1 /*
2 * Copyright (c) 2008, 2011, Oracle and/or its affiliates. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * - Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * - Neither the name of Oracle nor the names of its
16 * contributors may be used to endorse or promote products derived
17 * from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
20 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
21 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 import java.nio.file.*;
33 import java.nio.file.attribute.*;
34 import static java.nio.file.attribute.PosixFilePermission.*;
35 import static java.nio.file.FileVisitResult.*;
36 import java.io.IOException;
37 import java.util.*;
38
39 /**
40 * Sample code that changes the permissions of files in a similar manner to the
41 * chmod(1) program.
42 */
43
44 public class Chmod {
45
46 /**
47 * Compiles a list of one or more <em>symbolic mode expressions</em> that
48 * may be used to change a set of file permissions. This method is
49 * intended for use where file permissions are required to be changed in
50 * a manner similar to the UNIX <i>chmod</i> program.
51 *
52 * <p> The {@code exprs} parameter is a comma separated list of expressions
53 * where each takes the form:
54 * <blockquote>
55 * <i>who operator</i> [<i>permissions</i>]
56 * </blockquote>
57 * where <i>who</i> is one or more of the characters {@code 'u'}, {@code 'g'},
58 * {@code 'o'}, or {@code 'a'} meaning the owner (user), group, others, or
59 * all (owner, group, and others) respectively.
60 *
61 * <p> <i>operator</i> is the character {@code '+'}, {@code '-'}, or {@code
62 * '='} signifying how permissions are to be changed. {@code '+'} means the
63 * permissions are added, {@code '-'} means the permissions are removed, and
64 * {@code '='} means the permissions are assigned absolutely.
65 *
66 * <p> <i>permissions</i> is a sequence of zero or more of the following:
67 * {@code 'r'} for read permission, {@code 'w'} for write permission, and
68 * {@code 'x'} for execute permission. If <i>permissions</i> is omitted
69 * when assigned absolutely, then the permissions are cleared for
70 * the owner, group, or others as identified by <i>who</i>. When omitted
71 * when adding or removing then the expression is ignored.
72 *
73 * <p> The following examples demonstrate possible values for the {@code
74 * exprs} parameter:
75 *
76 * <table border="0">
77 * <tr>
78 * <td> {@code u=rw} </td>
79 * <td> Sets the owner permissions to be read and write. </td>
80 * </tr>
81 * <tr>
82 * <td> {@code ug+w} </td>
83 * <td> Sets the owner write and group write permissions. </td>
84 * </tr>
85 * <tr>
86 * <td> {@code u+w,o-rwx} </td>
87 * <td> Sets the owner write, and removes the others read, others write
88 * and others execute permissions. </td>
89 * </tr>
90 * <tr>
91 * <td> {@code o=} </td>
92 * <td> Sets the others permission to none (others read, others write and
93 * others execute permissions are removed if set) </td>
94 * </tr>
95 * </table>
96 *
97 * @param exprs
98 * List of one or more <em>symbolic mode expressions</em>
99 *
100 * @return A {@code Changer} that may be used to changer a set of
101 * file permissions
102 *
103 * @throws IllegalArgumentException
104 * If the value of the {@code exprs} parameter is invalid
105 */
106 public static Changer compile(String exprs) {
107 // minimum is who and operator (u= for example)
108 if (exprs.length() < 2)
109 throw new IllegalArgumentException("Invalid mode");
110
111 // permissions that the changer will add or remove
112 final Set<PosixFilePermission> toAdd = new HashSet<PosixFilePermission>();
113 final Set<PosixFilePermission> toRemove = new HashSet<PosixFilePermission>();
114
115 // iterate over each of expression modes
116 for (String expr: exprs.split(",")) {
117 // minimum of who and operator
118 if (expr.length() < 2)
119 throw new IllegalArgumentException("Invalid mode");
120
121 int pos = 0;
122
123 // who
124 boolean u = false;
125 boolean g = false;
126 boolean o = false;
127 boolean done = false;
128 for (;;) {
129 switch (expr.charAt(pos)) {
130 case 'u' : u = true; break;
131 case 'g' : g = true; break;
132 case 'o' : o = true; break;
133 case 'a' : u = true; g = true; o = true; break;
134 default : done = true;
135 }
136 if (done)
137 break;
138 pos++;
139 }
140 if (!u && !g && !o)
141 throw new IllegalArgumentException("Invalid mode");
142
143 // get operator and permissions
144 char op = expr.charAt(pos++);
145 String mask = (expr.length() == pos) ? "" : expr.substring(pos);
146
147 // operator
148 boolean add = (op == '+');
149 boolean remove = (op == '-');
150 boolean assign = (op == '=');
151 if (!add && !remove && !assign)
