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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 | } | ||