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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 | } | ||