1 /*
2 * Copyright (c) 2007, 2011, 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.nio.file.attribute;
27
28 import static java.nio.file.attribute.PosixFilePermission.*;
29 import java.util.*;
30
31 /**
32 * This class consists exclusively of static methods that operate on sets of
33 * {@link PosixFilePermission} objects.
34 *
35 * @since 1.7
36 */
37
38 public final class PosixFilePermissions {
39 private PosixFilePermissions() { }
40
41 // Write string representation of permission bits to {@code sb}.
42 private static void writeBits(StringBuilder sb, boolean r, boolean w, boolean x) {
43 if (r) {
44 sb.append('r');
45 } else {
46 sb.append('-');
47 }
48 if (w) {
49 sb.append('w');
50 } else {
51 sb.append('-');
52 }
53 if (x) {
54 sb.append('x');
55 } else {
56 sb.append('-');
57 }
58 }
59
60 /**
61 * Returns the {@code String} representation of a set of permissions. It
62 * is guaranteed that the returned {@code String} can be parsed by the
63 * {@link #fromString} method.
64 *
65 * <p> If the set contains {@code null} or elements that are not of type
66 * {@code PosixFilePermission} then these elements are ignored.
67 *
68 * @param perms
69 * the set of permissions
70 *
71 * @return the string representation of the permission set
72 */
73 public static String toString(Set<PosixFilePermission> perms) {
74 StringBuilder sb = new StringBuilder(9);
75 writeBits(sb, perms.contains(OWNER_READ), perms.contains(OWNER_WRITE),
76 perms.contains(OWNER_EXECUTE));
77 writeBits(sb, perms.contains(GROUP_READ), perms.contains(GROUP_WRITE),
78 perms.contains(GROUP_EXECUTE));
79 writeBits(sb, perms.contains(OTHERS_READ), perms.contains(OTHERS_WRITE),
80 perms.contains(OTHERS_EXECUTE));
81 return sb.toString();
82 }
83
84 private static boolean isSet(char c, char setValue) {
85 if (c == setValue)
86 return true;
87 if (c == '-')
88 return false;
89 throw new IllegalArgumentException("Invalid mode");
90 }
91 private static boolean isR(char c) { return isSet(c, 'r'); }
92 private static boolean isW(char c) { return isSet(c, 'w'); }
93 private static boolean isX(char c) { return isSet(c, 'x'); }
94
95 /**
96 * Returns the set of permissions corresponding to a given {@code String}
97 * representation.
98 *
99 * <p> The {@code perms} parameter is a {@code String} representing the
100 * permissions. It has 9 characters that are interpreted as three sets of
101 * three. The first set refers to the owner's permissions; the next to the
102 * group permissions and the last to others. Within each set, the first
103 * character is {@code 'r'} to indicate permission to read, the second
104 * character is {@code 'w'} to indicate permission to write, and the third
105 * character is {@code 'x'} for execute permission. Where a permission is
106 * not set then the corresponding character is set to {@code '-'}.
107 *
108 * <p> <b>Usage Example:</b>
109 * Suppose we require the set of permissions that indicate the owner has read,
110 * write, and execute permissions, the group has read and execute permissions
111 * and others have none.
112 * <pre>
113 * Set<PosixFilePermission> perms = PosixFilePermissions.fromString("rwxr-x---");
114 * </pre>
115 *
116 * @param perms
117 * string representing a set of permissions
118 *
119 * @return the resulting set of permissions
120 *
121 * @throws IllegalArgumentException
122 * if the string cannot be converted to a set of permissions
123 *
124 * @see #toString(Set)
125 */
126 public static Set<PosixFilePermission> fromString(String perms) {
127 if (perms.length() != 9)
128 throw new IllegalArgumentException("Invalid mode");
129 Set<PosixFilePermission> result = EnumSet.noneOf(PosixFilePermission.class);
130 if (isR(perms.charAt(0))) result.add(OWNER_READ);
131 if (isW(perms.charAt(1))) result.add(OWNER_WRITE);
132 if (isX(perms.charAt(2))) result.add(OWNER_EXECUTE);
133 if (isR(perms.charAt(3))) result.add(GROUP_READ);
134 if (isW(perms.charAt(4))) result.add(GROUP_WRITE);
135 if (isX(perms.charAt(5))) result.add(GROUP_EXECUTE);
136 if (isR(perms.charAt(6))) result.add(OTHERS_READ);
137 if (isW(perms.charAt(7))) result.add(OTHERS_WRITE);
138 if (isX(perms.charAt(8))) result.add(OTHERS_EXECUTE);
139 return result;
140 }
141
142 /**
143 * Creates a {@link FileAttribute}, encapsulating a copy of the given file
144 * permissions, suitable for passing to the {@link java.nio.file.Files#createFile
145 * createFile} or {@link java.nio.file.Files#createDirectory createDirectory}
146 * methods.
147 *
148 * @param perms
149 * the set of permissions
150 *
151 * @return an attribute encapsulating the given file permissions with
152 * {@link FileAttribute#name name} {@code "posix:permissions"}
153 *
154 * @throws ClassCastException
155 * if the set contains elements that are not of type {@code
156 * PosixFilePermission}
157 */
158 public static FileAttribute<Set<PosixFilePermission>>
159 asFileAttribute(Set<PosixFilePermission> perms)
160 {
161 // copy set and check for nulls (CCE will be thrown if an element is not
162 // a PosixFilePermission)
163 perms = new HashSet<>(perms);
164 for (PosixFilePermission p: perms) {
165 if (p == null)
166 throw new NullPointerException();
167 }
168 final Set<PosixFilePermission> value = perms;
169 return new FileAttribute<>() {
170 @Override
171 public String name() {
172 return "posix:permissions";
173 }
174 @Override
175 public Set<PosixFilePermission> value() {
176 return Collections.unmodifiableSet(value);
177 }
178 };
179 }
180 }