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| 1 | +/* | |
| 2 | + * Copyright (c) 1997, 2009, 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.security; | |
| 27 | + | |
| 28 | +/** | |
| 29 | + * Abstract class for representing access to a system resource. | |
| 30 | + * All permissions have a name (whose interpretation depends on the subclass), | |
| 31 | + * as well as abstract functions for defining the semantics of the | |
| 32 | + * particular Permission subclass. | |
| 33 | + * | |
| 34 | + * <p>Most Permission objects also include an "actions" list that tells the actions | |
| 35 | + * that are permitted for the object. For example, | |
| 36 | + * for a <code>java.io.FilePermission</code> object, the permission name is | |
| 37 | + * the pathname of a file (or directory), and the actions list | |
| 38 | + * (such as "read, write") specifies which actions are granted for the | |
| 39 | + * specified file (or for files in the specified directory). | |
| 40 | + * The actions list is optional for Permission objects, such as | |
| 41 | + * <code>java.lang.RuntimePermission</code>, | |
| 42 | + * that don't need such a list; you either have the named permission (such | |
| 43 | + * as "system.exit") or you don't. | |
| 44 | + * | |
| 45 | + * <p>An important method that must be implemented by each subclass is | |
| 46 | + * the <code>implies</code> method to compare Permissions. Basically, | |
| 47 | + * "permission p1 implies permission p2" means that | |
| 48 | + * if one is granted permission p1, one is naturally granted permission p2. | |
| 49 | + * Thus, this is not an equality test, but rather more of a | |
| 50 | + * subset test. | |
| 51 | + * | |
| 52 | + * <P> Permission objects are similar to String objects in that they | |
| 53 | + * are immutable once they have been created. Subclasses should not | |
| 54 | + * provide methods that can change the state of a permission | |
| 55 | + * once it has been created. | |
| 56 | + * | |
| 57 | + * @see Permissions | |
| 58 | + * @see PermissionCollection | |
| 59 | + * | |
| 60 | + * | |
| 61 | + * @author Marianne Mueller | |
| 62 | + * @author Roland Schemers | |
| 63 | + */ | |
| 64 | + | |
| 65 | +public abstract class Permission implements Guard, java.io.Serializable { | |
| 66 | + | |
| 67 | + private static final long serialVersionUID = -5636570222231596674L; | |
| 68 | + | |
| 69 | + private String name; | |
| 70 | + | |
| 71 | + /** | |
| 72 | + * Constructs a permission with the specified name. | |
| 73 | + * | |
| 74 | + * @param name name of the Permission object being created. | |
| 75 | + * | |
| 76 | + */ | |
| 77 | + | |
| 78 | + public Permission(String name) { | |
| 79 | + this.name = name; | |
| 80 | + } | |
| 81 | + | |
| 82 | + /** | |
| 83 | + * Implements the guard interface for a permission. The | |
| 84 | + * <code>SecurityManager.checkPermission</code> method is called, | |
| 85 | + * passing this permission object as the permission to check. | |
| 86 | + * Returns silently if access is granted. Otherwise, throws | |
| 87 | + * a SecurityException. | |
| 88 | + * | |
| 89 | + * @param object the object being guarded (currently ignored). | |
| 90 | + * | |
| 91 | + * @throws SecurityException | |
| 92 | + * if a security manager exists and its | |
| 93 | + * <code>checkPermission</code> method doesn't allow access. | |
| 94 | + * | |
| 95 | + * @see Guard | |
| 96 | + * @see GuardedObject | |
| 97 | + * @see SecurityManager#checkPermission | |
| 98 | + * | |
| 99 | + */ | |
| 100 | + public void checkGuard(Object object) throws SecurityException { | |
| 101 | + SecurityManager sm = System.getSecurityManager(); | |
| 102 | + if (sm != null) sm.checkPermission(this); | |
| 103 | + } | |
| 104 | + | |
| 105 | + /** | |
| 106 | + * Checks if the specified permission's actions are "implied by" | |
| 107 | + * this object's actions. | |
| 108 | + * <P> | |
| 109 | + * This must be implemented by subclasses of Permission, as they are the | |
| 110 | + * only ones that can impose semantics on a Permission object. | |
| 111 | + * | |
| 112 | + * <p>The <code>implies</code> method is used by the AccessController to determine | |
| 113 | + * whether or not a requested permission is implied by another permission that | |
| 114 | + * is known to be valid in the current execution context. | |
| 115 | + * | |
| 116 | + * @param permission the permission to check against. | |
| 117 | + * | |
| 118 | + * @return true if the specified permission is implied by this object, | |
| 119 | + * false if not. | |
| 120 | + */ | |
| 121 | + | |
| 122 | + public abstract boolean implies(Permission permission); | |
| 123 | + | |
| 124 | + /** | |
| 125 | + * Checks two Permission objects for equality. | |
