001/* FilePermission.java --
002   Copyright (C) 1998, 2000, 2003, 2004, 2005, 2006
003   Free Software Foundation, Inc.
004
005This file is part of GNU Classpath.
006
007GNU Classpath is free software; you can redistribute it and/or modify
008it under the terms of the GNU General Public License as published by
009the Free Software Foundation; either version 2, or (at your option)
010any later version.
011
012GNU Classpath is distributed in the hope that it will be useful, but
013WITHOUT ANY WARRANTY; without even the implied warranty of
014MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
015General Public License for more details.
016
017You should have received a copy of the GNU General Public License
018along with GNU Classpath; see the file COPYING.  If not, write to the
019Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02002110-1301 USA.
021
022Linking this library statically or dynamically with other modules is
023making a combined work based on this library.  Thus, the terms and
024conditions of the GNU General Public License cover the whole
025combination.
026
027As a special exception, the copyright holders of this library give you
028permission to link this library with independent modules to produce an
029executable, regardless of the license terms of these independent
030modules, and to copy and distribute the resulting executable under
031terms of your choice, provided that you also meet, for each linked
032independent module, the terms and conditions of the license of that
033module.  An independent module is a module which is not derived from
034or based on this library.  If you modify this library, you may extend
035this exception to your version of the library, but you are not
036obligated to do so.  If you do not wish to do so, delete this
037exception statement from your version. */
038
039
040package java.io;
041
042import java.security.Permission;
043
044public 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}