = securityCheckCache; // read volatile | |
| 233 | + Class<?> targetClass = clazz; | |
| 234 | + if (obj != null | |
| 235 | + && Modifier.isProtected(modifiers) | |
| 236 | + && ((targetClass = obj.getClass()) != clazz)) { | |
| 237 | + // Must match a 2-list of { caller, targetClass }. | |
| 238 | + if (cache instanceof Class[]) { | |
| 239 | + Class<?>[] cache2 = (Class<?>[]) cache; | |
| 240 | + if (cache2[1] == targetClass && | |
| 241 | + cache2[0] == caller) { | |
| 242 | + return; // ACCESS IS OK | |
| 243 | + } | |
| 244 | + // (Test cache[1] first since range check for [1] | |
| 245 | + // subsumes range check for [0].) | |
| 246 | + } | |
| 247 | + } else if (cache == caller) { | |
| 248 | + // Non-protected case (or obj.class == this.clazz). | |
| 249 | + return; // ACCESS IS OK | |
| 250 | + } | |
| 251 | + | |
| 252 | + // If no return, fall through to the slow path. | |
| 253 | + slowCheckMemberAccess(caller, clazz, obj, modifiers, targetClass); | |
| 254 | + } | |
| 255 | + | |
| 256 | + // Keep all this slow stuff out of line: | |
| 257 | + void slowCheckMemberAccess(Class<?> caller, Class<?> clazz, Object obj, int modifiers, | |
| 258 | + Class<?> targetClass) | |
| 259 | + throws IllegalAccessException | |
| 260 | + { | |
| 261 | + Reflection.ensureMemberAccess(caller, clazz, obj, modifiers); | |
| 262 | + | |
| 263 | + // Success: Update the cache. | |
| 264 | + Object cache = ((targetClass == clazz) | |
| 265 | + ? caller | |
| 266 | + : new Class<?>[] { caller, targetClass }); | |
| 267 | + | |
| 268 | + // Note: The two cache elements are not volatile, | |
| 269 | + // but they are effectively final. The Java memory model | |
| 270 | + // guarantees that the initializing stores for the cache | |
| 271 | + // elements will occur before the volatile write. | |
| 272 | + securityCheckCache = cache; // write volatile | |
| 273 | + } | |
| 274 | +} | |