001 /* FilePermission.java --
002 Copyright (C) 1998, 2000, 2003, 2004, 2005, 2006
003 Free Software Foundation, Inc.
004
005 This file is part of GNU Classpath.
006
007 GNU Classpath is free software; you can redistribute it and/or modify
008 it under the terms of the GNU General Public License as published by
009 the Free Software Foundation; either version 2, or (at your option)
010 any later version.
011
012 GNU Classpath is distributed in the hope that it will be useful, but
013 WITHOUT ANY WARRANTY; without even the implied warranty of
014 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 General Public License for more details.
016
017 You should have received a copy of the GNU General Public License
018 along with GNU Classpath; see the file COPYING. If not, write to the
019 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
020 02110-1301 USA.
021
022 Linking this library statically or dynamically with other modules is
023 making a combined work based on this library. Thus, the terms and
024 conditions of the GNU General Public License cover the whole
025 combination.
026
027 As a special exception, the copyright holders of this library give you
028 permission to link this library with independent modules to produce an
029 executable, regardless of the license terms of these independent
030 modules, and to copy and distribute the resulting executable under
031 terms of your choice, provided that you also meet, for each linked
032 independent module, the terms and conditions of the license of that
033 module. An independent module is a module which is not derived from
034 or based on this library. If you modify this library, you may extend
035 this exception to your version of the library, but you are not
036 obligated to do so. If you do not wish to do so, delete this
037 exception statement from your version. */
038
039
040 package java.io;
041
042 import java.security.Permission;
043
044 public final class FilePermission extends Permission implements Serializable
045 {
046 private static final long serialVersionUID = 7930732926638008763L;
047
048 private static final String ALL_FILES = "<<ALL FILES>>";
049
050 private boolean readPerm = false;
051 private boolean writePerm = false;
052 private boolean executePerm = false;
053 private boolean deletePerm = false;
054 private final String actionsString;
055
056 // Checks and caches the actions
057 private void checkPerms() throws IllegalArgumentException
058 {
059 String action;
060 int i = actionsString.indexOf(',');
061 int startI = 0;
062 while (i != -1)
063 {
064 action = actionsString.substring(startI, i).trim().toLowerCase();
065 if (action.equals("read"))
066 readPerm = true;
067 else if (action.equals("write"))
068 writePerm = true;
069 else if (action.equals("execute"))
070 executePerm = true;
071 else if (action.equals("delete"))
072 deletePerm = true;
073 else
074 throw new IllegalArgumentException("Unknown action: " + action);
075
076 startI = i + 1;
077 i = actionsString.indexOf(',', startI);
078 }
079
080 action = actionsString.substring(startI).trim().toLowerCase();
081 if (action.equals("read"))
082 readPerm = true;
083 else if (action.equals("write"))
084 writePerm = true;
085 else if (action.equals("execute"))
086 executePerm = true;
087 else if (action.equals("delete"))
088 deletePerm = true;
089 else
090 throw new IllegalArgumentException("Unknown action: " + action);
091 }
092
093 /**
094 * Create a new FilePermission.
095 *
096 * @param pathExpression an expression specifying the paths this
097 * permission represents.
098 * @param actionsString a comma-separated list of the actions this
099 * permission represents. The actions must be "read", "write",
100 * "execute" and/or "delete".
101 */
102 public FilePermission(String pathExpression, String actionsString)
103 {
104 // FIXME: what to do when the file string is malformed?
105 super(pathExpression);
106 if (pathExpression == null)
107 throw new NullPointerException("pathExpression");
108 if (actionsString == null)
109 throw new IllegalArgumentException("actionsString");
110 this.actionsString = actionsString;
111 checkPerms();
112 }
113
114 /**
115 * Get the actions this FilePermission supports.
116 * @return the String representing the actions this FilePermission supports.
117 */
118 public String getActions()
119 {
120 return actionsString;
121 }
122
123 /**
124 * Get the hash code for this Object.<P>
125 * FilePermission's hash code is calculated as the exclusive or of the
126 * target
127 * String's hash code and the action String's hash code.
128 * @specnote Sun did not specify how to calculate the hash code;
129 * I made this up.
130 * @return the hash code for this Object.
131 */
132 public int hashCode()
133 {
134 return getName().hashCode() ^ actionsString.hashCode();
135 }
136
137 /**
138 * Check two FilePermissions for semantic equality.
