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1: /* AccessControlContext.java --- Access Control Context Class 2: Copyright (C) 1999, 2004 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: package java.security; 39: 40: /** 41: * AccessControlContext makes system resource access decsion 42: * based on permission rights. 43: * 44: * It is used for a specific context and has only one method 45: * checkPermission. It is similar to AccessController except 46: * that it makes decsions based on the current context instead 47: * of the the current thread. 48: * 49: * It is created by call AccessController.getContext method. 50: * 51: * @author Mark Benvenuto 52: * @since 1.2 53: */ 54: public final class AccessControlContext 55: { 56: private ProtectionDomain[] protectionDomains; 57: private DomainCombiner combiner; 58: 59: /** 60: * Construct a new AccessControlContext with the specified 61: * ProtectionDomains. <code>context</code> must not be 62: * null and duplicates will be removed. 63: * 64: * @param context The ProtectionDomains to use 65: */ 66: public AccessControlContext(ProtectionDomain[] context) 67: { 68: int i, j, k, count = context.length, count2 = 0; 69: for (i = 0, j = 0; i < count; i++) 70: { 71: for (k = 0; k < i; k++) 72: if (context[k] == protectionDomains[i]) 73: break; 74: if (k != i) //it means previous loop did not complete 75: continue; 76: 77: count2++; 78: } 79: 80: protectionDomains = new ProtectionDomain[count2]; 81: for (i = 0, j = 0; i < count2; i++) 82: { 83: for (k = 0; k < i; k++) 84: if (context[k] == protectionDomains[i]) 85: break; 86: if (k != i) //it means previous loop did not complete 87: continue; 88: 89: protectionDomains[j++] = context[i]; 90: } 91: } 92: 93: /** 94: * Construct a new AccessControlContext with the specified 95: * ProtectionDomains and DomainCombiner 96: * 97: * @since 1.3 98: */ 99: public AccessControlContext(AccessControlContext acc, 100: DomainCombiner combiner) 101: { 102: this(acc.protectionDomains); 103: this.combiner = combiner; 104: } 105: 106: /** 107: * Returns the Domain Combiner associated with the AccessControlContext 108: * 109: * @return the DomainCombiner 110: */ 111: public DomainCombiner getDomainCombiner() 112: { 113: return combiner; 114: } 115: 116: /** 117: * Determines whether or not the specific permission is granted 118: * depending on the context it is within. 119: * 120: * @param perm a permission to check 121: * 122: * @throws AccessControlException if the permssion is not permitted 123: */ 124: public void checkPermission(Permission perm) throws AccessControlException 125: { 126: for (int i = 0; i < protectionDomains.length; i++) 127: if (protectionDomains[i].implies(perm) == true) 128: return; 129: 130: throw new AccessControlException("Permission not granted"); 131: } 132: 133: /** 134: * Checks if two AccessControlContexts are equal. 135: * 136: * It first checks if obj is an AccessControlContext class, and 137: * then checks if each ProtectionDomain matches. 138: * 139: * @param obj The object to compare this class to 140: * 141: * @return true if equal, false otherwise 142: */ 143: public boolean equals(Object obj) 144: { 145: if (obj instanceof AccessControlContext) 146: { 147: AccessControlContext acc = (AccessControlContext) obj; 148: 149: if (acc.protectionDomains.length != protectionDomains.length) 150: return false; 151: 152: for (int i = 0; i < protectionDomains.length; i++) 153: if (acc.protectionDomains[i] != protectionDomains[i]) 154: return false; 155: return true; 156: } 157: return false; 158: } 159: 160: /** 161: * Computes a hash code of this class 162: * 163: * @return a hash code representing this class 164: */ 165: public int hashCode() 166: { 167: int h = 0; 168: for (int i = 0; i < protectionDomains.length; i++) 169: h ^= protectionDomains[i].hashCode(); 170: 171: return h; 172: } 173: }