152 throw new IllegalArgumentException("Invalid mode");
153
154 // who= means remove all
155 if (assign && mask.length() == 0) {
156 assign = false;
157 remove = true;
158 mask = "rwx";
159 }
160
161 // permissions
162 boolean r = false;
163 boolean w = false;
164 boolean x = false;
165 for (int i=0; i<mask.length(); i++) {
166 switch (mask.charAt(i)) {
167 case 'r' : r = true; break;
168 case 'w' : w = true; break;
169 case 'x' : x = true; break;
170 default:
171 throw new IllegalArgumentException("Invalid mode");
172 }
173 }
174
175 // update permissions set
176 if (add) {
177 if (u) {
178 if (r) toAdd.add(OWNER_READ);
179 if (w) toAdd.add(OWNER_WRITE);
180 if (x) toAdd.add(OWNER_EXECUTE);
181 }
182 if (g) {
183 if (r) toAdd.add(GROUP_READ);
184 if (w) toAdd.add(GROUP_WRITE);
185 if (x) toAdd.add(GROUP_EXECUTE);
186 }
187 if (o) {
188 if (r) toAdd.add(OTHERS_READ);
189 if (w) toAdd.add(OTHERS_WRITE);
190 if (x) toAdd.add(OTHERS_EXECUTE);
191 }
192 }
193 if (remove) {
194 if (u) {
195 if (r) toRemove.add(OWNER_READ);
196 if (w) toRemove.add(OWNER_WRITE);
197 if (x) toRemove.add(OWNER_EXECUTE);
198 }
199 if (g) {
200 if (r) toRemove.add(GROUP_READ);
201 if (w) toRemove.add(GROUP_WRITE);
202 if (x) toRemove.add(GROUP_EXECUTE);
203 }
204 if (o) {
205 if (r) toRemove.add(OTHERS_READ);
206 if (w) toRemove.add(OTHERS_WRITE);
207 if (x) toRemove.add(OTHERS_EXECUTE);
208 }
209 }
210 if (assign) {
211 if (u) {
212 if (r) toAdd.add(OWNER_READ);
213 else toRemove.add(OWNER_READ);
214 if (w) toAdd.add(OWNER_WRITE);
215 else toRemove.add(OWNER_WRITE);
216 if (x) toAdd.add(OWNER_EXECUTE);
217 else toRemove.add(OWNER_EXECUTE);
218 }
219 if (g) {
220 if (r) toAdd.add(GROUP_READ);
221 else toRemove.add(GROUP_READ);
222 if (w) toAdd.add(GROUP_WRITE);
223 else toRemove.add(GROUP_WRITE);
224 if (x) toAdd.add(GROUP_EXECUTE);
225 else toRemove.add(GROUP_EXECUTE);
226 }
227 if (o) {
228 if (r) toAdd.add(OTHERS_READ);
229 else toRemove.add(OTHERS_READ);
230 if (w) toAdd.add(OTHERS_WRITE);
231 else toRemove.add(OTHERS_WRITE);
232 if (x) toAdd.add(OTHERS_EXECUTE);
233 else toRemove.add(OTHERS_EXECUTE);
234 }
235 }
236 }
237
238 // return changer
239 return new Changer() {
240 @Override
241 public Set<PosixFilePermission> change(Set<PosixFilePermission> perms) {
242 perms.addAll(toAdd);
243 perms.removeAll(toRemove);
244 return perms;
245 }
246 };
247 }
248
249 /**
250 * A task that <i>changes</i> a set of {@link PosixFilePermission} elements.
251 */
252 public interface Changer {
253 /**
254 * Applies the changes to the given set of permissions.
255 *
256 * @param perms
257 * The set of permissions to change
258 *
259 * @return The {@code perms} parameter
260 */
261 Set<PosixFilePermission> change(Set<PosixFilePermission> perms);
262 }
263
264 /**
265 * Changes the permissions of the file using the given Changer.
266 */
267 static void chmod(Path file, Changer changer) {
268 try {
269 Set<PosixFilePermission> perms = Files.getPosixFilePermissions(file);
270 Files.setPosixFilePermissions(file, changer.change(perms));
271 } catch (IOException x) {
272 System.err.println(x);
273 }
274 }
275
276 /**
277 * Changes the permission of each file and directory visited
278 */
279 static class TreeVisitor implements FileVisitor<Path> {
280 private final Changer changer;
281
282 TreeVisitor(Changer changer) {
283 this.changer = changer;
284 }
285
286 @Override
287 public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
288 chmod(dir, changer);
289 return CONTINUE;
290 }
291
292 @Override
293 public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
294 chmod(file, changer);
295 return CONTINUE;
296 }
297
298 @Override
299 public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
300 if (exc != null)
301 System.err.println("WARNING: " + exc);
302 return CONTINUE;
303 }
304
305 @Override
306 public FileVisitResult visitFileFailed(Path file, IOException exc) {
307 System.err.println("WARNING: " + exc);
308 return CONTINUE;
309 }
310 }
311
312 static void usage() {
313 System.err.println("java Chmod [-R] symbolic-mode-list file...");
314 System.exit(-1);
315 }
316
317 public static void main(String[] args) throws IOException {
318 if (args.length < 2)
319 usage();
320 int argi = 0;
321 int maxDepth = 0;
322 if (args[argi].equals("-R")) {
323 if (args.length < 3)
324 usage();
325 argi++;
326 maxDepth = Integer.MAX_VALUE;
327 }
328
329 // compile the symbolic mode expressions
330 Changer changer = compile(args[argi++]);
331 TreeVisitor visitor = new TreeVisitor(changer);
332
333 Set<FileVisitOption> opts = Collections.emptySet();
334 while (argi < args.length) {
335 Path file = Paths.get(args[argi]);
336 Files.walkFileTree(file, opts, maxDepth, visitor);
337 argi++;
338 }
339 }
340 }