139 * Two FilePermissions are exactly equivalent if they have identical path
140 * expressions and have exactly the same access permissions.
141 * @param o the Object to compare to.
142 * @return whether the Objects are semantically equivalent.
143 */
144 public boolean equals(Object o)
145 {
146 if (! (o instanceof FilePermission))
147 return false;
148 FilePermission p = (FilePermission) o;
149
150 String f1 = getName();
151 String f2 = p.getName();
152
153 // Compare names, taking into account if they refer to a directory
154 // and one has a separator and the other does not.
155 if (f1.length() > 0 && f1.charAt(f1.length() - 1) == File.separatorChar)
156 {
157 if (f2.length() > 0
158 && f2.charAt(f2.length() - 1) == File.separatorChar)
159 {
160 if (! f2.equals(f1))
161 return false;
162 }
163 else
164 {
165 if (! f2.equals(f1.substring(0, f1.length() - 1)))
166 return false;
167 }
168 }
169 else
170 {
171 if (f2.length() > 0
172 && f2.charAt(f2.length() - 1) == File.separatorChar)
173 {
174 if (! f1.equals(f2.substring(0, f2.length() - 1)))
175 return false;
176 }
177 else
178 {
179 if (! f1.equals(f2))
180 return false;
181 }
182 }
183 return (readPerm == p.readPerm
184 && writePerm == p.writePerm
185 && executePerm == p.executePerm
186 && deletePerm == p.deletePerm);
187 }
188
189 /**
190 * Check to see if this permission implies another.
191 * Permission A implies permission B if these things are all true:
192 * <OL>
193 * <LI>A and B are both FilePermissions.</LI>
194 * <LI>All possible files in B are included in A
195 * (possibly more are in A).</LI>
196 * <LI>All actions B supports, A also supports.</LI>
197 * </OL>
198 * @param p the Permission to compare against.
199 * @return whether this Permission implies p
200 */
201 public boolean implies(Permission p)
202 {
203 if (! (p instanceof FilePermission))
204 return false;
205
206 String f1 = getName();
207
208 if (f1.equals(ALL_FILES))
209 return true;
210
211 FilePermission fp = (FilePermission) p;
212 String f2 = fp.getName();
213
214 if (f2.equals(ALL_FILES))
215 return false;
216
217 try
218 {
219 f1 = new File(f1).getCanonicalPath();
220 f2 = new File(f2).getCanonicalPath();
221 }
222 catch (IOException ioe)
223 {
224 return false;
225 }
226
227 String sub1;
228
229 switch (f1.charAt(f1.length() - 1))
230 {
231 case '*':
232 sub1 = f1.substring(0, f1.length() - 1); // chop off "*"
233 if (f2.length() <= sub1.length())
234 {
235 // If it's smaller, there is no way it could be part of
236 // this directory. If it's the same (or length - 1), it
237 // could be the same directory but specifies access to
238 // the directory rather than the files in it.
239 return false;
240 }
241 else if (f2.charAt(sub1.length() - 1) == File.separatorChar)
242 {
243 // Make sure the part before the "/" is the same.
244 if (! f2.substring(0, sub1.length()).equals(sub1))
245 return false;
246 // Make sure there are no subdirectories specified
247 // underneath this one.
248 if (f2.substring(sub1.length() + 1).indexOf(File.separatorChar)
249 != -1)
250 return false;
251 }
252 else
253 {
254 // Obviously not equal: f2 is either not a directory or
255 // is not the same directory (its name continues further
256 // than we want).
257 return false;
258 }
259 break;
260 case '-':
261 // Chop off "/-".
262 sub1 = f1.substring(0, f1.length() - 2);
263 if (f2.length() < sub1.length())
264 {
265 // If it's smaller, there is no way it could be part of
266 // this directory.
267 return false;
268 }
269 else if (f2.length() > sub1.length()
270 && f2.charAt(sub1.length()) != File.separatorChar)
271 return false;
272 else if (! f2.substring(0, sub1.length()).equals(sub1))
273 return false;
274 break;
275
276 default:
277 if (!f1.equals(f2))
278 return false;
279 break;
280 }
281
282 if (fp.readPerm && ! readPerm)
283 return false;
284 if (fp.writePerm && ! writePerm)
285 return false;
286 if (fp.executePerm && ! executePerm)
287 return false;
288 if (fp.deletePerm && ! deletePerm)
289 return false;
290
291 return true;
292 }
293 }