| 126 | + * <P> | |
| 127 | + * Do not use the <code>equals</code> method for making access control | |
| 128 | + * decisions; use the <code>implies</code> method. | |
| 129 | + * | |
| 130 | + * @param obj the object we are testing for equality with this object. | |
| 131 | + * | |
| 132 | + * @return true if both Permission objects are equivalent. | |
| 133 | + */ | |
| 134 | + | |
| 135 | + public abstract boolean equals(Object obj); | |
| 136 | + | |
| 137 | + /** | |
| 138 | + * Returns the hash code value for this Permission object. | |
| 139 | + * <P> | |
| 140 | + * The required <code>hashCode</code> behavior for Permission Objects is | |
| 141 | + * the following: <p> | |
| 142 | + * <ul> | |
| 143 | + * <li>Whenever it is invoked on the same Permission object more than | |
| 144 | + * once during an execution of a Java application, the | |
| 145 | + * <code>hashCode</code> method | |
| 146 | + * must consistently return the same integer. This integer need not | |
| 147 | + * remain consistent from one execution of an application to another | |
| 148 | + * execution of the same application. <p> | |
| 149 | + * <li>If two Permission objects are equal according to the | |
| 150 | + * <code>equals</code> | |
| 151 | + * method, then calling the <code>hashCode</code> method on each of the | |
| 152 | + * two Permission objects must produce the same integer result. | |
| 153 | + * </ul> | |
| 154 | + * | |
| 155 | + * @return a hash code value for this object. | |
| 156 | + */ | |
| 157 | + | |
| 158 | + public abstract int hashCode(); | |
| 159 | + | |
| 160 | + /** | |
| 161 | + * Returns the name of this Permission. | |
| 162 | + * For example, in the case of a <code>java.io.FilePermission</code>, | |
| 163 | + * the name will be a pathname. | |
| 164 | + * | |
| 165 | + * @return the name of this Permission. | |
| 166 | + * | |
| 167 | + */ | |
| 168 | + | |
| 169 | + public final String getName() { | |
| 170 | + return name; | |
| 171 | + } | |
| 172 | + | |
| 173 | + /** | |
| 174 | + * Returns the actions as a String. This is abstract | |
| 175 | + * so subclasses can defer creating a String representation until | |
| 176 | + * one is needed. Subclasses should always return actions in what they | |
| 177 | + * consider to be their | |
| 178 | + * canonical form. For example, two FilePermission objects created via | |
| 179 | + * the following: | |
| 180 | + * | |
| 181 | + * <pre> | |
| 182 | + * perm1 = new FilePermission(p1,"read,write"); | |
| 183 | + * perm2 = new FilePermission(p2,"write,read"); | |
| 184 | + * </pre> | |
| 185 | + * | |
| 186 | + * both return | |
| 187 | + * "read,write" when the <code>getActions</code> method is invoked. | |
| 188 | + * | |
| 189 | + * @return the actions of this Permission. | |
| 190 | + * | |
| 191 | + */ | |
| 192 | + | |
| 193 | + public abstract String getActions(); | |
| 194 | + | |
| 195 | + /** | |
| 196 | + * Returns an empty PermissionCollection for a given Permission object, or null if | |
| 197 | + * one is not defined. Subclasses of class Permission should | |
| 198 | + * override this if they need to store their permissions in a particular | |
| 199 | + * PermissionCollection object in order to provide the correct semantics | |
| 200 | + * when the <code>PermissionCollection.implies</code> method is called. | |
| 201 | + * If null is returned, | |
| 202 | + * then the caller of this method is free to store permissions of this | |
| 203 | + * type in any PermissionCollection they choose (one that uses a Hashtable, | |
| 204 | + * one that uses a Vector, etc). | |
| 205 | + * | |
| 206 | + * @return a new PermissionCollection object for this type of Permission, or | |
| 207 | + * null if one is not defined. | |
| 208 | + */ | |
| 209 | + | |
| 210 | + public PermissionCollection newPermissionCollection() { | |
| 211 | + return null; | |
| 212 | + } | |
| 213 | + | |
| 214 | + /** | |
| 215 | + * Returns a string describing this Permission. The convention is to | |
| 216 | + * specify the class name, the permission name, and the actions in | |
| 217 | + * the following format: '("ClassName" "name" "actions")', or | |
| 218 | + * '("ClassName" "name")' if actions list is null or empty. | |
| 219 | + * | |
| 220 | + * @return information about this Permission. | |
| 221 | + */ | |
| 222 | + public String toString() { | |
| 223 | + String actions = getActions(); | |
| 224 | + if ((actions == null) || (actions.length() == 0)) { // OPTIONAL | |
| 225 | + return "(\"" + getClass().getName() + "\" \"" + name + "\")"; | |
| 226 | + } else { | |
| 227 | + return "(\"" + getClass().getName() + "\" \"" + name + | |
| 228 | + "\" \"" + actions + "\")"; | |
| 229 | + } | |
| 230 | + } | |
| 231 | +} | |